https://github.com/stefh/fluentvalidation.extensions.automapper
FluentValidation Extensions for AutoMapper
https://github.com/stefh/fluentvalidation.extensions.automapper
Last synced: 2 months ago
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FluentValidation Extensions for AutoMapper
- Host: GitHub
- URL: https://github.com/stefh/fluentvalidation.extensions.automapper
- Owner: StefH
- License: mit
- Created: 2018-12-29T22:41:14.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2025-05-01T07:11:31.000Z (2 months ago)
- Last Synced: 2025-05-06T22:29:28.098Z (2 months ago)
- Language: C#
- Size: 40 KB
- Stars: 1
- Watchers: 2
- Forks: 1
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
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README
# FluentValidation.Extensions.AutoMapper
FluentValidation Extensions for AutoMapper 7, 8 and 11.
## NuGet
[](https://www.nuget.org/packages/FluentValidationExtensions.AutoMapper)
# Problem
When the normal MVC validation is defined on a ViewModel and additional validation is done in the business-layer on the dto's using FluentValidation, the error messages are using the property names from the dto instead of the view-model.
The following code shows this problem:
### ViewModel Example
The flattened **Person** view model class.
``` c#
public class Person
{
[Required]
public string FirstName { get; set; }
public string Street { get; set; }
public string City { get; set; }
}
```
# DTO models example
The **PersonDto** model class:
``` c#
public class PersonDto
{
public string First { get; set; }
public AddressDto Address { get; set; }
}
```
The **AddressDto** model class:
``` c#
public class AddressDto
{
public string Street { get; set; }
public string City { get; set; }
}
```
When posting an invalid Person object to the WebAPI, you get an error back like (notice that the property names from the DTO are used!):
``` json
{
"First": [
"no 'a' allowed"
],
"Address.City": [
"The length of 'City' must be 2 characters or fewer. You entered 3 characters."
],
"Address.Street": [
"The length of 'Street' must be 3 characters or fewer. You entered 4 characters."
]
}
```
# Solution
This library solves this issue by implementing a custom **FluentValidation - PropertyNameResolver** which uses the AutoMapper mapping definitions to translate the errors with DTO property names into view model errors.
Example response will be like:
``` json
{
"City": [
"The length of 'City' must be 2 characters or fewer. You entered 3 characters."
],
"Street": [
"The length of 'Street' must be 3 characters or fewer. You entered 4 characters."
],
"FirstName": [
"no 'a' allowed"
]
}
```
## Code Changes
To get this working you need the following changes for a DotNet Core MVC WebAPI project:
#### 1. Install the `FluentValidationExtensions.AutoMapper` package
``` cmd
dotnet add package FluentValidationExtensions.AutoMapper
```
#### 2. Dependency Injection Configuration changes
Let the DI framework inject an instance of `IMapper` into your `Configure(...)` method.
You can then use the injected `IMapper` to create a new instance from the `FluentValidationPropertyNameResolver` and assign this to the static `ValidatorOptions` class.
``` diff
-public void Configure(IApplicationBuilder app, IHostingEnvironment env)
+public void Configure(IApplicationBuilder app, IHostingEnvironment env, IMapper mapper)
{
mapper.ConfigurationProvider.AssertConfigurationIsValid();
+ var resolver = new FluentValidationPropertyNameResolver(mapper);
+ ValidatorOptions.PropertyNameResolver = resolver.Resolve;
}
```
For a complete example, see the code from [FluentValidationExample.Web](https://github.com/StefH/FluentValidation.Extensions.AutoMapper/tree/master/examples/FluentValidationExample.Web).