docs do not describe how bigint type is treated as string to avoid rounding issues

Issue type:

[ ] question [ ] bug report [ ] feature request [x] documentation issue

Database system/driver:

[ ] cordova [ ] mongodb [ ] mssql [ ] mysql / mariadb [ ] oracle [x] postgres [ ] sqlite [ ] sqljs [ ] react-native

TypeORM version:

[ ] latest [ ] @next [x] 0.2.7 (or put your version here)

Steps to reproduce or a small repository showing the problem:

I ran console.log(entity, typeof entity.myBigIntColumn) and noticed that my column was a string instead of Number. This makes sense because the maximum postgres bigint value is 9223372036854775807 and yet in JavaScript Number.MAX_SAFE_INTEGER is 9007199254740991. However, the documentation at http://typeorm.io/#/entities/column-types-for-postgres doesn’t mention that at all.

[albrow]

I just wanted to point out that this issue means that the type definitions for methods like find and findOne are incorrect. If you have an entity that looks like this:

@Entity()
export class Person {
    @PrimaryColumn() public name!: string;

    @Column({ type: 'bigint' })
    public age!: number;
}

And you call findOne like this:

const person = await personRepository.findOne({where: {name: 'Alice'}});

The TypeScript compiler thinks that person has type Person because that is what the type definition for findOne specifies. But in reality the type of the person.age will be string instead of number. This can lead to some surprising and confusing errors.

[DanielLoyAugmedix]

I’ll leave some bread crumbs because I got this to work for my application.

In creating the the TypeOrm connection, I’m using Nest but that doesn’t matter, you can add the option

      bigNumberStrings: false,

And typescript 3.2 supports bigint types.

We can therefor declare:

  @PrimaryGeneratedColumn({type: 'bigint'})
  public id: bigint;

This works for me and presents no risk of overflow. I hope this helps.