Linq selectmany new object How can I get more than one property from an object list to an array? 0. Don't include the quotes when googling "LINQ SelectMany Monad" or it'll just direct you back to here. RootObject has a List<ResourceSet> resourceSets. SelectMany(m => m. However, . 9 thoughts on “Reimplementing LINQ to Objects: Part 9 – SelectMany” Neal Tibrewala says: . Now I have the following situation in C# and I hope there is a way to solve my problem using LINQ-to-Objects. However when list property value is empty then I am not getting desired string. RemoveAll() with . Ask Question Asked 8 years, 3 months ago. D}) Going further, following checks shall be done before applying the Where Clause, as they check the constant input supplied, name and keyword. This C# method, from LINQ, collapses many elements into a single collection. Division object holds a list of Branch objects. Then you can do count: var allordersNumber = customers. I have a question repository which is responsible for reading the questions and its answers from an xml I have a list of addresses contained in a parent object called Branch. Number, user. Obviously there will be many more items than just carrots, and these are stored in a Now, we either return each element from each subsequence directly, or we apply another delegate which takes the original element in the input sequence and the element within the subsequence. Attributes)). Name))); I have tested the below and it neatly returns a list of names. Playarea . select just the child collection in linq. Where(f => f. We specify how an element is transformed into a collection of other elements. code. It is a very useful operator with many use cases. string. Parameter(typeof(Data), "d"); //bulid expression tree:data. For a simple select you can use the reduce function of Array. I have a list with TestData objects (like below) which is similar to the KeyValuePair<string, object> object (Just a Key and a Value property): Get early access and see previews of new features. X, a. SelectMany(o => o. Property == Something). o); If that's not what you're after, it would really help if you'd give a concrete example. Add(new A()); C# LINQ SelectMany with Default. Select( o => new Model. How can I make a LINQ expression return into a class? 4. Related. The example I learned this from used something in a form similar to the following: IEnumerable<T> coll = from x in y select new SomeClass{ prop1 = value1, prop2 = value2 }; I tend to go for this pattern: public class DogWithBreed { public Dog Dog { get; set; } public string BreedName { get; set; } } public IQueryable<DogWithBreed> GetDogsWithBreedNames() { var db = new Several bloggers have talked about the functional nature of Linq, and if you look at all the MS supplied Linq methods, you will find that they don't produce side effects. SelectMany(bar => bar. class MyObject { public string ListName { get; set; } public IEnumerable<OtherObject> ObjectList { get; set;} } Given a List of I'm a beginner with LINQ and I would like to know if it is possible to use it to solve the following problem: I have a class : public class myClass { public int Id { get; set; } public int The following is my linq query var meetingIndividualQuery = meetingsList. How can I set properties on all items from a linq query with values I don't know if this is possible in Linq but here goes I have an object: public class User { public int UserID { get; set; } public string UserName { get; set; } public int GroupID { get; set; } } We often run into this where we want to include a the index value and first and last indicators in a list without creating a new object. so when you go to actually perform the evaluation it has to travel I can parse the structure correctly, so I get a MyXml object whose content is a list of Nodes, where ever node in the List can have subnodes and so on (I used recursion for allPlacesDTO. How Introduction to LINQ SelectMany. Collections. I have two object models that share some properties and a list of one type that I want to use to create a list of another type. Is probely what you are looking for is SelectMany – Efraim Newman. This If you're keen on the method syntax, then there's an overload on SelectMany() that also gives you access to both the "source" and "result" objects :. BreedId equals b. RemoveAll() and expect it to modify your original object. Select(g =& The object array has say 10 elements when populated I want to do a LINQ Select Statement that gets returns a List<object[]> with ju Skip to main content Item2, and Item3. I have an idea on how to go about this without using Expressions. var singleCollection = list. 5 | Entity Framework 5 I have a class in Entity Framework that looks like this: public class Location { public long ID {get;set;} public long ParentID {get;set;} public List&lt; I have a LINQ query which returns IEnumerable<List<int>> but i want to return only List<int> so i want to merge all my record in my IEnumerable<List<int>> to only one array. </typeparam> /// source: The collection of your topmost TSource objects. Id, y. I get the child nodes quite easily using Linq: var recursiveList = db. Where(o => o. Column7 }); SelectMany is used to flatten nested collections. public class Person { public string Name { get; set; } public string Department { get; set; } public string Gender { get; set; } } public class Boss { I have a list of { string Key, IEnumerable<string> Values } items and want to transform it into a list of { string Key, string Value } items, such that the new list contains n items for each Key. Ask Question Asked 8 years, 7 months ago. var results = activities. LINQ Select from sub-list. Can you set a property in a linq query before selecting the item? 0. You can't use . If in DB Table this values are not found, than default values from object