開發 MVC 元件/使用資料庫
From Joomla! Documentation
< J3.x:Developing an MVC Component
在選單類型中新增一個變數請求
使用資料庫
基本的後台
新增語言管理
新增後台行為
新增後台的佈置
新增表單驗證
新增類別
新增設定介面
新增一個安裝/移除/更新程式碼檔案
新增一個前台表單
使用語言過濾功能
新增更新伺服器
這是一系列的多篇文章，旨在介紹如何開發一個 Joomla! Version
Model-View-Controller 元件
讓我們從簡介開始，您可以使用底下的導覽按鈕來瀏覽文章，或是右側的方塊中的連結(列出所有的文章)。
介紹
- 本教學是 開發Joomla! 3.x MVC 元件 系列文章的一部分，閱讀本文之前，您應該先看過前面幾篇文章。此外，閱讀此步驟的同時，鼓勵您可以閱讀和資料庫 query 、從資料表選擇資料、獲取不同格式的資料等相關的學習資源
以下三個影片教學和這個步驟有關 資料庫設定, 顯示訊息 (using JTable) 以及 Admin message selection (and JDatabase).
使用資料庫
Components usually manage their contents using the database. During the install/uninstall/update phase of a component, you can execute SQL queries through the use of SQL text files.
With your favourite file manager and editor create two files called admin/sql/install.mysql.utf8.sql and admin/sql/updates/mysql/0.0.6.sql. They should both have the same content, as follows:
admin/sql/install.mysql.utf8.sql and admin/sql/updates/mysql/0.0.6.sql
DROP TABLE IF EXISTS `#__helloworld`;
CREATE TABLE `#__helloworld` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`greeting` VARCHAR(25) NOT NULL,
`published` tinyint(4) NOT NULL DEFAULT '1',
PRIMARY KEY (`id`)
)
ENGINE =MyISAM
AUTO_INCREMENT =0
DEFAULT CHARSET =utf8;
INSERT INTO `#__helloworld` (`greeting`) VALUES
('Hello World!'),
('Good bye World!');
注意： 在今時，Joomla! 推薦使用指定編碼的：
ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 DEFAULT COLLATE=utf8mb4_unicode_ci;
instead of what is above. InnoDB is the more modern (and now default) MySQL database engine, replacing MyISAM, and utf8mb4 supports a wider range of character sets including emojis. However, I haven't tested all the steps in the tutorial with this setting, so if you use it and go through the complete tutorial series and find no problems please consider updating this file and where it occurs in other tutorial steps.
Also note that if you look at a Joomla database many of the key database tables have a field called 'title' for the sort of information which we're storing in our 'greeting' field. It's generally advisable to follow the Joomla pattern, and use 'title' as the field name, as when we try to use more complex functionality (such as ACL and associations) some of the core Joomla javascript routines we want to reuse expect a 'title' field to be present. (Something to consider changing when this tutorial series is next updated).
Often you will find that the database table has a field to keep track of the published/unpublished state of an item. Using the name 'state' within Joomla is not recommended as it can lead to conflicts, instead the name 'published' is used.
Note: How to tell Joomla to store the value of the published form field into a different name database field? We do this by using the method setColumnAlias() (since 3.4.0).
The file install.mysql.utf8.sql will be executed when you install this component. The file 0.0.6.sql is executed when you do an update.
This is the install file. It will be executed if you put an appropriate order in the helloworld.xml file.
