Querying array elements with MongoDB?
MongoDB is better when you are querying array elements. Let us use the following syntax for querying array elements −
db.yourCollectionName.find({yourArrayFieldName:"yourValue"}).pretty();The above syntax will return all those documents which have the value “yourValue” in an array field.
To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −
> db.queryArrayElementsDemo.insertOne({
... "StudentName":"John","StudentFavouriteSubject":["C","Java"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c90c0354afe5c1d2279d694")
}
> db.queryArrayElementsDemo.insertOne({ "StudentName":"Carol","StudentFavouriteSubject":["C","C++"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c90c0434afe5c1d2279d695")
}
> db.queryArrayElementsDemo.insertOne({ "StudentName":"David","StudentFavouriteSubject":["MongoDB","Java"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c90c0584afe5c1d2279d696")
}Display all documents from a collection with the help of find() method. The query is as follows −
> db.queryArrayElementsDemo.find().pretty();
The following is the output −
{
"_id" : ObjectId("5c90c0354afe5c1d2279d694"),
"StudentName" : "John",
"StudentFavouriteSubject" : [
"C",
"Java"
]
}
{
"_id" : ObjectId("5c90c0434afe5c1d2279d695"),
"StudentName" : "Carol",
"StudentFavouriteSubject" : [
"C",
"C++"
]
}
{
"_id" : ObjectId("5c90c0584afe5c1d2279d696"),
"StudentName" : "David",
"StudentFavouriteSubject" : [
"MongoDB",
"Java"
]
}Querying array elements with MongoDB −
> db.queryArrayElementsDemo.find({StudentFavouriteSubject:"Java"}).pretty();The following is the output −
{
"_id" : ObjectId("5c90c0354afe5c1d2279d694"),
"StudentName" : "John",
"StudentFavouriteSubject" : [
"C",
"Java"
]
}
{
"_id" : ObjectId("5c90c0584afe5c1d2279d696"),
"StudentName" : "David",
"StudentFavouriteSubject" : [
"MongoDB",
"Java"
]
}Look at the above sample output, the above query returns all those documents with the value “Java”.
Published on 01-Apr-2019 13:01:36
