Forms Generator

Forms Generator is a library for Node.js that helps with HTML forms.

A very simple and concise JS description is used to define forms. Form definitions are separate from things like label values, label internationalisation, style attributes and field data validation. Such separation provides a way not to mix model and view related things, but still eliminating typical HTML forms redundancy.

Features

• Simple syntax that allows both manually and by-software forms creation.
• API for setting and running data validation functions.
• Separate definition of fields variables and labels with a build-in internationalisation support.
• Easy to define fields HTML attributes (internationalisation is also supported).
• API for inserting element attributes or even custom HTML elements into generated forms.

Tutorial

This demonstration will show the basic workflow for express with Jade and i18n integration.

So lets create a simple singup form:

var regForm = new Form(
  "regForm", null, { action : "forms/regForm" },
  [ "name", "text" ],
  [ "pass", "password" ],
  [ "mail", "email"],
  [ "mailVisibility", "radio", null, "none", "friends", ["all" , {checked : true}]],
  [ "acceptTerms", "checkbox"],
  [ "register", "button"]);

This will create the form definition, with the custom action route (by default a generated action for this form is "regFormSend").

Then lets assign a data validator for the name field:

function validateName(data, i18n, cb) {
  process.nextTick(
    function() {
      if(!data || !validator.isLength(data[0], 4, 20)) {
        cb(i18n.__("error_short_name"));
      } else {
        cb(false);
      }});
}
regForm.setValidator("name", validateName);

It will emulate some DB based login checking, which is an asynchronous operation. Note that error data can be an arbitrary non-false object, using i18n is optional here.

The form send route with parsing, validation and response will be:

regForm.setFormRoute(app, function(req, res, next) {
  var cbFAIL = function(errors) {
    res.setHeader('Content-Type', 'text/html');
    res.send(JSON.stringify(errors));
  };
  var cbOK = function(fields, files) {
    res.send(JSON.stringify(null));
  };
  var parser = new fg.FormParser();
  parser.parse(req, function(err, fields, files) {
    console.log("Fields:\n%s\nFiles:\n%s", util.inspect(fields), util.inspect(files));
    regForm.validate(fields, files, req, cbOK, cbFAIL);
  });
});

setFormRoute method will add a route to an application/router according to forms action and method attributes.

Form get route is simple:

app.use('/', function(req, res) {
  res.render("index", {
    regForm: regForm.getContent(req)
  });
});

It will pass regForm object to the index template. getContent method will populate and cache labels for the request locale (or the default locale, if the request one is not enabled).

The procces of creating field labels is separated and depends on language settings. Here is our en.json file with the labels mapping for "en" locale:

{
    "regForm-name": "Username",
    "regForm-pass": "Password",
    "regForm-mail": "Mail",
    "regForm-mailVisibility-none": "None",
    "regForm-mailVisibility-friends": "Friends only",
    "regForm-mailVisibility-all": "Everyone",
    "regForm-mailVisibility": "Show mail to:",
    "regForm-acceptTerms": "I accept the Terms of Service",
    "regForm-register": "Submit",
    "error_short_password": "Short password",
    "error_malformed_mail": "Malformed mail",
    "error_terms": "You have to agree with the Terms of Service",
    "error_short_name": "Short name"
}

Another separate operation is form styling. Here is index.jade file:

mixin link(name, url)
  a(href=url) #{name}
doctype html
html
  head
    meta(charset='utf-8')
    link(rel='stylesheet', href='http://yui.yahooapis.com/pure/0.6.0/pure-min.css')
    script(src='https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js')
    script(src='/res.js')
  body
    +Form( regForm, { "@::attributes" : { "class" : "pure-form pure-form-stacked" },
                      "@-acceptTerms--name::after" : [ "link", "(?)", "/terms.txt" ] } )
    hr
    div#response

From mixin call renders an actual HTML form. The second argument is additional information that is inserted into rendered forms. Here we are adding class attributes to the form tag and appending results of link mixin to the acceptTerms label element. So elements, that are used only in styling and not affecting server form parsing, are kept separate.

And the last thing is res.js browser code.

function regFormOnload() {
  var response = $("#regFormIframe").contents().find("body").text();
  $("#response").text(response);
}

regFormOnload function name and regFormIframe are generated from the form definition. It will just output a server response, but errors object is a simple name to object store, so displaying errors in a pretty way is rather trivial.

Note that no any browser code is provided with the library and no any assumptions about client side stack are made. But integration with existing solutions for client side validation, live validation/completion is possible. For example HTML5 data- attributes in a form definition can be used for mapping client side functions.

The full application code is in a tutorial directory. For more information look at Description, Example and API sections.

Description

The main interface is Form class, which creates form definitions. These definitions could be directly rendered to HTML via render method. Or getContent method could be used to get an object suitable as an argument for Jade Form mixin. In this case HTML will be rendered as a part of Jade template.

Note: Neither i18n nor jade are included in the production dependencies, but rather they are expected by some methods as arguments. Jade should be compatible with version ^1.9.0 (also pug 1.x may be used) and i18n with version ~0.5.0 or ~0.8.0.

