> For the complete documentation index, see [llms.txt](https://api-docs.devhub.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://api-docs.devhub.com/advanced/custom-fields.md).

# Custom fields

Many objects within the DevHub platform support `custom_fields` that can then be used throughout the templates and pages within projects.

### Supported objects

* [Sites](/core-resources/sites.md)
* [Locations](/core-resources/locations.md)
* [Pages](/content-resources/pages.md)
* Posts
* Menu items

## Datamodels and list of associated fields

Using the dashboard, you can visit `Manage fields` and view a specific datamodel to see its associated fields including the field `slug` and `field_type`.

To get the list of fields available programmatically for an object, these are tied to Datamodels (`/api/v2/datamodels/:datamodel_id/`) by type

* For Page templates, the `Datamodel.id` associated with the template is available via the `Page.datamodel_id` value on the Page template (`page.type` of `template`) object itself.
* For Site > Manage content fields, these are defined in two ways
  * Specific `Datamodel.id` associated with the Theme assigned to the Site (via `site.theme_id`)
  * If no specific assignment is set, uses the first datamodel of `datamodel_type` `site_custom_fields`

## Field serialization

Guidance on how to send structured fields based on field type and slug

### Text fields

Field types of `short_text`, `long_text` or `multi_line_text`.

```json
"custom_fields": {
	"<field.slug>": "Field value",
	...
}
```

For multiline text, you will just send the value serialized with the linebreaks `\n` escaped within the JSON

```json
"custom_fields": {
	"<field.slug>": "Multi-line.\nValue.",
	...
}
```

### HTML fields

Field types of `html` or `simple_html`.

```json
"custom_fields": {
	"<field.slug>": "<h1>Headline</h1><p>Some content</p>"
}
```

Linebreaks in the HTML are not needed

### Images

Field type of `image`

To host the image within DevHub and supporting this native Image field, images will need to be first uploaded to DevHub using the [Images](/content-resources/images.md) endpoint (`/api/v2/images/`)

From the uploaded image, you will need to use the `image.absolute_path` and `image.id` values for sending within the custom fields

For storing in the `custom_fields` you would send the following pattern based on the `field.slug`

```json
"custom_fields": {
	"<field.slug>": image.absolute_path,
	"<field.slug>_id": image.id,
	"<field.slug>_alt": "Optional alt tag associated with the image"
	...
}
```

Example of an image field with a slug of `hero_image`

```json
"custom_fields": {
	"hero_image": "/img/upload/custom-hero-image.jpg",
	"hero_image_id": 12345,
	"hero_image_alt": "Optional alt tag associated with the image"
	...
}
```

### Nested objects / Related models

Field type of `related_model_list`

We support nested objects, each with separated defined list of fields that can be used for each item in the list. Each of those fields then has a type. Nesting of related models (a `related_model_list` within a `related_model_list` item) is not currently supported.

```json
"custom_fields": {
	"<field.slug>": [
		{
			"<related model field.slug>": "Field value",
			...
		},
		{
			"<related model field.slug>": "Field value",
			...
		}
	],
	...
}
```

Example of a FAQ related/nested field with a `question` and `answer` field

```json
"custom_fields": {
	"faqs": [
		{
			"question": "Question 1?",
			"answer": "Answer to the question"
		},
		{
			"question": "Question 2?",
			"answer": "Answer to the question"
		}
	],
	...
}
```

### Select field

Field type of `select`

Similar to the Text fields, the selected choice will be sent as a string. But this value must match the available `field.choices` strings.

```json
"custom_fields": {
	"<field.slug>": "Option 2",
	...
}
```

### Boolean field

Field type of `boolean`

Sent as a JSON true/false value

```json
"custom_fields": {
	"<field.slug>": true,
	...
}
```