# Using JMESPath expressions Use **JMESPath expressions** to map and transform JSON response from webhook action into the desired data structure.

Example of using JMESPath expression in your output attributes mapping

Be aware of the following: * If your JMESPath expression is incorrect or points to non-existent fields, the output attribute value will be empty. * If the resulting value of your JMESPath does not match the target attribute type, the attribute value will also be empty. Resources on JMESPath: * [Official specification](https://jmespath.org/specification.html#jmespath-specification). * [Comprehensive examples](https://jmespath.org/examples.html). * [Tutorials](https://jmespath.org/tutorial.html). ### Examples **Custom function: `json_decode(...)`** Webhook V2 supports a custom JMESPath function called `json_decode(...)`. Use it when an API returns JSON **inside a string field** and you need to read values from that encoded object. Without `json_decode(...)`, string fields are treated as plain text and cannot be traversed with dot notation. **Syntax:** ``` json_decode() ``` You can combine it with normal JMESPath traversal, for example: ``` json_decode(payload).order.status ``` If the string is not valid JSON, the result is treated as empty for mapping purposes. **Example: extract values from a JSON-encoded field**
Input JSONJMESPath
{
  "eventId": "evt_901",
  "payload": "{\"order\":{\"id\":\"ORD-1007\",\"status\":\"shipped\",\"tracking\":{\"carrier\":\"DHL\",\"number\":\"TRK-7788\"}}}"
}

Expression:
json_decode(payload).order.tracking.number

Output:

TRK-7788
**Example: decode and return multiple fields**
Input JSONJMESPath
{
  "payload": "{\"order\":{\"id\":\"ORD-1007\",\"status\":\"shipped\"}}"
}

Expression:
{order_id: json_decode(payload).order.id, order_status: json_decode(payload).order.status}

Output:

{
  "order_id": "ORD-1007",
  "order_status": "shipped"
}
**Select a Single Field**
Input JSONJMESPath
{
  "name": "Alice",
  "age": 30,
  "city": "London"
}

Expression:
name

Output:

Alice
**Access Nested Fields**
Input JSONJMESPath
{
  "user": {
    "profile": {
      "name": "Charlie",
      "location": "London"
    }
  }
}

Expression:
user.profile.location

Output:

London
**Select Multiple Fields**
Input JSONJMESPath
{
  "id": 123,
  "name": "Bob",
  "email": "bob@example.com",
  "age": 25
}

Expression:
{name: name, email: email}

Output:

{
  "name": "Bob",
  "email": "bob@example.com"
}
**Select all array element's properties**
Input JSONJMESPath
{
  "products": [
    {"name": "Laptop", "price": 999},
    {"name": "Mouse", "price": 25},
    {"name": "Keyboard", "price": 75}
  ]
}

Expression:
products[*].name

Output:

[
  "Laptop",
  "Mouse",
  "Keyboard"
]
**Filter array by condition**
Input JSONJMESPath
{
  "items": [
    {"name": "Apple", "price": 1.5, "inStock": true},
    {"name": "Banana", "price": 0.8, "inStock": false},
    {"name": "Orange", "price": 2.0, "inStock": true}
  ]
}

Expression:
items[?inStock == `true`]

Output:

[
  {"name": "Apple", "price": 1.5, "inStock": true},
  {"name": "Orange", "price": 2.0, "inStock": true}
]
**Select root-level array**
Input JSONJMESPath
[
  {"id": 1, "name": "Alice", "role": "admin"},
  {"id": 2, "name": "Bob", "role": "user"},
  {"id": 3, "name": "Charlie", "role": "user"}
]

Expression:
@

Output:

[
  {"id": 1, "name": "Alice", "role": "admin"},
  {"id": 2, "name": "Bob", "role": "user"},
  {"id": 3, "name": "Charlie", "role": "user"}
]
**Use bult-in functions**
Input JSONJMESPath
{
  "items": [
    {"name": "Apple", "price": 15 },
    {"name": "Banana", "price": 999 },
    {"name": "Orange", "price": 75 }
  ]
}

Expression:
max(products[*].price)

Output:

999
#### Select array elements for a form message with dynamic data You can create [a from message with dynamic](/opendialog-platform/conversation-designer/message-design/message-types/form-message.md#creating-form-messages-with-dynamic-data) data retrieved from a webhook action. For example:
Input JSONJMESPath
{
  "products": [
    {"sku": "LAP-001", "name": "Laptop", "price": 999},
    {"sku": "MOU-002", "name": "Mouse", "price": 25},
    {"sku": "KEY-003", "name": "Keyboard", "price": 75}
  ]
}

Expression:
products[*].{key: sku, value: name}

Output:

[
  {"key": "LAP-001", "value": "Laptop"},
  {"key": "MOU-002", "value": "Mouse"},
  {"key": "KEY-003", "value": "Keyboard"}
]
This can then be used as a data source for your searchable select in a form message. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.opendialog.ai/opendialog-platform/actions/webhook-action/using-jmespath-expressions.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.