MongoDB Update Document

What is the MongoDB Update Document?

To update a document in MongoDB, we use the update() method.

The update() method refreshes the values in a MongoDB collection's existing document. The _id field's value does not change when you update your document. The db.collection.update() method, by default, only updates one document. Use the multi: true option to update all documents that match the query. 

This approach can be used to update a single document as well as multiple documents at the same time.

Syntax

db.COLLECTION_NAME.update({SELECTION_CRITERIA}, {$set:{UPDATED_DATA}}, {

     upsert: <boolean>,

     multi: <boolean>,

     writeConcern: <document>,

     collation: <document>,

     arrayFilters: [ <filterdocument1>, ... ],

     hint:  <document|string>        

   })

Now, let us discuss the parameters required for the update() method in MongoDB.

Parameters for MongoDB Update Document

Some of the Parameters required for the MongoDB update() method are given below.

Non-Negotiable Parameters

• The Older value in Documents is the first parameter. Similar to JSON objects, documents are made up of file and value pairs.
• To alter the next specified document value, the second parameter must have the $set keyword.
• The third parameter can be left blank if you don't want to use it, i.e., it is optional.

Optional Parameters

• Collation: This describes the collation used in operations. A user can easily set language-specific string comparison criteria, like rules for letter case and accent marks.
• Upsert: Upset parameter's default value is false. If it changes to true, it will create a new document in the collection if no other document meets the update method's criterion.
• hint: It's a file or field that specifies the index that will be used to support the filter. It can accept an index specification document or an index name string, and it will return an error if you specify an index that does not exist.
• multi: This parameter's default value is false. When this parameter is set to true, the update method updates all documents that satisfy the query condition. Otherwise, only one document will be updated.
• arrayFilters: This is an array of filter documents that tell the update operation on an array field which array items to modify. This parameter has the type of array.
• writeConcern: Only use writeConcern if you don't want to utilize the default write concern. This option has the type of document.

Let us now discuss how to update a Single Document using MongoDB.

How to Update a Single Document?

To update a single document in MongoDB, the following steps are followed:

• First, utilize the update() method.

Syntax

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

• Specify the condition that will be applied to the document when it is updated. We need to edit the document with the Employee id of 100 in the example below.
• To update the values, use the $set operator.
• Select the Field Name that has to be modified and fill in the new values –

Employee_Name = ”Keerthana Suresh”

db.Employees.update(

{"Emp_ID" :100},

{$set:{"Employee_Name" :"Keerthana Suresh"}});

WriteResult({"nMatched": 1,  "nUpserted: 0, "nModified":1 })

Now that we have understood how to update a single document in MongoDB, let us see how to Update Multiple Documents using MongoDB.

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How to Update Multiple Documents?

In MongoDB, we must use the multi option to update several documents at once. Otherwise, only one document will be updated at a time by default.

The example below demonstrates how to update a large number of documents. In this example, we'll find the document with the Emp ID id of 10, modify the Emp ID to 32, and alter the Employee Name to "Stacy Fowler". 

Follow the steps below to update multiple documents:

• First, use the MongoDB update() method.

Syntax

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

• Indicate the condition that will be used to update the document. We need to edit the document with the Employee id of 10 in the example below.
• To update the values, use the $set operator.
• Select the Names of the Fields that need to be modified and fill in the new values –

Employee_Name =”Stacy Fowler”

Emp_ID = 32

db.Employees.update({ Emp_ID : 10},{$set :{"Employee_Name" : "Stacy Fowler"," Emp_ID" : 32}})

What if the Update Operation Doesn’t Match Documents in the Collection? 

If the update operation does not match any documents in the collection, the upsert option can be set to true to immediately insert a document that is new into the collection that meets the update query.

db.Employees.update(

{type:"PartTime"},

{$set:{salary:1500000}},

{upsert : true}

)

WriteResult ("nMatched": 0; "nUpserted": 1; "nModified":1)

The upsert is also represented in the Write Result of the preceding procedure.

MongoDB's upsert operation is utilized to save documents into collections.

If the document meets the query conditions, it will be updated; else, it will be added to the collection as a new document.

Related Topics

1. Drop Database In MongoDB
2. Create a Database in MongoDB
3. Create Collection in MongoDB
4. Data Types In MongoDB 
5. Indexing in MongoDB

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