How can I avoid duplicate code when I create a query builder?

Question

Good morning, I have an order's service. Here I have two methods find( findAll ) and findByKey( find all by keys ) because it is a query builder I need to join in other tables.

Method find:

find(): Promise<Order[]> {
    return this.orderRepository
      .createQueryBuilder('order')
      .leftJoinAndSelect('order.restaurant', 'restaurant')
      .leftJoinAndSelect('order.user', 'media')
      .leftJoinAndSelect('order.orderCustomer', 'orderCustomer')
      .innerJoinAndSelect('order.orderCart', 'orderCart')
      .leftJoinAndSelect('orderCart.product', 'product')
      .leftJoinAndSelect('product.media', 'product_media')
      .leftJoinAndSelect('order.orderPayment', 'orderPayment')
      .getMany();
  }

Method findByKey:

findByKey(data: FindByKeyInput): Promise<Order[]> {
    const { field, value } = data;
    return this.orderRepository
      .createQueryBuilder('order')
      .where(`order.${field} = :${field}`, { [field]: value })
      .leftJoinAndSelect('order.restaurant', 'restaurant')
      .leftJoinAndSelect('order.user', 'media')
      .leftJoinAndSelect('order.orderCustomer', 'orderCustomer')
      .innerJoinAndSelect('order.orderCart', 'orderCart')
      .leftJoinAndSelect('orderCart.product', 'product')
      .leftJoinAndSelect('product.media', 'product_media')
      .leftJoinAndSelect('order.orderPayment', 'orderPayment')
      .getMany();
  }

How Can I avoid this duplication, Can I put this part of the code into a variable and reuse it? Thanks!

Answer 1

You can make one function with optional params, something like:

find(data: FindByKeyInput = { field=null, value=null }): Promise<Order[]> {
const { field, value } = data;
let query = this.orderRepository
  .createQueryBuilder('order') ;

 if(field != null && value != null)
 query.where(`order.${field} = :${field}`, { [field]: value });

 query.leftJoinAndSelect('order.restaurant', 'restaurant')
  .leftJoinAndSelect('order.user', 'media')
  .leftJoinAndSelect('order.orderCustomer', 'orderCustomer')
  .innerJoinAndSelect('order.orderCart', 'orderCart')
  .leftJoinAndSelect('orderCart.product', 'product')
  .leftJoinAndSelect('product.media', 'product_media')
  .leftJoinAndSelect('order.orderPayment', 'orderPayment')
  .getMany();
 return query
   }

UPDATE
to do what you desire, you can create a function that return the querybuilder:

getOrderRepoWithRelations(){
 return  this.orderRepository
   .createQueryBuilder('order')
  .leftJoinAndSelect('order.restaurant', 'restaurant')
  .leftJoinAndSelect('order.user', 'media')
  .leftJoinAndSelect('order.orderCustomer', 'orderCustomer')
  .innerJoinAndSelect('order.orderCart', 'orderCart')
  .leftJoinAndSelect('orderCart.product', 'product')
  .leftJoinAndSelect('product.media', 'product_media')
  .leftJoinAndSelect('order.orderPayment', 'orderPayment')
}

then you can use it in your functions like:

find(): Promise<Order[]> {
return this.getOrderRepoWithRelations()
  .getMany();
 }


 findByKey(data: FindByKeyInput): Promise<Order[]> {
    const { field, value } = data;
    let query = this.getOrderRepoWithRelations();
    return query
      .where(`order.${field} = :${field}`, { [field]: value })
      .getMany();
  }