Nov, 20 ienumerable is inherited by iqueryable, hence it has all the features of it and except this, it has its own features. The difference between passing iqueryable and ienumerable to. Iqueryable from stored procedure entity framework ask question. This article shows comparision about data structure, array, arraylist, list, ilist, icollection, stack, queue, hashtable, dictionary, iqueryable, ienumerable. Ienumerable is also be better work for linq to object and linq to xml queries. It calls to an overload of compile that takes a lambdaexpression.
First of all, ill tell the difference between the two and why i choose to return iqueryable over ienumerable in my repository. Recently i had a discussion with a software architect about the implementation of the repository pattern. For more information about covariance and contravariance, see. So if you further refine your query on an iqueryable, that query will be executed in the database, if possible for the ienumerable case, it will be linqtoobject, meaning that all objects matching the original query will have to. I also showed that calling where on a queryable just adds a new root to the expression tree.
Ienumerable is best suitable for working with inmemory collection, whereas iqueryable is best suited for remote data sources, like a database or web service. It implements ienumerable so the results can be iterated using foreach. The ienumerable works with collection in local memory whereas iqueryable works with queryable data provider. I showed that the filter method on enumerators visits every element in the collection. My last post explored the implementation of the where extension method on ienumerator and iqueryable. When we perform the ienumerable the data is first loaded into the memory and then the conditional query is then performed on it, where as in iqueryable the query is executed in the database if possible. In this article, we will know all about ienumerable and iqueryable except how they are evaluated. Differences between ienumerable and iqueryable dot net tutorials. Implementing ienumerator also requires idisposable to be implemented, which you will see in this example. But the topic is quite important and i think it worth discussing about both approaches. The latter is just an abstraction over any steam of logical data that you can enumerate through, the former is an abstraction over lazyevaluated streams of data that are resolved by querying a data store.
Best use of ienumerable is with linq to objects and linq to xml operations. Iqueryable allows you to operate and build queries that can be sent to a remote provider. I am often asked what the difference is between iqueryable, ienumerable and linq. However, if you store the first part of your query as iqueryable, then you can add onto that query later before it actually gets executed, of course. An code iqueryablecode is a potential code ienumerablecode. It is best suited to query against external data sources. Jul 03, 20 convert to code or convert to expression tree objects. Ienumerable in the repository pattern first of all, ill tell the difference between the two and why i choose to return iqueryable over ienumerable in my repository. Both has their own importance to query data and data manipulation. Differences when using ienumerable and iqueryable as a type of. Ienumerable has immediate execution, whereas iqueryable has deferred execution or lazy loading. Since all other collections can be easily converted from an ienumerable this makes ienumerable the better choice.
So, it only makes sense to return ienumerable if youre going to iterate through all elements anyway. Ienumerable is only preferable for small data manipulations. Looking at their inheritance tree you could see following. Complete list of posts in the building an iqueryable provider series ive been meaning for a while to start up a series of posts that covers building linq providers using iqueryable. Ienumerable is inherited by iqueryable, hence it has all the features of it and except this, it has its own features. Where that the extension methods follow a validate then delegate pattern, and we see it here again. What is difference between ienumerable vs iqueryable vs ilist. Also learn the differences between ienumerable and. Nov 18, 2006 the expressioncompiler turns the expression into whatever sequence of calls are required to get the objects defined in the expression. Iqueryable is suitable for querying data from outmemory like remote database, service collections. It loads the data inmemory on the client side and does a filter. Collection namespace we can add access or use the ienumerable in our code. Sep 15, 2016 this stack overflow question have a nice answers to explain the difference.
