feat: throw 422 status code when validation fails

Author: rtablada

src/JsonApiDotNetCore/Controllers/BaseJsonApiController.cs

@@ -156,7 +156,7 @@ public virtual async Task<IActionResult> PostAsync([FromBody] T entity)
                 return Forbidden();
 
             if (_jsonApiContext.Options.ValidateModelState && !ModelState.IsValid)
-                return BadRequest(ModelState.ConvertToErrorCollection<T>(_jsonApiContext.ContextGraph));
+                return UnprocessableEntity(ModelState.ConvertToErrorCollection<T>(_jsonApiContext.ContextGraph));
 
             entity = await _create.CreateAsync(entity);
 
@@ -169,8 +169,9 @@ public virtual async Task<IActionResult> PatchAsync(TId id, [FromBody] T entity)
 
             if (entity == null)
                 return UnprocessableEntity();
+
             if (_jsonApiContext.Options.ValidateModelState && !ModelState.IsValid)
-                return BadRequest(ModelState.ConvertToErrorCollection<T>(_jsonApiContext.ContextGraph));
+                return UnprocessableEntity(ModelState.ConvertToErrorCollection<T>(_jsonApiContext.ContextGraph));
 
             var updatedEntity = await _update.UpdateAsync(id, entity);
 

test/UnitTests/Controllers/BaseJsonApiController_Tests.cs

@@ -200,8 +200,8 @@ public async Task PatchAsync_ModelStateInvalid_ValidateModelStateEnabled()
 
             // assert
             serviceMock.Verify(m => m.UpdateAsync(id, It.IsAny<Resource>()), Times.Never);
-            Assert.IsType<BadRequestObjectResult>(response);
-            Assert.IsType<ErrorCollection>(((BadRequestObjectResult) response).Value);
+            Assert.IsType<UnprocessableEntityObjectResult>(response);
+            Assert.IsType<ErrorCollection>(((UnprocessableEntityObjectResult) response).Value);
         }
 
         [Fact]
@@ -278,8 +278,8 @@ public async Task PostAsync_ModelStateInvalid_ValidateModelStateEnabled()
 
             // assert
             serviceMock.Verify(m => m.CreateAsync(It.IsAny<Resource>()), Times.Never);
-            Assert.IsType<BadRequestObjectResult>(response);
-            Assert.IsType<ErrorCollection>(((BadRequestObjectResult)response).Value);
+            Assert.IsType<UnprocessableEntityObjectResult>(response);
+            Assert.IsType<ErrorCollection>(((UnprocessableEntityObjectResult)response).Value);
         }
 
         [Fact]