MediatRItemExtensionV2K19

MediatRItemExtension scaffolds the MediatR + FluentValidation boilerplate you write by hand on every feature: the operation class (Query, Command, Notification, or Stream), its handler, and its validator. You fill in a name and a few options in a tool window, click confirm, and the extension creates the files in the selected project folder — using directives included.

It targets developers working in Visual Studio 2019 or 2022 (also work on 2026) who already use MediatR and FluentValidation in their projects and want to stop writing the same structural boilerplate for every operation.

Prerequisites: the target project must already reference the MediatR and FluentValidation NuGet packages. The extension adds using directives that reference those namespaces; it does not install the packages itself.

Overview

Activate the extension from any project folder via right-click → MediatR Items Creation, or with the keyboard shortcut SHIFT + INSERT + M.

The tool window lets you configure the operation type, execution model (sync/async), blueprint type (class or record), response type, file layout, and the operation name — then generates all required files in one step.

Features

Save all classes in one file
Create a file for each class
Add import references (for MediatR and FluentValidation)
Select how the request will be executed: Sync or Async
Select which type of operation you want to create
Specify the name of the folder/file
Use one name for the folder/file where information will be stored
Select option if you want to add IStringLocalizer to the Validator or/and to the Handler
Specify any base class to add to the operation class (Query, Command, Notification, Stream)
Select the operation blueprint: Class or Record

Example output

The examples below show what the extension generates. Class names and namespaces are derived from the name you enter in the tool window.

Query operation and handler

using System.Threading;
using MediatR;
using System;
using System.Threading.Tasks;

namespace ProjectNamespace.GetArticle
{
    public class GetArticleQuery : IRequest<int>
    {
    }

    public class GetArticleHandler : IRequestHandler<GetArticleQuery, int>
    {
        public async Task<int> Handle(GetArticleQuery request, CancellationToken cancellationToken)
        {
            throw new NotImplementedException();
        }
    }
}

Validator

using FluentValidation;

namespace ProjectNamespace.GetArticle
{
    public class GetArticleValidator : AbstractValidator<GetArticleQuery>
    {
    }
}

With IStringLocalizer injected

When you check Add to Validator and Add to Handler, the extension adds the IStringLocalizer constructor parameter to both generated classes:

using Microsoft.Extensions.Localization;
using FluentValidation;

namespace ProjectNamespace.GetArticle
{
    public class GetArticleValidator : AbstractValidator<GetArticleQuery>
    {
        public GetArticleValidator(IStringLocalizer stringLocalizer)
        {
        }
    }
}

using Microsoft.Extensions.Localization;
using System.Threading;
using MediatR;
using System;
using System.Threading.Tasks;

namespace ProjectNamespace.GetArticle
{
    public class GetArticleHandler : IRequestHandler<GetArticleQuery, int>
    {
        public GetArticleHandler(IStringLocalizer stringLocalizer)
        {
        }

        public async Task<int> Handle(GetArticleQuery request, CancellationToken cancellationToken)
        {
            throw new NotImplementedException();
        }
    }
}

Class vs Record blueprint

Selecting Record as the blueprint type changes the operation declaration keyword. Everything else (handler, validator, file layout) stays the same.

// Blueprint: Class
public class GetArticleQuery : IRequest<int>
{
}

// Blueprint: Record
public record GetArticleQuery : IRequest<int>
{
}

Operation inheritance

When you fill in the Operation inheritance field, the specified base class is inserted before the MediatR interface in the declaration:

public class GetArticleQuery : BaseClass, IRequest<int>
{
}

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