# JMESPath custom functions
```json metadata
{
"schema_version": 2,
"title": "JMESPath custom functions",
"description": "JMESPath custom function reference",
"categories": ["docs","integrate","rs","rdi"],
"group": "di",
"tableOfContents": {"sections":[]}
,
"codeExamples": []
}
```
See also the [JMESPath functions proposal](https://jmespath.org/proposals/functions.html)
for a full description of the function syntax and a list of built-in functions.
| Function | Description | Example | Comments |
| -------------------- | ----------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `base64_decode` | Decodes a base64(RFC 4648) encoded string | Input: `{"encoded": "SGVsbG8gV29ybGQh"}`
Expression: `base64_decode(encoded)`
Output: `Hello World!` | |
| `capitalize` | Capitalizes all the words in the string | Input: `{"name": "john doe"}`
Expression: `capitalize(name)`
Output: `John Doe` | |
| `concat` | Concatenates an array of variables or literals | Input: `{"fname": "john", "lname": "doe"}`
Expression: `concat([fname, ' ' ,lname])`
Output: `john doe` | This is equivalent to the more verbose built-in expression: `' '.join([fname,lname])` |
| `filter_entries` | Filters entries in a dictionary (object) using the given JMESPath predicate | Input: `{ "name": "John", "age": 30, "country": "US", "score": 15}`
Expression: `` filter_entries(@, `key == 'name' \|\| key == 'age'`)``
Output:`{"name": "John", "age": 30 }` | |
| `from_entries` | Converts an array of objects with `key` and `value` properties into a single object | Input: `[{"key": "name", "value": "John"}, {"key": "age", "value": 30}, {"key": "city", "value": null}]`
Expression: `from_entries(@)`
Output: `{"name": "John", "age": 30, "city": null}` | |
| `hash` | Calculates a hash using the `hash_name` hash function and returns its hexadecimal representation | Input: `{"some_str": "some_value"}`
Expression: `hash(some_str, `sha1`)`
Output: `8c8181715...` | Supported algorithms: sha1 (default), sha256, md5, sha384, sha3_384, blake2b, sha512, sha3_224, sha224, sha3_256, sha3_512, blake2s |
| `in` | Checks if an element matches any value in a list of values | Input: `{"el": "b"}`
Expression: `in(el, `["a", "b", "c"]`)`
Output: `True` | |
| `left` | Returns a specified number of characters from the start of a given text string | Input: `{"greeting": "hello world!"}`
Expression: `left(greeting, `5`)`
Output: `hello` | |
| `lower` | Converts all uppercase characters in a string into lowercase characters | Input: `{"fname": "John"}`
Expression: `lower(fname)`
Output: `john` | |
| `mid` | Returns a specified number of characters from the middle of a given text string | Input: `{"greeting": "hello world!"}`
Expression: `mid(greeting, `4`, `3`)`
Output: `o w` | |
| `json_parse` | Returns parsed object from the given JSON string | Input: `{"data": '{"greeting": "hello world!"}'}`
Expression: `json_parse(data)`
Output: `{"greeting": "hello world!"}` | |
| `regex_replace` | Replaces a string that matches a regular expression | Input: `{"text": "Banana Bannnana"}`
Expression: `regex_replace(text, 'Ban\w+', 'Apple Apple')`
Output: `Apple Apple` | |
| `replace` | Replaces all the occurrences of a substring with a new one | Input: `{"sentence": "one four three four!"}`
Expression: `replace(sentence, 'four', 'two')`
Output: `one two three two!` | |
| `right` | Returns a specified number of characters from the end of a given text string | Input: `{"greeting": "hello world!"}`
Expression: `right(greeting, `6`)`
Output: `world!` | |
| `split` | Splits a string into a list of strings after breaking the given string by the specified delimiter (comma by default) | Input: `{"departments": "finance,hr,r&d"}`
Expression: `split(departments)`
Output: `['finance', 'hr', 'r&d']` | Default delimiter is comma - a different delimiter can be passed to the function as the second argument, for example: `split(departments, ';')` |
| `time_delta_days` | Returns the number of days between a given `dt` and now (positive) or the number of days that have passed from now (negative) | Input: `{"dt": '2021-10-06T18:56:16.701670+00:00'}`
Expression: `time_delta_days(dt)`
Output: `365` | If `dt` is a string, ISO datetime (2011-11-04T00:05:23+04:00, for example) is assumed. If `dt` is a number, Unix timestamp (1320365123, for example) is assumed. |
| `time_delta_seconds` | Returns the number of seconds between a given `dt` and now (positive) or the number of seconds that have passed from now (negative) | Input: `{"dt": '2021-10-06T18:56:16.701670+00:00'}`
Expression: `time_delta_days(dt)`
Output: `31557600` | If `dt` is a string, ISO datetime (2011-11-04T00:05:23+04:00, for example) is assumed. If `dt` is a number, Unix timestamp (1320365123, for example) is assumed. |
| `to_entries` | Converts a given object into an array of objects with `key` and `value` properties | Input: `{"name": "John", "age": 30, "city": null}`
Expression: `to_entries(@)`
Output: `[{"key": "name", "value": "John"}, {"key": "age", "value": 30}, {"key": "city", "value": null}]` | |
| `upper` | Converts all lowercase characters in a string into uppercase characters | Input: `{"fname": "john"}`
Expression: `upper(fname)`
Output: `JOHN` | |
| `uuid` | Generates a random UUID4 and returns it as a string in standard format | Input: None
Expression: `uuid()`
Output: `3264b35c-ff5d-44a8-8bc7-9be409dac2b7` | |
| `xml_to_dict` | Converts an XML string to a dictionary | Input: `{"xml": "John30"}`
Expression: `xml_to_dict(xml)`
Output: `{"root": {"name": "John", "age": "30"}}` | Returns `null` if the input is `null`; returns an empty string if the input is an empty string |