Description
openedon Feb 3, 2022
Is there an existing issue for this?
- I have searched the existing issues
Describe the bug
When creating a mutation resolver that uses the new mutation conventions feature, using Optional<T?> argument types instead of the base type, results in an Unable to convert the value of the argument... error when executing the mutation.
This only occurs when the input types are automatically generated from the mutation resolver method signature and one or more of those arguments is wrapped in an Optional<> type.
When mutation conventions are disabled and a DTO is created for the input and payload types, the optional values work perfectly and no value conversion errors occur.
Steps to reproduce
- Enable mutation conventions for the entire project or a specific mutation resolver method.
- Add an
Optional<T?>parameter to the method signature.
Here is a repository that demonstrates both the broken mutation conventions and the working DTOs:
https://github.com/kirkbrauer/HotChocolateMutationConventionsOptional
Relevant log output
{
"errors": [
{
"message": "Unable to convert the value of the argument `description` to `System.String`. Check if the requested type is correct or register a custom type converter.",
"locations": [
{
"line": 14,
"column": 3
}
],
"path": [
"createBookMutationConvention"
],
"extensions": {
"fieldName": "createBookMutationConvention",
"argumentName": "description",
"requestedType": "System.String"
}
}
]
}Additional Context?
Here are the basic resolver implementations for both the working and broken resolvers:
public class Mutation
{
public Book CreateBookMutationConvention(
string title,
Optional<string?> description)
{
return new Book
{
Id = Guid.NewGuid(),
Title = title,
Description = description.HasValue ? description : "No Description"
};
}
[UseMutationConvention(Disable = true)]
public CreateBookPayload CreateBookOld(CreateBookInput input)
{
return new CreateBookPayload(new Book
{
Id = Guid.NewGuid(),
Title = input.Title,
Description = input.Description.HasValue ? input.Description : "No Description"
});
}
}Here are the queries that produce the error using the two types of resolvers:
# Fails with "Unable to convert the value of the argument `description` to `System.String`. Check if the requested type is correct or register a custom type converter."
mutation CreateBookMutationConventionsHasValue {
createBookMutationConvention(input: { title: "Hello, world", description: "This is a book's description." }) {
book {
id
title
description
}
}
}
# Fails with "Unable to convert the value of the argument `description` to `System.String`. Check if the requested type is correct or register a custom type converter."
mutation CreateBookMutationConventionsNoValue {
createBookMutationConvention(input: { title: "Hello, world" }) {
book {
id
title
description
}
}
}
# Fails with "Unable to convert the value of the argument `description` to `System.String`. Check if the requested type is correct or register a custom type converter."
mutation CreateBookMutationConventionsNull {
createBookMutationConvention(input: { title: "Hello, world", description: null }) {
book {
id
title
description
}
}
}
# Works perfectly
mutation CreateBookOld {
createBookOld(input: { title: "Hello, world", description: "This is a book's description." }) {
book {
id
title
description
}
}
}
# Works perfectly
mutation CreateBookOldNoValue {
createBookOld(input: { title: "Hello, world" }) {
book {
id
title
description
}
}
}
# Works perfectly
mutation CreateBookOldNoValueNull {
createBookOld(input: { title: "Hello, world", description: null }) {
book {
id
title
description
}
}
}Product
Hot Chocolate
Version
12.6.0, 12.7.0-preview.4
