# Forms, fields and service

Source: https://govform.com/resources/documentation/article/34-06-liquid-forms-fields-and-service-filters
Topic: Liquid Templates

Use these filters when a template needs field or form output, component visibility information or the current repeating-row context. Pass inner field IDs—not an outer group ID—and test hidden, blank and repeated values.

## Standard Liquid filters

These filters are provided as standard by the Liquid language. They are available anywhere Govform accepts a Liquid template.

| Filter | What it does | Example |
| --- | --- | --- |
| `default(fallback)` | **Provides fallback for empty values**  
Returns fallback if input is null, undefined, or empty string. | `{{ empty_var | default: "N/A" }} → N/A` |
| `first()` | **Gets first element of array**  
Returns first item in array or first character of string. | `{{ "hello" | first }} → h` |
| `json()` | **Converts value to JSON string**  
Serializes value as JSON. | `{{ my_object | json }} → {"key":"value"}` |
| `last()` | **Gets last element of array**  
Returns last item in array or last character of string. | `{{ "hello" | last }} → o` |
| `map(property)` | **Extracts property from array of objects**  
Creates array of property values from object array. | `{{ users | map: "name" }} → array of name values` |
| `size()` | **Returns size of array or string**  
Gets length/count of elements. | `{{ "hello" | size }} → 5` |
| `where(property, expected)` | **Selects matching array items**  
Returns objects whose property equals the expected value. If expected is omitted, the property must be truthy. | `{{ users | where: "active", true | json }}` |

## Govform filters

These filters are added by Govform for service-building and data-handling tasks.

| Filter | What it does | Example |
| --- | --- | --- |
| `field_to_text(field_value, field_id, field_defs, part_id)` | **Converts field value to display text**  
Formats field value according to field type for display. | `{{ my_field_value | field_to_text: "field1", form.fieldDefs }}` |
| `form_to_json(form)` | **Converts form data to JSON object**  
Extracts all field values into clean JSON structure. | `{{ form | form_to_json }}` |
| `form_to_text(form, newlines)` | **Converts form data to formatted text**  
Creates human-readable text summary of form data. | `{{ form | form_to_text: 2 }}` |
| `is_editing_table_group_iteration(field_in_group_id)` | **Checks if currently editing table group row**  
Pass the ID of a field inside the group. The group itself is not addressed by ID. | `{{ "line_item_name" | is_editing_table_group_iteration }}` |
| `is_hidden(field_id)` | **Checks if field is hidden by conditional logic**  
Returns true if field is currently hidden by show/hide rules. | `{{ "conditional_field" | is_hidden }}` |
| `is_visible(field_id)` | **Checks if field is visible**  
Returns true if field is currently visible (opposite of is\_hidden). | `{{ "conditional_field" | is_visible }}` |
| `not(boolean)` | **Logical NOT operation**  
Returns opposite boolean value. | `{{ true | not }} → false` |
| `show_hidden_component(change_text, reset_text, visually_hidden_prefix, visually_hidden_suffix, field_id, classes, iteration, dont_save)` | **Creates toggle for hidden form components**  
Generates button to show/hide optional form fields. | `{{ "Add details" | show_hidden_component: "Remove details", "", "", "optional_field", "btn-link" }}` |

## Related guidance

-   [Write Liquid templates](<https://govform.com/resources/documentation/article/11-write-liquid-templates>)
-   [Use Markdown and HTML](<https://govform.com/resources/documentation/article/12-use-markdown-and-html>)