MongoDB

MongoDBKim 2015.05.01

Document

{

"_id": "10280",

"city": "NEW YORK",

"state": "NY",

"pop": 5574,

"loc": [-74.016323, 40.710537]

}

Query Documents

db.collection.find(query, projection)

Query Documents

Select All Documents in a Collection

db.inventory.find( {} )

db.inventory.find()

Query Documents

Specify Equality Condition

To specify equality condition, use the query document { <field>: <value> } to select all documents that contain the

<field> with the specified <value>.

db.inventory.find( { type: "snacks" } )

Query Documents

Specify Conditions Using Query Operators

The following example selects all documents in the inventory collection where the value of the typefield is either

'food' or 'snacks'

db.inventory.find( { type: { $in: [ 'food', 'snacks' ] } } )

Although you can express this query using the $or operator, use the $in operator rather than the $oroperator when

performing equality checks on the same field.

Query Documents

Specify AND Conditions

db.inventory.find( { type: 'food', price: { $lt: 9.95 } } )

This query selects all documents where the type field has the value 'food' and the value of the pricefield is less than

9.95. See comparison operators for other comparison operators.

Query Documents

Specify OR Conditions

db.inventory.find(

{

$or: [ { qty: { $gt: 100 } }, { price: { $lt: 9.95 } } ]

}

)

Query Documents

Embedded Documents

In the following example, the query matches all documents where the value of the field producer is an embedded

document that contains only the field company with the value 'ABC123' and the field address with the value '123 Street', in the exact order:

db.inventory.find({

producer: {

company: 'ABC123',

address: '123 Street'

}

})

Query Documents

Equality Match on Fields within an Embedded Document

In the following example, the query uses the dot notation to match all documents where the value of the field produceris an embedded document that contains a field company with the value 'ABC123' and may contain other fields:

db.inventory.find( { 'producer.company': 'ABC123' } )

Query Documents

{ _id: 5, type: "food", item: "aaa", ratings: [ 5, 8, 9 ] }

{ _id: 6, type: "food", item: "bbb", ratings: [ 5, 9 ] }

{ _id: 7, type: "food", item: "ccc", ratings: [ 9, 5, 8 ] }

The following example queries for all documents where the field ratings is an array that holds exactly three elements,

5, 8, and 9, in this order:

db.inventory.find( { ratings: [ 5, 8, 9 ] } )

The operation returns the following document:

{ "_id" : 5, "type" : "food", "item" : "aaa", "ratings" : [ 5, 8, 9 ] }

Query Documents

Match an Array Element

db.inventory.find( { ratings: 5 } )

The operation returns the following documents:

{ "_id" : 5, "type" : "food", "item" : "aaa", "ratings" : [ 5, 8, 9 ] }

{ "_id" : 6, "type" : "food", "item" : "bbb", "ratings" : [ 5, 9 ] }

{ "_id" : 7, "type" : "food", "item" : "ccc", "ratings" : [ 9, 5, 8 ] }

Query Documents

Match a Specific Element of an Array

In the following example, the query uses the dot notation to match all documents where the ratings array contains 5 as

the first element:

db.inventory.find( { 'ratings.0': 5 } )

The operation returns the following documents:

{ "_id" : 5, "type" : "food", "item" : "aaa", "ratings" : [ 5, 8, 9 ] }

{ "_id" : 6, "type" : "food", "item" : "bbb", "ratings" : [ 5, 9 ] }

Insert Documents

db.inventory.insert(

{

item: "ABC1",

details: {

model: "14Q3",

manufacturer: "XYZ Company"

},

stock: [ { size: "S", qty: 25 }, { size: "M", qty: 50 } ],

category: "clothing"

}

)

Insert Documents

var mydocuments =

[

{

item: "ABC2",

details: { model: "14Q3", manufacturer: "M1 Corporation" }

},

{

item: "MNO2",

stock: [ { size: "S", qty: 5 }, { size: "M", qty: 5 }, { size: "L", qty: 1 } ]

},

];

db.inventory.insert( mydocuments );

Insert Documents

Insert Multiple Documents with Bulk

Initialize a Bulk operations builder for the collection inventory.

var bulk = db.inventory.initializeUnorderedBulkOp();

Insert Documents

bulk.insert(

{

item: "BE10",

details: { model: "14Q2", manufacturer: "XYZ Company" },

stock: [ { size: "L", qty: 5 } ],

}

);

bulk.insert(

{

item: "ZYT1",

details: { model: "14Q1", manufacturer: "ABC Company" },

stock: [ { size: "S", qty: 5 }, { size: "M", qty: 5 } ],

}

);

bulk.execute();

Modify Documents

db.collection.update(query, update, options)

db.collection.update(

<query>,

<update>,

{

upsert: <boolean>,

multi: <boolean>

}

)

Modify Documents

Update Specific Fields in a Document

db.inventory.update(

{ item: "MNO2" },

{

$set: {

category: "apparel",

details: { model: "14Q3", manufacturer: "XYZ Company" }

},

$currentDate: { lastModified: true }

}

)

Modify Documents

Update an embedded field

db.inventory.update(

{ item: "ABC1" },

{ $set: { "details.model": "14Q2" } }

)

Modify Documents

Update multiple documents

db.inventory.update(

{ category: "clothing" },

{

$set: { category: "apparel" },

$currentDate: { lastModified: true }

},

{ multi: true }

)

Modify Documents

Specify upsert: true for the update replacement operation

db.inventory.update(

{ item: "TBD1" },

{

item: "TBD1",

details: { "model" : "14Q4", "manufacturer" : "ABC Company" },

stock: [ { "size" : "S", "qty" : 25 } ],

category: "houseware"

},

{ upsert: true }

)

Modify Documents

Specify upsert: true for the update specific fields operation.

db.inventory.update(

{ item: "TBD2" },

{

$set: {

details: { "model" : "14Q3", "manufacturer" : "IJK Co." },

category: "houseware"

}

},

{ upsert: true }

)

Remove Documents

db.collection.remove(

<query>,

<justOne>

)

Remove Documents

The following example removes all documents from the inventory collection:

db.inventory.remove({})

Remove Documents

Remove Documents that Match a Condition

db.inventory.remove( { type : "food" } )

Iterate a Cursor in the mongo Shell

The db.collection.find() method returns a cursor. To access the documents, you need to iterate the cursor.

var myCursor = db.inventory.find( { type: 'food' } );

myCursor.forEach(printjson);

Iterate a Cursor in the mongo Shell

● cursor.count() Returns the total number of documents in a cursor.

● cursor.forEach() Applies a JavaScript function for every document in a cursor.

● cursor.hasNext() Returns true if the cursor has documents and can be iterated.

● cursor.limit() Constrains the size of a cursor’s result set.

● cursor.sort() Returns results ordered according to a sort specification.

● cursor.toArray() Returns an array that contains all documents returned by the cursor.