Customizing Drupal

mymodule.info

name = My Module
description = A description of what your module does.
version = 7.x-1.x-dev
core = 7.x

mymodule.module

<?php

/*
* Implements hook_menu().
*/
function mymodule_permission() {
  return array(
    'mycustomform access' => array(
      'title' => t('MyForm Access'), 
      'description' => t('Provide access to your form.'),
    ),
    'mycustompage access' => array(
      'title' => t('MyPage Access'), 
      'description' => t('Provide access to your page.'),
    ),
  );
}

/*
* Implements hook_menu().
*/
function mymodule_menu() {
  $items = array();
  $items['mymodule/mypage'] = array(
    'title' => t('My Page'),
    'page callback' => 'mypage_content',
    'access callback' => 'user_access',
    'access arguments' => array('mycustompage access'),
  );
  $items['mymodule/myform'] = array(
    'title' => t('My Form'),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('my_custom_form'),
    'access callback' => 'user_access',
    'access arguments' => array('mycustomform access'),
  );
  return $items;
}


function mypage_content() {
  $output = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi sed sapien diam, id elementum eros. Fusce at auctor tortor.";
  return $output;
}

// My Custom Form
function my_custom_form() { 
  $form = array();
  $form['name'] = array(
    '#type' => 'textfield',
    '#title' => t('Name'),
    '#size' => 60,
    '#maxlength' => 128,
    '#required' => TRUE,
    '#weight' => 0,
  );
  $form['email'] = array(
    '#type' => 'textfield',
    '#title' => t('Email'),
    '#size' => 60,
    '#maxlength' => 128,
    '#required' => TRUE,
    '#weight' => 1,
  );
  $form ['city'] = array(
        '#type' => 'select',
        '#title' => t('City'),
        '#options' => array(
          '' => t('Choose City'),
          'Pune' => 'Pune',
          'Mumbai' => 'Mumbai',
        ),
        '#required' => TRUE,
        '#weight' => 2,
   );
  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Submit'),
    '#weight' => 3,
  );
  return $form;
}

// Validation function of my_custom_form
function my_custom_form_validate($form, &$form_state) {
  $email = $form_state['values']['email'];
  if(!preg_match("/^([a-zA-Z0-9])+([a-zA-Z0-9\._-])*@([a-zA-Z0-9_-])+([a-zA-Z0-9\._-]+)+$/",$email)){
    form_set_error('email',t('Please enter valid email.'));
  }
}

// Submit function of my_custom_form
function my_custom_form_submit($form, &$form_state) {
  $name = $form_state['values']['name'];
  $email = $form_state['values']['email'];
  $city = $form_state['values']['city'];
  drupal_set_message(t('Your name is %name.', array('%name' => $name)));
  drupal_set_message(t('Your email is %email.', array('%email' => $email)));
  drupal_set_message(t('Your city is %city.', array('%city' => $city)));
}

/*
* Implements hook_form_alter().
*/
function mymodule_form_alter(&$form, &$form_state, $form_id) {
  switch ($form_id) {
    case 'my_custom_form':
      $form['address'] = array(
        '#type' => 'textarea',
        '#title' => t('Address'),
        '#cols' => 60,
        '#rows' => 5,
        '#weight' => 2,
      );
      $form['#validate'][] = 'my_form_custom_validate';
      $form['#submit'][] = 'my_form_custom_submit';
      break;
  } 
}

function my_form_custom_validate($form, &$form_state) {
  // custom validation script goes here.....
}

function my_form_custom_submit($form, &$form_state) {
  // custom submit script goes here.....
}

/*
* Implements hook_node_insert().
*/
function mymodule_node_insert($node) {
  if($node->type == 'article') {
    variable_set('node_custom_value_'.$node->nid, 'Inserted Custom Value');
  }
}

/*
* Implements hook_node_insert().
*/
function mymodule_node_load($nodes, $types) {
  foreach($types as $type) {
    if($type == 'article'){
      foreach($nodes as $node) {
        $node->custom_value = variable_get('node_custom_value_'.$node->nid, '');
      }
    }
  } 
}

/*
* Implements hook_node_view().
*/
function mymodule_node_view($node, $view_mode, $langcode) {
  if($node->type == 'article'){
    $node->content['custom_value'] = array(
      '#markup' => $node->custom_value, 
      '#weight' => -10, 
    );
  }
}

/*
* Implements hook_node_update().
*/
function mymodule_node_update($node) {
  $node->custom_value = variable_set('node_custom_value_'.$node->nid, 'Updated Custom Value');
}

/*
* Implements hook_node_delete().
*/
function mymodule_node_delete($node) {
  variable_del('node_custom_value_'.$node->nid);
}