Question

我正在使用带有NodeJ的MongoDB，我正在尝试提取部分文档，以便在我的应用程序中使用它。我想直接在mongo中做这一切，但我不确定它是否可能。我有一堆文件结构：

{ _id:something1,
 firstName: somefirstname,
 gyms: [{ name: "somename1",
          address: "somewhere1"},
        { name: "somename2",
          address: "somewhere2"}]
},
{ _id:something2,
 firstName: somefirstname,
 gyms: [{ name: "somename3",
          address: "somewhere3"},
        { name: "somename4",
          address: "somewhere4"}]
},
{ _id:something3,
 firstName: somefirstname,
 gyms: [{ name: "somename5",
          address: "somewhere5"},
        { name: "somename6",
          address: "somewhere6"}]
}

是否有可能以某种方式提取数据，所以我最终会得到如下所示的结构？

[{ id: soemthing1,
  name: "somename1",
  address: "somewhere1"},
{ id: soemthing1,
  name: "somename2",
  address: "somewhere2"},

{ id: soemthing2,
  name: "somename3",
  address: "somewhere3"},
{ id: soemthing2,
  name: "somename4",
  address: "somewhere4"},

{ id: soemthing3,
  name: "somename5",
  address: "somewhere5"},
{ id: soemthing3,
  name: "somename6",
  address: "somewhere6"}]

Answer 1

在MongoDB聚合框架中有运算符$unwind

db.test.aggregate([
    {$unwind : "$gyms"},
    {$project: { 
        _id: 0, 
        id : '$_id' ,  
        firstName: 1, 
        name: '$gyms.name', 
        address: '$gyms.address'
     }} 
])

示例结果http://prntscr.com/5crtqm

如何从MongoDB文档中提取数据？

1 个答案: