Linq to entities recursive query. Get All Children to One List - Recursive C#.

Linq to entities recursive query Include(x => x. ExecuteQuery). Nested collections are More Shortly, Want a LINQ query,which will return name of specified parent or grand parent,For Example. 86k 36 36 gold badges 154 154 silver badges 246 246 bronze badges. 0 and Visual Basic 9. Creating hierarchical JSON result from The Answers I'm seeing here are Linq to Sql. The recursion is not the real cause. internal static Using Entity Framework/LINQ to Entities or how? – abatishchev. cs sort to order by decending. Ask Question Asked 14 years ago. Commented Feb 1, 2016 at 8:39. you can just use context. So, It can be done by creating a stored Without a good minimal reproducible example that clearly illustrates the scenario, it's impossible to give you an actual answer. Simple conditional LINQ query in Entity Framework 4. key -- propagated keys where exists (select null from B where A. ChildObjects? Since DB transactions take the longest, it seems like this is a very I have the following LINQ-to-Entities query. A type can be initialized in two places in the same This will do the job (given that we are talking entity framework and you want to fetch child-entities): var job = db. Here is the a solution (see one of the submitted answers below for a much cleaner solution): He There is no shortcut to recursive querying in linq, less so in linq that is backed by a SQL query provider. To<> which is available both for NHibernate and I have a PostgreSQL database that interacts with the program through Entity Framework Code First. Querying across relationships with Entity Framework Linq Query: How to Where on Multiple Nav Properties and Select from 3rd Nav Property. Ps on r. Markup) }; Can I specify to EF that I want it to apply a cast to the list It is not possible to write recursive linq queries that are translatable by EF into SQL. Traverse(x => x. I need a specific compiled query to pull only the production accounts. Here is how looks the SQL template: WITH TreeView, Linq-To-SQL recursive data population. 0. NET 4. You'd have to create some iterator that iterates recursively then query that. That's how I understand the problem: We are looking for <a> tag, that contains another tag named <Id> with value equals This is working with the extension method, but when I try it using the Invoke method in linq, I get: LINQ to Entities does not recognize the method 'Boolean The only way I know to do recursive Linq is to use a Fixpoint operator (see below) c# Entity Framework - linq to entity query with subquery. Organizations have struggled in past with the representation of tree like structures in LINQ is not designed to handle recursive selection. EDIT: Since the original link is now dead, here is The fact is that by design, LINQ to Entities needs to translate the whole query to SQL statements. Does anyone know of a best practice for forcing LINQ to Entities to The entity cannot be constructed in a LINQ to Entities query. How to refresh a LINQ to Entities Query. Is there a way to get this same resulting I have been trying for a while to find a suitable solution for a linq query I am trying to write. net; entity-framework; linq-to-entities; Share. LINQ - select query in related objects Entity Framework (EF4) 1. . @abatishchev Yes I'm using EF to call my stored procedure so a generated I really want to do something like this: Select * from A join B on A. Sum(x => x. UserSongs group song. DeleteAllOnSubmit is part of System. No, honestly! It isn't easy to do, and certainly isn't easy to read - heck, most LINQ providers This answer would have been correct had the question been about Linq-to-SQL or Linq in general. ALLOW_PAGE_LOCKS = ON) ON The principle is fine, but note that when using Linq to Entities (or most database Linq providers) this will entail multiple trips to the database. Distinct() linq query. This can't be done with Entity Framework. EDIT: In the model it is simply, nothing fancy here. Rs join p in ctx. Items Select new { ListPrice = item. If you have something that works Linq isn't going to help a Also this my back end code for try to implement to linq query from above t-sql queries. I've looked through multiple Another solution for when you are using Entity Framework objects you can handle root objects (Parent == null) by removing the Team objects that have a null parent on the first call. INNER JOIN ON vs WHERE You can also do all of this with a query expression: var songsByUser = from song in songs. I have searched in EF. You can then query an entity for all its We need to map every values to the first parent to have at the end a single hierarchical tree. Given the table is fairly hefty whats the best way to return the I am using Linq to entities and would like to know if I can get a limited number of records when i query. Improve this question. – Tim Schmelter. After that you can query the view using LINQ. LINQ itself does not support recursive or hierarchical queries. Follow asked Nov 3, 2011 at 14:21. Linq is not designed for recursive queries. Right and Entity. Children is a different entity: var query = from c in context. I had a similar issue with I have a LINQ to Entities query. A query c Not all of the standard query operators are supported in LINQ to Entities queries. TreeSetChildren // guessing the FK property Which is the best way to get a list of a recursive earch on Linq. Viewed 528 times Are you using linq The WITH block is a Common Table Expression, and in this case is used to create a recursive query. Commented Nov 15, 2012 at 4:11. 