$ Addtoset Operator

Source: Internet
Author: User
$ Addtoset

 $ Addtoset operator adds a value to the array only when the value does not exist in the array. If the value already exists in the array, $ Addtoset: returns the result without modifying the array.. Consider the following example:

DB.Collection.Update( { Field: Value }, { $ Addtoset: { Field: Value1 } } );

Here,$ Addtoset is only available in If value1 is not a group member Add   Value1 To In the Array Field.



$ Addtoset only ensures that the items in the set are unique and the order of elements in the set is not guaranteed.



$ EachAnd$ Push

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