Windows 10: Entity Framework Core 3.0 Preview 9 and Entity Framework 6.3 Preview 9

Brink · Sep 5, 2019

The Preview 9 versions of the EF Core 3.0 package and the EF 6.3 package are now available for download from nuget.org.

These are the last planned previews before we release the final versions later this month. We have almost completely stopped making changes to the product code, but we are still actively monitoring feedback for any important bugs that may be reported. So please install the previews to validate that all the functionality required by your applications is available and works correctly, and report any issues you find to either the EF Core issue tracker or the EF 6 issue tracker on GitHub.

Even if we may not be able to fix many more issues in EF Core 3.0 at this point, we’ll consider important bugs and regressions for the upcoming 3.1 release.

What’s new in EF Core 3.0 Preview 9

Besides all the other improvements in EF Core 3.0, preview 9 includes fixes for more than 100 issues that we resolved since Preview 8. Here are a few highlights:

Support for translating queries that project a single result form a collection using window functions (issue #10001)

Support for translating queries with constants or parameters in the GROUP BY key (issue #14152).

Improvements to our thread concurrency detection logic to reduce false positives (issue #14534).

Consider installing daily builds

In Preview 9 the functionality of the in-memory provider is still very limited, but this is already fixed in our daily builds. In fact, we have already fixed more than 20 issues that aren’t included in Preview 9, and we may still fix a few more before RTM.

Detailed instructions to install daily builds, including the necessary NuGet feeds, can be found in the How to get daily builds of ASP.NET Core article.

Common workarounds for LINQ queries

The LINQ implementation in EF Core 3.0 is designed to work very differently from the one used in previous versions of EF Core. For this reason, you are likely to run into issues with LINQ queries, especially when upgrading existing applications. Here are some workarounds that might help you get things working:

Try a daily build (as previously mentioned) to confirm that you aren’t hitting an issue that has already been fixed.

Switch to client evaluation explicitly: If your query filters data based on an expression that cannot be translated to SQL, you may need to switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync() in the middle of the query. For example, the following query will no longer work in EF Core 3.0 because one of the predicates in the where clause requires client evaluation:

1
2 var specialCustomers = context.Customers
.Where(c => c.Name.StartsWith(n) && IsSpecialCustomer(c));
But if you know it is reasonable to process part of the filter on the client, you can rewrite the query as:

1
2
3
4 var specialCustomers = context.Customers
.Where(c => c.Name.StartsWith(n))
.AsEnumerable() // Start using LINQ to Objects (switch to client evaluation)
.Where(c => IsSpecialCustomer(c));
Remember that this is by-design: In EF Core 3.0, LINQ operations that cannot be translated to SQL are no longer automatically evaluated on the client.

Use raw SQL queries: If some expression in your LINQ query is not translated correctly (or at all) to SQL, but you know what translation you would want to have generated, you may be able to work around the issue by executing your own SQL statement using the FromSqlRaw() or FromSqlInterpolated() methods.Also make sure an issue exists in our issue tracker on GitHub to support the translation of the specific expression.

Breaking changes

All breaking changes in this release are listed in the Breaking changes in EF Core 3.0 article. We keep the list up to date on every preview, with the most impactful changes near the top of the list, to make it easier for you to react.

Obtaining the Preview 9 packages

EF Core 3.0 is distributed exclusively as NuGet packages. As usual, add or upgrade the runtime to Preview 9 via the NuGet user interface, the Package Manager Console in Visual Studio, or via the dotnet add package command. In all cases, include the option to allow installing pre-release versions. For example, you can execute the following command to install the SQL Server provider:

1 dotnet add package Microsoft.EntityFrameworkCore.SqlServer --version 3.0.0-*
With .NET Core 3.0, the dotnet ef command-line tool is no longer included in the .NET Core SDK. Before you can execute EF Core migration or scaffolding commands, you’ll have to install it as either a global or local tool. Due to limitations in dotnet tool install, installing preview tools requires specifying at least part of the preview version on the installation command. For example, to install the 3.0 Preview 9 version of dotnet ef as a global tool, execute the following command:

1 dotnet tool install --global dotnet-ef --version 3.0.0-*
What’s new in EF 6.3 Preview 9

All of the work planned for the EF 6.3 package has been completed. We are now focused on monitoring your feedback and fixing any important bugs that may be reported.
As with EF Core, any bug fixes that happened after we branched for Preview 9 are available in our daily builds.

How to work with EDMX files in .NET Core projects

On the tooling side, we plan to release an updated EF6 designer in an upcoming update of Visual Studio 2019 which will work with projects that target .NET Core (tracked in issue #883).

