The @Column('decimal') decorator in TypeOrm with Postgres and NestJs is displaying a string instead of a decimal value

Question

The @Column('decimal') decorator in TypeOrm with Postgres and NestJs is displaying a string instead of a decimal value

When I have columns with type decimal and I am using query builder for aggregation, I face an issue where the decimal values are returned as strings after executing the query.

I am looking for a way to globally set my project to recognize decimal numbers in entity as decimal numbers while executing queries, instead of treating them as strings.

Although I attempted to use a transformer with @Column(), it did not work as expected:

  @Column('decimal', {
    transformer: {
      to(value) {
        return value;
      },
      from(value) {
        return parseFloat(value);
      },
    },
  })
  price: number;

Even if this workaround does work, I do not want to repeat the same code for all columns. I am seeking a way to configure this setting globally across my project.

typescript postgresql nestjs typeorm nestjs-typeorm

Answer 1

Answer №1

In the PostgreSQL system, there is a safeguard in place to prevent issues with aggregate operations that may produce values outside the range of the number type in JavaScript. As a precaution, these values are returned as string.

Similar protection measures can be found in mysql, which can be managed by adjusting the supportBigNumbers: false setting in the node-mysql package.

To customize this safeguard, you can create a NestJS transformer as shown below and apply it to your entities. Modifying the precision and scale settings will allow you to tailor it to your specific requirements.

// transformer
export class DecimalColumnTransformer {
    to(data: number): number {
        return data;
    }
    from(data: string): number {
        return parseFloat(data);
    }
}

// entity
@Column('decimal', {
    precision: 5,
    scale: 2,
    transformer: new DecimalColumnTransformer(),
})
price: number;

Answer 2

In the PostgreSQL system, there is a safeguard in place to prevent issues with aggregate operations that may produce values outside the range of the number type in JavaScript. As a precaution, these values are returned as string.

Similar protection measures can be found in mysql, which can be managed by adjusting the supportBigNumbers: false setting in the node-mysql package.

To customize this safeguard, you can create a NestJS transformer as shown below and apply it to your entities. Modifying the precision and scale settings will allow you to tailor it to your specific requirements.

// transformer
export class DecimalColumnTransformer {
    to(data: number): number {
        return data;
    }
    from(data: string): number {
        return parseFloat(data);
    }
}

// entity
@Column('decimal', {
    precision: 5,
    scale: 2,
    transformer: new DecimalColumnTransformer(),
})
price: number;

The @Column('decimal') decorator in TypeOrm with Postgres and NestJs is displaying a string instead of a decimal value

Answer №1

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