CODEWITHSUNDEEP
mongodbgo
Algebra8
Algebra8

Reputation: 1385

Mongo field null vs empty

SQL has the convention of leaving fields as null when not present.

Is there a convention in Mongo to leave the field as null or use an empty value (such as an empty array) if the field is not set?

To be specific, I am using Go and Mongo 4.2 with the official Go mongo driver.

For example,

type A struct {
    ID string `bson:"_id"`

    Bs []B `bson:"bs"`
}

type B struct {
    ID string `bson:"_id"`
}

If an A does not have any Bs (Bs is empty), should it be defined as a zero-value ([]B(nil)) or as an empty array ([]B{}).

Note this affects the way the data is stored:

for zero-value

{
    "_id" : ...,
    "bs" : null
}

vs for empty value

{
    "_id" : ...,
    "bs" : [ ]
}

As well as construction before InsertOne (or insertion in general), since you would want to make sure memory is allocated beforehand for such objects.

Upvotes: 0

Views: 431

Answers (1)

DDMM
DDMM

Reputation: 11

In GO a string can not be null but a pointer to a string can be null so just use a pointer.

Upvotes: 1

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