If you are interested to learn about the Insertion of MongoDB
Find Data
There are 2 methods to find and select data from a MongoDB collection, find() and findOne().
find()
To select data from a collection in MongoDB, we can use the find() method. This method accepts a query object. If left empty, all documents will be returned.
Example
db.posts.find()
findOne()
To select only one document, we can use the findOne() method. This method accepts a query object. If left empty, it will return the first document it finds.
Note: This method only returns the first match it finds.
Example
db.posts.findOne()
Querying Data
To query, or filter, data we can include a query in our find() or findOne() methods.
Example
db.posts.find( {category: "News"} )Projection
Both find methods accept a second parameter called projection. This parameter is an object that describes which fields to include in the results.
Note: This parameter is optional. If omitted, all fields will be included in the results.
Example
This example will only display the title and date fields in the results.
db.posts.find({}, {title: 1, date: 1})Notice that the _id field is also included. This field is always included unless specifically excluded. We use a 1 to include a field and 0 to exclude a field.
Example
This time, let’s exclude the _id field.
db.posts.find({}, {_id: 0, title: 1, date: 1})Note: You cannot use both 0 and 1 in the same object. The only exception is the _id field. You should either specify the fields you would like to include or the fields you would like to exclude.
Let’s exclude the date category field. All other fields will be included in the results.
Example
db.posts.find({}, {category: 0})We will get an error if we try to specify both 0 and 1 in the same object.
Example
db.posts.find({}, {title: 1, date: 0})
