MongoDB Update Modifiers
As mentioned in the section “Updating Documents in a Collection”, MongoDB comes with a set of operators for performing atomic modifications on documents.
Table 2-3. MongoDB update modifiers
Modifier | Meaning | Example |
---|---|---|
$inc | Atomic Increment | “$inc”:{"score”:1} |
$set | Set Property Value | “$set”:{"username”:"niall"} |
$unset | Unset (delete) Property | “$unset”:{"username”:1} |
$push | Atomic Array Append (atom) | “$push”:{"emails”:"foo@example.com"} |
$pushAll | Atomic Array Append (list) | “$pushall”:{"emails”:["foo@example.com”,"foo2@example.com"]} |
$addToSet | Atomic Append-If-Not-Present | “$addToSet”:{"emails”:"foo@example.com"} |
$pop | Atomic Array Tail Remove | “$pop”:{"emails”:1} |
$pull | Atomic Conditional Array Item Removal | “$pull”:{"emails”:"foo@example.com"} |
$pullAll | Atomic Array Multi Item Removal | “$pullAll”:{"emails”:["foo@example.com”, “foo2@example.com"]} |
$rename | Atomic Property Rename | “$rename”:{"emails”:"old_emails"} |
As with the MongoDB query operators listed earlier in this chapter, this table is mostly for your reference. These operators will be introduced in greater detail in Chapter 3.
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