# Create a Custom Field

## API Overview

> \[!WARNING]
>
> This covers the obsolete Legacy Marketing Campaigns API.

> \[!NOTE]
>
> For the most up-to-date information on the Custom Fields API, please visit the [new Marketing Campaigns Custom Fields API](/docs/sendgrid/api-reference/custom-fields).

The Custom Fields API lets you create and manage custom fields for your contacts. Custom fields are used to store additional information about your contacts. For example, you might use custom fields to store a contact's birthday, their favorite color, or any other information that is relevant to your business.

## Operation overview

```json
{"path":"https://api.sendgrid.com/v3/contactdb/custom_fields","method":"post","servers":[{"url":"https://api.sendgrid.com","description":"The Twilio SendGrid v3 API"}]}
```

**This endpoint allows you to create a custom field.**

**You can create up to 120 custom fields.**

## Operation details

### Authentication

API Key

### Headers

```json
[{"in":"header","name":"Authorization","required":true,"default":"Bearer <<YOUR_API_KEY_HERE>>","schema":{"type":"string"}},{"name":"on-behalf-of","in":"header","description":"The `on-behalf-of` header allows you to make API calls from a parent account on behalf of the parent's Subusers or customer accounts. You will use the parent account's API key when using this header. When making a call on behalf of a customer account, the property value should be \"account-id\" followed by the customer account's ID (e.g., `on-behalf-of: account-id <account-id>`). When making a call on behalf of a Subuser, the property value should be the Subuser's username (e.g., `on-behalf-of: <subuser-username>`). See [**On Behalf Of**](/docs/sendgrid/api-reference/how-to-use-the-sendgrid-v3-api/on-behalf-of) for more information.","required":false,"schema":{"type":"string"},"refName":"#/components/parameters/OnBehalfOf","modelName":"__components_parameters_OnBehalfOf"}]
```

### Request body

```json
{"schema":{"type":"object","example":{"name":"pet","type":"text"},"properties":{"name":{"type":"string"},"type":{"type":"string"}}},"encodingType":"application/json"}
```

### Responses

```json
[{"responseCode":"201","schema":{"description":"","content":{"application/json":{"schema":{"title":"ContactDB Custom field schema with ID.","type":"object","refName":"ContactdbCustomFieldId2xx","modelName":"ContactdbCustomFieldId2xx","properties":{"name":{"type":"string","description":"The name of the field"},"type":{"type":"string","description":"The type of the field.","enum":["date","text","number"],"refName":"Type","modelName":"Type"},"id":{"type":"number","description":"The ID of the custom field."}}},"examples":{"response":{"value":{"id":1,"name":"pet","type":"text"}}}}}}},{"responseCode":"400","schema":{"description":"The request was formatted incorrectly or missing required parameters.","content":{"application/json":{"schema":{"type":"object","example":{"errors":[{"field":"field_name","message":"error message"}]},"refName":"ErrorResponse","modelName":"ErrorResponse","properties":{"errors":{"type":"array","items":{"type":"object","properties":{"message":{"type":"string","description":"An error message."},"field":{"description":"When applicable, this property value will be the field that generated the error.","nullable":true,"type":"string"},"help":{"type":"object","description":"When applicable, this property value will be helper text or a link to documentation to help you troubleshoot the error."}}}},"id":{"type":"string","description":"When applicable, this property value will be an error ID."}}},"examples":{"response":{"value":{"errors":[{"field":null,"message":"Returned if request body is invalid JSON"},{"field":"type","message":"Returned if custom field type is invalid or not provided"},{"field":"name","message":"Returned if custom field name is not provided"}]}}}}}}}]
```

