Read Documents: Part 5
Learn and practice array operators.
We'll cover the following...
Array operators
$all operator
The $all operator is used to match documents with the field containing all the values defined in it.
Let’s look at an example. First, we insert some documents in the terminal.
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db.tasks.insertMany([{name: 'Task 1',tags: ["urgent", "non-important"],},{name: 'Task 2',tags: ["urgent", "important"],},{name: 'Task 3',tags: ["non-urgent", "non-important"],}]);
Next, we build a query using the $all operator to fetch documents with the tag urgent.
db.tasks.find({
tags: {
$all: ["urgent"]
}
});
This query returns the below output.
[
{
_id: ObjectId("60fa85c2384ee438a9eb2f9f"),
name: 'Task 1',
tags: [ 'urgent', 'not-important' ]
},
{
_id: ObjectId("60fa85c2384ee438a9eb2fa0"),
name: 'Task 2',
tags: [ 'urgent', 'important' ]
}
]
Notice that the query does not return the Task 3 document.
Let’s build another query using the $all operator to fetch documents that have both urgent and important tags. ...