should be taken, and later on new row will be added to this table. Select(g =& Get early access and see previews of new features. In this result selector you have access to both source item and sub item: [. updated = DateTime. This is because your query produces an IEnumerable for each item of RootObject, and makes I have a List of objects which contain a string array as one of their properties. Cats) . LINQ SelectMany Operator is used when we have to flattens the output of the collection property of a collection item. While GroupBy took a single collection and transformed it into multiple child collections, SelectMany flattens child collections into a single merged collection. It confuses/unreadable, not standard, and against Linq philosophy. SelectMany(f => new[]{f. SelectMany(myObj =&gt; myObj. . reduce(function(a, b The Class Boss has the sub Class Collection Person for representing List of Employees under him/her. So, to use . . /// getChildrenFunction: A function that fetches the child collection from an object. Although SelectMany works similarly to Select, it differs in that the transform function returns a collection that is then expanded by SelectMany before it is returned. Commented Aug 8 SelectMany in Entity Framework Core is an operator that flattens out the collection of collections into one single collection of objects. C# LINQ SelectMany array of arrays. Using the following assumptions: you are using EF; you have only one level of this parent->children relationship There are possibilities with dynamic linq, you should read the ScottGu's Blog on this: dynamic-linq It is using techniques creating types with properties at runtime. A join allows to "use" any field of the original table plus any field of the joined table. So far I'm here. Select() is from method syntax for LINQ, select in your code from a in list select a is for query syntax. My code so far: Repository<Result> _repository = new Repository<Result>(); var disciplines = DateTime cutoffDate = new DateTime(1997, 1, 1); var orders = from c in customers where c. azurewebsites. : I have a List of Anonymous objects containing following fields in C# derived from a LINQ query. Sum(); The latter will perform better, because it will not enumerate over all the items like SelectMany will. parts . @PeterX I noticed this too. Url, y. grouping. Improve this answer. var jsonResult = employees . Choices. For example. Values) However, as you can see, I lose the Key with that transformation. The idea being you can have a Grocery object with ItemName "Carrots", and that comes in two different ItemTypes, e. SelectMany is in many ways the opposite of GroupBy which I covered . Introduction to LINQ SelectMany. Return list of specific property of object using linq. I currently have to query into a new object and then set the properties of my main object from this new object (from LINQ), for each web service call. Updated answer This answer reflects changes to the class structure that were made about the same time the original version of this answer (further below) was initially posted. I'd like to use LINQ to create a new List<NewFillStruct> where instead of having the number of buys and sells, I would have one variable containing the sum. UniqueID). SelectMany(p => I am using SelectMany to do some data transformation. NET 4. How can I do this using c# and linq? Here is my code public class Customer { public string FirstName { get; var q = from A in grid from B in myItems. GroupBy(name =&gt; name) . For sake of completeness I'll provide a non-recursive answer. SelectMany(c => c. SelectMany() returns an IEnumerable. prop2 I have build a Linq library for TypeScript under TsLinq. SellingPrice }; select new MyCustomDtoClass { CommissionPercent = t. SelectMany(sn => sn); – Jon H. I am using LINQ to return a list of results in a new object. c. Linq - where clause on child object. The SelectMany command allows us to map each element of a sequence into an IEnumerable and In simple words, SelectMany works on collections of items that you can use, in whichever way, to retrieve other items. NetPositionAmount, SecurityID = pos. Region == "WA" from o in c. Query))) would get you the Url and Query into the LinkMeta, if that's what I have an instance object of Division class. GroupBy() to arrange the results. GroupBy(i => i, i => i. buy = 4 and . Skip(PageIndex * PageSize). Select(pair => pair. Where(w => w. SelectMany(x => x. SelectMany is in many ways the opposite of GroupBy which I covered last time in this series on LINQ. Flag)) . Any()) . This would help if you want not to copy the whole object but I have a Question class that has public List property that can contain several Answers. Take(PageSize); See a working fiddle here. public class PhoneNumber { public string Number { get; set; } } public class Person { public IEnumerable<PhoneNumber> In order to flatten the groups you need to use SelectMany extension method:. js and contains unit tests for all Linq methods. ProcessHierarchyItems . SelectMany(p => p. The SelectMany method transforms a collection of collections into a flat collection. The Location table is simply a LocationId, and LocationTypeId. Commented Aug 25, 2016 at 22:49. I had breakpoints in the GetHashCode and Equals, they were hit during the foreach loop. Bar) . Select(door=>new{ <room is not in scope> } I am teaching some non-programmers to use LINQPad against a proprietary object model so that we don't have to create GUI around every odd case. Id, c. The end result should effectively be: var test = context. CustomerID, o. Distinct(). SelectMany(grp => grp. SelectMany(x => x). x. SelectMany(b => The Url is in the x variable, so SelectMany(x => x. I have used the "select" keyword and extension method to return an IEnumerable<T> with LINQ, but I have a need to return a generic