Identifiers or IDs

Each form field should have an ID that is used for several purposes. All IDs should match /^~?[a-zA-Z_][a-zA-Z0-9_]*$/ regular expression. ~ prefix is stripped from actual IDs.

The first one is generating HTML ID attributes. All fields IDs are prefixed with a form ID. Also field entries (they are used for some field types like radio buttons) are prefixed with a field ID. So generated HTML ID attributes will look like FormID-FieldID-EntryID. Single - is used as a nesting separator, -- is used to separate ID suffixes for additional elements like labels or wrappers.

The second one is generating translation labels for fields. By default translation IDs generation algorithm is the same as the HTML one, but using non-prefixed IDs is allowed. nTP function disables prefixing for a single ID. Prefixing ID with ~ is similar to using nTP function. Also from class constructor options allow customisation of form translation IDs generation. HTML ID attributes are not affected by any of these options.

The last one is form data format. Forms field names will be the same as IDs. Also radio, select and checkbox field values will contain values matching theirs entries IDs.

Form parsing and validation

By default no any validation is performed. User supplied asynchronous functions can be used in a validation. Validators can be set by setValidator and setGlobalValidator methods. Each field can have one validation function that validates only a field data. Global validator can be used for a more complex validation that requires an access to all fields data. It is possible to run a full validation with validate method, or execute just one validator with runValidatator and runGlobalValidatator methods. All data for validation should be in the Multiparty parser (it is provided by FormParser class) format.

Field definitions

• fields = field-array | fields
• field-array = [ ID , type , [ attributes , subfields ] ]
• ID = /^~?[a-zA-Z_][a-zA-Z0-9_]*$/
• type = "div" | "fieldset" | "textarea" | "select" | "button" | "datalist" | "keygen" | "output" | "text" | "password" | "radio" | "checkbox" | "file" | "hidden" | "image" | "reset" | "submit" | "color" | "date" | "datetime-local" | "email" | "month" | "number" | "range" | "search" | "tel" | "time" | "url" | "week"
• attributes = attributes-object | null | attributes-array
• attributes-array = [ attributes-object , [ attributes-object , attributes-object , attributes-object ] ]
• subfields = entries | fields
• entries = entry | entries
• entry = ID | entry-array | group-object
• entry-array = [ ID, attributes-object , [ attributes-object , attributes-object , attributes-object ] ]
• group-object = { group : group-array }
• group-array = [ ID, attributes , entries ]

Subfields can be used only with with several field types. Entries are allowed for "checkbox", "radio", "select" and "datalist" types. Entries groups are only allowed for "select", the depth must be only of one level (it makes possible to define HTML select optgroups). "radio" and "select" fields must contain one or more entries. Fields nesting is only allowed for "div" and "fieldset" types, nested fields are wrapped with respective tags. "fieldset" must contain one or more fields, but "div" can be empty.

attributes-object with attribute : value pairs is used to set input HTML elements attributes. attributes-array is used to set attributes to the following elements: attributes-array[0] - actual form input attributes, attributes-array[1] - wrapper attributes, attributes-array[2] - label attributes, attributes-array[3] - attributes for an additional element (it is used for datalist, checkbox/radio field names and form iframe elements). If there is no such element, then its attributes are ignored.

HTML and attributes insertion

This operations doesn't alter a form definition, separating view style operations. As a result a form can have several custom view renders.

It is possible to insert attributes and HTML elements into generated forms with an object. Object key are the following selectors prefixed by an element HTML ID:

• ::before insertion before an element
• ::after insertion after an element
• ::attributes insertion of element attributes

For ::before and ::after selectors values can be either HTML strings or arrays with mixin name and arguments (up to 9 mixin arguments are supported). Or attribute objects for ::attributes selector. Class attributes are concatenated, preserving classes defined in a form constructor.

Another way to insert attributes, based on tag/type combination, is a user supplied attrsExtender function. It should return an attributes-object and it recieves the following arguments:

• tag - string HTML tag name.
• type - string almost the same as field type, with the exeption of "checkboxSingle"type, that is used for single checkboxes.
• class - string with a class that is added to some form elements by default or null.

IDs can be abbreviated with the help of @ syntax, so selectors will look like @-FieldID-EntryID::Selector.

Example

Express 4 example application with pure-form CSS style is in an example directory.

API

Form(id, options, attributes, ...fields)

Constructor

Throws:

• Error with a string description on malformed item definitions.

Arguments:

• id - string matching /^~?[a-zA-Z_][a-zA-Z0-9_]*$/ regular expression, or a result of nTP function.
• options - object with form options or null. Fields:
  • i18nNoPrefix - boolean option to turn off all prefixes for translation ids, false by default.
  • i18nFormID - string with a form ID, overrides a default form ID in translations.
  • i18nNoEntryPrefix - boolean option to turn off entries prefixing with field IDs, false by default.
• attributes - object or array for form tag attributes or null.
• ...fields - Rest arguments are interpreted as field definitions.

Form.setFormRoute(router, callback)

Method

Express form receive route helper.

