# Conditional custom fields

This guide explains how to set a custom field to only appear only when the traveler gives a particular answer to another custom field.
For example, a company might ask whether a traveler is extending their stay, and collect an emergency contact number only if the traveler answers **Yes**.

Be sure to read [custom field concepts](/spotnana/basic_custom_field_concepts) to familiarize yourself with this feature before starting to use it.

## Creating the main custom field

Create the custom field that asks a question. For example, **Are you planning to extend your stay?**.
You would do this using the [create custom field](/openapi/customfieldapi/custom-field-v3/createcustomfieldv3) endpoint as shown below:


```json POST /v3/companies/{companyId}/custom-fields?companyRole=ORG
{
  "name": "Are you planning to extend your stay?",
  "description": {
    "value": "Captures whether the traveler stays beyond the event dates"
  }
}
```

Add an arm with a [create custom field arm](/openapi/customfieldapi/custom-field-v3/createarm) request.
This arm has no audience conditions, so it applies to every traveler who makes a booking.
The `action` is set to `USER` and the option source `type` is set to `MANUAL` as it requires a manual response from the traveler.

The API response contains an `optionGroupId` which will be used in [creating a dependent custom field](#creating-the-dependent-custom-field).


```json POST /v3/companies/{companyId}/custom-fields/{customFieldId}/arms
{
  "name": "All travelers",
  "action": {
    "type": "USER",
    "required": true,
    "format": {
      "type": "OPTION_LIST",
      "optionListTypeFormat": {
        "isMultiSelect": false,
        "isPctType": false
      },
      "customValueFormat": {
        "isCustomValueAllowed": false
      }
    },
    "userOptionSource": {
      "type": "MANUAL"
    }
  }
}
```

Add the two answers with an [update options](/openapi/customfieldapi/custom-field-v3/updatecustomfieldoptiongroupv3) API call.
The `name` of each option will be displayed to the traveler for them to choose.


```json PATCH /v3/companies/{companyId}/custom-fields/{customFieldId}/option-groups/{optionGroupId}
{
  "toUpdate": [
    {
      "name": "Yes"
    },
    {
      "name": "No"
    }
  ]
}
```

## Creating the dependent custom field

Create the second custom field using the same [create custom field](/openapi/customfieldapi/custom-field-v3/createcustomfieldv3) endpoint.


```json POST /v3/companies/{companyId}/custom-fields?companyRole=ORG
{
  "name": "Enter your emergency contact number",
  "description": {
    "value": "Collected only when the traveler extends their stay"
  }
}
```

[Create a custom field arm](/openapi/customfieldapi/custom-field-v3/createarm) to include it's dependency on the [main custom field](#creating-the-main-custom-field).

Set the following values:

* `audience` > `predicates` > `type` as `CUSTOM_FIELD_RESPONSE`
* `id` as the `optionGroupId` of the main custom field's [arm](#creating-the-main-custom-field)
* `comparator` as `EQ`
* `values` as `Yes`.


The above set of conditions translates to: *Answers where the main custom field response equals to **Yes***.

Now that we have the condition, set the action in the same API request as follows:

* `action` > `type` as `USER` (i.e., requires a user input)
* `format` > `type` as `TEXT_INPUT` (i.e., the user needs to type into a text box)
* `allowedChars` as `NUMERIC` (i.e., only allow numbers since the user is entering their phone number).


Below is a sample request where all the fields mentioned above are being set as described:


```json POST /v3/companies/{companyId}/custom-fields/{customFieldId}/arms
{
  "name": "Travelers extending their stay",
  "audiences": [
    {
      "name": "Answered Yes to the extended stay question",
      "predicates": [
        {
          "type": "CUSTOM_FIELD_RESPONSE",
          "id": "c73b1e58-9d24-4f07-a6b8-1e5c9d380f2a",
          "comparator": "EQ",
          "values": [
            "Yes"
          ]
        }
      ]
    }
  ],
  "action": {
    "type": "USER",
    "required": true,
    "format": {
      "type": "TEXT_INPUT",
      "userInputFormat": {
        "type": "NON_REGEX",
        "allowedChars": "NUMERIC",
        "minLength": 7,
        "maxLength": 15
      }
    }
  }
}
```

Every new custom field is disabled by default.
Use the [update custom field status](/openapi/customfieldapi/custom-field-v3/updatecustomfieldstatus) endpoint to enable the custom fields using their `ids`.