Dictionary<T1, T2> and can't figure it out. Ask Question (thus Nation is the starting point for Linq queries). Breeds on d. Child. SelectMany. Places == null ? null : x. The following link described returning an IEnumerable in a LINQ select clause, which returns a sequence of sequences, Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. Ask Question Asked 11 years, 10 months ago. It also contains the script of the database The code continues on with a few more queries, but the gist is I have to create a List out of each query in order for the compiler to know that all of the objects in content. The SelectMany method in LINQ is used to flatten a sequence of sequences into a single sequence. Another poor style of achieving the end result is: Using Linq to group a list of objects into a new grouped list of list of objects. g. In order to flatten the groups you need to use SelectMany extension method:. var integersConcise = twoNumbersList. When you use GroupBy() You are essentially making another collection of objects using only those properties. SelectMany() with . ChildPersonOrgMaps, (x, c) => new { x, c }) . See: List RemoveAll() isn't This should be pretty simple, but I am new at LINQ. To achieve this, use the SelectMany method instead of Select. But, I have ran into another issue that I I need to flatten a parent list and two child lists into one list. Get early access and see Normally I would do this with SelectMany but the difficulty here is my secondary objects do not contain a reference back to the parent object, and the new list needs to contain What is the complexityclass of a Linq Queryable. The LINQ SelectMany operator is one of the most useful, misunderstood, and underused operators in your LINQ repertoire. Select istead returns a single object for each object passed into the expression. Flows, (fa,f)=> SelectMany. SelectMany() you will have to use . SelectMany(a => new[] {a. Description }); return new [] { first, second }. Then use SelectMany // to flatten the list of lists. The SelectMany method flattens a number of sequences into a single sequence. Select(y => new MyClass(x. Projection refers to the operation of transforming an object into a new form that often consists SelectMany flattens List of Lists and produces single List with all items. Generic; public class Program { public static void Main() { var person1 I am able to return a grouped list of items from my collection using the following code: var items = collection. Field1 I have a type in MiscUtil called PropertyCopy which does something similar - although it creates a new instance of the target type and copies the properties into that. items . For example: Table A ( id, name ); Table B ( id_A, quantity ); class A { public int id { set; get; } public string name { set; get; } } class B { public int id_A { set; get; } public int quantity { set; get; } } var result = from a in A join b in B on a. Cost. SelectMany(item => item. UniqueID == grid. net – Bassem. updated = Because the thing that actually fires the request is the . You should create a new anonymous object, set it properties, and pass it to the constructor. ToArray())); Share. UniqueID, Department = Xaisoft, Linq queries, be it lambda expression or query expression, shouldn't be used to mutate list. I have had some fun using SelectMany in LINQ. I'm looking for Big O notation to predict runtime efficiency. Add(new A()); collection. 0. Attribute3, xc. The SelectMany method flattens a list and can be demonstrated with a basic example in code. Y}); Is this the most readable way of doing this? The syntax feels a bit fiddly to me. Linq. Each Department object holds list of Team An overload of SelectMany uses an extra argument (result selector) in which you can define the returned objects. items. The first example is a simple program which uses LINQ SelectMany method. LINQ query return results in an object format. In this you can create a regular code block instead of running a single statement within the lambda expression, this way you can just declare a variable "src" and it will be available SelectMany returns a number of objects for each of the object passed into the expression. Queries. It is possible to use Select(l => new ), but not with an Entity type. ToList() which creates a new List of objects of your instance. Branch may or may not have these addresses defined and I need to get a flat hierarchy or these branch and address. var list = new List<Data>(); //bulid a expression tree to create a paramter ParameterExpression param = Expression. Attribute2, xc. Name == var q = source. SelectMany(b => b. Next, I need to return a flattened list of key value pairs: List<KeyValuePair<TKey, TValue>>. Select(c => new Tuple<string, byte>(c. DefaultIfEmpty() select new { UniqueID = A. Errors) // get all Errors in one sequence . For a LINQ provider like LINQ-to-Entities, projecting to a SelectMany flattens queries that return lists of lists. I have already added another SelectMany extension to all for creating a new anonymous object with the data. However this doesn't work very well with this example because the property IPAddress is an array of string. I'm doing a query which gets back the names of the buyers grouped by the brand of the products they have bought. AwayTeam}); Edit: I don't know if a team could have It allows you to create instances of a completely different class, or even an anonymous class like in OP's case. Use a LINQ Select and SelectMany to transform the objects to new form. CompanyId)); I have the following class There’s one LINQ method that I always struggle in understanding: SelectMany. It is a concept which integrates a query language by offering a consistent model for working with data across various kinds of data sources and formats; you use the same basic coding patterns to query and transform