Ticket T1192806

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How to use dependency injection in modules

Michael de Vlieger

created a year ago (modified a year ago)

[DevExpress Support Team: CLONED FROM T1191645: How to always call the database updater in E1344 (for scheme changes based on tenants)]
I am trying to add Custom Modules to a solution, based on the tennant.
To perform that, I wrote a test in Blazor Module:

C#
[ActivatorUtilitiesConstructor]
public BlazorModule(ICurrentTennant tennant):this()
{
    this._tennant = tennant;

    if (tennant.Code.ToLower() == "test")
        this.RequiredModuleTypes.Add(typeof(TestModule));
}

public BlazorModule() : base() {
}

It seems not to work.
How to inject in ModuleBase?

Answers approved by DevExpress Support

Anatol (DevExpress)

created a year ago

Hello Michael,

This approach works only for Controllers. To get a service in a module, use the XafApplication.ServiceProvider property, as described in our documentation:
Dependency Injection (DI)
Register Services in the Dependency Injection Container

An XafApplication is passed to a module in the ModuleBase.Setup method: How to: Show Notifications to a Specific User.

Show previous comments (3)

Michael de Vlieger a year ago

So How do I load additional modules based on the current logged in user (tenant information is available in ICurrentTennant). As far as my knowledge reaches, it needs to be done in the constructor.

Dennis Garavsky (DevExpress) a year ago

Hello, Michael.

Custom modules per user/tenant are unsupported in the current XAF Blazor/Web API version (much like custom fields we discussed recently in your other ticket). We will take this requirement into account for the future as we develop our built-in multi-tenancy modules, though I can't give you any promises or ETA.

At present, we recommend that you load all the modules, and disable their features via Controller per user/tenant instead. All the tenants will have the same set of business classes and database tables in their own databases.

Let me know if you have additional questions on current XAF's architecture or our plans regarding multi-tenancy modules, roadmaps, limitations, etc. Ultimately, we want you to succeed with XAF, and at the same time I want to avoid confusion and unrealistic expectations from the platform, as a PM.

Regards,
Dennis

Michael de Vlieger a year ago

Hi Dennis,

Thank you for your response.

I don't care to extend XAF to make this all work, we work for over 15 years with this framework and are very happy with it. We also extended the framework heavily to make it work for us. So we use our own DI container, etc. etc. (I made this partial available on github about a year ago, as you may recall, because you commented on it)
However, we do not see this work in Blazor, as this is a completely new environment for us (so for example: i was surprised, there's no model editor in runtime, but there's some understanding there).

As I am aware, Multi-Tenancy means you have an application which is the same for every one, but actually, with modules you can extend for one customer additional functionality, like for example an accounting application, you can add a module for tax, online payments, bank statements, etc. etc. Customers should pay extra for that. I am on the other hand very understanding, that this is a new feature for xaf, and still work in progress.

This is awesome, because this is the base of XAF in itself. I can create business objects, controllers, additional logic etc. etc. in a module. Another great feature is that I can extend the Model per module. This obviously is priceless to us.

Our standard software in Winforms works this way (We have created > 50 XAF Modules which are loaded, or not, based on the configuration, there's no tenant service there, we used another approach).

Point is:
If you are unable of unwilling (for what reason that may be) to implement this feature. I am willing to write it on my own. However; I should get some directions then, because we are all doing it with extending controllers and adding additional features, I never replaced a certain feature.

Dennis Garavsky (DevExpress) a year ago

Thanks for your warm words, Michael. It's not that we are unwilling to implement this functionality - we want to have it just like you do. This year we are just focusing on the things from our roadmap at https://community.devexpress.com/blogs/xaf/archive/2023/08/24/xaf-cross-platform-net-app-ui-amp-web-api-service-year-end-roadmap-v23-2.aspx. As part of this huge undertaking, we hope to ship the first version of our multi-tenancy module with the most requested basic functionality. Then we hope to gather additional user feedback and iterate in v24.1, v24.2 or even drop this idea completely, if our implementation does not have the same traction, for instance, as our Web API Service did a year ago. If you read my previous roadmaps, then you also saw that feature licensing or module management for tenants is a part of our long-term vision. It's just not planned for this year, because we have more important things to do based on user feedback and our existing resources.

I also can't give you exact instructions on how to build this feature yourself, because it's like asking me to make a car designed for roads to fly, in your garage (we have not yet done it ourselves yet + it requires architectural changes at the core level, which you will unlikely would be able to implement on your side). It's also not about replacing A with B and overriding C in a few places - it's building a totally new car engine, wheels, and adding wings, probably preserving a similar color or body shape.
For more information on such advanced tasks, I can only recommend that you study the source code of XAF's core (like types info system, application model, module manager, XafApplication, etc.), because you will see all the insights and explanations yourself - this sort of tasks is a way beyond our support service regardless how much I am willing to help you.

As for general directions, I gave you them previously, and that is the best we can do here:

At present, we recommend that you load all the modules, and disable their features via Controller per user/tenant instead. All the tenants will have the same set of business classes and database tables in their own databases.

My idea is to act like there are no modules per tenant and setup XafApplication.Modules with all the modules you have, much like in a default XAF project setup. Then, disable certain standard and custom module features based on required conditions at runtime.
I believe you already implemented such things multiple times considering your past experience with XAF (no Blazor specificities here). Our docs are also full of examples where certain standar or custom features are disabled or added for all or a certain user at runtime:

Reviewing my advice for advanced tasks from https://www.devexpress.com/products/net/application_framework/xaf-considerations-for-newcomers.xml may also help you.

I hope this makes sense and helps you move forward the best way for your business/projects. If not, then probably waiting for our potential built-in implementation one day (no promises/ETA) or building your own multi-tenancy solution without XAF are better options for you and your dev team.

Michael de Vlieger a year ago

Hi Dennis,

I was not trying to offend you by considering unwillingness. There may be a lot of good reasons to not wanting to Implement my personal requests (although I think my requests are all sound ).

I understand all of what you told and I agree with you. I think it May indeed be too complex to implement it myself. Not working with expressapp does not sound like a great solution for me.

I will work around it as long as required.and will keep you informed.

Please note I am used to the freedom of winforms (working with devexpress products since version 7.1) and not that much into web, so I am just trying…

Dennis Garavsky (DevExpress) a year ago

No worries, Michael.

Yeah, the client-server architecture of distributed/Web apps and API services is totally different from "fat" WinForms clients, and requires a lot of additional considerations (unrelated to DevExpress/XAF directly).

My team and I (and probably other XAFers) will be happy to hear of your results/implementations as you go - thanks.

Created: September 29, 2023 6:10 AM

Modified: October 2, 2023 9:56 PM

Platform: App Frameworks (UI, API, ORM)

Product: XAF Blazor (Cross-Platform .NET App UI)

Framework / Specific: XPO

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How to use dependency injection in modules

Answers approved by DevExpress Support

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