Add Single File Upload

Audience: Low-code Engineers

Skill Prerequisites: Forms, Tokens

Adds an upload field for one file to a Dynamic Field Container when the form loads. It works like a Single File Upload field placed in the form builder.

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

Typical Use Cases

• Ask for a supporting document for each item in a list, for example a receipt for each expense line
• Add an upload field only when it's needed, for example a certificate for certain user types

Don't use it to

• Upload several files in one field. Use Add Multi File Upload instead.

Related Actions

Action Name	Description
Add Multi File Upload	Adds an upload field for several files.
Copy File	Copies the uploaded file to another folder after submit.

Input Parameter Reference

This action has the common parameters, except Secure Input and Readonly. It also has:

Parameter	Description	Supports Tokens	Default	Required
Folder Input Mode	How the upload folder is given: Folder Path or Folder ID.	No	Folder Path	No
Upload to Folder	Folder Path mode. The folder to save the file in. Leave empty to use the Temp folder; files in Temp are deleted after the submit actions finish.	See note	none selected	Yes
Upload to Folder ID	Folder ID mode. The numeric ID of the folder to save the file in.	See note	empty string	Yes
Filename Pattern	The name to save the file under, for example [User:Username]-receipt. You can use [<FieldId>:FileName] and [<FieldId>:FileExtension] for the original name. Leave empty to keep the original name.	See note	empty string	No
File Types	The allowed file extensions, separated by commas, for example pdf,jpg,png. Leave empty to allow any extension the site allows.	See note	empty string	No
File Size Limit	The largest file allowed, in MB, for example 5 or 12.5. Leave empty for no limit.	See note	empty string	No
Show max size in error	When checked, the error for a file that's too large includes the size limit.	No	Unchecked	No
Handle Duplicates	What happens when a file with the same name already exists: Rename or Overwrite.	See note	Rename	No

note

Tokens in the upload settings are replaced when the form is displayed and submitted, not when the action runs. Tokens that only exist while the action runs, such as the tokens of an Execute Actions for each List Entry loop, aren't available in these settings. Use them in Field Id and Field Title instead.

Output Parameters Reference

Parameter	Description
Field ID Token Name	Optional. Token that receives the cleaned field ID. If empty, the ID is saved in [<FieldId>:Name].

When the form is submitted, the uploaded file is described by the same tokens as a Single File Upload field, for example [<FieldId>:FileId], [<FieldId>:RelativeUrl] and [<FieldId>:FilePath]. See Single File Upload for the full list.

Examples

tip

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

1. Add a PDF upload

Add this action to the form's On PreInit or On Init actions. It adds a required upload field to the ExtraFields container that accepts PDF files up to 5 MB and saves them in the Documents folder.

{
    "Title": "Add Single File Upload",
    "ActionType": "AddSingleFileUpload",
    "Description": "Add the certificate upload",
    "Condition": null,
    "Parameters": {
        "ContainerId": "ExtraFields",
        "FieldId": "Certificate",
        "FieldName": "Certificate (PDF)",
        "FolderInputMode": {
            "Expression": "",
            "Value": "FolderPath",
            "IsExpression": false,
            "Parameters": {}
        },
        "Folder": {
            "Expression": "",
            "Value": "/Documents",
            "IsExpression": false,
            "Parameters": {}
        },
        "Pattern": "",
        "FileExt": "pdf",
        "FileLimit": "5",
        "MaxSizeInError": true,
        "Duplicates": {
            "Expression": "",
            "Value": "Rename",
            "IsExpression": false,
            "Parameters": {}
        },
        "IsRequired": "true",
        "FieldIdTokenName": ""
    }
}

Revised 09/25/2026