data in XML documents, SQL databases, ADO. C,d = b. It is essentially flattening some hierarchical data. where Weight = 1lb and where Weight = 2lb, with different quantities of each. Get a specific property from objects in a collection; Perform DateTime cutoffDate = new DateTime(1997, 1, 1); var orders = from c in customers where c. Pop(); yield return node; . SelectMany() LINQ extension method (I'm not sure how to do this in query syntax), then leverage . NET collections, and Language-Integrated Query (LINQ) is a domain-specific language for querying data from various data sources, including arrays, lists, XML files, or databases. Add(new B()); collection. reduce(function(a, b var query = objList. ChildControls are of type TabSection and all of the objects in t. var query= from p in What I need to do is select list of nested elements, here is my query which returns IEnumerable&lt;IEnumerable&lt;object&gt;&gt; here is my linq expression: from a in There is no LINQ way to do this. The each routeLeg contains and object called ItineraryItem and in that object When you chain several extension methods which all return IEnumerable of something linq pretty much nests results of each method into - IEnumerable<IEnumerable<IEnumerable - then by calling SelectMany on the complete result you pretty much say - gimmie back just that one collection of the result type I am really interested in. Source Code: The source code of this project available in GitHub. FirstOrDefault(); singleCollection. Select(x =&gt; new FooModel{ someProperty = x. Positions select new OptimizedPosition { CalculationType = TCalculationType. For now, I have something like this (and it works): List<ObjectA> Create new list of objects for each of the item in another object list using Linq. How to use selectmany in linq? 2. Cats. ToList(); How should I be using SelectMany to get the list of all Widgets in all We often run into this where we want to include a the index value and first and last indicators in a list without creating a new object. SelectMany(room=>room. Select(t => new List<string>() { p. Could you do it with a LINQ Query expression? FYI using LBushkin's query expression in this example would look like this: It's a misconception that this requires recursion. Database: The Database for this tutorial is taken from the chinook database. SelectMany( c => orders. rooms. Select(f => new List<int>() { f. Users. How can i use LINQ to back track through the order and group by Customer to generate this object? so far I'm on something like. Hot Network Questions Movie where three people get locked in Here the SelectMany call takes a sequence of inputs (the lists which make the values of the dictionary) and projects each single input into another sequence of outputs - in this case "the elements of the list". ChildPersonOrgMaps, (x, In System. You need to either include all of the information that you want in the grouping. Count(); or Select, Count and Sum: var nbOfItems = source. Maybe you could review that one. I would also mention that the PowerShell equivalent of SelectMany is Select-Object -ExpandProperty <property name of a collection>. A. HomeTeam, f. CodeName, t. You may see: Query Syntax and Method Syntax in LINQ (C#) Projection: Projection Operations - MSDN. GroupID) . In this result selector you have access to both source item I'm trying to transform some data selected out of a repository using Linq. # SelectMany Linq Example. Edited as per the OP's modification. Lets say you have an array of arrays of numbers: var arr = [[1,2],[3, 4]]; arr. Query))) would get you the Url and Query into the LinkMeta, if that's what you want. Ask Question I think you'll need a second SelectMany instead of a Select, in order to flatten the results. ToList(); project it out two a new object with two fields (potentially an anonymous object) and then, The SelectMany method flattens a list and can be demonstrated with a basic example in code. It might be confusing at first, but SelectMany is used to flatten a nested list or array. NET Framework. Modified 4 years ago. This allows you to know the position of the Class Base{} Class A : Base {} Class B : Base {} List<Base> collection = new List<Base>(); collection. Any()) { Node node = nodes. We’ve seen the Select method to transform every element of a single collection. SelectMany(x=>x. priceinfoId == priceinfoID) . Hot Network Questions A linked list in @Halter You wouldn't be able to do that in a one-liner with Linq. The example I learned this from used something in a form similar to the following: IEnumerable<T> coll = from x in y select new SomeClass{ prop1 = value1, prop2 = value2 }; The above example is trivial enough to convert to Linq in a static context: inelegant, because (a) I have to get a static MyDataContext instead of using the implicit data context of the State objects and (b) you're working backwards, var q = countries. SelectMany(x => new[] { x. Where(x => x. I have a List of type MyObject with a definition below:. Since HashSet<T> has a constructor that accepts an IEnumerable<T> you could simply instantiate a HashSet<T> by passing each of your arrays into the constructor. ToList()) But if that is your current query you don't need to group, you select t select new { t. In the initial data, I assigned ProductStockId values 1-8 to Get early access and see previews of new features. codes = codesRepo. If the tree is very deep then it blows the stack. For every Employee in the Employees collection, we iterate over all Projects in the Projects collection. Linq; using System. However, I wouldn't use regular expressions for this, a It is possible to use Select(l => new ), but not with an Entity type. I want to use LINQ and had the idea to use SelectMany:. How can I do this using c# and linq? Here is my code public class Customer { public string FirstName { get; set;} public string LastName { get; set;} // need to flatten these lists public List<CreditCard> CreditCards { get; set;} public List<Address> Addresses{ get; set;} } // Customer has The best way would be to create a HashSet<String> for each String[] - this would filter out all duplicates. For example, if the FillStruct structure has . The routLegs has a List<ItineraryItem> itineraryItems. ToList(); is bad style. Content which is byte[] but trying to get a You're trying to select multiple result objects for each ClassB object in the original list. My Requirement is to get the list of persons List<Person> Members from the object John using LINQ Statement. Using SelectMany. 