---
title: "jsonSet"
description: "Takes a JSON friendly string, a path string, and value, and will return a new JSON friendly string with the provided path set to the provided value."
---

# jsonSet

> Takes a JSON friendly string, a path string, and value, and will return a new JSON friendly string with the provided path set to the provided value.

**This function is used by Ignition's Expression language.**
## Description
Takes a JSON friendly string, a path string, and value, and will return a new JSON friendly string with the provided path set to the provided value. This is best used in conjunction with the [Derived Tags](tags/understanding-tags/types-of-tags.md#derived-tags) write back value.

## Syntax
` jsonSet(json, path, value)`

- Parameters

    - string **json** - The JSON string. The string must be in a JSON friendly format.
    ```
    //The json parameter must be wrapped in {}, and contain a colon between the key and the value.
    //Since the parameter passed is a string datatype, the whole parameter must be wrapped in quotes.
    "{key:value}"
  
    //You may optionally wrap strings in quotation marks.
    "{'key':'value'}"
 
    //You may also nest objects inside of the value, much like you can do with Python dictionaries.
    "{keyCollection1:{firstKey:value1, secondKey:value2}, keyCollection2:{firstKey:value1, secondKey:value2}}"
    ```

    - string **path** - The path string.

    - object **value** - The replacement for the value at the path.

- Results
    - string - A JSON friendly string with a new value set at the specified path.

## Examples
```python title="Code Snippet"
// This example takes a JSON friendly string and sets the provided path to the given value. This would then return the string {'item':{'firstThing':1, 'secondThing':5}}
 
jsonSet("{'item':{'firstThing':1, 'secondThing':2}}", "item.secondThing", 5)
```