FluentValidation使用方法

安装包FluentValidation与FluentValidation.AspNetCore

新建GreetingCommand.cs文件

using FluentValidation;
using MediatR;

namespace WebApplication1
{
    public class GreetingCommand : IRequest<string>
    {
        public string Name { get; set; }
        public string? Age { get; set; }
    }

    public class GreetingCommandHandler : IRequestHandler<GreetingCommand, string>
    {
        public Task<string> Handle(GreetingCommand request, CancellationToken cancellationToken)
        {
            return Task.FromResult($"Hello, {request.Name}!");
        }
    }

    public class GreetingCommandValidator : AbstractValidator<GreetingCommand>
    {
        public GreetingCommandValidator()
        {
            RuleFor(v => v.Age).NotEmpty().WithMessage("年龄不能为空");
        }
    }


    public class ValidationBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
        where TRequest : IRequest<TResponse>
    {
        private readonly IEnumerable<IValidator<TRequest>> _validators;

        public ValidationBehavior(IEnumerable<IValidator<TRequest>> validators)
        {
            _validators = validators;
        }

        public async Task<TResponse> Handle(TRequest request, RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken)
        {
            var context = new ValidationContext<TRequest>(request);

            var failures = _validators
                .Select(v => v.Validate(context))
                .SelectMany(result => result.Errors)
                .Where(f => f != null)
                .ToList();

            if (failures.Count != 0)
            {
                throw new ValidationException(failures);
            }

            return await next();
        }
    }
}

修改Program.cs文件

using WebApplication1;

using FluentValidation;
using FluentValidation.AspNetCore;
using MediatR;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.  

builder.Services.AddControllers();

builder.Services.AddValidatorsFromAssemblyContaining<GreetingCommandValidator>();//注册FluentValidation
builder.Services.AddFluentValidationAutoValidation(); //让FluentValidation验证webapi的输入参数
// MediatR 注入FluentValidation验证
//builder.Services.AddTransient(typeof(IPipelineBehavior<,>), typeof(ValidationBehavior<,>));

// Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi  
builder.Services.AddOpenApi();
//builder.Services.AddSwaggerGen();

// Fix: Use the correct overload for AddMediatR  
builder.Services.AddMediatR(cfg => cfg.RegisterServicesFromAssembly(typeof(GreetingCommandHandler).Assembly));

var app = builder.Build();

// Configure the HTTP request pipeline.  
//if (app.Environment.IsDevelopment())
{
    app.MapOpenApi();
    //app.UseSwagger();
    app.UseSwaggerUI(options =>
    {
        options.SwaggerEndpoint("/openapi/v1.json", "v1");
    });
}

app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

app.Run();