How to read the declared metadata on a field or prop ?

[binaryangel-noa]

Hi,

is there a way to get the initially declared Metadata on a decorator ?, For example with the MaxLength decorator. MaxLength(255, { message: "somemessage" }) , i am looking for a way to retrive that 255 .

Thanks alot!

[LiamLB]

I'm also interested in this, I'm trying to generate forms with required fields using the @IsDefined decorator metadata.

[vlapo]

You have to use internal API to get this kind of data. Check a code and how internally class-validator works/store data you need.

[LiamLB]

Hey again,

I spent a bit of time looking at this today and the best I could come up with is the following:

import { getFromContainer, MetadataStorage } from 'class-validator';

const validatorStorage: MetadataStorage = getFromContainer(MetadataStorage);

const createUserDtoValidationMetadata = validatorStorage.getTargetValidationMetadatas(CreateUserDto, null, null);

console.log(validatorStorage.groupByPropertyName(createUserDtoValidationMetadata));

For reference here is what the CreateUserDto looks like:

export class CreateUserDto {
    @IsString({
        message: 'Name must be a text value'
    })
    name: string;
    @IsString({
        message: 'Surname must be a text value'
    })
    surname: string;
    @IsString()
    @IsOptional()
    password?: string;
    @IsEmail()
    email: string;
    @IsString()
    type: UserType;
    @IsOptional()
    @IsString()
    cellphoneNumber?: string;
}

[Flashantik]

Hey again,

I spent a bit of time looking at this today and the best I could come up with is the following:

import { getFromContainer, MetadataStorage } from 'class-validator';

const validatorStorage: MetadataStorage = getFromContainer(MetadataStorage);

const createUserDtoValidationMetadata = validatorStorage.getTargetValidationMetadatas(CreateUserDto, null, null);

console.log(validatorStorage.groupByPropertyName(createUserDtoValidationMetadata));

For reference here is what the CreateUserDto looks like:

export class CreateUserDto {
    @IsString({
        message: 'Name must be a text value'
    })
    name: string;
    @IsString({
        message: 'Surname must be a text value'
    })
    surname: string;
    @IsString()
    @IsOptional()
    password?: string;
    @IsEmail()
    email: string;
    @IsString()
    type: UserType;
    @IsOptional()
    @IsString()
    cellphoneNumber?: string;
}

Unfortunately, this solution does not work at the moment.

[joelybahh]

Is there any update on this? We are looking to generate a form using this metadata, as we have a mono-repo, all of our types are easily accessible between our frontend/backend apps, figured there must be a way to get the decorator data somehow, has anyone figured this out?

[NoNameProvided]

We do not expose the metadata about classes officially but you can access it. Keep in mind that this API is considered private and can break without any mention in the changelog.

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