How to set table name in #Entity dynamically? - nestjs

Question

I read the article https://medium.com/#terence410/working-with-dynamic-table-name-with-typeorm-6a67128b9671
import {Entity, PrimaryColumn, Column} from "typeorm";
export function createEntity(tableName: string) {
#Entity({name: tableName})
class EntityClass {
public static tableName = tableName;
#PrimaryColumn()
public name: string = "";
#Column()
public value: number = 0;
}
return EntityClass;
}
I have error - Return type of exported function has or is using private name 'EntityClass'.
How to set table name dynamic ?

Answer 1

I also followed the post the article https://medium.com/#terence410/working-with-dynamic-table-name-with-typeorm-6a67128b9671. It need to do some change in code to make it work.
Here is the code:
[1] Create the base entity, this entity will contain all properties that you need for your model and we can export this entity for other the class use.
import {Column, PrimaryGeneratedColumn} from 'typeorm'
export class BaseCategory {
#PrimaryGeneratedColumn({unsigned: true})
id: number
#Column({type: 'varchar', length: 255, nullable: true})
name: string
#Column({type: 'bigint', width: 3, nullable: true})
quantity: number
}
[2] Define the CategoryService
#Injectable()
export class CategoryService {
constructor(
#Logger() private readonly logger: LoggerService,
private configService: ConfigService
) {}
public connections: Map<any, Promise<Connection>> = new Map()
/**
* Gets the connection for dynamic entity. By this way, the dynamic entity can register with
* EntityManger and can get the repository for this dynamic entity.
* If don't use this way, the EntityManager don't know the dynamic entity and will throw error
* when try to get the repository for this dynamic entity.
*
* There is the problem with approach: there is too many connections, each merchant will help its own connection.
*
* #param entityType
* #returns
*/
public async getConnection(entityType: object) {
const commissionTableName = (entityType as any).tableName
if (!this.connections.has(commissionTableName)) {
const mysqlConfig = this.configService.get('mysql')
const name = `table:${commissionTableName}`
const newOptions = {...mysqlConfig, name, entities: [entityType] as any}
const connection = createConnection(newOptions)
this.connections.set(commissionTableName, connection)
}
return this.connections.get(commissionTableName) as Promise<Connection>
}
public async getRepository(
dynamicTableName
): Promise<Repository<BaseCategory>> {
#Entity({name: dynamicTableName})
class EntityClass extends BaseCategory {
public static tableName = dynamicTableName
}
const connection = await this.getConnection(EntityClass)
const repository = connection.getRepository(
dynamicTableName
) as Repository<BaseCategory>
return repository
}
public async create() {
// Example we want to create a new entity & table `organ_category`
const repository = await this.getRepository('organ_category')
const entity = new BaseCategory()
await repository.save(entity)
}
}
It worked for me. There are some consider points with this code:
Each category will one connection, it is not good point but we can improve it by using list of dynamic table to init instead of
init one by one. By this way, it can reduce number of connection.