Hướng dẫn create array field mongodb

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• How do I create an array of data in MongoDB?
• How do you do query an array in MongoDB explain with an example?
• How do I query an array object in MongoDB?
• Can we insert array in MongoDB?

You can use the concept of toArray() to create array. Following is the syntax −

db.yourCollectonName.find({}, {yourFieldName:1}).toArray();

Let us create a collection with documents −

> db.createArrayDemo.insertOne({"UserName":"Chris"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cbd6461de8cc557214c0e00")
}
> db.createArrayDemo.insertOne({"UserName":"David"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cbd6467de8cc557214c0e01")
}
> db.createArrayDemo.insertOne({"UserName":"Robert"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cbd646cde8cc557214c0e02")
}
> db.createArrayDemo.insertOne({"UserName":"Sam"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5cbd6470de8cc557214c0e03")
}

Display all documents from a collection with the help of find() method −

> db.createArrayDemo.find().pretty();

This will produce the following output −

{ "_id" : ObjectId("5cbd6461de8cc557214c0e00"), "UserName" : "Chris" }
{ "_id" : ObjectId("5cbd6467de8cc557214c0e01"), "UserName" : "David" }
{ "_id" : ObjectId("5cbd646cde8cc557214c0e02"), "UserName" : "Robert" }
{ "_id" : ObjectId("5cbd6470de8cc557214c0e03"), "UserName" : "Sam" }

Case 1 − Create array with MongoDB.

If you want to create an array of field UserName and do not want the field _id, use the below query.

> db.createArrayDemo.find({},{_id:0}, {UserName:1}).toArray();

This will produce the following output −

[
   {
      "UserName" : "Chris"
   },
   {
      "UserName" : "David"
   },
   {
      "UserName" : "Robert"
   },
   {
      "UserName" : "Sam"
   }
]

Case 2 − Create array with MongoDB with field name_id only

If you want to create an array with field name _id only, use the below query.

> db.createArrayDemo.find({}, {_id:1}).toArray();

This will produce the following output −

[
   {
      "_id" : ObjectId("5cbd6461de8cc557214c0e00")
   },
   {
      "_id" : ObjectId("5cbd6467de8cc557214c0e01")
   },
   {
      "_id" : ObjectId("5cbd646cde8cc557214c0e02")
   },
   {
      "_id" : ObjectId("5cbd6470de8cc557214c0e03")
   }
]

Updated on 30-Jul-2019 22:30:25

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How do I create an array of data in MongoDB?

Build a To-Do List App with Node, Express, React and MongoDB. Case 1 − Create array with MongoDB. If you want to create an array of field UserName and do not want the field _id, use the below query. If you want to create an array with field name _id only, use the below query.

How do you do query an array in MongoDB explain with an example?

To query if the array field contains at least one element with the specified value, use the filter { : } where is the element value. To specify conditions on the elements in the array field, use query operators in the query filter document: { : { : , ... } }

How do I query an array object in MongoDB?

To search the array of object in MongoDB, you can use $elemMatch operator. This operator allows us to search for more than one component from an array object.

Can we insert array in MongoDB?

MongoDB Array of Objects using insert() with Example The “insert” command can also be used to insert multiple documents into a collection at one time. The below code example can be used to insert multiple documents at a time. The output shows that those 3 documents were added to the collection.