abp/docs/en/Blog-Posts/2021-01-14 v4_2_Preview/POST.md

ABP Framework 4.2 RC Has Been Published

Today, we have released the ABP Framework and the ABP Commercial 4.2.0 RC (Release Candidate). This blog post introduces the new features and important changes in this new version.

The planned release date for the 4.2.0 final version is January 28, 2021.

Get Started with the 4.2 RC

If you want to try the version 4.2.0 today, follow the steps below;

1. Upgrade the ABP CLI to the version 4.2.0-rc.1 using a command line terminal:

dotnet tool update Volo.Abp.Cli -g --version 4.2.0-rc.1

or install if you haven't installed before:

dotnet tool install Volo.Abp.Cli -g --version 4.2.0-rc.1

2. Create a new application with the --preview option:

abp new BookStore --preview

See the ABP CLI documentation for all the available options.

You can also use the Direct Download tab on the Get Started page by selecting the Preview checkbox.

What's new with the ABP Framework 4.2

IRepository.GetQueryableAsync()

This version comes with an important change about using IQueryable features over the repositories. It is suggested to read this section carefully and apply in your applications.

IRepository interface inherits IQueryable, so you can directly use the standard LINQ extension methods, like Where, OrderBy, First, Sum... etc.

Example: Using LINQ directly over the repository object

public class BookAppService : ApplicationService, IBookAppService
{
    private readonly IRepository<Book, Guid> _bookRepository;

    public BookAppService(IRepository<Book, Guid> bookRepository)
    {
        _bookRepository = bookRepository;
    }

    public async Task DoItInOldWayAsync()
    {
        //Apply any standard LINQ extension method
        var query = _bookRepository
            .Where(x => x.Price > 10)
            .OrderBy(x => x.Name);

        //Execute the query asynchronously
        var books = await AsyncExecuter.ToListAsync(query);
    }
}

See the documentation if you wonder what is the AsyncExecuter.

Beginning from the version 4.2, the recommended way is using IRepository.GetQueryableAsync() to obtain an IQueryable, then use the LINQ extension methods over it.

Example: Using the new GetQueryableAsync method

public async Task DoItInNewWayAsync()
{
    //Use GetQueryableAsync to obtain the IQueryable<Book> first
    var queryable = await _bookRepository.GetQueryableAsync();

    //Then apply any standard LINQ extension method
    var query = queryable
        .Where(x => x.Price > 10)
        .OrderBy(x => x.Name);

    //Finally, execute the query asynchronously
    var books = await AsyncExecuter.ToListAsync(query);
}

ABP may start a database transaction when you get an IQueryable (If current Unit Of Work is transactional). In this new way, it is possible to start the database transaction in an asynchronous way. Previously, we could not get the advantage of asynchronous while starting the transactions.

The new way has a significant performance and scalability gain. The old usage (directly using LINQ over the repositories) will be removed in the next major version. You have a lot of time for the change, but we recommend to immediately take the action since the old usage has a big scalability problem.

About IRepository Async Extension Methods

Using IRepository Async Extension Methods has no such a problem. The examples below are pretty fine:

var countAll = await _personRepository
    .CountAsync();

var count = await _personRepository
    .CountAsync(x => x.Name.StartsWith("A"));

var book1984 = await _bookRepository
    .FirstOrDefaultAsync(x => x.Name == "John");   

See the repository documentation to understand the relation between IQueryable and asynchronous operations.

Repository Bulk Operations

This version adds the following methods to the repositories:

• InsertManyAsync
• UpdateManyAsync
• DeleteManyAsync

The purpose of these methods to insert, update or delete many entities in one call with a better performance.

Currently, MongoDB provider implements these methods as a single bulk operation since MongoDB API natively supports. But current Entity Framework Core implementation is not a real bulk operation. Instead, it does its best with the native API of the EF Core. If you want to implement in a more performant way, you can customize the bulk operations with your own implementation or by using a library. We could find a good open source library for EF Core 5.0 to implement it.

Selecting DBMS on Template Creation

And DbMigrator creates the initial migration if no migration exists.

TODO

Angular Unit Testing

We've improved the modules and the startup template to setup and write unit tests easier with the Angular UI. See the Angular Unit Testing document for details.

Other News

• Improved HTTP request-response performance by resolving dependencies in a deferred way in the action/page filters, interceptors and some other services.
• Removed MultipleActiveResultSets from connection strings for new templates for SQL Server, since the new EF Core gives a warning when using it. If you want to use it, you need to change the connection string yourself.
• Added HardDeleteAsync extension method that takes a predicate to delete multiple entities. This extension method is available if the entity Soft Delete.
• Implemented the Page Alerts for Angular UI.
• Implemented Page Progressbar. It automatically shows an undetermined progress bar on top of the page while performing an AJAX request. It also proves an API to you if you need to show/hide the progress bar in your code.

What's new with the ABP Commercial 4.2

TODO

ABP Commercial

TODO

About the Next Release(s)

TODO

Feedback

Please check out the ABP Framework 4.2.0 RC and provide feedback to help us to release a more stable version. The planned release date for the 4.2.0 final version is January 28, 2021.