---
title: "Extract fields by path"
slug: "extract-fields-by-path"
description: "Use the extract fields by path adapter to copy a value, such as a currency code, onto every data row in an API response."
updated: 2026-06-04T07:44:29Z
published: 2026-06-04T07:44:29Z
canonical: "docs.supermetrics.com/extract-fields-by-path"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.supermetrics.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Extract fields by path

The `extract_fields_by_path` adapter pulls a value from one part of the response (often a metadata or headers section) and inserts it as a new field on each row in another part. Useful when a value such as a currency code appears once in the response but you want it available on every data row.

| Field | Type | Default | Required | Description |
| --- | --- | --- | --- | --- |
| `dataPath` | string | `$` | Yes | JSONPath to the rows that should receive the extracted field. |
| `sourcePath` | string | `$` | Yes | JSONPath to the source items that hold the value to extract. |
| `keyPath` | string | `$` | Yes | JSONPath, relative to each source item, identifying the name of the new field. |
| `valuePath` | string | `$` | Yes | JSONPath, relative to each source item, identifying the value to extract. |
| `fieldPath` | string | `$` | No | JSONPath structure under which the extracted value is wrapped on each row (for example, `$.value` produces `{ "value": ... }`). When left at the default, the extracted value is inserted as a plain key-value pair. |
| `suffix` | string | `''` | No | Suffix appended to the new field's name (for example, `_CURRENCY`). |

Below you can find a before/after example. The original response keeps the currency code only in `headers`:

```
{
  "headers": [
    {
      "name": "ESTIMATED_EARNINGS",
      "currencyCode": "EUR"
    },
    {
      "name": "CLICKS"
    }
  ],
  "rows": [
    {
      "ESTIMATED_EARNINGS": {
        "value": "200"
      },
      "CLICKS": {
        "value": "5"
      }
    }
  ]
}
```

After the adapter runs, every row carries the currency code as a new field on the matching metric:

```
{
  "rows": [
    {
      "ESTIMATED_EARNINGS": {
        "value": "200"
      },
      "CLICKS": {
        "value": "5"
      },
      "ESTIMATED_EARNINGS_CURRENCY": {
        "value": "EUR"
      }
    }
  ]
}
```

Configuration:

```
"response": {
  "dataRows": {
    "source": "jsonPath",
    "value": "$.rows.*"
  },
  "dataAdapters": {
    "items": [
      {
        "type": "extract_fields_by_path",
        "config": {
          "dataPath": "$.rows.*",
          "sourcePath": "$.headers.*",
          "keyPath": "$.name",
          "valuePath": "$.currencyCode",
          "fieldPath": "$.value",
          "suffix": "_CURRENCY"
        }
      }
    ]
  }
}
```

Below you can find example field definitions that read from the transformed structure:

```
[
  {
    "id": "estimated_earnings",
    "label": "Estimated earnings",
    "dataType": "float.currency.value",
    "value": {
      "source": "jsonPath",
      "value": "$.ESTIMATED_EARNINGS.value"
    }
  },
  {
    "id": "clicks",
    "label": "Clicks",
    "dataType": "int.number.value",
    "value": {
      "source": "jsonPath",
      "value": "$.CLICKS.value"
    }
  },
  {
    "id": "currency_code",
    "label": "Currency code",
    "dataType": "string.currency.code",
    "value": {
      "source": "jsonPath",
      "value": "$.ESTIMATED_EARNINGS_CURRENCY.value"
    }
  }
]
```