AzureGems.MediatR.Extensions 3.0.1

AzureGems MediatR Extensions

Extension library for the popular MediatR library by Jimmy Bogard to add clear distinction between requests without any side-effects (aka Reads or Queries) or requests with side-effects (aka Writes or Commands).

Queries and QueryHandlers

Create a Query class and inherit from IQuery<out TResult>:

public class GetRecipeByName : IQuery<Recipe>
{
    public string RecipeName {get; set;}
    ...
}

To send / execute the query, use the SendQuery() extension on the standard IMediator interface.

var yummySpaghetti = new GetRecipeByName()
{
    RecipeName = "Spaghetti Bolognese"
}

Recipe recipe = await _mediator.SendQuery(yummySpaghetti);

Create a handler for the GetRecipe query that executes the required business logic to obtain a result:

public class GetRecipeHandler : IQueryHandler<GetRecipe, Recipe>
{
    ...
    public async Task<Recipe> Handle(GetRecipe query, CancellationToken ct)
    {
        ...
    }
}

Commands & CommandHandlers

Create a Command class and inherit from ICommand<out TResult>:

public class CreateRecipe : ICommand<Guid>
{
    public string Name {get; set;}
    public string Cuisine {get; set;}
    public Ingredient[] Ingredients {get; set;}
    ...
}

To send / execute the command, use the SendCommand() extension on the standard IMediator interface.

var yummySpaghetti = new CreateRecipe()
{
    Name = "Spaghetti Bolognese",
    Cuisine = "Italian",
    Ingredients = new[]
    {
        new Ingredient() { Name = "Spaghetti", WeightInGrams = "500"},
        new Ingredient() { Name = "Bolognese Sauce", VolumeInMilliliters = "500"},
        new Ingredient() { Name = "Parmesan cheese", WeightInGrams = "250"},
    }
}

Guid recipeId = await _mediator.SendCommand(yummySpaghetti);

Create a handler for the CreateRecipe command that executes the required business logic:

public class CreateRecipeHandler : ICommandHandler<CreateRecipe, Guid>
{
    ...
    public async Task<Guid> Handle(CreateRecipe cmd, CancellationToken ct)
    {
        ...
    }
}