Filter Functions
A filter function is a named function that can be called as part of a filter selector expression. Here we describe built-in filters. You can define your own function extensions too.
count()
Return the number of items in obj. If the object does not respond to Python's len() function, None is returned.
isinstance()
New in version 0.6.0
Return True if the type of obj matches t. This function allows t to be one of several aliases for the real Python "type". Some of these aliases follow JavaScript/JSON semantics.
| type | aliases |
|---|---|
| UNDEFINED | "undefined", "missing" |
| None | "null", "nil", "None", "none" |
| str | "str", "string" |
| Sequence (array-like) | "array", "list", "sequence", "tuple" |
| Mapping (dict-like) | "object", "dict", "mapping" |
| bool | "bool", "boolean" |
| int | "number", "int" |
| float | "number", "float" |
For example :
And is() is an alias for isinstance():
length()
Return the number of items in the input object. If the object does not respond to Python's len() function, None is returned.
match()
Return True if obj is a string and is a full match to the regex pattern.
If pattern is a string literal, it will be compiled at compile time, and raise a JSONPathTypeError at compile time if it's invalid.
If pattern is a query and the result is not a valid regex, False is returned.
search()
Return True if obj is a string and it contains the regexp pattern.
If pattern is a string literal, it will be compiled at compile time, and raise a JSONPathTypeError at compile time if it's invalid.
If pattern is a query and the result is not a valid regex, False is returned.
typeof()
New in version 0.6.0
Return the type of obj as a string. The strings returned from this function use JavaScript/JSON terminology like "string", "array" and "object", much like the result of JavaScript's typeof operator.
type() is and alias for typeof().
jsonpath.function_extensions.TypeOf takes a single_number_type argument, which controls the behavior of typeof() when given and int or float. By default, single_number_type is True and "number" is returned. Register a new instance of TypeOf with a JSONPathEnvironment with single_number_type set to False and "int" and "float" will be returned when given integers and floats, respectively.
| instance | type string |
|---|---|
| UNDEFINED | "undefined" |
| None | "null" |
| str | "string" |
| Sequence (array-like) | "array" |
| Mapping (dict-like) | "object" |
| bool | "boolean" |
| int | "number" or "int" if single_number_type is False |
| float | "number" or "float" if single_number_type is False |
value()
Return the first value from nodes resulting from a JSONPath query, if there is only one node, or undefined otherwise.