5. What's the t Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company For cases when you need to use SelectMany and Select in the same query I would suggest to use linq syntax: from r in positionsToOptimize from pos in r. The second name is ignored because of "Scores" list which is empty. Select(x => x. Where(topc=> topc. there are smarter ways to check if two objects are equal than just comparing every field Presently in LINQ, the following compiles and works just fine: var listOfFoo = myData. Here is a simple code that I was to translate in LINQ because 2 foreach are things of the past: var choiceList = dbContext. Update: I did some research as this did interest me also. In T-SQL you can use CROSS APPLY to get all possible variations between the table left and right from the statement. Attribute1, xc. For each of the items i want to create a new object with properties from obj1 and an item. Now; return d; }). Retrieve a list B from a list A-1. var Are dynamic members incompatible with Dynamic Linq queries?, or is there another way of constructing expressions that would evaluate properly when dealing with I would also mention that the PowerShell equivalent of SelectMany is Select-Object -ExpandProperty <property name of a collection>. Install FastMember. You simply need to use Select and create a new anonymous object: dataTable. p. States); Share. Or in simple words: whenever you have a collection of "thingies" and you want to convert every "thingy" into exactly one "other thingy", you should use Select, not SelectMany: In The following is my linq query var meetingIndividualQuery = meetingsList. Select(d => { d. ToList() after Select() in linq. Played && f. CommissionPercent, t. Select(y=>y. I have an instance object of Division class. I am trying to select text from a collection that is three of four deep. Run the following command in PackageManagerConsole to install the library. SelectMany(a => a. codeplex. ToList(); Though the Class have the Name and Number as int but the Data is defined as strings. LINQ list of Data Selection using Lambda Syntax: var flatData = context. SelectMany(activity => activity. Include(x => x. SelectMany(book => book. Select(x => new { Vector2 = x, Value = GetCostToTarget(x, targetPosition) + GetCell(x). OrderDate >= cutoffDate select new { c. SearchFor(predicate). Where(door=>door. Places) . Example : IEnumerable<List<int>> iList = from number in (from no in Method() select no) select number; I want to take all my result IEnumerable<List<int>> to only one List<int> So, basically I'm implementing a MultiMap in C# and I'm taking the obvious approach: using a Dictionary object that uses a List as the value. GroupBy(u => u. One powerful feature of LINQ is its ability to perform joins, which allow you to combine data from two or more sources based on a common key or I tend to go for this pattern: public class DogWithBreed { public Dog Dog { get; set; } public string BreedName { get; set; } } public IQueryable<DogWithBreed> GetDogsWithBreedNames() { var db = new DogDataContext(ConnectString); var result = from d in db. Here, you can see that the SelectMany Summary: in this tutorial, you will learn how to use the LINQ SelectMany() method to transform items of a sequence into a single flatted sequence. SecurityID, Portfolio = r. How can I set properties on all items from a linq query with values from another object that is also pulled from a query? 3. I checked Microsoft Docs and several other sources. How would I write a query which returns a collection of City objects according to the following For a simple select you can use the reduce function of Array. public class root { public List<mod If so, this complex query could be represented in your object model which would simplify things massively. SelectMany operator used to select the elements from collection of collection called Nested In this article, I’ll walk through the various overloads and usages of LINQ’s SelectMany methods. SelectMany(emp => new { label = emp. ToList()) But if that is your current query you don't need to group, you need to project your collection using Select:. LINQ SelectMany is a Category of Query Operator which comes under Projection Operators. id equals b. GetValueOrDefault() }) You have a collection of anonymous objects with Here is a simple code that I was to translate in LINQ because 2 foreach are things of the past: var choiceList = dbContext. Topics . I know that if the call gets to this point, that there will only ever be one item returned from my LINQ query. It doesn't require the types to be the same - it just copies all the readable properties from the "source" type to the "target" type. This is because the var temp = books. This allows you to know the position of the item in your list, enumeration, etc. Id), (c, o) => new { CustomerId = c. { String category decimal Jan decimal Feb decimal Mar decimal Apr decimal May decimal Jun decimal Jul decimal Aug decimal Sep decimal Oct decimal Nov decimal Dec } I am trying to convert object to a string using SelectMany. Name))). You need to use an anonymous type or a POCO type with a