Load dynamic field from JSON

Audience: Low-code Engineers

Skill Prerequisites: Forms, JSON, Tokens

Adds several fields of any type to a Dynamic Field Container in one step, from a JSON description. It's useful when the form's fields are stored somewhere else, for example in a database table that defines a questionnaire.

See Dynamic Fields for how dynamic fields work and how to set up the container.

Typical Use Cases

• Build a form from field definitions stored in the database, for example survey questions
• Add a mix of field types without one action per field

Don't use it to

• Add one simple field. The individual Add actions, such as Add Textbox, are easier to set up and check their settings.

Related Actions

Action Name	Description
Run SQL Query	Loads the JSON from the database.
Add Textbox	Adds a single field, with checked settings.

Input Parameter Reference

Parameter	Description	Supports Tokens	Default	Required
Container Id	The ID of the Dynamic Field Container to add the fields to.	Yes	empty string	Yes
Fields Json	A JSON array of field objects. See JSON format.	Yes	empty string	Yes

JSON format

Each object in the array describes one field. The most useful properties are:

Property	Description
Name	The field ID, cleaned like Field Id in the other actions. If empty, Title is used.
Title	The field's label.
InputTypeStr	The field type. See the table below. Unknown types become a textbox.
ShortDesc	Help text shown with the field.
IsRequired	true to make the field required.
EnableCondition, BindShow, BindValue, BindOnChange, ValidationCondition	The same expressions as in the form builder.
CssClass, CssStyles, LabelCssClass, LabelCssStyles	CSS, added to the container's CSS.
Parameters	An object with the field type's own settings. Value is the initial value. For list fields, DataSource holds the options, for example {"Value": "Items", "Items": "Red|red\nBlue|blue"}.

Common field types:

InputTypeStr	Field
open-text	Text Box
open-text-large	Large Text
open-number	Number
closed-truefalse	CheckBox (True/False)
closed-multiple-dropdown	Dropdown
closed-multiple-radio	Radio Boxes
closed-multiple-checkbox	Checkbox List
dropdown-checkboxes	Dropdown with Checkboxes
dropdown-autocomplete	Dropdown with Autocomplete
tags-input	Tags Input
hiden-constant	Hidden Field with Custom Value (the ID is spelled this way in the product)
static-text	Static Text
slider	Slider
date-flatpickr, time-flatpickr, datetime-flatpickr	Date, time, or date and time picker
upload.single, upload.multi	Single or Multi File Upload

The layout settings (position, columns, visibility and enabled state) always come from the container and can't be set in the JSON.

Considerations

• Silent when there's nothing to do. If Fields Json is empty or an empty array, or no container has the given ID, the action finishes without adding anything and without an error.
• Invalid JSON makes the action fail with the JSON parser's error message.
• Unique IDs. The action fails if two fields in the JSON have the same ID, or if a field's ID is already used on the form.
• Fewer checks. Unlike the individual Add actions, this action doesn't create [<FieldId>:Name] tokens or place initial values in tokens, and IsRequired must be true or false, not a condition.
• Use On PreInit or On Init, like the other Dynamic Fields actions.

Examples

tip

To understand how to use the below examples, please see Running Examples.

1. Add a textbox and a dropdown from JSON

Add this action to the form's On PreInit or On Init actions. It adds a required Nickname text box, prefilled with the user's display name, and a Favorite Color dropdown to the ExtraFields container.

{
    "Title": "Load dynamic field from JSON",
    "ActionType": "LoadDynamicFieldsFromJson",
    "Description": "Add the profile questions",
    "Condition": null,
    "Parameters": {
        "ContainerId": "ExtraFields",
        "FieldsJson": "[{\"Name\":\"Nickname\",\"Title\":\"Nickname\",\"InputTypeStr\":\"open-text\",\"IsRequired\":true,\"Parameters\":{\"Value\":\"[User:DisplayName]\"}},{\"Name\":\"Color\",\"Title\":\"Favorite Color\",\"InputTypeStr\":\"closed-multiple-dropdown\",\"ShortDesc\":\"Pick one\",\"Parameters\":{\"DataSource\":{\"Value\":\"Items\",\"Items\":\"Red|red\\nBlue|blue\"}}}]"
    }
}

The JSON in Fields Json, formatted for reading:

[
    {
        "Name": "Nickname",
        "Title": "Nickname",
        "InputTypeStr": "open-text",
        "IsRequired": true,
        "Parameters": { "Value": "[User:DisplayName]" }
    },
    {
        "Name": "Color",
        "Title": "Favorite Color",
        "InputTypeStr": "closed-multiple-dropdown",
        "ShortDesc": "Pick one",
        "Parameters": {
            "DataSource": { "Value": "Items", "Items": "Red|red\nBlue|blue" }
        }
    }
]

Revised 09/25/2026