Query on Embedded/Nested Documents

标签：Documents Embedded field inventory query Query document uom size

This page provides examples of query operations on embedded/nested documents using the db.collection.find() method in mongosh.

The examples on this page use the inventory collection. Connect to a test database in your MongoDB instance then create the inventory collection:

                         

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" }

]);

  MongoDB Shell                          

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" }:

 

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

  MongoDB Shell                          

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 the inventory collection:

 

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

  MongoDB Shell                          

Query on Nested Field

 

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

NOTE

When querying using dot notation, the field and nested field must be inside quotation marks.

Specify Equality Match on a Nested Field

 

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

 

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

  MongoDB Shell                          

Specify Match using Query Operator

   

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

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

  MongoDB Shell                        

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

 

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

  MongoDB Shell                          

Specify AND Condition

 

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

 

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

标签：Documents,Embedded,field,inventory,query,Query,document,uom,size
From： https://www.cnblogs.com/kungfupanda/p/17624343.html