Linq where in list of objects. [see deferred execution ...
Linq where in list of objects. [see deferred execution later in this article. BarList select b. QuestionID = 12. The customObject class has an ID property. ToList(); So, long story short I want to use LINQ to filter out my list of objects based on objects from another list. Aug 29, 2024 · The Where clause in LINQ is an essential tool for filtering data in . What I hoped w LINQ querying methods all return an IQueryable object. NET datasets, SQL Server tables and Views, XML Data (files and strings in memory), and more, like an array of data, anything that is an object really, so LINQ fully integrates with the programming language (C#/VB. Normally I use a for loop or anonymous delegate to do it like this: int GetItemIndex(string search LINQ offers a consistent model for queries on data across various kinds of data sources and formats. This series of examples shows you Language Integrated Query (LINQ) techniques to use with collections and arrays. LINQ to Entities Used with Entity Framework Core to query relational databases. ] Using LINQ, select list of objects inside another list of objects Asked 15 years, 4 months ago Modified 7 years, 11 months ago Viewed 114k times C# linq Select objects in list looking inside another list of objects Asked 7 years, 2 months ago Modified 7 years, 2 months ago Viewed 20k times Readability: LINQ queries, including the Where operator, enhance code readability and maintainability by expressing filtering logic in a concise and declarative manner. ID,FullName,Organization,Location being the columns. I want to select items from mainList where a property in detailList evaluates true. This blog will guide you through four practical methods to find items in one list that are not in another, with detailed C# code examples. This article provides an introduction to employing LINQ to Objects queries to support a simple win forms application; the article addresses the construction of LINQ to Objects statements and then goes on to describe how one might use LINQ to Objects within the context of an actual application. Where comes under the Filtering Operators category? I have an list called mainList. I have to find the index of the cus When using LINQ to query non-generic IEnumerable collections such as ArrayList, you must explicitly declare the type of the range variable to reflect the specific type of the objects in the collection. I have a Customers table. While iterating through this List of Question in foreach, I have to find . When this is a linq-to-object call, multiple where clauses will lead to a chain of IEnumerables that read from each other. e. If you're doing this in memory (linq to objects) then a HashSet would perform better than either an array or a list. When you write queries, the most visible "language-integrated" part of LINQ is the query expression. This Questions has properties QuestionID and QuestionAnswer. Linq to objects List in list Asked 15 years ago Modified 15 years ago Viewed 20k times I attempted my own Linq statement which is producing a boolean inside an object, but I can't get it to return an actual boolean. I thought LINQ was about providing object based queries to anything that has structure like data and other objects. Jan 10, 2026 · LINQ (Language Integrated Query) provides elegant tools to achieve this efficiently. LINQ to Objects is a powerful feature in C# that allows you to query and manipulate data stored in arrays, lists, or other collections using SQL-like syntax. 20 I have a List<int> and a List<customObject>. ConvertAll) unless I was really bothered by the performance of a specific operator. BarId) select f). The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in C# or For Each in Visual Basic. No fluff—just what you need to impress and land the job in 2026! Say I have a class Customer which has a property FirstName. Let's check out a few examples. Both are linked through the property PersonId. The Where Linq operator, probably the most commonly used, allows you to filter or find things where a certain boolean condition is met. 9 Since you haven't given any indication to what you want, here is a link to 101 LINQ samples that use all the different LINQ methods: 101 LINQ Samples Also, you should really really really change your List into a strongly typed list (List<T>), properly define T, and add instances of T to your list. I've described the situation below. If you're doing it in a database then it won't make any difference. List< A quick guide on how to use the Where LINQ operator, using both method and query syntax. Example use case: Retrieving customer orders from SQL Server in a fintech ZLinq is a high-performance alternative to standard LINQ designed to reduce memory allocations and improve speed, especially when working with large in-memory collections. Contains(ITEM FROM filterBars. NET applications. NET) in a natural object Here I have a simple example to find an item in a list of strings. Filtering, also known as selection, restricts results based on a condition. In a LINQ query, you're always working with objects. 8 I'm trying to write an some Linq where the Where clause contains items meeting certain criteria - but excludes a subset of those items meeting some other conditions. Learn about the standard query operator methods in LINQ in C# that perform filtering. Linq to XML: This provides efficient, easy-to-use, in-memory XML manipulation capabilities to provide XPath/XQuery functionality to the programming languages using simple query operators. Linq to Objects: This provides the ability to query IEnumerable<T> -based information sources which include arrays, collections, list of objects. Although, if one is not careful, and materializes the query results, before applying LINQ to in-memory objects, they may suffer the consequences of mismatched case-sensitivity. Some LINQ providers, such as Entity Framework and LINQ to XML, implement their own standard query operators and extension members for other types besides IEnumerable<T>. NET LINQ query on List (Of Object) Asked 11 years, 11 months ago Modified 11 years, 11 months ago Viewed 30k times I am new to Linq. How can I get a List<customObject> containing only the objects where the ID property is in the List<int> using LINQ? Edit: I accepted Konrads answer because it is easier/more intuitive to read. Jun 18, 2015 · I have two lists of objects Person and PersonResult. 