difference between ienumerable and iqueryable and list in c#

But if you were instantiating your collection all at once, you could use IEnumerable. Though both these terms appear alike and are quite similar for coding purposes, they are different in many ways. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Finally, when I run the application, this time I will see a difference. In order to check this, just mouse over the pointer onto the QuerySynntax variable and you will see that the type is IEnumerable which is a generic type. IQueryable vs IEnumerable - C# Corner When it comes to writing code, both look very similar. Both have its own importance to query data and data manipulation. Is there a finite abelian group which is not isomorphic to either the additive or multiplicative group of a field? Once this class is ready, it is time to create an IEnumerable implementation for Employee. Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages. Hence does less work and becomes fast. All product names are trademarks of their respective companies. Is IEnumerable suitable for querying data from in-memory collections? When we have an in memory list, this Where LINQ statement is defined on the IEnumerable interface. Thanks in advance! The methods provided by the IQueryProvider are used to create all Linq Providers. Generating X ids on Y offline machines in a short time period without collision. IQueryable exists in System. SQL Database), results returned and mapped to C# objects. In a real-world scenario, the table may contain many more records and additional columns with various data types. One is works as in database come from System.Linq and other is works in memory come from System.Collections.Generic. In the course of querying data from databases, it is possible to observe that IEnumerable executes by selecting query on the server-side, loading data in-memory on the client-side, and then filtering the data. If you just need to read, sort and/or filter your collection, IEnumerable is sufficient for that purpose. And inside of this overridden method, I will take two steps: Now, I will update the Main method, to create an instance of EmployeeContext. 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IEnumerable and IQueryable, both are interfaces to a .NET collection. IDictionary is a different animal in the sense that it is a mapping of unique keys to values. When developers find it essential to apply filters on data right at the data source. This class will implement IEnumerable and provide an implementation of the GetEnumerator method of the IEnumerable interface. Your email address will not be published. If you are working with data in C#, you might have heard about IEnumerable and IQueryable interfaces. Note: This is just an example table with a few records to demonstrate the concept. . The main purpose of the IQueryable interface is to provide the functionality to query data against a specific data source. And for this, we are using the LINQ Query to fetch the Male students from the student collection data source, and then using a for each loop we are iterating through the IEnumerable collection. But what is the difference between IEnumerable and IQueryable? EmpEntities ent = new EmpEntities(); IEnumerable emp = ent.Employees; IEnumerable temp = emp.Where(x => x.Empid == 2).ToList(); This where filter is executed on the client side where the IEnumerable code is. And for that I will create a new class EmployeeEnumerator. Please read our previous article where we discussed the different ways to write LINQ queries with Examples. As you can see in the above image, the IQueryable is an interface and it is available in System.Linq namespace. There is a key difference between IQueryable & IEnumerable, IEnumerable fetches all the data from SQLServer then it applies filters over fetched data. Fifthly, I will create a local variable for ILoggerFactory instance. IEnumerable is inherited by IList, hence it has all the features of it and except this, it has its own features. For the most part, this class is responsible for calling the QueryTranslator to get the SQL statement representation of the Expression Tree. In order to have access to the user whos Id is 1, it needs to run this LINQ statement against a database. Finally, I will override the OnConfiguring method from the DbContext class. IEnumerable is most suited for iterating through collections. Both can move forward only over a collection. IEnumerable supports extension methods for making functional objects. IEnumerable is used mostly for working with in-memory collection data where as IQueryable suits best when working with remote data sources or database. EmpEntities ent = new EmpEntities(); IQueryable emp = ent.Employees; IQueryable temp = emp.Where(x => x.Empid == 2).ToList(); So the difference between IQueryable and IEnumerable is about where the filter logic is executed. Linq Namespace. This time, as you can see above, the SQL query is different. The MoveNext() method advances the enumerator to the next element in the collection and returns true if there is a next element, and false . What is the practical difference between the two? Simple to use and provides a straightforward way to iterate through, More complex to use and provides a more extensive set of. For instance, why does Croatia feel so safe? When you do that you will cast this to list which comes from Enumerable, you put that data on your ram. IEnumerable can not return no of elements without iteration whereas IList having extra methods e.g. IQueryable exists in the System.Linq Namespace. And post that in-memory the reduction is happening. Just like before, now, I will update the code to use Take(2) LINQ query on the result and see what is the output. And also, I will remove the Take(2) LINQ statement for the time being. IQueryable derives from IEnumerable. Key Difference in IEnumerable and IQueryable. Be careful when using complex queries that involve joins and multiple tables, as these can be challenging to optimize and may result in poor performance. However, its essential to note that using IQueryable requires some knowledge of how the database engine works and the query may need to be optimized to get the best performance. The main difference between the two is that IEnumerable performs the query on the client side, while IQueryable performs the query on the server side. IQueryableinterface inherits fromIEnumerable, so whateverIEnumerablecan do,IQueryablecan also do. It is time to create a class to return the enumerator. By reading similar posts I've learned that a List is a type of IEnumerable. One of the confusion I had when I initially started using IQueryable, was why do we have both IEnumerable and IQueryable. They cannot be used to read the data in a collection. I will open Visual Studio 2019, and in Create a new project popup I will select Console App (.NET Core). Do note that enumerators can only be used to modify data in any collection. IEnumerable is preferable mainly for small data manipulations, while IQueryable is useful for performing big-sized data manipulation tasks. Lets take the following examples. Within the Main method, we have created a collection to hold a list of students. an ORM such as LINQ to SQL, or Entity Framework. Secondly, we will update the EmployeeContext class to derive from the DbContext Entity Framework Core base class. (Which Ive slightly modified to make it easier to read). Understanding the Key Differences between IEnumerable and IQueryable in Yes, IQueryable supports lazy loading. IEnumerable interface is useful when your collection is loaded using LINQ or Entity framework and you want to apply a filter on the collection. IEnumerable supports the feature of deferred execution. As IEnumerable inherits Iqueryable, IQueryable adds its features to IEnumerable interfaces to help manipulate and query the collections of data. What is the point of that? This where filter is executed on the client side where theIEnumerablecode is. 2. IEnumerable VS IList - DotNetTricks Hence, when we use IQueryable with Entity Framework Core, the actual data processing happens in the database. Both executes "select query" on the server-side, loads data in-memory on the client-side and then filters the data. And explain both of these interfaces. IQueryable is suitable for querying data from out-memory (like remote database, service) collections. All rights reserved. * It is under System.Linq namespace. IEnumerable. To see the basic workings of a query provider lets go ahead and create a very minimal query provider. Generally, we use IEnumerable and IQueryable to hold collection of data and perform data manipulation operations like filtering, etc. There are many differences but let us discuss the one big difference which makes the biggest difference. I am using a package called Bogus to generate a list of Person records. Continue with Recommended Cookies, Back to: LINQ Tutorial For Beginners and Professionals. 3. IEnumerable is implemented by collections such as Lists. As you can see the bottom picture, derived from IEnumerable, There are basic methods but enough for many thing, also you know the count :), And the last one is a IList derived from Icollections and IEnumerable.
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difference between ienumerable and iqueryable and list in c# 2023