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IeuanWalkerIeuanWalker
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HttpValidationProblemDetails helper (#77)
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-45
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8 files changed

+512
-45
lines changed

‎example/ExampleApi/Endpoints/Validation/GetValidationErrors/GetValidationErrorsEndpoint.cs‎

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using System.Diagnostics.CodeAnalysis;
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using ExampleApi.Infrastructure;
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using IeuanWalker.MinimalApi.Endpoints;
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using Microsoft.AspNetCore.Http.HttpResults;
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namespace ExampleApi.Endpoints.Validation.GetValidationErrors;
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public class GetValidationErrorsEndpoint : IEndpointWithoutRequest<ProblemHttpResult>
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{
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[ExcludeFromCodeCoverage]
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public static void Configure(RouteHandlerBuilder builder)
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{
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builder
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.Group<ValidationEndpointGroup>()
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.Get("/ValidationErrors")
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.Version(1)
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.WithSummary("ValidationErrors");
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}
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public Task<ProblemHttpResult> Handle(CancellationToken ct)
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{
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ProblemHttpResult result = new ValidationErrors<RequestModel>()
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.Add(x => x.Name, "Name is required")
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.Add(x => x.Nested.Description, "Description is required")
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.ToProblemResponse();
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return Task.FromResult(result);
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}
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}

‎example/ExampleApi/Endpoints/Validation/GetValidationErrors/RequestModel.cs‎

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using System.Diagnostics.CodeAnalysis;
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namespace ExampleApi.Endpoints.Validation.GetValidationErrors;
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[ExcludeFromCodeCoverage]
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public class RequestModel
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{
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public string Name { get; set; } = string.Empty;
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public NestedRequest Nested { get; set; } = new();
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}
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[ExcludeFromCodeCoverage]
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public class NestedRequest
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{
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public string Description { get; set; } = string.Empty;
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}

‎src/IeuanWalker.MinimalApi.Endpoints/ValidationErrors.cs‎

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using System.Linq.Expressions;
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using Microsoft.AspNetCore.Http;
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using Microsoft.AspNetCore.Http.HttpResults;
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namespace IeuanWalker.MinimalApi.Endpoints;
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/// <summary>
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/// Collects validation errors and formats them as HTTP problem details.
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/// </summary>
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/// <typeparam name="T">The request model type used for property expressions.</typeparam>
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public sealed class ValidationErrors<T>
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{
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readonly Dictionary<string, List<string>> _errors = [];
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/// <summary>
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/// Returns true when at least one error has been added.
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/// </summary>
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public bool HasErrors()
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{
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return _errors.Count != 0;
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}
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/// <summary>
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/// Adds one or more error messages for a property expression.
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/// </summary>
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/// <param name="property">The property expression to build the error key.</param>
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/// <param name="messages">One or more error messages.</param>
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/// <returns>The same <see cref="ValidationErrors{T}"/> instance for chaining.</returns>
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/// <exception cref="ArgumentException">Thrown when no messages are provided or the expression is invalid.</exception>
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public ValidationErrors<T> Add(Expression<Func<T, object>> property, params string[] messages)
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{
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ValidateMessages(messages);
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string name = GetPropertyPath(property.Body);
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return Add(name, messages);
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}
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/// <summary>
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/// Adds one or more error messages for a specific key.
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/// </summary>
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/// <param name="key">The error key to associate with the messages.</param>
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/// <param name="messages">One or more error messages.</param>
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/// <returns>The same <see cref="ValidationErrors{T}"/> instance for chaining.</returns>
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/// <exception cref="ArgumentNullException">Thrown when <paramref name="key"/> is null or whitespace.</exception>
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/// <exception cref="ArgumentException">Thrown when no messages are provided.</exception>
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public ValidationErrors<T> Add(string key, params string[] messages)
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{
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ArgumentNullException.ThrowIfNullOrWhiteSpace(key, nameof(key));
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ValidateMessages(messages);
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if (!_errors.TryGetValue(key, out List<string>? list))
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{
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list = [];
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_errors[key] = list;
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}
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list.AddRange(messages);
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return this;
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}
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/// <summary>
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/// Creates <see cref="HttpValidationProblemDetails"/> from the collected errors.
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/// </summary>
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/// <returns>A validation problem details object.</returns>
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public HttpValidationProblemDetails ToProblemDetails()
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{
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Dictionary<string, string[]> errorDict = _errors.ToDictionary(kvp => kvp.Key, kvp => kvp.Value.ToArray());
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return new HttpValidationProblemDetails(errorDict);
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}
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/// <summary>
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/// Returns a problem response containing the validation errors.
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/// </summary>
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/// <returns>A <see cref="ProblemHttpResult"/> with validation details.</returns>
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public ProblemHttpResult ToProblemResponse()
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{
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return TypedResults.Problem(ToProblemDetails());
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}
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static string GetPropertyPath(Expression expression)
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{
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Stack<string> members = new();
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while (expression is MemberExpression memberExpr)
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{
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members.Push(memberExpr.Member.Name);
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expression = memberExpr.Expression!;
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}
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if (expression is ParameterExpression)
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{
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return string.Join(".", members);
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}
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if (expression is UnaryExpression unary && unary.Operand is MemberExpression)
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{
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return GetPropertyPath(unary.Operand);
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}
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if (expression is MethodCallExpression call && call.Method.Name == "get_Item")
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{
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if (call.Object is MemberExpression memberObject)
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{
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string basePath = GetPropertyPath(memberObject);
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string indexedPath = $"{basePath}[{call.Arguments[0]}]";
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if (members.Count == 0)
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{
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return indexedPath;
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}
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return $"{indexedPath}.{string.Join(".", members)}";
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}
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throw new ArgumentException("Indexer expressions are only supported on direct member access, e.g. x => x.Items[0]");
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}
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throw new ArgumentException("Expression must select a (possibly nested) property, e.g. x => x.Prop1.Prop2");
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}
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static void ValidateMessages(string[] messages)
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{
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if (messages.Length == 0)
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{
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throw new ArgumentException("At least one validation message must be provided.", nameof(messages));
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}
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}
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}