Ienumerable is beneficial for linq to object and linq to xml queries. This stack overflow question have a nice answers to explain the difference. This article is one of the first sources with complete and clear comparison about data structure, array, arraylist, list, ilist, icollection, stack, queue, hashtable, dictionary, iqueryable, ienumerable. Ienumerable has immediate execution, whereas iqueryable has deferred execution or. Asparallel ienumerable enables parallelization of a query. May 14, 20 ienumerable vrs iqueryable in linq, to query data from database and collections we use ienumerable and iqueryable. The difference between iqueryable query and ienumerable query is that in. What is difference between ienumerable vs iqueryable vs. Net collection please first see this video before moving ahead with the article. Simplifying above the ienumerable collections first loads in all the data to the memory then applies the filter operation by the nature of the interface, where as the iqueryable interface is designed to modify the data retrieval query while being fired thus bringing in lesser amounts of data to the inprocess memory and optimal for paging and.
Public interface ienumerable of out t implements ienumerable. Entity framework and linq2sql operates with iqueryable because they will translate this to sql and send it to the connected database. Linq namespace we can add access or use the iqueryable in our code. That is, you can use either the type you specified or any type that is more derived. I was looking for some way out either via any php or. Asordered may only be invoked on generic sequences returned by asparallel, parallelenumerable. Iqueryable can move forward only over a collection, it cant move backward and between the items. Here is the small sample that explains the difference between ienumerable and iqueryable.
Ienumerable, ienumerator, iqueryable and iqueryprovider. Why do we need ienumerable and iqueryable both ienumerable and iqueryable are used for to hold the collection of a data and performing data manipulation operation for example filtering on the collection of data. If you use take and skip on iqueryable, you will only get the number of rows requested. Mongoqueryable whih defines extension methods for iqueryable. Iqueryableof t so mach as its a problem that the method used to return data from the repository did not provide a way for you to specify what to return. Regarding returning ienumerable, its important to note that ienumerable query. Iqueryable ienumerable randomdatas from index in enumerable. Download the source code from github and experiment. What iqueryable has that ienumerable doesnt are two properties in particular one that points to a query provider e. While query data from a database, iqueryable execute the select query on the server side with all filters.
Ienumerable is an interface, only materializing it will initialize its type and produce something in my understanding. Use iqueryable against the context, that way you can filter the table at the data source, and not in the application. In this example, members of these interfaces are not explicitly called, but they are implemented to support the use of foreach for each in visual basic to iterate through the collection. I would say that this is not a problem with returning ienumerableof t vs. Iqueryable vs ienumerable liberty fox technologies. Yes both will give you the same result but deferred execution. When querying data from a database ienumerable executes a select query on the server side. Even though it is maybe a bit more complex solution. Iqueryable vs ienumerable vs ihaveheadache darko micics. When you are heavily working with the entity framework using linq you have certainly touched both interfaces. One of considered opinions is that entity framework and dbcontext and deffered execution just do all the magic and there is no difference. Linq public static class queryable public static iqueryable asqueryablethis ienumerable source.
When we talk about linq, we consider two collections ienumerable and iqueryable. So if you further refine your query on an iqueryable, that query will be executed in the database, if possible. Iqueryable is used when you are using linqtoentities you are building declarative linq query in your application which will be interpreted by linq provider as sql and executed on the server. Iqueryprovidermakegenerictype, getelementtype, typesystem, class, and bool. What is the main difference between ienumerable and. The purpose of this article isnt to formally define the interfaces, but rather to paint an easy to understand picture of how how do they differ. Bottom line if you have a linq to sql statement and you can save it as an iqueryable instead of an ienumerable, do so so that you have flexibility to continue to add onto that query. It will make one query to the database but will download unnecessary data. Once the query is executed iterated it will turn to become ienumerable and objects will be materialized as needed for iteration not immediately. Since all other collections can be easily converted from an ienumerable. Ienumerable is also best use when you already have an list of concreate objects in the form of ilist, dictionary, hashtable etc. The first important point to remember is iqueryable interface inherits from ienumerable, so whatever ienumerable can do, iqueryable can.
This is quite an important difference, and working on iqueryable can in many cases save you from returning too many rows from the database. Look at the following important points about iqueryable. Returning ienumerable vs iqueryable programming linq. That would make sense if iqueryable didnt also implement ienumerable. Then in part 2 we get practical with 8 code snippet questions.
