PM> Install-Package FluentValidation -Version 9.3.0 PM> Install-Package FluentValidation.AspNetCore -Version 9.3.0 PM> Install-Package FluentValidation.DependencyInjectionExtensions -Version 9.3.0using FluentValidation; using FluentValidation.AspNetCore; public void ConfigureServices(IServiceCollection services) { // .. services.AddControllers().AddFluentValidation(); services.AddTransient<IValidator<TDto>, TDtoValidator>(); // .. }public class WithAttributeDto { [Required] [MaxLength(100)] public string Foo { get; set; } [MaxLength(100)] public string Bar { get; set; } [Required] [Range(1, 100)] public int Fizz { get; set; } [Range(1, 100)] public int? Buzz { get; set; } [Required] [DataType(DataType.DateTime)] [Range(typeof(DateTime), "2000-01-01", "3000-01-01")] public DateTime StartDate { get; set; } [Required] [DataType(DataType.DateTime)] [Range(typeof(DateTime), "2000-01-01", "3000-01-01")] public DateTime EndDate { get; set; } } public class WithoutAttributeDto { public string Foo { get; set; } public string Bar { get; set; } public int Fizz { get; set; } public int? Buzz { get; set; } public DateTime StartDate { get; set; } public DateTime EndDate { get; set; } } public class WithoutAttributeDtoValidator : AbstractValidator<WithoutAttributeDto> { public WithoutAttributeDtoValidator() { RuleFor(dto => dto.Foo) .Cascade(CascadeMode.Stop) .NotNull() .WithMessage("Foo should not be null") .NotEmpty() .WithMessage("Foo should not be empty") .MaximumLength(100) .WithMessage("Foo should have a max length of 100"); RuleFor(dto => dto.Bar) .Cascade(CascadeMode.Stop) .NotEmpty() .When(dto => dto.Bar != null, ApplyConditionTo.CurrentValidator) .WithMessage("Bar should not be empty") .MaximumLength(100) .When(dto => dto.Bar != null, ApplyConditionTo.CurrentValidator) .WithMessage("Bar should have a max length of 100"); RuleFor(dto => dto.Fizz) .Cascade(CascadeMode.Stop) .NotNull() .WithMessage("Fizz should not be null") .InclusiveBetween(1, 100) .WithMessage("Fizz should have a value between 1 and 100"); RuleFor(dto => dto.Buzz) .Cascade(CascadeMode.Stop) .InclusiveBetween(1, 100) .When(dto => dto.Buzz.HasValue, ApplyConditionTo.CurrentValidator) .WithMessage("Buzz should have a value between 1 and 100"); RuleFor(dto => dto.StartDate) .Cascade(CascadeMode.Stop) .NotNull() .WithMessage("Start date should not be null") .InclusiveBetween(new DateTime(2000, 1, 1), new DateTime(3000, 1, 1)) .WithMessage("Start date should have a value between 2000-01-01 and 3000-01-01"); RuleFor(dto => dto.EndDate) .Cascade(CascadeMode.Stop) .NotNull() .WithMessage("End date should not be null") .InclusiveBetween(new DateTime(2000, 1, 1), new DateTime(3000, 1, 1)) .WithMessage("End date should have a value between 2000-01-01 and 3000-01-01"); } }[POST] /api/framework-validation/test [POST] /api/fluent-validation/test // Request { "foo": "isRequired", "bar": null, "fizz": 24, "buzz": 42, "startDate": "2020-01-01T12:00:00.000Z", "endDate": "2020-12-31T12:00:00.000Z" } // Response { "foo": "isRequired", "bar": null, "fizz": 24, "buzz": 42, "startDate": "2020-01-01T12:00:00Z", "endDate": "2020-12-31T12:00:00Z" }[POST] /api/framework-validation/test // Request { "foo": "12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901", "bar": "12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901", "fizz": -1, "buzz": -1, "startDate": "1999-12-31T23:59:59.999Z", "_endDate": "1999-12-31T23:59:59.999Z" } // Response { "type": "..", "title": "One or more validation errors occurred.", "status": 400, "traceId": "..", "errors": { "Bar": [ "The field Bar must be a string or array type with a maximum length of '100'." ], "Foo": [ "The field Foo must be a string or array type with a maximum length of '100'." ], "Buzz": [ "The field Buzz must be between 1 and 100." ], "Fizz": [ "The field Fizz must be between 1 and 100." ], "EndDate": [ "The field EndDate must be between 01/01/2000 00:00:00 and 01/01/3000 00:00:00." ], "StartDate": [ "The field StartDate must be between 01/01/2000 00:00:00 and 01/01/3000 00:00:00." ] } }[POST] /api/fluent-validation/test // Request { "foo": "12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901", "bar": "12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901", "fizz": -1, "buzz": -1, "startDate": "1999-12-31T23:59:59.999Z", "_endDate": "1999-12-31T23:59:59.999Z" } // Response { "type": "..", "title": "One or more validation errors occurred.", "status": 400, "traceId": "..", "errors": { "Bar": [ "Bar should have a max length of 100" ], "Foo": [ "Foo should have a max length of 100" ], "Buzz": [ "Buzz should have a value between 1 and 100" ], "Fizz": [ "Fizz should have a value between 1 and 100" ], "EndDate": [ "End date should have a value between 2000-01-01 and 3000-01-01" ], "StartDate": [ "Start date should have a value between 2000-01-01 and 3000-01-01" ] } }[POST] /api/fluent-validation/test-mixed // Request { "foo": "12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901", "bar": "12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901", "fizz": -1, "buzz": -1, "startDate": "1999-12-31T23:59:59.999Z", "_endDate": "1999-12-31T23:59:59.999Z" } // Response { "type": "..", "title": "One or more validation errors occurred.", "status": 400, "traceId": "..", "errors": { "Bar": [ "The field Bar must be a string or array type with a maximum length of '100'." ], "Foo": [ "The field Foo must be a string or array type with a maximum length of '100'." ], "Buzz": [ "The field Buzz must be between 1 and 100." ], "Fizz": [ "The field Fizz must be between 1 and 100." ], "EndDate": [ "End date should have a value between 2000-01-01 and 3000-01-01" ], "StartDate": [ "Start date should have a value between 2000-01-01 and 3000-01-01" ] } }