MongoDb – Update Queries

MongoDB Update Method

The update method modifies the document(s) in a collection. Using the update method we can modify an entire document or a specific field of a document. The update method is similar to the update command in relational databases. It generally updates a single document at a time but we can update multiple documents using the “Multi” parameter. Finally, the update() method returns an object that contains the status of the operation.

Syntax: db.collection_Name.updat( { query , update , { upsert: , multi: } } )

Parameter	Type	Description
Query	Document	Query is selection criteria for the update command.
Update	Document	Update criteria
Upsert	Boolean	Optional. By default set to False. If set to true, creates a new document when no document matches the query criteria otherwise doesn’t insert a new document.
Multi	Boolean	Optional. By default set to False. If set to true, updates multiple documents that meet the query criteria otherwise updates a single document.

Behavior of Update Method
When we use an update command, then there are two possibilities:

1. Update method modifies the specific fields.
2. Update method replaces an existing document entirely.

Case 1: Update Specific Fields
If the parameter contains only an update operator such as: $set, $inc, $mul then the update() method updates only the corresponding fields in the document. If we want to modify an embedded document or an array as a whole then specify the replacement value for the field. To update a specific field of an embedded document or array use the dot (.) notation for the specific field

1. Query: db.Demo.update({Title:”MongoDB-Day1″},{$set:{Likes:10}})
2. Query: db.Demo.update({Title:”MongoDB-Day1″},{$inc:{Likes:5}})

Update Embedded Document

3. Query : db.Demo.update({Title:”MongoDB-Day1″},{$set:{“Author.PostBy”:”Pankaj Choudhary”,”Author.Views “:6000}})

Update Multiple Document

4. Query: db.Demo.update({“Author.PostBy”:”Pankaj”},{$set:{Likes:13}},{multi:true})

Case 2: Replace the Entire Document
To replace an entire document the parameter contains only a field:value expression. In other words, parameters should not contain any update operator. We can’t replace the _id field and the update method can’t replace multiple documents.
Query

db.Demo.update({Title:”MongoDB-Day1″ },{Title:”Introduction to NoSQL”,Author:”Nitin Yadav”,Ta
gs:[“NoSQL”,”MongoDB”,”SQL”]})

Use Upsert Method
Query

db.Demo.update({Title:”MongoDB-Day5″ },{Title:”MongoBD-Day6″,Author:”Narendra Sharma”,Tags:[” NoSQL”,”MongoDB”,”SQL”]},{upsert:true})

Combine use of Upsert and Multi Options

In a combined use of the upsert and multi-option, there are two possibilities:
1. If any document doesn’t match the query pattern then a new document will be inserted.
Query

db.Demo.update(
{Title:"ASP.Net MVC5"},
{
    $set:{"Likes" : 5, 
            Author:{
                PostBy:"Sanjeev",
                Views:3200},
                Tags:["ASP.Net","MVC"]
                }
},
{Multi:1,upsert:1}
)

2. If any document(s) match the query pattern then it will update all those document(s).
When the document matches the query pattern

Query

db.Demo.update(
{"Author.PostBy":"Pankaj"},
{
    $set:{
        "Likes" : 5, 
        Author:{
            PostBy:"Sanjeev",
            Views:3200},
            Tags:["ASP.Net","MVC"]
    }
},
{Multi:1,upsert:1}
)

3.Update Embedded Document Array: To update a document of an embedded document array, use the index number of that document and the dot (.) notation.

Example 1 :

{      
    "Title": "MongoDB-Day4",  
    "Likes": 9,  
    "Author": {  
        "PostBy": "Pankaj",  
        "Views": 6500  
    },  
    "Tags": ["MogoDB", "Database"],  
    "Rating": [{  
        "By": "Sanjeev",  
        "Rate": 5  
    }]  
}

db.Demo.update(
{Title:"MongoDB-Day2"},
{$set:
    {
        "Rating.1":{
            By:"Nivin",
            Rate:3
            }
     }
})

Create Collection Command:

db.createCollection(“Demo”,{autoIndexID:true,size:5040321,max:100})

Insert Document

db.shoppingCart.insertMany(
    [
        {index: NumberInt(1)},{index: NumberInt(2)},
        {index: NumberInt(3)},{index: NumberInt(4)},
        {index: NumberInt(5)}
    ]
)

1.$set Operator

$set Example –

db.shoppingCart.update(
//query
{index: 2},
//update
{$set: {
    cartId: NumberInt(325),
    customer: {
        name: "Mike Foster",
        email: "mfoster@gmail.com",
        age: NumberInt(27)
        },
        cart:[]
    }
 },
 //update Options
 {}
)

2.$unSet Operator

fieldValue can be any integers or empty string.

//1. Remove field : 
db.shoppingCart.update(
//query
{index: 1},
//update
{$unset: {
    cartId: 1,
    cart:""
    }
 },
 //update Options
 {}
)
//2.Remove from child document field : 
db.shoppingCart.update(
//query
{index: 2},
//update
{$unset: {
    "customer.name":1,
    "customer.age":1
    }
 },
 //update Options
 {}
)
//3.Remove Child document : 
db.shoppingCart.update(
//query
{index: 2},
//update
{$unset: {
    customer: 1
    }
 },
 //update Options
 {}
)

By default update method found first document, if we did not provide the find query (find({}))

db.shoppingCart.update(
//query
{},
//update
{$unset: {
    customer: 1
    }
 },
 //update Options
 {}
)

3. Update – one Document

If any changes in the field value , it can only be modified. Else modification will not happen , we can verify in the result count.

db.shoppingCart.update(
{}, //query
{ //update
    $set: {processed: false}
}
)
//
db.shoppingCart.update(
{index: 1}, 
{ 
    $set: {processed: false} 
}
)

3. Update – Many Document

db.shoppingCart.update(
{}, 
{ 
    $set: {processed: false} 
},
{multi: true}
)

4. updateOne – One Document

db.shoppingCart.updateOne(
    {cartId: 325}, 
    { 
        $set: {processed: true} 
    },
    {}
)

5. updateMany – Many Document

db.shoppingCart.updateMany(
    {cart: {$exists: false}}, 
    { 
        $set: {cart: []} 
    },
    {}
)

6. replaceOne – replace one Document

db.shoppingCart.replaceOne(
    {"index":1}, 
    //replacement Object
    { 
        "index": NumberInt(1),
        "processed": false,
        "cart": ["item1", "item2"]
    },
    {}
)

7. Combine multiple update operators

db.shoppingCart.updateOne(
    {"index":4}, 
    //replacement Object
    { 
        $set: {
            cartId: NumberInt(435),
            "customer.name":"Samanta Larsen",
            "customer.email":"slarsent@tgs.com"
            },
        $unset: { newOrder: 1}
    },
    {}
)

8. $rename

db.shoppingCart.updateMany(
    {cartId: {$exists: true}}, 
    //replacement Object
    { 
        $rename: {
            cartId: "orderId"            
        }
    },
    {}
)

9. $currentDate

//Using $set Operator 
db.shoppingCart.updateOne(

    {index: 1}, 
    //replacement Object
    { 
        $set: {
            updatedAt: new Date()
        }
    },
    {}
)
//Using $currentDate 
db.shoppingCart.updateMany(

    {updatedAt: {$exists: false}}, 
    //replacement Object
    { 
        $currentDate: {
            updatedAt: true
        }
    },
    {}
)
//Add Field and update date
db.shoppingCart.updateMany(

    {orderId: 325}, 
    //replacement Object
    { 
        $set: {
            cart: ["item1"]
            },
        $currentDate: {
            updatedAt: true
        }
    },
    {}
)