Tutorial: Security rules API

RuleDataSnapshot

Presentation

This is the JavaScript object type of predefined variables data, newData and root.

Methods

val()

• No argument
• return value: the value of the data node (as a JavaScript number, boolean, string or JSON object) or null if the data node has no value.

child()

• Arguments:
  • childPath: string
• return value: a RuleDataSnapshot at the sub-path given by childPath.
  The childPath may include several path segments separated by the "/" character, as well as the "." and ".." relative path segments.

parent()

• No argument
• return value: a RuleDataSnapshot instance representing the parent data node.

hasChild()

• Arguments:
  • childPath: string
• return value: a boolean indicating if a child at the sub-path given by childPath exists (i.e. has a non-null value)

childCount()

• No argument
• return value: a number representing the child count of the data node, or 0 if it is not an object.

hasChildren()

• Arguments:
  • (optional) children: array of string
• return value: a boolean indicating if:
  • at least one child exists (if no children argument is passed),
  • a child exists at each sub-path given in the children argument.

exists()

• No argument
• return value: a boolean indicating whether this data node has a non-null value (if so, the val() function returns a non-null value).

isNumber()

• No argument
• return value: a boolean indicating if the data node has a value and this value is a number.

isString()

• No argument
• return value: a boolean indicating if the data node has a value and this value is a string.

isBoolean()

• No argument
• return value: a boolean indicating if the data node has a value and this value is a boolean.

hash()

• No argument
• return value: a string containing the "hash value" of the (complete) node. That is a unique string value that can be used to test node equality or if a node has changed.