> For the complete documentation index, see [llms.txt](https://docs.pentaho.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pentaho.com/pdia-data-integration/10.2-data-integration/pdi-transformation-steps-reference-overview/json-input/options-json-input/fields-tab.md).

# Fields tab

![Fields tab](/files/hknSlLkPzTMrbyTPcqBM)

The **Fields** tab displays field definitions to extract values from the JSON structure. The table in this tab contain the following columns:

| Column        | Description                                                                                                                                                                                                                                                                           |
| ------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Name**      | Name of field that maps to the corresponding field in the JSON input stream.                                                                                                                                                                                                          |
| **Path**      | Complete path of the field name in the JSON input stream. All records can be retrieved by adding the asterisk `*` in the path. For example, `$.mydata.*`                                                                                                                              |
| **Type**      | Data type of the input field.                                                                                                                                                                                                                                                         |
| **Format**    | An optional mask for converting the format of the original field. See [Common Formats](/pdia-data-integration/10.2-data-integration/pdi-transformation-steps-reference-overview/common-formats.md) for information on common valid date and numeric formats you can use in this step. |
| **Length**    | Length of the field.                                                                                                                                                                                                                                                                  |
| **Precision** | Number of floating point digits for number-type fields.                                                                                                                                                                                                                               |
| **Currency**  | Currency symbol (`$` or `€`, for example).                                                                                                                                                                                                                                            |
| **Decimal**   | A decimal point can be a `.` (`5,000.00` for example) or `,` (`5.000,00` for example).                                                                                                                                                                                                |
| **Group**     | A grouping can be a `,` (`10,000.00` for example) or `.` (`5.000,00` for example).                                                                                                                                                                                                    |
| **Trim type** | The trim method to apply to a string.                                                                                                                                                                                                                                                 |
| **Repeat**    | The corresponding value from the last row repeated if a row is empty.                                                                                                                                                                                                                 |

Click **Select Fields** to have the step populate the table with fields derived from the source file. All fields identified by this step will be added to the table.

See [Understanding PDI data types and field metadata](/pdia-data-integration/10.2-data-integration/data-integration-perspective-in-the-pdi-client/advanced-topics-pdi-perspective/understanding-pdi-data-types-and-field-metadata.md) to maximize the efficiency of your transformation and job results.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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.pentaho.com/pdia-data-integration/10.2-data-integration/pdi-transformation-steps-reference-overview/json-input/options-json-input/fields-tab.md?ask=<question>
```

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.