Until this new version of the designer is available, we recommend that you work with your EDMX files inside projects that target .NET Framework. You can then add the EDMX file and the generated classes for the entities and the DbContext as linked files to a .NET Core 3.0 or .NET Standard 2.1 project in the same solution. For example, the project file for the .NET Core project can include the linked files like this:

1
2
3
4
5
6 <ItemGroup>
<EntityDeploy Include="..\EdmxDesignHost\Entities.edmx" Link="Model\Entities.edmx" />
<Compile Include="..\EdmxDesignHost\Entities.Context.cs" Link="Model\Entities.Context.cs" />
<Compile Include="..\EdmxDesignHost\Thing.cs" Link="Model\Thing.cs" />
<Compile Include="..\EdmxDesignHost\Person.cs" Link="Model\Person.cs" />
</ItemGroup>
Note that the EDMX file is linked with the EntityDeploy build action. This is a special MSBuild task (now included in the EF 6.3 package) that takes care of adding the EF model into the target assembly as embedded resources (or copying it as files in the output folder, depending on the setting on the Metadata Artifact Processing setting in the EDMX). For more details on how to get this set up, see our EDMX .NET Core sample.

You can choose to copy the files instead of linking them, but keep in mind that due to a bug in current builds of Visual Studio, copying the files from the .NET Framework project to the .NET Core project within Solution Explorer may cause hangs, so it is better to copy the files from the command line.

Feedback requested: Should we build a dotnet ef6 tool?

We are also seeking feedback and possible contributions to enable a cross-platform command line experience for migrations commands, similar to dotnet ef but for EF6 (tracked in issue #1053). If you would like to see this happen, or if you would like to contribute to it, please vote or comment on the issue.

Weekly status updates

If you’d like to track our progress more closely, we now publish weekly status updates to GitHub. We also post these status updates to our Twitter account, @efmagicunicorns.

Thank you

Once more, thank you for trying our preview bits, and for all the bug reports and contributions that will help make EF Core 3.0 and EF 6.3 much better releases.

Diego Vega,
Program Manager , .NET Data Access
Click to expand...

Source: https://devblogs.microsoft.com/dotne...6-3-preview-9/

:)

Brink · Sep 5, 2019

Announcing .NET Core 3 Preview 4

Today, we are announcing .NET Core 3.0 Preview 4. It includes a chart control for Windows Forms, HTTP/2 support, GC updates to use less memory, support for CPU limits with Docker, the addition of PowerShell in .NET Core SDK Docker container images, and other improvements. If you missed it, check out the improvements we released in .NET Core 3.0 Preview 3 just last month.

Download .NET Core 3 Preview 4 right now on Windows, macOS and Linux.

ASP.NET Core and Entity Framework Core updates are also being released today.
Click to expand...

Read more: Announcing .NET Core 3 Preview 4 | .NET Blog

Brink · Sep 5, 2019

Announcing Entity Framework Core 2.2
Today we’re making the final version of EF Core 2.2 available, alongside ASP.NET Core 2.2 and .NET Core 2.2. This is the latest release of our open-source and cross-platform object-database mapping technology.

EF Core 2.2 RTM includes more than a hundred bug fixes and a few new features:

Spatial data support

Spatial data can be used to represent the physical location and shape of objects. Many databases can natively store, index, and query spatial data. Common scenarios include querying for objects within a given distance, and testing if a polygon contains a given location. EF Core 2.2 now supports working with spatial data from various databases using types from the NetTopologySuite (NTS) library.

Spatial data support is implemented as a series of provider-specific extension packages. Each of these packages contributes mappings for NTS types and methods, and the corresponding spatial types and functions in the database. Such provider extensions are now available for SQL Server, SQLite, and PostgreSQL (from the Npgsql project). Spatial types can be used directly with the EF Core in-memory provider without additional extensions.

Once the provider extension is installed, you can add properties of supported types to your entities. For example:

Code:
Code:
using NetTopologySuite.Geometries;  namespace MyApp {   public class Friend   {     [Key]     public string Name { get; set; }      [Required]     public Point Location { get; set; }   } }
You can then persist entities with spatial data:

Code:
Code:
using (var context = new MyDbContext()) {     context.Add(         new Friend         {             Name = "Bill",             Location = new Point(-122.34877, 47.6233355) {SRID = 4326 }         });     context.SaveChanges(); }
And you can execute database queries based on spatial data and operations:

Code:
Code:
  var nearestFriends =       (from f in context.Friends       orderby f.Location.Distance(myLocation) descending       select f).Take(5).ToList();
For more information on this feature, see the spatial data documentation.

Collections of owned entities

EF Core 2.0 added the ability to model ownership in one-to-one associations. EF Core 2.2 extends the ability to express ownership to one-to-many associations. Ownership helps constrain how entities are used.

For example, owned entities: – Can only ever appear on navigation properties of other entity types. – Are automatically loaded, and can only be tracked by a DbContext alongside their owner.