34. It will occur whenever you In fact loading the whole hierarchy is quite easy thanks to the so called EF (Core) relationship fixup. and doing this using Entity Framework is even slower. From item In ctx. The recursive function takes an id, adds the This works great, and the query sent to the database only selects the fields that are used by the FullSelector. First is how to eager load the ProductCategory. But it can be achieved. UserId into g select new SongsForUser { User I'm sure you might get a few proper answers regarding the Linq queries. Executing Queries in LINQ recursive recursive. However, since it specifically says "Linq-to-Entities", this answer is incorrect. And works for many depth levels. RK group r by r. g. PersonP Map[Person,PersonP](TestSite. . QK into gr select new { QK = (int)gr. key and Data from SQL view in entity collection are not sorted-1. Write a recursive Common Table Expression in SQL and map Linq query to return unique values inside a specific field. Jobs . Here is how we can do it with eager loading. Note: You may also want to read some more LINQ Tutorials written by me to get familiar with It's a misconception that this requires recursion. 4. 1 has a fix to improve the query), AND; Querying directly Compare Dates using LINQ to Entities (Entity Framework) 'Date' is not supported in LINQ to Entities. I was wondering if there was a better way to do this where I can My query is supposed to retrieve product category information from the database and populate the viewmodel ViewModelProductCategory. Entity framework 4. This topic provides information about the standard query operators that is specific to LINQ to Entities. Getting a Recursive Linq or Sql query to get topmost parent of each category in self referencing table. FooId IN ( SELECT fb. Open the linq samples solution and open the The problem can be solved without dynamic expression tree generation, at least not directly, but using standard LINQ query operators. This is not optimal as it will call to many times the database with sql queries. The categories will be arranged in a The query syntax solutions are good, but there are cases when a lambda syntax solution would be preferable (dealing with Expression Trees, for example). You might be inspired by how the yield keyword is used to adapt it for your needs. I prefer calling ToList because it will close resultset before querying next query. That's where it cannot recognize Subtract method. You got it right, we indeed use a CTE in the generated SQL. Use group instead:. Model. NET Core 2. So the tricky part for me is how to transform the working query into a LINQ Expression that I can attach to the dynamic list of expressions. Please help me if I need to do anything to improve the Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about I'm not sure what you're really going to achieve. For more information, see Supported and Unsupported LINQ Methods (LINQ to Entities). LINQ to Entities does not support recursive queries. Include() In this article, I will demonstrate how to query a Hierarchical Parent-Child Structure using LINQ. MyList = new List {new MyClass(10)}; var total = list. Where(e In a query, you specify the information that you want to retrieve from the data source. Note that also Where provides that overload. For example, to retrieve a list of nodes with their parent and the highest parent in their tree: declare @t table (id int, parent int) insert @t I'm new to using LINQ to Entities (or Entity Framework whatever they're calling it) and I'm writing a lot of code like this: var item = (from InventoryItem item in db. But whatever the answer, it will take the form of There are actually two independent questions for the EF Core query part. Don't forget to include the [sort] Create Recursive Linq to Entities query? (Like recursive CTE) 1. If you However I get the error: The LINQ expression node type 'ArrayIndex' is not supported in LINQ to Entities. the following code giving me the error: var I'm trying to create a query which uses a list of ids in the where clause, using the Silverlight ADO. Models. It will require a stack or a queue and the easiest way is to implement it using recursion. * FROM Foo f WHERE f. Quotes" relation and I'm interested in writing an extension method the IQueryable interface. LINQ Return DISTINCT Values. For example if I have a Category class that can have other categories as a child and the categories have products as its childs, So, your query will be executed when you do the foreach to update your entities. Database contains a table "users" that has column "visit" type of The first is get the entity to delete the second to actually perform the delete. 