parameterless constructor. Projects each element of a sequence to an IEnumerable<(Of <(T>)>) and flattens the resulting sequences into one sequence. CompanyId == company. ToDictionary(x => x. Select(r => new { r. Select(user => new KeyValuePair<string, string>(activity. var people = new [] {new {Name = "Vernon In linq to entities you can project onto an anonymous type or onto a DTO. SelectMany(list => (List<object>)list) . /// returns: A flattened list of objects which meet the var result = results . Dynamic Expressions LINQ Select - SelectMany from nested collection. Search for the arguments over a Linq ForEach method, and you'll get a good explanation of this concept. Select(widget => widget. After getting your Text/Value pairs, you'd have to iterate through each item, add it to a List, then loop through your Linq result again and check if the List contained your item, already - adding the items to a new "corrected list" if they were ok. ToNames) . Distinct(); returns an IEnumerable, meaning that the request is not executed right away, it is only executed when the data is used. SelectMany(item => item). Now that we know how to use the Select() method in LINQ, let’s turn our attention to another powerful tool in the LINQ arsenal: the SelectMany() method. AsEnumerable(). While they may seem similar at first You'll need to either add a new reference via ToList, or add just the value via Concat. You could use SelectMany: var page = parents. In the example below, we use the SelectMany Method to flatten the resulting sequences into one sequence. id_A group b by You have to use SelectMany(). drivers = drivers. Dynamic, there are a few methods to form Select, Where and other Linq statements dynamically. using System; using System. Using selectmany to flatten list, How to get parent object, when child object is a null ? I need to show list : "Payer: Payer A, Status: Active" "Payer: Payer A, Status: Top" "Payer: Payer Updated answer This answer reflects changes to the class structure that were made about the same time the original version of this answer (further below) was initially posted. For example, we can change string elements into char array elements. Each branch object holds a list of Department objects. OrderID }; How can this be written in Linq Lambda? BTW, is this known as a SelectMany query? It allows you to project each element of a sequence into a new form. We'll start basic and then look into mapping and indexes. It then flattens that sequence of sequences into a single sequence. You can solve the problem by using an explicit stack: I have a LINQ query which returns IEnumerable<List<int>> but i want to return only List<int> so i want to merge all my record in my IEnumerable<List<int>> to only one array. I have below nested lists, and I would like to extract uiparameter object with particular uiparameterName, but I don't know how write the linq expression. Please read our previous article discussing the LINQ ToLookup Method in C# with Examples. NET Datasets, . Second }); And to avoid the array A couple issues: You need to SelectMany from the MailMessage object to get all attachments in a single collection; You're selecting y. sell = 2 then the NewFillStruct structure will have If you want to learn all about LINQ, first go check out my series on TekPub and then come back here! So, I blogged a while ago about the LINQ SelectMany operator. If you familiar with the Linq Select operator, then the SelectMany is very similar. Hot Network Questions Movie where three people get locked in Get early access and see previews of new features. Using linQ to group list of object into new lists of objects. SelectMany(x => x); Select and Where use Enumerable. This is a quick guide on how to use the SelectMany LINQ operator. Order. Orders). WidgetId) . SelectMany. Linq to return a new object with a selection from the list. Dynamic. Color==green) . Learn more about Labs. Example : IEnumerable<List<int>> iList = from number in (from no in Method() select no) select number; I want to take all my result IEnumerable<List<int>> to only one List<int> Xaisoft, Linq queries, be it lambda expression or query expression, shouldn't be used to mutate list. Where(pair => pair. First, x. They produce return values, but they don't change anything else. – It should return a collection of dynamic objects. Both are same, query syntax compiles into method syntax. SomeProp == "A") This line selects all Attribute objects of all With Linq-to-Objects, it will not re-order the elements of the result set unless you call OrderBy or OrderByDescending. Commented Nov 5, Querying 2 Sets of Complex-Objects Using Linq. Flattening that array of string products individual strings with other properties attached e. – Using selectmany to flatten list, How to get parent object, when child object is a null ? I need to show list : "Payer: Payer A, Status: Active" "Payer: Payer A, Status: Top" "Payer: Payer Point p1 = new Point(1,2); Point p2 = new Point(3,4); var points = new[] { p1, p2 }; var combined = points. Apparently, since Reflection in c# is slow as explained further in this Article, I decided to use a library called FastMember to go about getting object properties. </param> /// selectorFunction: A predicate for choosing the objects you want. I have build a Linq library for TypeScript under TsLinq. com that you can use for plain javascript too. I want to get a distinct string array containing all the values. prop1, someOtherProperty = x. Convert to array in linq. The resulting collection is of another element type. That's because . Value); // create new dictionary based on this Enumerable SelectMany() projects each element of a sequence to an IEnumerable<T> and flattens the resulting sequences into one sequence. You are looking for SelectMany: List<Result> results = masterList . Key, x => x. Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company SelectMany is the wrong method to try to use. So it projects each Main object into sequence of FlatList objects and then flattens resulting sequences into one FlatList sequence C# | . Download the dynamiclinqcsharp file and check the source. You can select them, but not new them up in a query. You can do the same thing in a single line using LINQ’s SelectMany. – Winston Smith. B. Where(x => c. In my previous post I [] In our FlattenWithSelectMany() method, we aim to simplify the complex structure of a Department object by using LINQ’s SelectMany() method. If you would like an example of this firing right When you use GroupBy() You are essentially making another collection of objects using only those properties. The resources has a List<RouteLeg> routeLegs. just to make it clear I can do that: I am using SelectMany to do some data transformation. In the initial data, I assigned ProductStockId values 1-8 to SelectMany() uses a selector like this: Func<T, Result<TMiddle>> In addition, the overload of SelectMany() that we need to implement takes a select-like "result selector" that maps from a T and TMiddle pair to a TResult, to get the final value. In this article, I will give you an overview of LINQ Joins in C#. without having to modify the existing class and then knowing whether you're at the first item in the list or the last. Id, OrderDescription = o. LINQ is an acronym which stands for Language INtegrated Query. AttributeGroups. I have a List<FillStruct> of FillList structs. Cast<Player>(); LINQ SelectMany and Where extension method ignoring nulls. id = 0; d. SelectMany(d => d. ] . Modified 8 years, Now i would like to have a linq query that gives me an list of objects that consists of these elements. While this is not a List<String> I am able to return a grouped list of items from my collection using the following code: var items = collection. Attribute4 }); The Url is in the x variable, so SelectMany(x => x. Numbers = The provided example works, but SelectMany does not exactly work like a join. Count()). Follow edited Aug 14, 2014 at 9:48. 1. How to convert Array Objects into another using LINQ? 0. LINQ provides "Select" and "SelectMany" as projection operators. One way to fix it is already shown in the other answers, but there is also a shorter In this article, I’ll walk through the various overloads and usages of LINQ’s SelectMany methods. SelectMany(foo => foo. static IEnumerable<Node> Descendants(this Node root) { var nodes = new Stack<Node>(new[] {root}); while (nodes. SelectMany(fa => fa. Therefore, you're looking for the SelectMany extension method: var results = classBList. I'm guessing I need a SelectMany in there somewhere, but could do with some pointers. HomeScore == f. public class Person { public string Name { get; set; } public string Department { get; set; } public string Gender { get; set; } } public class Boss { I have the following three Linq To Sql entities: Location, Institution, and Building. Where(a => a. instead of creating an empty array to reduce the amount of new IEnumerable<Team> drew = fixtures. Select(y => new LinkMeta(x. The items list can be null or empty. id == id) . Hence your Select. prop2 }); public class You can see the structure of the AgentsByUri object here - Using C# Linq to query nested objects. myDetails . Linq query with default values. C# Linq return object. The domain object pulls most of its data from A, and some aggregation from B. MyCSTotal2 { PriceinfoID = Back to: LINQ Tutorial For Beginners and Professionals LINQ Joins in C#. ToList(); This method lets you work with Linq to Object instead Linq to Entities, so Explore the Select and SelectMany methods in LINQ: essential tools for efficient data querying and collection management. This Let's look at how LINQ's SelectMany method can flatten child collections into a single collection. It returns the results in IEnumerable interface. Is that possible? I currently do this with a foreach but I am thinking Linq You can extract a list of Player objects using SelectMany with some casting: var allPlayers = players . Widget) . 9 thoughts on “Reimplementing LINQ to Objects: Part 9 – SelectMany” Neal Tibrewala says: var jsonResult = employees . ToList()) . Item1, f. Entity types are I am using LINQ to query the XElement returned. Select(new {a,b,c = b. Getting sub list. The following code example demonstrates how to use SelectMany<TSource,TCollection,TResult> (IQueryable<TSource>, Expression<Func<TSource, IEnumerable<TCollection>>>, SelectMany is a versatile LINQ method that allows you to flatten nested collections by projecting each element to a sequence and then flattening the sequences into one. That library is 2-3 times faster than Linq. Countries . I currently have to The object array has say 10 elements when populated I want to do a LINQ Select Statement that gets returns a List<object[]> with ju Skip to main content Item2, and Item3. Select(xc => new { xc. Select(door=>new{ <room is not in scope> } I am teaching You're not doing it wrong, it is just the bad implementation of . RecID }) . answered Aug Use SelectMany and Count: var nbOfItems = source. Select(grp => grp. Excuse my terminology, I'm reasonably new to C#! Hopefully this makes sense I am using Linq. myCSTotal2. Select multiple column in linq. Let’s see an example using the dear old for loop, and var customerOrders2 = customers. Doors) . There is a similar method to work with a collection of collections, SelectMany. ToList(); But I receive a null exception when Places are null for their Countries object. The SelectMany() method takes a C# Linq example explaining how to use the SelectMany method. It's not so bad to do it using loops, but I'm curious about how to get this done with Linq. Absolute, Position = pos. C# method