crisp fern
Say I have an entity type like this ```ts
export class Order {
@ApiProperty()
DocEntry: number;
@ApiProperty()
CardCode: string;
@ApiProperty()
DocDate: string;
}```
From this, I want to get all of it's properties and store them in a list like so ['DocEntry', 'CardCode', 'DocDate']
How do I achieve this??
torpid flax
Do you want it as a type, or as a variable you can reference?
crisp fern
a variable
import { plainToClass } from 'class-transformer';
import { validateSync } from 'class-validator';
export function getPropertyNames(entityClass: any): string[] {
const entityInstance: object = plainToClass(entityClass, {});
const errors = validateSync(entityInstance);
const propertyNames = Object.keys(entityInstance);
// Remove properties with validation errors
errors.forEach((error) => {
const property = error.property;
const index = propertyNames.indexOf(property);
if (index !== -1) {
propertyNames.splice(index, 1);
}
});
return propertyNames;
}
Chat-gpt got me this function
but it doesnt work
const propertyNames = getPropertyNames(Order);
console.log(propertyNames); // []```
propertyNames is just empty.
lone gale
You can't. Typescript (javascript) does not have a capability to list non-method properties of a class. CGPT is wrong here.
crisp fern
smh
lone gale
However, Nest goes around it by using decorators which allow storing metadata on the class itself. You can try using Reflect to read the medstada off the class, you can probably extract something from there
crisp fern
ah
I got a response that has something todo with that from ChatGPT when I prompted that does not work sadly
lone gale
This should list all metadata available on the class: Reflect.getOwnMetadataKeys(Order).forEach((k) => console.log(k, Reflect.getMetadata(k, Order)))
torpid flax
It also depends on how the metadata is set..I believe Typeorm and class-validator/class-transformer use their own metadata storage engine
lone gale
Yeah, that's also true. I was sad to discover that nestjs/graphql also does not use Reflect, so you can't easily read the metadata off of a query handler 😦
crisp fern
I fail to run the console log
nothing logs
what is Reflect?
GPT tells me this ```ts
function getPropertyNames(entityClass: any): string[] {
const propertyNames = Object.getOwnPropertyNames(entityClass.prototype)
.filter((propertyName) => {
const metadata = Reflect.getMetadata('includedProperty', entityClass.prototype, propertyName);
return metadata === true;
});
return propertyNames;
}
Reflect is from the ttypescript Reflect API. You can read more about it from the npm package reflect-metadata
crisp fern
ok