> For the complete documentation index, see [llms.txt](https://docs.scraperapi.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.scraperapi.com/ai-parser/endpoints/update-a-parser.md).

# Update a Parser

Modifiy an existing parser's fields. Some changes generate a new version asynchronously, others are applied immediately.

```bash
PATCH https://aiparser.scraperapi.com/parsers/{parser_id}/{version}
```

#### **When to use this endpoint**

You have an existing parser, ran a few `/parse` calls, but the output isn't quite right:

* A field you want is missing → use `add_fields`.
* A field is being extracted wrong → use `modify_fields` with clearer description.
* A field name is awkward → use `rename_fields`.
* A field is no longer relevant → use `remove_fields`.

You can do any combination in a **single** request

**Request body**

```json
{
  "api_key": "API_KEY",
  "add_fields": [
    { "name": "products.discount", "description": "Discount percentage as a number", "type": "number" }
  ],
  "modify_fields": [
    { "name": "price", "description": "Price in USD as a number, no currency symbol", "type": "number" }
  ],
  "rename_fields": [
    { "name": "products.name", "new_name": "products.title" }
  ],
  "remove_fields": ["obsolete_field"]
}
```

Only `api_key` is required. Include *only* the operations you need.

**Response**

<table><thead><tr><th width="153.44451904296875">Status</th><th width="413.2962646484375">When</th><th>Body</th></tr></thead><tbody><tr><td><code>200 OK</code></td><td>Only <code>rename_fields</code> and/or <code>remove_fields</code> were sent - changes apply immediatelly.</td><td>New version number</td></tr><tr><td><code>202 Accepted</code></td><td><code>add_fields</code> or <code>modify_fields</code> were sent - a new version is generating asynchronously.</td><td>New version number</td></tr></tbody></table>

{% hint style="info" %}
After a `202`, poll `GET /parsers/{id}` until status is `FINISHED` before parsing with the new version.
{% endhint %}

#### **Step-by-step Example**

Suppose you create a parser and you get `version: 0`, but notice that the price field is being returned as string that includes the `$` symbol. Here's how you would clean up the field and update the parser, so the price is returned in a more usable numeric format:

```bash
# Run the parser first
curl "https://aiparser.scraperapi.com/parse/<PARSER_ID>?api_key=API_KEY&url=URL"
# { "price": "$1,212.02" } - string with currency symbol

# PATCH with a clearer description
curl -X PATCH https://aiparser.scraperapi.com/parsers/<PARSER_ID> \
  -H "Content-Type: application/json" \
  -d '{
    "api_key": "API_KEY",
    "modify_fields": [
      { "name": "price", "description": "Price in USD as a number, excluding currency symbols and commas", "type": "number" }
    ]
  }'
# 202 Accepted - { "version": 1 }

# Wait for FINISHED status
curl "https://aiparser.scraperapi.com/parsers/<PARSER_ID>/1?api_key=API_KEY"

# Re-run with the new version
curl "https://aiparser.scraperapi.com/parse/<PARSER_ID>/1?api_key=API_KEY&url=URL"
# { "price": 1212.02 } - now returned as number
```

**Field definition reference**

Each entry in `add_fields` and `modify_fields` supports

<table><thead><tr><th width="173.74078369140625">Property</th><th width="117.8885498046875">Required</th><th>Description</th></tr></thead><tbody><tr><td><code>name</code></td><td>Yes</td><td>Field name. Use dot notation for nested fields (e.g. <code>products.images.url</code>)</td></tr><tr><td><code>description</code></td><td>Yes</td><td>Field description. The more specific - the better the results.</td></tr><tr><td><code>type</code></td><td>No</td><td><code>string</code>, <code>number</code> or <code>array</code>.</td></tr><tr><td><code>selector</code></td><td>No</td><td>CSS or XPATH selector.</td></tr></tbody></table>

{% hint style="success" %}
`selectors` are optional, but they often produce more reliable results.
{% endhint %}


---

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