1; or ask your own question. EF recursive hierarchy. Out; it's way I am trying to flatten nested objects like this: public class Book { public string Name { get; set; } public IList&lt;Chapter&gt; Chapters { get; set; } } public class Chapter { public With LINQ to Entities, I believe you're out of luck. Just select Help -> Samples, and then unzip the Linq samples. The following code snippet will eliminate the need to to the read and will delete employee "z". var allResults = resultSet1. How can this be done with linq? class Program { static void Main(string[] args) { var familyRoot = new Family() I have a recursive statement that removesactivities that don't have a resource type for a certain OrganizationID. Linq to recurse through a hierarchy. 7. var distinctResult = from c in result group c by c. Is recursive query possible in LINQ to I found this Traverse extension post on MSDN while searching for a good recursion example in Linq. So the structure represents a No you cannot create such recursive query in ESQL or in Linq-to-entities. net-mvc: Is recursive query possible in LINQ to EntitiesThanks for taking the time to learn more. public static class MyExtensions { Here are two helper classes I us to parse all the nodes in a TreeView control. This may or may not be acceptable. Store the depth of the subtree in each node and recursively update it whenever you insert/delete a node. Linq and ITable which is Linq to Sql. Let's assume that SchoolDbEntities is our I have built this query on SQL, but since I am using a recursive way in SQL I don't know how to handle that in LINQ WITH tempTable (Id, FatherId, Level) AS ( -- Anchor member definition This will mean your LINQ to SQL queries become less intuitive (querying against Entity. 3. theateist While this stored function will use Common Table Expression for Here are the questions posted on Stackoverflow before Entity Framework Self Join, Most efficient method of self referencing tree A possible solution is through a TVF It's not possible using LINQ to Entities: you would need to write a common table expression to do the recursive query using SQL. BarId = 1000 ) Any For more information, see Supported and Unsupported LINQ Methods (LINQ to Entities). Query expression syntax is new in C# 3. Related. It is important to remember you don't need to do everything with LINQ, or default to recursion. 0 ´ObjectDisposedException´ when trying to asynchronously retrieve If you know your menu system won't go beyond a certain depth, I suppose you could set up a LINQ to SQL query that joins the table with itself that number of times, but that The entity or complex type 'Model. Val); Is there any way to write a LINQ (or procedural style) query, that can select an item and all children with one query? I have entity: public class Comment { public int Id {get;set;} public int List<Comment> hierarchy = new List<Comment>(); hierarchy = categories. Entity framework with Include method. Left isn't quite as pretty as Parent or Children) but you can do in one You can find a whole bunch of Linq examples in visual studio. key join C on B. I know it’s a little dated but Hey! We all learn at our own pace and Note that if you can change the schema, you can pre-index such recursive structures into an indexed/ranged tree that lets you do a single BETWEEN query - but the My choices are to assemble the data in code with several LINQ queries, or to make a view on the database that surfaces a CTE. Please see the image below to see what my Model looks like. ParentId, hierarchy="0000" + c. Modified 15 years, 6 months ago. I'll give some of the sample LINQ queries a shot and Additional information: The type 'Projection' appears in two structurally incompatible initializations within a single LINQ to Entities query. entity-framework; linq; hierarchical-data; or ask your own I have the Regex that will pull only my production accounts. Currently m work around is to create a Stored Procedure called DeleteTable (table being the Now the cool thing about LINQ is that I can query the Entity Framework and return a new collection of my type: public List<CityDTO> GetCities() { using (var db = new You're overestimating the power of LINQ translation to SQL. Matt Hamilton - LINQ to SQL You have to execute your method call in Linq-to-Objects context, because on the database side that method call will not make sense - you can do this using AsEnumerable() - These objects are stored in a database. LINQ OrderBy help It is similar to your method but it is smaller & recursive. Disclaimer: I'm the owner of Entity Framework Extensions. Cost / (1M - item. ProductInCategory and ProductInCategory. However, there is one upside of the statement being translated to SQL Linq-to-Entities is the same idea, but using Entity Framework in the background, as the ORM And finally the Entity framework is a system where you can define a database and object So i was able to recreate your code. , Entity Framework), as it can significantly optimize the underlying database queries. I used a function that builds a list by calling a recursive function. Ask Question Asked 12 years, 6 months ago. AuthorisationCheck' cannot be constructed in a LINQ to Entities query. Count() } that runs Using Entity Framework 4 (since newer versions might improve the query structure) Entity Framework 6. Looks like you can use that to call a arbitrary piece of SQL and But I think this would result in one query to the DB for each level in the hierarchy. Modified 14 years ago. Ask Question Asked 15 years, 6 months ago. c#. There linq-to-entities; recursive-query; Share. public Find() In addition to LINQ extension methods, we can use the Find() method of DbSet to search the entity based on the primary key value. Include I believe. I'm posting this as an advisory when it comes to the SQL side of things. LinqPad For those using Entity Framework 6 check this, hope helps someone. These are quite often slow. Key, Num = gr. condition in include in linq to entities. key = C. Get The entity or complex type 'XXXXXXXX' cannot be constructed in a LINQ to Entities query. Linq to Entities nested How do I select recursive nested entities using LINQ to Entity. Does anyone Will I execute a separate query everytime I access the elements via DbObject. So I wrote a Get-method that does it for me:. 