‎tests/ExampleApi.IntegrationTests/Endpoints/Validation/ValidationErrorsTests.cs‎

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using System.Net;
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using System.Text.Json;
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namespace ExampleApi.IntegrationTests.Endpoints.Validation;
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public class ValidationErrorsTests : IClassFixture<ExampleApiWebApplicationFactory>
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{
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readonly HttpClient _client;
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public ValidationErrorsTests(ExampleApiWebApplicationFactory factory)
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{
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_client = factory.CreateClient();
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}
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[Fact]
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public async Task GetValidationErrors_ReturnsProblemDetailsWithErrors()
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{
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// Act
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HttpResponseMessage response = await _client.GetAsync("/api/v1/validation/ValidationErrors");
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// Assert
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response.StatusCode.ShouldBe(HttpStatusCode.BadRequest);
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response.Content.Headers.ContentType?.MediaType.ShouldBe("application/problem+json");
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string content = await response.Content.ReadAsStringAsync();
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using JsonDocument json = JsonDocument.Parse(content);
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JsonElement errors = json.RootElement.GetProperty("errors");
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errors.TryGetProperty("Name", out JsonElement nameErrors).ShouldBeTrue();
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nameErrors[0].GetString().ShouldBe("Name is required");
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errors.TryGetProperty("Nested.Description", out JsonElement nestedErrors).ShouldBeTrue();
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nestedErrors[0].GetString().ShouldBe("Description is required");
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}
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}

