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

# Denormalize response

Some API endpoints return JSON data where each value is nested under different keys that change between responses. This creates problems when mapping response fields to a destination table.

## The problem

For example, if calling a currency conversion API gives us this JSON:

```
{
  "base": "EUR",
  "start_date": "2020-01-01",
  "end_date": "2020-01-07",
  "rates": {
    "2020-01-01": {
      "USD": 1.1221,
      "GBP": 0.8462
    },
    "2020-01-02": {
      "USD": 1.1221,
      "GBP": 0.8466
    },
    "2020-01-03": {
      "USD": 1.1171,
      "GBP": 0.8495
    }
  }
}
```

When mapping this [response using field mapping](/create-requests/response-field-mapping), we get a different field name for each date key under `rates`. For example, `rates.2020-01-01.USD` and `rates.2020-01-02.USD` would be treated as separate fields.

If we change the request parameters to use different dates (like `2021-01-01` to `2021-01-03`), we get completely new keys under `rates` that won't map to any existing fields:

```
{
   "base":"EUR",
   "start_date":"2021-01-01",
   "end_date":"2021-01-03",
   "rates":{
      "2021-01-01":{
         "USD":1.217582
      },
      "2021-01-02":{
         "USD":1.2135
      },
      "2021-01-03":{
         "USD":1.223409
      }
   }
}
```

## The solution

What we really want is just two consistent fields: a `Date` field and a `USD` field. We want different dates to appear as separate records with these same two fields.

We can do this by denormalizing the response. We set:

1. **Denormalize Path** to `$.rates` (the [JSONPath](https://github.com/json-path/JsonPath) expression for the top-level `rates` key)
2. **Denormalize Field Name** to `Date`

After denormalization, the response becomes:

```
{
  "base": "EUR",
  "start_date": "2020-01-01",
  "end_date": "2020-01-07",
  "rates": [
    {
      "Date": "2020-01-01",
      "USD": 1.1221,
      "GBP": 0.8462
    },
    {
      "Date": "2020-01-02",
      "USD": 1.1221,
      "GBP": 0.8466
    },
    {
      "Date": "2020-01-03",
      "USD": 1.1171,
      "GBP": 0.8495
    }
  ]
}
```

Now all dates appear under a consistent `rates.Date` field and all USD exchange rates appear under a consistent `rates.USD` field. This gives us stable field names that we can reliably map to our destination table.

## How to denormalize the response

1. On the create screen, scroll to the bottom and click to open the **Advanced Settings**.
2. Under **Denormalize Path**, enter the JSONPath to where you want to denormalize the data (for the example above, use `$.rates`).
3. Enter a **Denormalize Field Name** for the field that will be added to each record (for the example above, use `Date`).

<video controls className="w-full aspect-video rounded-xl" src="https://mintcdn.com/datafetcher/t2ATq476pO0kGK3Q/videos/Denormalize.mp4?fit=max&auto=format&n=t2ATq476pO0kGK3Q&q=85&s=f3bfc382a2686e910a1c52f84d4dc30f" data-path="videos/Denormalize.mp4" />