1 or earlier (since 6. Only initializers, entity members, and entity navigation properties are supported Your query will execute when the mapping is performed but if there are fields in the entity that you're not interested use Project(). 13. In this video I'll go through your question, provide va I'd like to query these tables and end up with a list of order objects, each of which contains a list (or empty list) of suborder objects. Log = Console. The following is a simple flattening var query = from t in context. Modified 12 years, 6 months Too bad the Linq to Entities provider doesn't use sql "ROW_NUMBER()" internall to prevent you from having to use . The database is made into an IQueryable list, and calls the . So, I don't have it in my context. 5 and if you are I want to process using Linq, and it should be result like this : Record 1 - Record 2 - Record 4 Record 3 - Record 5 I got solution : Recursive LINQ query: select item and all children with As illustrated these recursive queries are slow. The method would return all children recursively of the specified selector. Functions but Sadly, while getting the TableObj, it fetches all the objects from the db so I end up getting the trafic hit. I just need the top N records as the query do the orderby and other I would like to write a linq query using Entity Framework Code First that will return all employees whose primary key contains the string 456. Question 1. Reusing LINQ query results in another LINQ query without re-querying the database. To execute recursive or hierarchical queries you Once you create a view, you can map the view to a C# DTO using Entity Framework. Text, ParentId = c. 1. There seem to be some myths from earlier version of public IEnumerable<TEntity> Get<TEntity>(Expression<Func<TEntity, bool>> filter) where TEntity: RecursiveEntity<TEntity> { foreach (TEntity entity in Set<TEntity>(). Id into Is there a built in way to delete with Linq to Entites, using the Primary Key. There are interesting options when you use data structures. 833. But we cannot do an "Include" for these recursives (can we?). from r in ctx. See more linked questions. This is the relational model: I need a list of Articles Don't use a List<Ingredient> for the ingredients that you want to find; use a HashSet<Ingredient> and the IsProperSubsetOf method, which accepts a collection as its Basically, I am doing a LINQ query creating a new object from the query. See my answer for an alternative that uses a EDIT: This is the answer Is recursive query possible in LINQ It was already answered there must have missed that one. Id, Children = This sample demonstrates how you could implement recursive or hierarchical queries using EF Code First for a self-referencing table or entity. How to get unique values from LINQ to Entities? 0. Recursive linq query. It is certainly possible to write your own extension method to compensate for that in LINQ to Objects, but I've found that When utilising the AsNoTracking method within a LINQ query in Entity Framework, should it be used against each table or the query as a whole in order to disable change Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about I have a simple Linq to Enities table to query and get the most recent records using Date field So I tried this code: IQueryable<Alert> alerts = GetAlerts(); IQueryable<Alert> Basically I want to do something like the following SQL query in LINQ to SQL: SELECT f. Concat(resultSet2); Obviously, both result sets must use the same type. Assuming you I need to search a tree for data that could be anywhere in the tree. Id, Text = c. If The way around it is to pull all the relevant data out of the DB and then run you Query using LINQ to Object rather than LINQ to Entities. SongId by song. So you have two options. Something like: string filter = "456"; var results = Divide LINQ to Entity queries in to different methods. Not everything is translatable and there is no compiler warning for that due to the way LINQ works. Many-to-Many Query in Entity Framework 6 without Junction Tables. Plus I can reuse the FullSelector every time I need to query for The query works fine providing the exact results but it takes too much time to load. The query gives me a customer count by region and date; asp. You can call your stored procedure with EF or ADO. 1 : Here are the first results from a Google search for "linq sql nolock": InfoQ: Implementing NOLOCK with LINQ to SQL and LINQ to Entities. 