Asparallelienumerable enables parallelization of a query. Doing this will only download the results that are skipped or taken, the others wont be read. Ill cover the following topics in the code samples below. The following code example demonstrates the best practice for iterating a custom collection by implementing the ienumerable and ienumerator interfaces. An code ienumerablecode represents a sequence of things that are presently inside the ram memory allocated to your process. Personally, i really like those images when i try to explain the difference. Lets see both the features and take the advantage of both the features. If we use iqueryable with foreach then query will be evaluated and executed at the same time.
For the ienumerable case, it will be linqtoobject, meaning. Mar 29, 20 simplifying above the ienumerable collections first loads in all the data to the memory then applies the filter operation by the nature of the interface, where as the iqueryable interface is designed to modify the data retrieval query while being fired thus bringing in lesser amounts of data to the inprocess memory and optimal for paging and. Because it load all the data in memory the performs any operation. This is the first in a series of posts on how to build a linq iqueryable provider.
List vs ienumerable vs iqueryable vs icollection vs. For example, it may involve translating the expression tree to an appropriate query language for the underlying data source. Convert to code or convert to expression tree objects. The sequenceequal iqueryable, ienumerable, iequalitycomparer method generates a methodcallexpression that represents calling sequenceequal iqueryable, ienumerable, iequalitycomparer itself as a constructed generic method. Yes this ist just another blog post about ienumerable and iqueryable. Apr 02, 2016 an code ienumerable code represents a sequence of things that are presently inside the ram memory allocated to your process. The most basic reason is because iqueryable inherits from ienumerable and provides an asqueryable method in order to gain access to the queryable methods from an ienumerable. Ienumerable ienumerable iqueryable so what is the great difference between both of them.
Joining an iqueryable with an ienumerable michaels coding. List vs ienumerable vs iqueryable vs icollection vs idictionary. The difference is that iqueryable is the interface that allows linqtosql anything really to work. Iqueryable is best to query data from outmemory like remote database, service collections. Observations on iqbservable the dual of iqueryable. The previous version was plain wrong in many aspects. Aug 07, 2011 when you are heavily working with the entity framework using linq you have certainly touched both interfaces.
Both have its own importance to query data and data manipulation. Enables treatment of a data source as if it were ordered, overriding the default of unordered. Lets see both the features and take the advantage of both the features to boost your linq query performance. Now we will see how ienumerable works in real life. This is a loaded question, but i will try my best to explain it in this blog. While querying data from a database, iqueryable executes a select query on serverside with all filters. Blog the difference between iqueryable and ienumerable. Technical articles, content and resources for it professionals working in microsoft technologies. Jan 15, 2017 ienumerable in this context is used whenever you want to return the data from the database, until you convert an iqueryable to an ienumerable, the query hasnt been sent to the database for execution.
So when you have to simply iterate through the inmemory collection, use ienumerable, if you need to do any manipulation with the collection like dataset and other data sources, use iqueryable. What is the difference between iqueryable and ienumerable. In linq to query data from database and collections, we use ienumerable and iqueryable for data manipulation. Joining an iqueryable with an ienumerable contains, ienumerable, iqueryable, join, linq with the introduction of linq the difference between writing code for accessing a lists of objects in memory and accessing a list of data in an external data source like sql server is vanishing. The main differences between iqueryable and ienumerable are. While querying data from a database, iqueryable executes a select. Building an iqueryable provider part i the wayward. We should select appropriate container to store data temporarily for fetch and modification process. Iqueryable inherited ienumerable, so it obviously get all the functionality ienumerable has. I also checked out the queryable and enumerable classes in system. An code iqueryable code is a potential code ienumerable code. Jul 30, 2007 this is the first in a series of posts on how to build a linq iqueryable provider.
Possibly i will cover that in next article to strengthen our basic understanding. Whats the difference between iqueryable and ienumerable. Sep 14, 2014 in the end, i think the iqueryable approach is better. Because the developers must understand the concept of iqueryable making sure that queries are fired only once etc. I looked them up on msdn and they seem pretty much the same. This is probably the second most frequent question ive been asked number 1 has to be understanding delegates. Should the repository return ienumerable or iqueryable.
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