从Strongloop/Loopback获取联接数据 [英] Getting joined data from strongloop/loopback

问题描述

如何从两个联接的表中获取数据? 假设有两个模型，分别称为Category(CategoryId，CategoryName)和Product(ProductId，ProductName，CategoryId)，有没有一种方法可以得到如下结果:(ProductId，ProductName，CategoryId，CategoryName)

How can I get data from two joined tables? Suppose, there are two models called Category (CategoryId, CategoryName) and Product(ProductId, ProductName, CategoryId), Is there a way to get a result like:(ProductId, ProductName, CategoryId, CategoryName)

推荐答案

您的类别"模型和产品"模型之间应该存在某种关系.类别有很多产品，每个产品属于一个类别.因此，您的模型json文件应该类似于

There should be a relation between your Category model and your Product model. A Category hasMany Products and each Product belongsTo a Category. So your model json files should be something like

类别:

{
  "name":"Category",
  "properties":{
    "CategoryId": {
      "type":"Number",
      "id":1
    },
    "CategoryName":{
      "type":"String"
    }
  },
  "relations": {
    "products": {
      "type":"hasMany",
      "model":"Product",
      "foreignKey":"CategoryId"
    }
  }
}

产品

{
  "name":"Product",
  "properties":{
    "ProductId: {
      "type":"Number",
      "id":1
    },
    "ProductName":{
      "type":"String"
    },
    "CategoryId": {
      "type":"Number"
    }
  },
  "relations": {
    "category": {
      "type":"belongsTo",
      "model":"Category",
      "foreignKey":"CategoryId"
    }
  }
}

当然，这些json定义必须使用相应的选项和数据源属性来完成，只有您确实知道.

Of course these json definitions must be completed with the corresponding options and datasource properties, which only you do know.

这两个模型之间的关系会将端点添加到回送资源管理器，以便您可以查询属于certan类别的产品:

The relation between those two models will add endpoints to loopback explorer so you can query for products in a certan category:

GET /api/Categorys/:id_category/products

产品所属类别的

GET /api/Products/:id_product/category

请注意，除非您为 Category 指定了复数选项，否则其复数将为 Categorys .这不是错字.

Please note that, unless you specify a plural option for Category, its plural will be Categorys. This is not a typo.

最后，如果要查询产品及其类别，则可以使用 include 过滤器

Finally, if you want to query for a product and its category, you would use the include filter

GET /api/Products/:id_product?filter[include]=category

希望有帮助.

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