Breeze Sharp with Blazor¶
Note
What you will read here are my personal opinions. I have been using Breeze from years for both web and desktop applications and I have no connection with Breeze team.
Recommended CRUD API design is too verborse and boring.
For each CRUD action Create, Read, Update and Delete you have to add a method to your API controller. Also you have to repeat the same pattern for every entity of your application domain.
In real use cases you cannot perform also single actions on entities, because changes have to happen at the same time in a transaction. So you have to write other code…
Do you know good coders are lazy? Do you know the DRY principle?
The solution is a Breeze Controller.
As you can read in the official documentation: “One controller to rule them all …”.
Breeze Server¶
In this project the Breeze Controller is ApplicationController and the EFPersistenceManager is ApplicationPersistenceManager.
The ApplicationController has no Authorize attribute, because to keep policy management with Breeze, I implemented a simple custom policy management in ApplicationPersistenceManager.
First of all you can mark the EF entities with Permissions attribute which takes CRUD Actions flag enum as parameter. Examples:
[Permissions(Actions.Delete)]
public partial class Todo
{
...
}
[Permissions(Actions.Create | Actions.Update)]
public partial class Todo
{
...
}
[Permissions(Actions.CRUD)]
public partial class Todo
{
...
}
In BeforeSaveEntities method of ApplicationPersistenceManager the actions of the entities to be saved are compared with the claims of permission type of the current user. If a policy is violated an EntityErrorsException is thrown.
To check Actions.Read in ApplicationController you have to access EF DbSet with GetEntities method of ApplicationPersistenceManager.
Breeze.Sharp (Breeze C# client)¶
To access Breeze Controller you have to use Breeze.Sharp. In Blazor BlazorBoilerplate ApiClient is what you need to query ApplicationController. You can inject IApiClient in every Razor page where entities are requested.
The Breeze.Sharp entities are the so called DTO and you should create one for every entities of your Entity Framework context in EF entities. To avoid repetitive tasks, I created EntityGenerator based on Source Generators. Every time you update EF entities, rebuild BlazorBoilerplate.Shared project to have Breeze entities automatically generated with namespace BlazorBoilerplate.Shared.Dto.Db.
Notes¶
At the moment Todo is the only entity used to demonstrate Breeze.Sharp capabilities. In fact you can extend the use to all other entities, but administrative entities (users, roles, etc.) are managed by others libraries like ASP.NET Core Identity and IdentityServer4, so I preferred to keep the dedicated AdminController.
If you think that is all wonderful, here it comes the drawback.
The used of C# as a replacement of javascript is something very new: it is the Blazor revolution. So till now Breeze.Sharp has been used a little only on desktop application. In fact the most used Breeze client is the javascript client BreezeJS and Breeze itself is not .NET centric.
For this reason breeze.sharp library is rarely updated, so to make BlazorBoilerplate working with Breeze I used my fork GioviQ/breeze.sharp where I fixed some issues. You can find the package in https://www.nuget.org/packages/Breeze.Sharp.Standard.Fork/.