9.Query on Embedded/Nested Documents-官方文档摘录

1.插入案例

db.inventory.insertMany( [
   { item: "journal", qty: 25, size: { h: 14, w: 21, uom: "cm" }, status: "A" },
   { item: "notebook", qty: 50, size: { h: 8.5, w: 11, uom: "in" }, status: "A" },
   { item: "paper", qty: 100, size: { h: 8.5, w: 11, uom: "in" }, status: "D" },
   { item: "planner", qty: 75, size: { h: 22.85, w: 30, uom: "cm" }, status: "D" },
   { item: "postcard", qty: 45, size: { h: 10, w: 15.25, uom: "cm" }, status: "A" }
]);

2.匹配内嵌文档

db.inventory.find({size:{h:14,w:21,uom:"cm"}})

如果顺序不一致，则无法出正确数据

3 在嵌套字段中查找

db.inventory.find({"size.uom":"in"})

db.inventory.find({"size.h":{$lt:15}})

db.inventory.find({
    "size.h":{$lt:15},
    "size.uom":"in",
    status:"D"
    })

This page provides examples of query operations on embedded/nested documents using thedb.collection.find() method in the mongo shell. The examples on this page use the inventorycollection. To populate the inventory collection, run the following:

Copy

db.inventory.insertMany( [
   { item: "journal", qty: 25, size: { h: 14, w: 21, uom: "cm" }, status: "A" },
   { item: "notebook", qty: 50, size: { h: 8.5, w: 11, uom: "in" }, status: "A" },
   { item: "paper", qty: 100, size: { h: 8.5, w: 11, uom: "in" }, status: "D" },
   { item: "planner", qty: 75, size: { h: 22.85, w: 30, uom: "cm" }, status: "D" },
   { item: "postcard", qty: 45, size: { h: 10, w: 15.25, uom: "cm" }, status: "A" }
]);

You can run the operation in the web shell below:

Match an Embedded/Nested Document

To specify an equality condition on a field that is an embedded/nested document, use the query filter document { <field>: <value> } where <value> is the document to match.

For example, the following query selects all documents where the field size equals the document { h: 14,w: 21, uom: "cm" }:

Copy

db.inventory.find( { size: { h: 14, w: 21, uom: "cm" } } )

Equality matches on the whole embedded document require an exact match of the specified <value>document, including the field order. For example, the following query does not match any documents in theinventory collection:

Copy

db.inventory.find(  { size: { w: 21, h: 14, uom: "cm" } }  )

Query on Nested Field

To specify a query condition on fields in an embedded/nested document, use the dot notation("field.nestedField").

Specify Equality Match on a Nested Field

The following example selects all documents where the field uom nested in the size field equals "in":

Copy

db.inventory.find( { "size.uom": "in" } )

Specify Match using Query Operator

A query filter document can use the query operators to specify conditions in the following form:

{ <field1>: { <operator1>: <value1> }, ... }

The following query uses the less than operator ($lt) on the field h embedded in the size field:

Copy

db.inventory.find( { "size.h": { $lt: 15 } } )

Specify AND Condition¶

The following query selects all documents where the nested field h is less than 15, the nested field uomequals "in", and the status field equals "D":

Copy

db.inventory.find( { "size.h": { $lt: 15 }, "size.uom": "in", status: "D" } )

Additional Query Tutorials

For additional query examples, see:

• Query Documents
• Query an Array
• Query an Array of Embedded Documents

←  Query DocumentsQuery an Array →