How to use select query for creating form in drupal 8? - drupal-modules

Question

I have a table in my database. I want to use the data of that table and create form of that data. I created a module and made a form.php page. Wrote select query in function but how to make form from that data?

Answer 1

I believe you want to create listing page of the table data. Here is how you can create a tabular listing with pagination and column sorting.
Suppose you have a table named "students" with the below fields.
id, name, email
1. Create a controller in your module in the below path.
modules/your_module/Src/Controller/StudentsController.php
<?php
namespace Drupal\your_module\Controller;
use Drupal\Core\Controller\ControllerBase;
class StudentsController extends ControllerBase {
public function __construct() {
}
public function list() {
$header = array(
array('data' => t('ID'), 'field' => 'st.id'),
array('data' => t('Name'), 'field' => 'st.name'),
array('data' => t('Email'), 'field' => 'st.email'),
);
$query = db_select('students', 'st')
->fields('st', array('id', 'name', 'email'))
->extend('Drupal\Core\Database\Query\TableSortExtender')
->extend('Drupal\Core\Database\Query\PagerSelectExtender')
->orderByHeader($header);
$data = $query->execute();
$rows = array();
foreach ($data as $row) {
$rows[] = array('data' => (array) $row);
}
$build['table_pager'][] = array(
'#type' => 'table',
'#header' => $header,
'#rows' => $rows,
);
$build['table_pager'][] = array(
'#type' => 'pager',
);
return $build;
}
}
So your controller action is ready, now you have to add routing in order to create path to this listing page.
2. Create routing.yml file inside your module folder as the file name mentioned below, and the code below.
modules/your_module/your_module.routing.yml
students.list:
path: 'admin/config/students/list'
defaults:
_controller: 'Drupal\your_module\Controller\StudentsController::list'
_title: 'Students List'
requirements:
_permission: 'access students list'
3. To create permissions, you can create the followin ing file in your module.
modules/your_module/your_module.permissions.yml
access students list:
title: 'Access students list page'
Clear CMS cache
Go to People => Permissions, Enable the permission for relevant user roles.
Then, browse your page "admin/config/students/list"