Drupal Forms API

This post is about the Form API of drupal6, You may find this post written in a little bit of unimpressive way, this is bcoz i am running short of time these days nonetheless i would like your suggestions and comments at any time and will try to make them happening:

Forms API

• The forms API abstracts forms into a nested array of properties and values.
• $form_values is array which holds form elements values.
• The form token (form unique id) is stored in the variables table as drupal_private_key.
• drupal_get_form() function interact with drupal form.
• hook_elements() function is used to define element type.
• hook_element() can be used to define your own element types in your module.
• element_info() hook collects all the properties for all form elements.

FORM PROPERTIES

• #validate property is used to validate the form elements.
• #base is used to apply same validator to several forms.
• #submit handles form submission. If there is no property named #submit, drupal looks for function name “formID_submit()” or failing that drupal again search for “#basevalue_submit”.
• #after_build property will call all functions of a form.
• #theme is used to set a theme to an existing form.
• #pre_render property used to call the functions just before the transformation of form from a data structure to HTML.
• #prepend, #suffix properties are used to prepend and append text to  the form elements. drupal also uses these properties while rendering the form.
• #method property is used to set the form method to post. By default it is set to post, Also get method is not supported by the form API.
• #tree : Setting #tree to TRUE gives a nested array of fields with there values. While #tree is set to FALSE, we get a flattened representation of field name and values.

FLOW of form formation:

when a module contains a form code is called by drupal the form datastructure renders form into html in the following sequence:

call drupal_get_form() -> call hook_elements()['defining element types such as radio buttons, chekcboxes, textfiels'] -> call elements_info() [information about the related properties ,values and functions] -> #validate property -> #submit property

Bibliography: Apress Pro Drupal Devlopement (ycu73k6ath)