‎tests/ExampleApi.IntegrationTests/ExpectedOpenApi.json‎

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@@ -1723,13 +1723,27 @@
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}
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}
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},
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"/api/v1/validation/ValidationErrors": {
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"get": {
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"tags": [
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"Validation"
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],
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"summary": "ValidationErrors",
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"operationId": "get_ValidationValidationErrors_21",
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"responses": {
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"200": {
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"description": "OK"
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}
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}
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}
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},
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"/api/v1/validation/DataValidation": {
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"post": {
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"tags": [
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"Validation"
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],
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"summary": "DataAnnotationsFromBody",
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"operationId": "post_ValidationDataValidation_21",
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"operationId": "post_ValidationDataValidation_22",
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"requestBody": {
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"content": {
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"application/json": {
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"Validation"
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],
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"summary": "FluentValidationFromBody",
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"operationId": "post_ValidationFluentValidation_22",
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"operationId": "post_ValidationFluentValidation_23",
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"requestBody": {
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"content": {
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"application/json": {
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"Validation"
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],
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"summary": "FluentValidationFromForm",
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"operationId": "post_ValidationFluentValidationFromForm_23",
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"operationId": "post_ValidationFluentValidationFromForm_24",
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"requestBody": {
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"content": {
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"multipart/form-data": {
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"Validation"
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],
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"summary": "FluentValidationEdgeCases",
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"operationId": "post_ValidationFluentValidationEdgeCases_24",
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"operationId": "post_ValidationFluentValidationEdgeCases_25",
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"requestBody": {
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"content": {
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"application/json": {
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"Validation"
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],
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"summary": "ManualWithValidation",
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"operationId": "post_ValidationWithValidation_25",
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"operationId": "post_ValidationWithValidation_26",
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"requestBody": {
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"content": {
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"application/json": {
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"Validation"
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],
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"summary": "WithValidationAlterAndRemove",
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"operationId": "post_ValidationWithValidationAlterAndRemove_26",
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"operationId": "post_ValidationWithValidationAlterAndRemove_27",
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"requestBody": {
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"content": {
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"multipart/form-data": {

‎tests/ExampleApi.IntegrationTests/Infrastructure/OpenApiTests.Validation.cs‎

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}
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}
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},
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"/api/v1/validation/FluentValidation/FromQuery": {
454+
"/api/v1/validation/FluentValidation/FromQuery": {
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"get": {
456456
"tags": [
457457
"Validation"
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748748
}
749749
}
750750
},
751-
"/api/v1/validation/DataValidation": {
751+
"/api/v1/validation/ValidationErrors": {
752+
"get": {
753+
"tags": [
754+
"Validation"
755+
],
756+
"summary": "ValidationErrors",
757+
"operationId": "get_ValidationValidationErrors_21",
758+
"responses": {
759+
"200": {
760+
"description": "OK"
761+
}
762+
}
763+
}
764+
},
765+
"/api/v1/validation/DataValidation": {
752766
"post": {
753767
"tags": [
754768
"Validation"
755769
],
756770
"summary": "DataAnnotationsFromBody",
757-
"operationId": "post_ValidationDataValidation_21",
771+
"operationId": "post_ValidationDataValidation_22",
758772
"requestBody": {
759773
"content": {
760774
"application/json": {
@@ -777,7 +791,7 @@ public async Task OpenApiJson_ValidValidationStructure()
777791
"Validation"
778792
],
779793
"summary": "FluentValidationFromBody",
780-
"operationId": "post_ValidationFluentValidation_22",
794+
"operationId": "post_ValidationFluentValidation_23",
781795
"requestBody": {
782796
"content": {
783797
"application/json": {
@@ -807,7 +821,7 @@ public async Task OpenApiJson_ValidValidationStructure()
807821
"Validation"
808822
],
809823
"summary": "FluentValidationFromForm",
810-
"operationId": "post_ValidationFluentValidationFromForm_23",
824+
"operationId": "post_ValidationFluentValidationFromForm_24",
811825
"requestBody": {
812826
"content": {
813827
"multipart/form-data": {
@@ -843,7 +857,7 @@ public async Task OpenApiJson_ValidValidationStructure()
843857
"Validation"
844858
],
845859
"summary": "FluentValidationEdgeCases",
846-
"operationId": "post_ValidationFluentValidationEdgeCases_24",
860+
"operationId": "post_ValidationFluentValidationEdgeCases_25",
847861
"requestBody": {
848862
"content": {
849863
"application/json": {
@@ -873,7 +887,7 @@ public async Task OpenApiJson_ValidValidationStructure()
873887
"Validation"
874888
],
875889
"summary": "ManualWithValidation",
876-
"operationId": "post_ValidationWithValidation_25",
890+
"operationId": "post_ValidationWithValidation_26",
877891
"requestBody": {
878892
"content": {
879893
"application/json": {
@@ -896,7 +910,7 @@ public async Task OpenApiJson_ValidValidationStructure()
896910
"Validation"
897911
],
898912
"summary": "WithValidationAlterAndRemove",
899-
"operationId": "post_ValidationWithValidationAlterAndRemove_26",
913+
"operationId": "post_ValidationWithValidationAlterAndRemove_27",
900914
"requestBody": {
901915
"content": {
902916
"multipart/form-data": {

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