File input

Create file upload inputs in your forms.

File input

Use the fileInput() function to create file upload inputs in your forms. It uses the HTML <input type="file"> element which allows users to upload files from their device.

---

Basic usage

import { Composer } from "formsmd";

const composer = new Composer({
  id: "my-form"
});

composer.fileInput("document", {
  question: "Upload your document"
});

Generates the following Markdown-like syntax:

#! id = my-form

document = FileInput(
  | question = Upload your document
)

Required

Add the required parameter to make the field mandatory:

composer.fileInput("document", {
  question: "Upload your document",
  required: true
});

Generates the following Markdown-like syntax:

document* = FileInput(
  | question = Upload your document
)

---

Function overview

The following is the overview of the function:

fileInput(name: string, params: object)

Arguments

Name	Type	Description
name	string	A unique name for your form field that you'll use to identify the user's response.*
params	object	An object containing all the configuration parameters for your file input field (see the parameters section below for the full list of options).

*Avoid values for the name argument which may be the names of HTML attributes, such as "name", "role", "id", etc. This is because by default, the form's template string is first sanitized using DOMPurify, and these values may be removed to prevent DOM clobbering.

---

Parameters

Shared parameters

These parameters are common to all form fields:

Name	Type	Description
question (required)	string	The main question or label of the form field.
required	true (boolean)	When set, the field becomes required.
description	string	Any extra information that the user may need to fill out the form. Appears right below the question.
fieldSize	"sm"	When set to "sm", the font sizes of the question, description, and answer are made smaller.
labelStyle	"classic"	When set to "classic", the question and description of the form field are made smaller.
subfield	true (boolean)	When set, the question and description of the form field are made smaller. Functionally the same as setting labelStyle to "classic".
disabled	true (boolean)	When set, the input is disabled.
autofocus	true (boolean)	When set, the input will be automatically focused when the parent slide becomes active, or immediately after page load.
id	string	The id attribute of the form field container.
classNames	string[]	The CSS class names of the form field. See the available CSS utility classes.
attrs	Array<{ name: string, value: string }>	Other HTML attributes of the form field. Each attribute has a name and value property.
displayCondition	{ dependencies: string[], condition: string }	Controls when the field is shown. The dependencies lists the fields to watch, and condition is the expression that must be true to show the field. The condition must be a valid Nunjucks expression. See example.

File input specific parameters

Name	Type	Description
sizeLimit	number	Maximum file size in MB. Defaults to 10. Client-side check only, make sure to also validate on the server.
imageOnly	true	When set, only image files are accepted. Client-side check only, make sure to also validate on the server.
currentFile	string	The current file that exists in the database. Use a URL for best results, for example, "https://example.s3.com/image.png".

---

Examples

File input with size limit

composer.fileInput("resume", {
  question: "Upload your resume",
  description: "PDF format preferred",
  sizeLimit: 5,
  required: true
});

Generates the following Markdown-like syntax:

resume* = FileInput(
  | question = Upload your resume
  | description = PDF format preferred
  | sizelimit = 5
)

Image-only file input

composer.fileInput("profilePicture", {
  question: "Profile picture",
  description: "Upload a clear photo of yourself",
  imageOnly: true,
  sizeLimit: 2,
  required: true
});

Generates the following Markdown-like syntax:

profilePicture* = FileInput(
  | question = Profile picture
  | description = Upload a clear photo of yourself
  | imageonly
  | sizelimit = 2
)

File input with existing file

composer.fileInput("document", {
  question: "Update your document",
  currentFile: "https://example.s3.com/previous-doc.pdf"
});

Generates the following Markdown-like syntax:

document = FileInput(
  | question = Update your document
  | currentfile = https://example.s3.com/previous-doc.pdf
)

Styled file input with custom attributes

Add CSS classes and other HTML attributes using the classNames and attrs parameters. Please note, these class names and attributes are added to the <div> or <fieldset> container that contains the actual input field(s).

composer.fileInput("attachment", {
  question: "Upload attachment",
  classNames: ["col-6", "xs:col-6"],
  attrs: [
    { name: "style", value: "font-size: 18px;" }
  ]
});

Generates the following Markdown-like syntax:

[.col-6 .xs:col-6 style="font-size: 18px;"]
attachment = FileInput(
  | question = Upload attachment
)

Please see the available CSS utility classes.

Conditional display

Conditionally show or hide a file input field using the displayCondition parameter. It works as follows:

• dependencies lists the fields to watch.

• condition is the expression that must be true to show the field. This must be a valid Nunjucks expression.

For instance, in the example below, the document upload field will only show up if the user indicates they have additional documents.

composer.choiceInput("hasDocument", {
  question: "Do you have any supporting document?",
  required: true,
  choices: ["Yes", "No"]
})

composer.fileInput("supportingDoc", {
  question: "Upload supporting document",
  description: "You can upload PDF, image, or a Word document",
  displayCondition: {
    dependencies: ["hasDocument"],
    condition: "hasDocument == 'Yes'"
  }
});

Generates the following Markdown-like syntax:

hasDocument* = ChoiceInput(
  | question = Do you have any supporting document?
  | choices = Yes, No
)

::: [{$ hasDocument $}]
{% if hasDocument == "Yes" %}
supportingDoc = FileInput(
  | question = Upload supporting document
  | description = You can upload PDF, image, or a Word document
)
{% endif %}
:::