Shulou(Shulou.com)06/02 Report--

Today, I will talk to you about how to simply implement a custom LINQ provider, which may not be well understood by many people. in order to make you understand better, the editor has summarized the following content for you. I hope you can get something from this article.

If you want to do good work, you must first sharpen its tools. This truth is applicable everywhere, whether it is the traditional manufacturing industry or today's software development industry. Take custom LINQ providers, for example, and today's development is changing with each passing day.

With the official release of .NET 3.5, implementations of custom LINQ providers are springing up. It takes a lot of effort to develop your own custom LINQ provider, but Mehfuz Hossain makes it easy to develop your own custom LINQ provider through his open source project, LinqExtender.

In his introduction to LinqExtender, Mehfuz Hossain introduced LinqExtender as follows:

LinqExtender exposes a model that allows developers to focus on the application logic rather than the internal mechanism of the query when creating a custom provider. It sits between the custom LINQ framework and the custom provider.

LinqExtender helps us do a lot of expression parsing and processing so that we can implement our own custom LINQ provider without using a library like Reflection.

LinqExtender mainly provides two base classes to help develop custom LINQ providers: QueryObjectBase and Query.

In order to introduce the use of LinqExtender, Mehfuz Hossain also gives a simple custom LINQ provider implementation-OpenLinqToSql. The basic implementation of OpenLinqToSql is as follows:

The entity class needs to inherit from the QueryObjectBase base class:

Class Book: QueryObjectBase {[LinqVisible, Identity] public int? Id {get; set;} [LinqVisible] public string Author {get; set;} [LinqVisible] public string Title {get; set;} [LinqVisible] public string ISBN {get; set;} [LinqVisible] public DateTime? LastUpdated {get; set;} public override bool IsNew {get {return Id = = null;}

The core class of a custom LINQ provider needs to inherit from the Query base class:

Public class SqlQuery: Query where T: QueryObjectBase {.... .... }

To implement the processing of SQL, you need to encode according to the following logic:

If (bucket.ItemsToTake! = null) {/ / 1.Build Select statement using WITH} else {/ / 2.General select statement followed by order by, if any} / / 3. Run query and fill IModify collection.

Although using LinqExtender can help developers easily implement their own custom LINQ provider, it is not so mature and complete, for example, the current version 1.3 lacks support for clauses such as Group and Join, and requiring entity classes to inherit from the QueryObjectBase base class is also a big weakness. Undefined

After reading the above, do you have any further understanding of how to easily implement a custom LINQ provider? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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