(MVC 6) How to get an instance of IServiceProvider after a class is instantiated.

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Sergey Sagan

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Feb 25, 2016, 10:31:10 PM2/25/16

to Autofac

Unfortunately, as of right now, MVC requires that it be added as a service in ConfigureServices before Autofac is Built() that means for a Custom Model Binder that needs IServiceProvider can't get it injected in the constructor.

We add our model binder like this:

services.AddMvc().AddMvcOptions(options =>

{

options.ModelBinders.Clear();

options.ModelBinders.Add(new IoCModelBinder());

});

and the binder itself looks like this:

public class IoCModelBinder : IModelBinder

{

internal static IServiceProvider ServiceProvider { get; set; }

public Task<ModelBindingResult> BindModelAsync(ModelBindingContext bindingContext)

{

var model = ServiceProvider.GetService(bindingContext.ModelType);

bindingContext.Model = model;

var binder = new GenericModelBinder();

return binder.BindModelAsync(bindingContext);

}

At this point, we have to manually set the ServiceProvider property from ConfigureServices after the DI is built! I know, super hacky. We'd like to somehow resolve it inside our BindModelAsync method. Basically make it look like this:

public class IoCModelBinder : IModelBinder

{

private IServiceProvider serviceProvider;

public Task<ModelBindingResult> BindModelAsync(ModelBindingContext bindingContext)

{

if (serviceProvider == null)

serviceProvider = RESOLVETHISTHING<IServiceProvider >();

var model = serviceProvider .GetService(bindingContext.ModelType);

bindingContext.Model = model;

var binder = new GenericModelBinder();

return binder.BindModelAsync(bindingContext);

}

How do we do it?

Travis Illig

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Feb 26, 2016, 11:43:33 AM2/26/16

to Autofac

I'm not sure if you've asked them, but since Autofac (and other IoC containers) are now all abstracted out by Microsoft.Extensions.DependencyInjection, this might be a good question for the MVC team. The answer will be the same for every IoC integration.