In relational databases, owned collections are mapped to separate tables from the owner, just like regular one-to-many associations. But in document-oriented databases, we plan to nest owned entities (in owned collections or references) within the same document as the owner.

You can use the feature by calling the new OwnsMany() API:

Code:
Code:
modelBuilder.Entity<Customer>().OwnsMany(c => c.Addresses);
For more information, see the updated owned entities documentation.

Query tags

This feature simplifies the correlation of LINQ queries in code with generated SQL queries captured in logs.

To take advantage of query tags, you annotate a LINQ query using the new TagWith() method. Using the spatial query from a previous example:

Code:
Code:
  var nearestFriends =       (from f in context.Friends.TagWith(@"This is my spatial query!")       orderby f.Location.Distance(myLocation) descending       select f).Take(5).ToList();
This LINQ query will produce the following SQL output:

Code:
Code:
-- This is my spatial query!  SELECT TOP(@__p_1) [f].[Name], [f].[Location] FROM [Friends] AS [f] ORDER BY [f].[Location].STDistance(@__myLocation_0) DESC
For more information, see the query tags documentation.

Getting EF Core 2.2

The EF Core NuGet packages are available on the NuGet Gallery, and also as part of ASP.NET Core 2.2 and the new .NET Core SDK.

If you want to use EF Core in an application based on ASP.NET Core, we recommend that first you upgrade your application to ASP.NET Core 2.2.

In general, the best way to use EF Core in an application is to install the corresponding NuGet package for the provider your application will use. For example, to add the 2.2 version of the SQL Server provider in a .NET Core project from the command line, use:

Code:
Code:
$ dotnet add package Microsoft.EntityFrameworkCore.SqlServer -v 2.2.0
Or from the Package Manager Console in Visual Studio:

Code:
Code:
PM> Install-Package Microsoft.EntityFrameworkCore.SqlServer -Version 2.2.0
For more information on how to add EF Core to your projects, see our documentation on Installing Entity Framework Core.

Compatibility with EF Core 2.1

We spent much time and effort making sure that EF Core 2.2 is backwards compatible with existing EF Core 2.1 providers, and that updating an application to build on EF Core 2.2 won’t cause compatibility issues. We expect most upgrades to be smooth, however if you find any unexpected issues, please report them to our issue tracker.

There is one known change in EF Core 2.2 that could require minor updates in application code. Read the description of the following issue for more details:

#13986 Type configured as both owned entity and regular entity requires a primary key to be defined after upgrading from 2.1 to 2.2

We intend to maintain a list of issues that may require adjustments to existing code on our issue tracker.

What’s next: EF Core 3.0

With EF Core 2.2 out the door, our main focus is now EF Core 3.0. There are several details of the next major release that we still need to figure out, but here are some of the main themes we know so far:

LINQ improvements: LINQ enables you to write database queries without leaving your language of choice, taking advantage of rich type information to get IntelliSense and compile-time type checking. But LINQ also enables you to write an unlimited number of complicated queries, and that has always been a huge challenge for LINQ providers. In the first few versions of EF Core, we solved that in part by figuring out what portions of a query could be translated to SQL, and then by allowing the rest of the query to execute in memory on the client. This client-side execution can be desirable in some situations, but in many other cases it can result in inefficient queries that may not identified until an application is deployed to production. In EF Core 3.0, we are planning to make profound changes to how our LINQ implementation works, and how we test it. The goals are to make it more robust (for example, to avoid breaking queries in patch releases), to be able to translate more expressions correctly into SQL, to generate efficient queries in more cases, and to prevent inefficient queries from going undetected.

Cosmos DB support: We’re working on a Cosmos DB provider for EF Core, to enable developers familiar with the EF programing model to easily target Azure Cosmos DB as an application database. The goal is to make some of the advantages of Cosmos DB, like global distribution, “always on” availability, elastic scalability, and low latency, even more accessible to .NET developers. The provider will enable most EF Core features, like automatic change tracking, LINQ, and value conversions, against the SQL API in Cosmos DB. We started this effort before EF Core 2.2, and we have made some preview versions of the provider available. The new plan is to continue developing the provider alongside EF Core 3.0.

C# 8.0 support: We want our customers to take advantage some of the new features coming in C# 8.0 like async streams (including await for each) and nullable reference types while using EF Core.

Reverse engineering database views into query types: In EF Core 2.1, we added support for query types, which can represent data that can be read from the database, but cannot be updated. Query types are a great fit for mapping database views, so in EF Core 3.0, we would like to automate the creation of query types for database views.

Property bag entities: This feature is about enabling entities that store data in indexed properties instead of regular properties, and also about being able to use instances of the same .NET class (potentially something as simple as a Dictionary<string, object>) to represent different entity types in the same EF Core model. This feature is a stepping stone to support many-to-many relationships without a join entity, which is one of the most requested improvements for EF Core.

