MongoDB and Python

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”:"[e-mail]"}
$pushAll	Atomic Array Append (list)	“$pushall”:{"emails”:["[e-mail]”,"[e-mail]"]}
$addToSet	Atomic Append-If-Not-Present	“$addToSet”:{"emails”:"[e-mail]"}
$pop	Atomic Array Tail Remove	“$pop”:{"emails”:1}
$pull	Atomic Conditional Array Item Removal	“$pull”:{"emails”:"[e-mail]"}
$pullAll	Atomic Array Multi Item Removal	“$pullAll”:{"emails”:["[e-mail]”, “[e-mail]"]}
$rename	Atomic Property Rename	“$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.