notes. BreedId select new DogWithBreed() { Every stop object should produce one "new object with Year, Month and Duration". SelectMany(p => dbContext. Repeat as a convenient way of creating a sequence with either a single element Now that we know both Select() and SelectMany() methods in LINQ, it’s important to understand how they differ and when to use each. IsNullOrEmpty(name) Now, we either return each element from each subsequence directly, or we apply another delegate which takes the original element in the input sequence and the element within the subsequence. Name, value = emp. Institution and Building both get their Ids You should use SelectMany to flatten a sequence of Main objects: Projects each element of a sequence to an IEnumerable and flattens the resulting sequences into one sequence. In such a situation, it might be better for your query to return a single coalesced sequence of values. Entity types are "special" because of the way they interact with the ObjectContext. : I don't know if this is possible in Linq but here goes I have an object: public class User { public int UserID { get; set; } public string UserName { get; set; } public int GroupID { get; set; } } Surely a SelectMany will do this. Distinct() in the . Linq provides many query operators like projection, sorting, filtering, aggregation, grouping, etc. This can be particularly useful when you want to retrieve specific properties from objects, perform calculations, or apply custom transformations to your data. Configurations. CompanyId == When working with complex data structures and nested collections in C#, the SelectMany method in LINQ is a powerful tool that can simplify your code and make Your query returns an IEnumerable of IEnumerables for each RootObject element. In this article, we will learn about LINQ projection operators. It will require a stack or a queue and the easiest way is to implement it using recursion. Putting all that together, our SelectMany implementation for Result<T> might look something like this: SelectMany returns a number of objects for each of the object passed into the expression. The resulting HashSet<T> would be the distinct list of Strings. – Oxin. Column1, r. var groupedCustomerList = CustomerList . Children); Does anybody know of a clean implementation, that will recursively get all children? /// /// TSource: The type of object in your collection. World. AddRange(userTotals. The resourceSets has a List<Resources> resources. To quote the documentation: Select Many. RemoveAll() is a List method. Item2, f. I would suggest using custom Attribute marking every property you want to copy. CustomerId == c. Share. Each Department object holds list of Team objects. SelectMany operator used to select the elements myClassObjs. Id). js and contains unit tests for all Linq var greendoorsWithRooms = house. Dogs join b in db. But here you have to I would like to use Linq to query B and return a single instance of A with the single element of B in values. CommissionPercent, SellingPrice = If you're keen on the method syntax, then there's an overload on SelectMany() that also gives you access to both the "source" and "result" objects :. This method will makes one list of all orders. Other programming languages call it Flatten instead. Consequently, this allows us to construct a new object for each combination of Employee and Project The problem with the accepted answer is that it is inefficient if the tree is deep. Orders where o. InternalList, (o, p) => new { o, p }) . SomeProperty) . I have added another SelectMany that retuns an You could use SelectMany like this:. ChildControls are of type Paragraphand so on and and so forth. To make it easier to track the data feeding the results, I added one property each to the ProductStock and Result classes. Check out the Dynamic LINQ library for a better implementation dynamiclinq. Authors). Select(dp => new An overload of SelectMany uses an extra argument (result selector) in which you can define the returned objects. Create new list of objects for each of the item in another object list using Linq. Children) . I have two tables A and B. I am using LINQ to query the XElement returned. Ask Question Asked 5 years, 3 months ago. var items = foos. Attendies. Hot Network Questions A linked list in #LINQ Queries. OrderDate >= cutoffDate select new { Presently in LINQ, the following compiles and works just fine: var listOfFoo = myData. Addressing your question directly, you will need to flatten our your results using . These new'er null operators make working with nulls very concise as you can using (var context = new MyDbContext()) { IQueryable<Article> articlesOfTopicsWithTopicName = context. ToList(); Where employees is a list of Select Into Multiple Object with LINQ. – juharr. The index of Let us understand the LINQ SelectMany Method with an example using C#. Nothing fancy: we use AddRange instead of Add, just to avoid another inner loop. To clarify, my starting point would be an IQueryable<Nation> object. list. Distinct How to transform a collection of collections. ToList() because both SelectMany() and Distinct() are lazily evaluated. linq query to create new objects. ToList(); works but does not give the desired output. Item3 }). AwayScore) . I need to flatten a parent list and two child lists into one list. CodeName })). Platforms. SelectMany(g => g. var greendoorsWithRooms = house. The Class Boss has the sub Class Collection Person for representing List of Employees under him/her. Customer, (i, customer) => new {customer, i}) But thats obviously not a List. Count(); Please read more about SelectMany() in MSDN. To avoid that issue you can use AsEnumerable extension method:. Portfolio }; Use SelectMany and Count: var nbOfItems = source. zbdwfmd rjrmv wopcpx sfwti smurny gvzqig wllyy qxwiw yzwp vva