EF 6.3 on .NET Core: We understand that many existing applications use previous versions of EF, and that porting them to EF Core only to take advantage of .NET Core can sometimes require a significant effort. For that reason, we will be adapting the next version of EF 6 to run on .NET Core 3.0. We are doing this to facilitate porting existing applications with minimal changes. There are going to be some limitations (for example, it will require new providers, spatial support with SQL Server won’t be enabled), and there are no new features planned for EF 6.

Thank you

The EF team would like to thank everyone for all the community feedback and contributions that went into EF Core 2.2. Once more, you can report any new issues you find on our issue tracker.
Click to expand...
Source: Announcing Entity Framework Core 2.2 | .NET Blog

Brink · Sep 5, 2019

.NET Core 3 Preview 1 and Open Source Windows Desktop Frameworks

Today, we are announcing .NET Core 3 Preview 1. It is the first public release of .NET Core 3. We have some exciting new features to share and would love your feedback. You can develop .NET Core 3 applications with Visual Studio 2019 Preview 1, Visual Studio for Mac and Visual Studio Code.

Download and get started with .NET Core 3 Preview 1 right now on Windows, Mac and Linux.

You can see complete details of the release in the .NET Core 3 Preview 1 release notes. Please report any issues you find in the comments or at dotnet/core #2099.

Visual Studio 2019 will be the release to support building .NET Core 3 applications and the preview was also released today so we also encourage you to check that out.

.NET Core 3 is a major update which adds support for building Windows desktop applications using Windows Presentation Foundation (WPF), Windows Forms, and Entity Framework 6 (EF6). ASP.NET Core 3 enables client-side development with Razor Components. EF Core 3 will have support for Azure Cosmos DB. It will also include support for C# 8 and .NET Standard 2.1 and much more!

.NET Framework 4.8

Before diving into .NET Core 3 let’s take a quick look at .NET Framework. Next year we will ship .NET Framework 4.8. With monitors supporting 4K and 8K resolutions we are adding better support for high DPI to WPF and Windows Forms. Many .NET applications use browser and media controls, which are based on older versions of Internet Explorer and Windows Media player. We are adding new controls that use the latest browser and media players in Windows 10 and support the latest standards. And WPF and Windows Forms applications will have access to Windows UI XAML Library (WinUI) via XAML Islands for modern look and touch support. Visual Studio 2019 is based on .NET Framework and uses many of these features. For more information on .NET Framework 4.8 see our post: Update on .NET Core 3.0 and .NET Framework 4.8.

Windows Desktop Comes to .NET Core

The first two versions of .NET Core focused primarily on supporting web applications, web APIs, IoT and console applications. .NET Core 3 adds support for building Windows desktop applications using WPF and Windows Forms frameworks and modern controls and Fluent styling from the Windows UI XAML Library (WinUI) via XAML Islands.

Many desktop applications today use Entity Framework for data access and so we are supporting Entity Framework 6 on .NET Core 3 as well. These frameworks enable developers building Windows desktop applications to take advantage of the new features in .NET Core such as side by side deployment, self-contained applications (shipping .NET Core inside the application), the latest improvements in CoreFX, and more.

WPF, Windows Forms, and WinUI Open Sourced

On November 12, 2014 we announced the open sourcing of .NET Core. It has been a tremendous success. The .NET platform has received over 60,000 community accepted pull requests from more than 3700 companies outside of Microsoft.

Today, we are excited to announce that are open sourcing WPF, Windows Forms, and WinUI, so the three major Windows UX technologies will be open sourced. For the first time ever, the community will be able to see the development of WPF, Windows Forms, and WinUI happen in the open and we will take contributions for these frameworks on .NET Core. The first wave of code will be available in GitHub today and more will appear over the next few months.

WPF and Windows Forms projects are under the stewardship of the .NET Foundation which also announced changes today so that the community will directly guide foundation operations. It is also expanding the current sponsors – Red Hat, JetBrains, Google, Unity, Microsoft and Samsung, by also welcoming Pivotal, Progress Telerik and Insight. This new structure will help the .NET Foundation scale to meet the needs of the growing .NET open source ecosystem.

Truly an exciting time to be a .NET developer!
Click to expand...

Read more: Announcing .NET Core 3 Preview 1 and Open Sourcing Windows Desktop Frameworks | .NET Blog

See also: Announcing Open Source of WPF, Windows Forms, and WinUI - Windows 10 Forums

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Windows 10: Entity Framework Core 3.0 Preview 9 and Entity Framework 6.3 Preview 9

Entity Framework Core 3.0 Preview 9 and Entity Framework 6.3 Preview 9

Entity Framework Core 3.0 Preview 9 and Entity Framework 6.3 Preview 9

Entity Framework Core 3.0 Preview 9 and Entity Framework 6.3 Preview 9

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