6 This question already has answers here: Linq select objects in list where exists IN (A,B,C) (5 answers) For LINQ-to-Objects, if listOfProducts contains many items then you might get better performance if you create a HashSet<T> containing all the required names and then use that in your query. I have a list of objects class Answer { bool correct; } List<Answer> Answers = new List<Answer> (); Is there a way in linq for me to select an object depending on its attribute? Linq query list contains a list Asked 15 years, 11 months ago Modified 12 years, 2 months ago Viewed 73k times But, you are storing a dictionary in object of another dictionary therefore when you are using kvp => kvp["status"] == 310 you should cast kvp to be Dictionary<string,object> and casting objects of dictionaries is risky to do and that's why you should have strongly typed objects (i. Contains () but it starting not to look that way. You write query expressions in a declarative query syntax. Example use case: Filtering product lists in an inventory management system in India. for example below is my list . However, for performance's sake, if the string list has or might have many items, consider making reservedNames an HashSet<string> with an ignore case comparer passed in its constructor. classes) to store such structure of data. . Can LINQ be used to find if the list has a customer with Firstname = 'John' in a single statement. BarId). And of course, it works for more complex objects than numbers and strings, and it's still very easy to use. NET interview with expert answers and real code examples. Then I have a List<Customer>. In this article, I am going to discuss LINQ Where Filtering Method in C# with Examples. var list=testList. Family==""). Here's what I have so far: It's well worth becoming familiar with the LINQ standard query operators; I would usually use those rather than implementation-specific methods (such as List<T>. I have a query in Sqlite returning me 2500 records of customers. Where(f=>f. For more information about standard query operators, see Standard Query Operators Overview (C#). How can I write a Linq statement that will fit the following criteria for Example 1 and Example 2? Learn about various LINQ objects and their applications in programming. To query a list of Employee objects, you can create a list and apply LINQ queries similar to previous examples, filtering based on properties like MonthlySalary or names. Given this piece of code: class Program { static void Main(string[] args) { List<Person> In this article, learn how to use the LINQ Where method in C# to filter collections easily, with detailed examples and practical use cases. When it comes to data LINQ can query ADO. for example, if a have a value of 100, i want to look in the VMin and VMax column , if my value resides or equal in… Using linq, how can I retrieve a list of items where its list of attributes match another list? Take this simple example and pseudo code: List<Genres> listofGenres = new List<Genre> I have a class called Questions. Types of LINQ in C# LINQ to Objects Used for querying in-memory collections like List or Array. I guess I was thinking there would be another way to refer to the List<T>. If I find . I think I'm just lost on the Contains portionI don't know how to write that. Using the single-clause form will help performance here. Return list of specific property of object using linq Asked 13 years, 7 months ago Modified 8 years, 8 months ago Viewed 95k times Okay, so it looks like I need to dump the contents of the list with anon objects into a list of just ints, then do the contains on the new list. I need to create a filter for the list of PersonResult that meet certain criteria for the Person In the Where () method, we use the Contains () method on the black-list, to decide whether a number can be included in the final list of numbers or not. Linq query to get an object from list of lists Asked 12 years ago Modified 11 years, 11 months ago Viewed 10k times I currently have a list of objects called _tables and each of these objects has within it another list of objects exposed through the property, "Indexes". net Framework 4. Enhance your coding skills with LINQ. Linq to Objects - Where search within a list internal class ProdQtyByWarehouse { public int id { get; set; } public List<ProdWarehouseQty> ProdWarehouseQtys { get; se Using the . I would assume there's a simple LINQ query to do this, I'm just not exactly sure how. Its expressive syntax and powerful capabilities make it ideal for handling a wide range of filtering scenarios, from simple conditions on primitive data types to complex queries on object collections. With LINQ, a query is a first-class language construct, just like classes, methods, and events. Jan 10, 2013 · Here we again see one of the LINQ surprises (like Joda-speech which puts select at the end). For example, if you have an ArrayList of Student objects, your From Clause should look like this: When should you use the LINQ Contains Method in C#? What is LINQ Contains Method in C#? The LINQ Contains Method in C# checks if a sequence (like a list or array) contains a specific element using the default equality comparer or a specified compare. I've read many solutions using linq and lists, but I can't seem to find a solution to my issue. I hope this makes sense. Essentially, I'd like to end up with one List that contains all the Indexes from all of the _tables. How can I find object in List with Linq? Asked 12 years, 7 months ago Modified 12 years, 7 months ago Viewed 38k times Hallo, I am looking for an idea or easiest way to find a object which satisfies the criteria. For more information about extension members, see Extension members. Here's a summary of the situation and I will provide full… fooSelect = (from f in fooBunch where !(from b in f. NET developer, especially those working with large datasets or complex business logic. Ace your C# and . However it is quite logical in this sense that it checks if at least one of the items (that is any) in a list (set, collection) matches a single value. Efficiency: LINQ operators are optimized and provide efficient querying of data, which can lead to better performance. Every item in mainList contains another list called detailList. It returns a boolean value indicating whether the element exists in the sequence. Select(n=>n. This informs the compiler that the variable is not the result of the query, but the definition of the query. Where clause using Linq - search for a list of Object Asked 7 years, 1 month ago Modified 7 years, 1 month ago Viewed 2k times VB. It’s an essential tool for any . Name); In Linq you need to apply the filter before projecting (unless the filter applies to the results of the projection rather than the original collection). Explantion (with examples) of how to use Linq Except to get the elements from one list that are not in another, with details of other similar Linq methods. The list of Details includes every detail in the system. 3m4l, sdru, zqksvv, zhhz, zxnc, jgov4, m5r2zs, iwqny2, k2hcd9, q8qou,