Data Annotated Model Validation Middleware for HotChocolate.
The purpose of this Middleware is to provide the same behavior like a ASP.Net controllers where all models would be validated according to the specified Data Annotations or the IValidatableObject implementation; in essence it's always on.
In addition individual method arguments can be validated using annotations from System.ComponentModel.Annotations.
Locate your GraphQL Server registration and append .AddDataAnnotationsValidator()
ex.
// Startup.cs
public void ConfigureServices(IServiceCollection services)
{
// ...
services
.AddGraphQLServer()
.AddDataAnnotationsValidator()
.AddQueryType<Query>();
// ...
}To exclude a certain method argument from being validated just add the IgnoreModelValidation attribute.
ex.
public class Sample
{
[Required]
[MinLength(3)]
[EmailAddress]
public string? Email { get; set; }
}
public class Query
{
public string? GetTextIgnoreValidation([IgnoreModelValidation][MinLength(5)] string? text) => text;
public Sample? GetSampleIgnoreValidation([IgnoreModelValidation] Sample? sample) => sample;
}In C# one may define models in a multitude of ways.
To help alleviate potential issues consider the following:
public class Sample
{
[Required]
[MinLength(3)]
[EmailAddress]
public string? Email { get; set; }
}public record Sample
{
[Required]
[MinLength(3)]
[EmailAddress]
public string? Email { get; set; }
}The auto-property is initialized to the value of the corresponding primary constructor parameter. Attributes can be applied to the synthesized auto-property and its backing field by using
property:orfield:targets for attributes syntactically applied to the corresponding record parameter.
https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/proposals/csharp-9.0/records
So per the documentation and following the guideline, a solution to the challenge mentioned would be adding the property: prefix to the validation attribute.
public record Sample(
[property:Required]
[property:MinLength(3)]
[property:EmailAddress]
string? Email
);When implementing the IValidatableObject interface HotChocolate considers the Validate as a resolver; to avoid getting schema errors said method needs to be ignored.
ex.
public class Sample : IValidatableObject
{
[Required]
[MinLength(3)]
[EmailAddress]
public string? Email { get; set; }
[GraphQLIgnore]
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) =>
Email?.StartsWith("no-property-name") == true
? new[] { new ValidationResult("no-property-name") }
: Enumerable.Empty<ValidationResult>();
}If you need to support numerical sequences in your validation results, consider adding the names as FieldName:[index].
The field name will be transformed in the error path as fieldName,_index_.
{
"errors": [
{
"message": "The field Count must be between 1 and 10.",
"path": ["sample", "obj", "children", "_2_", "count"],
"extensions": {
"code": "DAMV-400",
"field": "sample",
"type": "Mutation",
"specifiedBy": "http://spec.graphql.org/June2018/#sec-Values-of-Correct-Type"
}
}
]
}If you choose to omit the : character and add the names as FieldName[index] the field name and the index will be represented as one entry, fieldName_index_.
{
"errors": [
{
"message": "The field Count must be between 1 and 10.",
"path": ["sample", "obj", "children_2_", "count"],
"extensions": {
"code": "DAMV-400",
"field": "sample",
"type": "Mutation",
"specifiedBy": "http://spec.graphql.org/June2018/#sec-Values-of-Correct-Type"
}
}
]
}If multiple member names are added they will be treated as distinct error messages.
Ex. validation error '"Some validation error!"' was assigned to properties hello and world:
{
"errors": [
{
"message": "Some validation error!",
"path": ["sample", "obj", "hello"],
"extensions": {
"code": "DAMV-400",
"field": "sample",
"type": "Query",
"specifiedBy": "http://spec.graphql.org/June2018/#sec-Values-of-Correct-Type"
}
},
{
"message": "Some validation error!",
"path": ["sample", "obj", "world"],
"extensions": {
"code": "DAMV-400",
"field": "sample",
"type": "Query",
"specifiedBy": "http://spec.graphql.org/June2018/#sec-Values-of-Correct-Type"
}
}
],
"data": {
"sample": null
}
}If there is a need to express a nested relationship of a property and it's parent, consider adding the names separated by a colon as ParentName:FieldName:[index]
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