Nestjs Graphql the mutation/query input dto is empty - graphql

Question

I don't know what I miss but the input for the mutation or the queries is always empty
when I debug seems that the input is empty object
This is my code:
resolver
#Query(() => String)
async testMutation(#Args('args') args: UpvotePostInput) {
return args.postId;
}
the dto
import { InputType, Field } from '#nestjs/graphql';
#InputType()
export class UpvotePostInput {
#Field(() => String)
postId: string;
}
the empty object
the error
{
"errors": [
{
"message": "Cannot return null for non-nullable field Query.testMutation.",
"locations": [
{
"line": 2,
"column": 3
}
],
"path": [
"testMutation"
],
"extensions": {
"code": "INTERNAL_SERVER_ERROR",
"exception": {
"stacktrace": [
"Error: Cannot return null for non-nullable field Query.testMutation.",
" at completeValue (/....js:559:13)",
" at /.....xecute.js:469:16",
" at processTicksAndRejections (internal/process/task_queues.js:97:5)",
" at async Promise.all (index 0)"
]
}
}
}
],
"data": null
}

Answer 1

The solution is to add #IsNotEmpty() or #IsOptional() decorator to the property:
#InputType()
export class UpdateCarInput extends PartialType(CreateCarInput) {
#Field(() => Int)
#IsNotEmpty()
id: number;
}
weird, but this resolve the problem.

Answer 2

I investigated this strange behaviour of nestjs and find out that this happens when use use global validation pipe with whitelist property set to true.
I tested this global validation pipe
app.useGlobalPipes(
new ValidationPipe({
// whitelist: true,
transform: true,
transformOptions: { enableImplicitConversion: true },
}),
);
for this resolver method
#Mutation()
createPost(#Args('input') input: CreatePostInput) {
return this.postsService.create(input);
}
CreatePostInput class is generated with nestjs graphql schema first approach
//graphql.ts file
export class CreatePostInput {
title: string;
authorId: number;
}
nestjs-cli.json file is configured to use #nestjs/graphql plugin
"compilerOptions": {
"plugins": [
{
"name": "#nestjs/graphql",
"options": {
"introspectComments": true
}
}
]
}
The input object is not an empty object

Answer 3

Add deep partial
https://gist.github.com/navix/6c25c15e0a2d3cd0e5bce999e0086fc9
#Query(() => String)
async testMutation(#Args('args') args: DeepPartial<UpvotePostInput>) {
return args.postId;
}