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 { :  } where  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 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 →