Duplicate column name with TypeORM in Nestjs - mysql

Question

We have 2 entities: EstateIntegrationEntity and EstateEntity
When we try to use .findOne on the estateIntegrationRepository we get the following error:
[Nest] 5537 - 10/01/2020, 8:37:55 AM
[ExceptionsHandler] ER_DUP_FIELDNAME: Duplicate column name 'EstateIntegrationEntity_estate_id' +1590ms
QueryFailedError: ER_DUP_FIELDNAME: Duplicate column name 'EstateIntegrationEntity_estate_id'
at ...
We created a OneToOne relation from the EstateIntegrationEntity to the EstateEntity.
import { EstateEntity } from "src/estates/estate.entity";
import { Column, Entity, JoinColumn, OneToOne, PrimaryGeneratedColumn, RelationId } from "typeorm";
#Entity({ name: 'estate_integrations' })
export class EstateIntegrationEntity {
#PrimaryGeneratedColumn()
id: number;
#RelationId((estateIntegrationEntity: EstateIntegrationEntity) => estateIntegrationEntity.estate)
estate_id: number;
#OneToOne(() => EstateEntity, { eager: true })
#JoinColumn({ name: 'estate_id' })
estate: EstateEntity;
...
}
And a relation from the EstateEntity to the EstateIntegrationEntity :
import { EstateIntegrationEntity } from 'src/integrations/estate.integration.entity';
import { Column, Entity, JoinColumn, ManyToOne, OneToOne, PrimaryGeneratedColumn } from 'typeorm';
#Entity('estates')
export class EstateEntity {
#PrimaryGeneratedColumn()
id: number;
#Column('varchar' || null)
uuid: string;
#OneToOne(
() => EstateIntegrationEntity,
estate_integration => estate_integration.estate,
)
estate_integration: EstateIntegrationEntity;
}
This error only occurs with .findOne() and not with .find():
async findEstateById(id: string): Promise<EstateIntegrationEntity> {
return await this.estateIntegrationRepository.findOne({
where: {
external_id: id
}
});
}

Answer 1

You can change the name of the fields. I just had a similar error and fixed it changing the name with #Column({ name: 'name_the_fields_with_different_name' }). Because the problem that if in the tables it has the same name when it does the find it has to fields with the same name.

Answer 2

For this case you have 3 solution for this:
1- change column name from 'estate_id' to anything else like 'id_estate'
2- write custom join statement with TypeORM
3- my favorite solution is to use name strategy like this:
first install npm i --save typeorm-naming-strategies
then in your typeorm config file
const SnakeNamingStrategy = require('typeorm-naming-strategies')
.SnakeNamingStrategy;
module.exports = {
name: 'name',
type: 'mysql',
host: 'localhost',
port: 3306,
...
namingStrategy: new SnakeNamingStrategy(),
}