Replacing a Document in MongoDB

To replace documents in MongoDB, we use the replaceOne() method. 

The  replaceOne() method takes the following parameters:

• filter : A query that matches the document to replace.

• replacement : The new document to replace the old one with.

• options : An object that specifies options for the update.

In the previous video, we use the 

_id

 field to filter the document. In our replacement document, we provide the entire document that should be inserted in its place. Here's the example code from the video:

db.books.replaceOne(

  {

    _id: ObjectId("6282afeb441a74a98dbbec4e"),

  },

  {

    title: "Data Science Fundamentals for Python and MongoDB",

    isbn: "1484235967",

    publishedDate: new Date("2018-5-10"),

    thumbnailUrl:

      "https://m.media-amazon.com/images/I/71opmUBc2wL._AC_UY218_.jpg",

    authors: ["David Paper"],

    categories: ["Data Science"],

  }

)

Updating MongoDB Documents by Using 

updateOne()

The updateOne()  method accepts a filter document, an update document, and an optional options object. MongoDB provides update operators and options to help you update documents. In this section, we'll cover three of them: 

$set, upsert and $push

.

$set

The $set operator replaces the value of a field with the specified value, as shown in the following code:

db.podcasts.updateOne(

  {

    _id: ObjectId("5e8f8f8f8f8f8f8f8f8f8f8"),

  },

  {

    $set: {

      subscribers: 98562,

    },

  }

)

upsert

Theupsert option creates a new document if no documents match the filtered criteria. Here's an example:

db.podcasts.updateOne(

  { title: "The Developer Hub" },

  { $set: { topics: ["databases", "MongoDB"] } },

  { upsert: true }

)

$push

The $push operator adds a new value to the hosts array field. Here's an example:

db.podcasts.updateOne(

  { _id: ObjectId("5e8f8f8f8f8f8f8f8f8f8f8") },

  { $push: { hosts: "Nic Raboy" } }

)

Updating MongoDB Documents by Using findAndModify()

The findAndModify() method is used to find and replace a single document in MongoDB. It accepts a filter document, a replacement document, and an optional options object. The following code shows an example:

db.podcasts.findAndModify({

  query: { _id: ObjectId("6261a92dfee1ff300dc80bf1") },

  update: { $inc: { subscribers: 1 } },

  new: true,

})

Updating MongoDB Documents by using updateMany()

To update multiple documents, use the  updateMany()method. This method accepts a filter document, an update document, and an optional options object. The following code shows an example:

db.books.updateMany(

  { publishedDate: { $lt: new Date("2019-01-01") } },

  { $set: { status: "LEGACY" } }

)

db.birds.updateMany({ common_name: { $in:['Grackle', 'Blue Jay']   } }, { $set: {in_date:new Date("2019-01-01") } } );

Deleting Documents in MongoDB

To delete documents, use the deleteOne() or  deleteMany() methods. Both methods accept a filter document and an options object.

Delete One Document

The following code shows an example of the  deleteOne() method:

db.podcasts.deleteOne({ _id: Objectid("6282c9862acb966e76bbf20a") })

Delete Many Documents

The following code shows an example of the deleteMany() method:

db.podcasts.deleteMany({category: “crime”})