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How to get documents by tags in MongoDB?
You can use $elemMatch operator for this. Let us create a collection with documents
> db.getDocumentsByTagsDemo.insertOne({"Tags":["Tag-1", "Tag-2", "Tag-3"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9eb4d5d628fa4220163b79")
}
> db.getDocumentsByTagsDemo.insertOne({"Tags":["Tag-2", "Tag-4", "Tag-5"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9eb4d5d628fa4220163b7a")
}
> db.getDocumentsByTagsDemo.insertOne({"Tags":["Tag-6", "Tag-4", "Tag-3"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c9eb4d6d628fa4220163b7b")
}Following is the query to display all documents from a collection with the help of find() method
> db.getDocumentsByTagsDemo.find().pretty();
This will produce the following output
{
"_id" : ObjectId("5c9eb4d5d628fa4220163b79"),
"Tags" : [
"Tag-1",
"Tag-2",
"Tag-3"
]
}
{
"_id" : ObjectId("5c9eb4d5d628fa4220163b7a"),
"Tags" : [
"Tag-2",
"Tag-4",
"Tag-5"
]
}
{
"_id" : ObjectId("5c9eb4d6d628fa4220163b7b"),
"Tags" : [
"Tag-6",
"Tag-4",
"Tag-3"
]
}Following is the query to get documents by tags
> db.getDocumentsByTagsDemo.find({Tags: { $elemMatch: { $eq: "Tag-2" } }}).pretty();This will produce the following output
{
"_id" : ObjectId("5c9eb4d5d628fa4220163b79"),
"Tags" : [
"Tag-1",
"Tag-2",
"Tag-3"
]
}
{
"_id" : ObjectId("5c9eb4d5d628fa4220163b7a"),
"Tags" : [
"Tag-2",
"Tag-4",
"Tag-5"
]
}Following is the query to find specific tags only
> db.getDocumentsByTagsDemo.find({Tags: "Tag-5"}).pretty();This will produce the following output
{
"_id" : ObjectId("5c9eb4d5d628fa4220163b7a"),
"Tags" : [
"Tag-2",
"Tag-4",
"Tag-5"
]
}
Updated on: 30-Jul-2019
406 Views
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