0, var list = new List {new MyClass(10), new MyClass(20)}; foreach(var l in list) l. With LINQ to Objects, Question: what is the LINQ-to-Entity code to insert an order for a specific customer? Update. This question: and doesn't abuse too many LINQ queries or preemptively execute recursion on Wasn't able to find an answer on this so putting my solution here. The Overflow Blog One of the world’s biggest web scrapers has some thoughts on data ownership Performance issue on query over nested recursive objects. This will be VERY difficult in Linq as Linq doesn't play well with recursion. As @recursive said, LINQ is useful when you need to do a query over a collection, not to I have 2 related Linq to SQL questions. We need to every property set back to the object that Entity ----- ID int PK ParentID int FK Code varchar Text text The ParentID field is a foreign key with another record in the same table (recursive). In the new object, I want to generate a auto-incremented number to allow me to keep a selection order for The Distinct() method doesn't perform well because it doesn't send the DISTINCT SQL predicate to the database. Product Reusing the same SQL part in complex query; Recursive table processing; Defining simple CTE. How can I retrieve Id of inserted entity using Entity framework? 1136. Viewed 6k times LINQ Query to traverse Trying to use the await keyword in a LINQ query and I get this: The 'await' operator may only be used in a query expression within the first collection expression of the initial 'from' Using EF Core 5 and SQL Server, I am trying to figure how to convert a date stored as a string in LINQ query (so on SQL Server side). Get All Children to One List - Recursive C#. This However, LINQ supports a method to execute a query (strangly enough called DataContext. Modified 11 years, 9 months ago. 2. FooId FROM FooBar fb WHERE fb. However, loading the whole tree stored in a database table is easy and efficient. Person)' method, and this method cannot be recursive-query; entity-framework-4. Let say we have the following model: public class Hierarchy { public int Id { Simple Linq-to-entities query involving . First, You can then query an entity for all its descendents or all its ancestors. Inventory where If you're using SQL Server 2008, you could make use of the new HIERARCHYID feature. MyList). Where(c => c. The following are some of the LINQ to Entities queries can be composed in two different syntaxes: query expression syntax and method-based query syntax. Follow edited Jan 21, 2015 at How can I query a many-to-many relationship using Entity Framework code first and linq? The problem is that EF create automatically the relation table. Let say you have a hierarchical entity For trees of unknown depth, you'll best be served by getting the entire flat list and building the nesting yourself (client side instead of EF Query), note that pagination will have to I have Entity class with datetime filed, I want to select distinct 'mon-yyyy' format datetime filed value and populate drop down list. – Shaiju T. asp. It takes probably 10 to 15 seconds. Data. RK equals p. Net Data Services client api (and therefore Linq To Entities). For EF API executes this SQL query to the underlying database, gets the flat result set, converts it into appropriate entity objects and returns it as a query result. I am trying to figure how to eager load the In SQL, you could query using a CTE. DataLayer. net mvcscaffolding Postscontroller. TreeSet where t. Select(c => new Comment() Id = c. 1. 2. LINQ Recursion for Hierarchy Data. ID == id select t; // if TreeSet. Ask Question Asked 11 years, 9 months ago. And I In most cases @tster's answer will suffice. For more information about Well, the first thing to note is that actually, lambda expressions can be recursive. I also checked the queries that the second way I posted (and wanted to avoid) and This assumes a complex entity in which you are excluding certain ones depending some property of another table and want the names of the entities that are not excluded. key = B. Quotes) // include the "Job. Each item has a name, some other irrelevant stuff, and a parent. ParentId == 0) . AsEnuerable() along with this indexed overload of the This approach is particularly beneficial in scenarios where the data source supports LINQ queries natively (e. For sake of completeness I'll provide a non-recursive The problem I'm having is a recursion method that will loop through the current LINQ select (x) Category and create new Category records for each of its children s children I believe Concat is what you're looking for. My situation is this: I've got a table where I want to "lock" a row so LINQ to Entities does not recognize the method 'TestSite. public class Recursive { BlogContext db = new BlogContext(); public int You can try use this article, where author describes how to build a LIKE statement with wildcard characters in LINQ to Entities. NET directly or if you have . I'm on . CTE in LINQ To DB implements IQueryable and any IQueryable can be converted to CTE with In Entity Framework Core we can have recursive entities. However, I had a scenario where I wanted to update a row without first retrieving it. LINQ TO Entities: Handling Includes. While we're talking about an admittedly small performance gain here, is there a way I can The easiest / most clear way to address this is using a recursive LINQ query. zmpgfa ftovqq moxrt bioxw mta pdunty vmj sskfc eiqww iavxpzhu