早上好,我有订单服务。这里我有两个方法 find( findAll )和 findByKey(通过键查找所有),因为它是一个查询生成器,我需要加入其他表。
方法查找:
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();
}
方法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();
}
如何避免这种重复,我可以将这部分代码放入变量中并重用吗?谢谢!
您可以使用可选参数创建一个函数,例如:
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
}
更新
要执行您想要的操作,您可以创建一个返回查询生成器的函数:
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')
}
然后你可以在你的函数中使用它,例如:
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();
}
您还可以使用 .clone() 方法。
//1. create a common query builder
const queryBuilder = 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');
// 2. clone and add more queries to it
const firstQueryResult = await queryBuilder.clone().getMany()
const secondQueryResult = await queryBuilder.clone()
.where(`order.${field} = :${field}`, { [field]: value })
.getMany()
但是,我主要使用 clone() 方法多次重复使用相同的 queryBuilder,例如当我想根据某些过滤器获取项目列表并获取计数时。 例如
const queryPrice = 10
const page= 1
const limit = 20
const queryBuilder = productRepo.createQueryBuilder('prod')
.select('prod.id', 'id')
.addSelect('prod.name', 'productName')
.addSelect('prod.price', 'productPrice')
.where('prod.price > :queryPrice', {queryPrice})
const count = await queryBuilder.clone().getCount()
const products = await queryBuilder.clone()
.orderBy('prod.price', 'DESC')
.skip((page - 1) * size)
.take(limit)
.getMany();