Arguments:

• router mutable - Express router.
• callback - Express route callback.

Form.validate(fields, files, i18n, callbackPass, callbackFail)

Method [async]

Asynchronous form validation against previously defined validators via setValidator function. Order of fields and files validation functions execution is undefined. After passing all local validations, global validator set by setGlobalValidator is executed. Local, global or both validators can be undefined, meaning that any data pass validation stage.

NOTE: For legacy reasons this method does not follow node style callbacks convention.

Arguments:

• fields - object with Multiparty fields data or null.
• files - object with Multiparty files data or null.
• i18n - i18n translation library.
• callbackPass - Function called on successful form validation. Arguments:
  • fields - object with Multiparty fields data.
  • files - object with Multiparty files data.
• callbackFail - function called when form validation fails. Arguments:
  • errors - object with validation errors or null. It contains either field : error pairs for field validation errors, or an object with one "form-error" : error pair for a global validation error.

Form.runValidatator(fieldID, data, i18n, callback)

Method [async]

Runs only a specific field validator.

Arguments:

• fieldID - string with a field ID.
• data - object with Multiparty field data.
• i18n - i18n translation library.
  • callback - function callback to run after validation. Arguments:
    • error - true value with an error or false value.
    • data - object with Multiparty field data or null.

Form.runGlobalValidatator(fields, files, i18n, callback)

Method [async]

Runs only a global validator.

Arguments:

• fields - Multiparty fields data or null.
• files - Multiparty files data or null.
• i18n - i18n translation library.
• callback - function callback to run after validation.
  • error - true value with an error or false value.
  • fields - Multiparty fields data or null.
  • files - Multiparty files data or null.

Form.getExpectedValues(fieldID)

Method

Validation helper. Returns expected values for fields that contain a fix set of entries.

Arguments:

• fieldID - string with a field ID.

Returns:

• Array with expected string values, or an empty Array if no specific values are expected, or undefined if a form has no such field.

Form.hasField(fieldID)

Method

Check whether or not a form has a field with a supplied ID.

Arguments:

• fieldID - string with a field ID.

Returns:

• boolean true if a form has a field with an ID, false otherwise.

Form.setValidator(fieldID, validator)

Method [mutable]

Field validator setter. Validator should always call a callback and expect data to be undefined or null.

Arguments:

• fieldID - string with a field ID.
• validator - function validator. Arguments:
  • data - Array of Multiparty file/field data.
  • i18n - i18n translation library.
  • cb - function callback to run after validation. Arguments:
    • error - true value with an error or false value.

Form.setGlobalValidator(globalValidator)

Method [mutable]

Global validator setter. Validator should always call a callback and expect fields, files or both to be null, undefined or miss some fields data.

Arguments:

• globalValidator - function global validator. Arguments:
  • fields - Multiparty fields data or null.
  • files - Multiparty fields data or null.
  • i18n - i18n translation library.
  • cb - function callback to run after validation. Arguments:
    • error - true value with an error or false value.

Form.getContent(i18n, skipCache)

Method [caches results]

Expands form for i18n locale and caches results.

Arguments:

• i18n - i18n translation library.
• skipCache optional - Ignore the current cache and re-expand content.

Returns:

• object for Jade form render.

Form.render(jade, options, i18n, insertions, ...includeJadeFiles)

Method

Renders HTML form.

Arguments:

• jade - jade library (also pug 1.x may be used).
• options - jade and render options or null. Render options:
  • attrsExtender - function that extends HTML tags attributes.
  • skipCache - Ignore the current cache and re-expand content.
• i18n - i18n translation library.
• insertions optional - object with HTML insertions or null.
• ...includeJadeFiles optional - The rest arguments are treated as jade files pathnames to include.

Returns:

• string HTML form.

FormParser(options)

Constructor

Same as multiparty.Form. External form parser with the same results format could be used.

__(str)

Function

Wrapper for strings translation via __ function.

Arguments:

• str - string to translate.

Returns:

object that will be translated with a form.

__n(str, n)

Function

Wrapper for strings translation via __n function.

Arguments:

• str - string to translate.
• n - integer.

Returns:

object that will be translated with a form.

nTP(id)

Function

Forces usage of unprefixed IDs for translation.

Arguments:

• id - string matching /^~?[a-zA-Z_][a-zA-Z0-9_]*$/ regular expression.

Returns:

object that could be used as ID in form definitions.

setLocalesGeneration(generator, locales)

Function [module configuration]

Enables auto-adding form IDs to locale files when a form is defined (by default locale files are filled only when a form is expanded to a locale).

Arguments:

• generator - i18n translation library or null to disable generation.
• locales - array of locales or null to disable generation.

includeJade

Constant

Path to Jade mixins file. This file contains Form mixin which performs HTML rendering.

Jade API

Form(data, insertions, attrsExtender)

Mixin

Renders form.

Arguments:

• data - form data (a result of js From.getContent method).
• insertions optional - object with HTML insertions data or null.
• attrsExtender optional - function that extends HTML tags attributes or null.