For this, use MongoDB $substr. Let us first create a collection with documents −
> dblimitTheNumberOfCharactersDemoinsertOne({"Title":"MongoDB is No SQL database"}); { "acknowledged" : true, "insertedId" : ObjectId("5cf23013b64a577be5a2bc0e") } > dblimitTheNumberOfCharactersDemoinsertOne({"Title":"MySQL is a relational database"}); { "acknowledged" : true, "insertedId" : ObjectId("5cf2302db64a577be5a2bc0f") }
Following is the query to display all documents from a collection with the help of find() method −
> dblimitTheNumberOfCharactersDemofind()pretty();
This will produce the following document −
{ "_id" : ObjectId("5cf23013b64a577be5a2bc0e"), "Title" : "MongoDB is No SQL database" } { "_id" : ObjectId("5cf2302db64a577be5a2bc0f"), "Title" : "MySQL is a relational database" }
Following is the query to limit the amount of the characters returned from a field in a MongoDB query −
> dblimitTheNumberOfCharactersDemoaggregate( [ { $project: { Characters: { $substr: [ "$Title", 0, 20 ] } } } ] );
This will produce the following document −
{ "_id" : ObjectId("5cf23013b64a577be5a2bc0e"), "Characters" : "MongoDB is No SQL da" } { "_id" : ObjectId("5cf2302db64a577be5a2bc0f"), "Characters" : "MySQL is a relationa" }