Create a Custom Field

```js
const client = require("@sendgrid/client");
client.setApiKey(process.env.SENDGRID_API_KEY);

const data = {
  name: "pet",
  type: "text",
};

const request = {
  url: `/v3/contactdb/custom_fields`,
  method: "POST",
  body: data,
};

client
  .request(request)
  .then(([response, body]) => {
    console.log(response.statusCode);
    console.log(response.body);
  })
  .catch((error) => {
    console.error(error);
  });
```

```python
import os
from sendgrid import SendGridAPIClient


sg = SendGridAPIClient(os.environ.get("SENDGRID_API_KEY"))

data = {"name": "pet", "type": "text"}

response = sg.client.contactdb.custom_fields.post(request_body=data)

print(response.status_code)
print(response.body)
print(response.headers)
```

```csharp
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using SendGrid;

public class Program {
    public static async Task Main() {
        string apiKey = Environment.GetEnvironmentVariable("SENDGRID_API_KEY");
        var client = new SendGridClient(apiKey);

        var data =
            @"{
            ""name"": ""pet"",
            ""type"": ""text""
        }";

        var response = await client.RequestAsync(
            method: SendGridClient.Method.POST,
            urlPath: "contactdb/custom_fields",
            requestBody: data);

        Console.WriteLine(response.StatusCode);
        Console.WriteLine(response.Body.ReadAsStringAsync().Result);
        Console.WriteLine(response.Headers.ToString());
    }
}
```

```java
import com.sendgrid.*;
import java.io.IOException;
import org.json.JSONObject;
import java.util.HashMap;

public class Example {
    public static void main(String[] args) throws IOException {
        try {
            SendGrid sg = new SendGrid(System.getenv("SENDGRID_API_KEY"));
            Request request = new Request();
            request.setMethod(Method.POST);
            request.setEndpoint("/contactdb/custom_fields");
            request.setBody(new JSONObject(new HashMap<String, Object>() {
                {
                    put("name", "pet");
                    put("type", "text");
                }
            }).toString());
            Response response = sg.api(request);
            System.out.println(response.getStatusCode());
            System.out.println(response.getBody());
            System.out.println(response.getHeaders());
        } catch (IOException ex) {
            throw ex;
        }
    }
}
```

```go
package main

import (
	"fmt"
	"github.com/sendgrid/sendgrid-go"
	"os"
)

func main() {
	apiKey := os.Getenv("SENDGRID_API_KEY")
	host := "https://api.sendgrid.com"
	request := sendgrid.GetRequest(apiKey, "/v3/contactdb/custom_fields", host)
	request.Method = "POST"
	request.Body = []byte(`{
  "name": "pet",
  "type": "text"
}`)
	response, err := sendgrid.API(request)
	if err != nil {
		fmt.Println(err.Error())
		os.Exit(1)
	} else {
		fmt.Println(response.StatusCode)
		fmt.Println(response.Body)
		fmt.Println(response.Headers)
	}
}
```

```php
<?php
// Uncomment the next line if you're using a dependency loader (such as Composer) (recommended)
// require 'vendor/autoload.php';

// Uncomment next line if you're not using a dependency loader (such as Composer)
// require_once '<PATH TO>/sendgrid-php.php';

$apiKey = getenv("SENDGRID_API_KEY");
$sg = new \SendGrid($apiKey);
$request_body = json_decode('{
    "name": "pet",
    "type": "text"
}');

try {
    $response = $sg->client
        ->contactdb()
        ->custom_fields()
        ->post($request_body);
    print $response->statusCode() . "\n";
    print_r($response->headers());
    print $response->body() . "\n";
} catch (Exception $ex) {
    echo "Caught exception: " . $ex->getMessage();
}
```

```ruby
require 'sendgrid-ruby'
include SendGrid

sg = SendGrid::API.new(api_key: ENV['SENDGRID_API_KEY'])
data = JSON.parse('{
  "name": "pet",
  "type": "text"
}')

response = sg.client.contactdb.custom_fields.post(request_body: data)
puts response.status_code
puts response.headers
puts response.body
```

```bash
curl -X POST "https://api.sendgrid.com/v3/contactdb/custom_fields" \
--header "Authorization: Bearer $SENDGRID_API_KEY" \
--header "Content-Type: application/json" \
--data '{"name": "pet", "type": "text"}'
```