List all values of a certain field in mongodb

Question

How would I get an array containing all values of a certain field for all of my documents in a collection?

db.collection:

{ "_id" : ObjectId("51a7dc7b2cacf40b79990be6"), "x" : 1 }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be7"), "x" : 2 }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be8"), "x" : 3 }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be9"), "x" : 4 }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990bea"), "x" : 5 }

"db.collection.ListAllValuesForfield(x)" Result: [1,2,3,4,5]

Also, what if this field was an array?

{ "_id" : ObjectId("51a7dc7b2cacf40b79990be6"), "y" : [1,2] }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be7"), "y" : [3,4] }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be8"), "y" : [5,6] }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be9"), "y" : [1,2] }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990bea"), "y" : [3,4] }

"db.collection.ListAllValuesInArrayField(y)" Result: [1,2,3,4,5,6,1,2,3,4]

Additionally, can I make this array unique? [1,2,3,4,5,6]

Answer 1

db.collection.distinct('x')

should give you an array of unique values for that field.

Answer 2

Notice: My answer is a fork from the original answer.

Before any "thumbs up" here, "thumbs up" the accepted answer :).

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db.collection.distinct("NameOfTheField")

Finds the distinct values for a specified field across a single collection or view and returns the results in an array.

Reference: https://docs.mongodb.com/manual/reference/method/db.collection.distinct/

Answer 3

This would return an array of docs, containing just it's x value...

db.collection.find(
    { },
    { x: 1, y: 0, _id:0 }
)

Answer 4

db.collection_name.distinct("key/field_name") - This will return a list of distinct values in the key name from the entire dictionary.

Just make sure you don't use the curly brackets after round brackets.