Important Note: When saving the SQL files in utf8, be sure to save them as utf8 NOT BOM or the query will fail with MySQL error #1064.
helloworld.xml
<?xml version="1.0" encoding="utf-8"?>
<extension type="component" version="3.0" method="upgrade">
<name>Hello World!</name>
<!-- The following elements are optional and free of formatting constraints -->
<creationDate>January 2018</creationDate>
<author>John Doe</author>
<authorEmail>john.doe@example.org</authorEmail>
<authorUrl>http://www.example.org</authorUrl>
<copyright>Copyright Info</copyright>
<license>License Info</license>
<!-- The version string is recorded in the components table -->
<version>0.0.6</version>
<!-- The description is optional and defaults to the name -->
<description>Description of the Hello World component ...</description>
<install> <!-- Runs on install -->
<sql>
<file driver="mysql" charset="utf8">sql/install.mysql.utf8.sql</file>
</sql>
</install>
<uninstall> <!-- Runs on uninstall -->
<sql>
<file driver="mysql" charset="utf8">sql/uninstall.mysql.utf8.sql</file>
</sql>
</uninstall>
<update> <!-- Runs on update; New since J2.5 -->
<schemas>
<schemapath type="mysql">sql/updates/mysql</schemapath>
</schemas>
</update>
<!-- Site Main File Copy Section -->
<!-- Note the folder attribute: This attribute describes the folder
to copy FROM in the package to install therefore files copied
in this section are copied from /site/ in the package -->
<files folder="site">
<filename>index.html</filename>
<filename>helloworld.php</filename>
<filename>controller.php</filename>
<folder>views</folder>
<folder>models</folder>
</files>
<administration>
<!-- Administration Menu Section -->
<menu link='index.php?option=com_helloworld'>Hello World!</menu>
<!-- Administration Main File Copy Section -->
<!-- Note the folder attribute: This attribute describes the folder
to copy FROM in the package to install therefore files copied
in this section are copied from /admin/ in the package -->
<files folder="admin">
<!-- Admin Main File Copy Section -->
<filename>index.html</filename>
<filename>helloworld.php</filename>
<!-- SQL files section -->
<folder>sql</folder>
<!-- tables files section -->
<folder>tables</folder>
<!-- models files section -->
<folder>models</folder>
</files>
</administration>
</extension>
Do the same for the uninstall file:
With your favourite file manager and editor put a file admin/sql/uninstall.mysql.utf8.sql containing:
admin/sql/uninstall.mysql.utf8.sql
DROP TABLE IF EXISTS `#__helloworld`;
Schema Numbering
Your component has a version number (which is specified inside the <version> tag in your helloword.xml manifest file), and your component's database schema has its own version number (which is based on the filenames of the sql update files).
Joomla keeps track of the database schema version of your component through a record in its #__schemas table. So when you first install a component, if there's a file called, say, admin/sql/updates/mysql/0.0.6.sql, then Joomla will store the value 0.0.6 it its schemas record.
When you next install a newer version of this component - it doesn't have to be the next version, you can skip versions - Joomla will do the following:
- it will retrieve the component's latest database schema version from its #__schemas table - so it might find in our example the value 0.0.6.
- it will get the filenames of all the files in the admin/sql/updates/mysql/ directory, and organise them in numerically increasing order.
- it will process in order the update files which have filenames numerically after the current schema version - so it might find files called 0.0.7.sql, 0.0.9.sql and 0.0.10.sql, and process these in order.
- it will update the schemas record to have the number of the last update file which it processed - eg 0.0.10.
If you have already released versions of your component when you introduce database use, as we have simulated in this tutorial series, then your first update file must have exactly the same content as the install file. If you have not, then it should be empty.
Although it may be a good idea to keep the two version numbers in step, you don't have to. Joomla takes the schema version from the name of the numerically last update file. That's why it is recommended that there should be an initial update file, even if it's empty. If you want to keep your schema numbers in step with the component version numbers when you update your code but not the database schema, you simply include an update file to go with the new release number, and that update file, too, will be empty.
As you make subsequent releases of your component the database install file must always contain the full schema and the update files only need to contain any changes you have made to the schema since the last update.
新增一個欄位類型
For the moment, we have used a hard coded field type for messages. We need to use our database for choosing the message, and for this we need to define a custom field type (which we call helloworld below) as described here.
Modify the site/views/helloworld/tmpl/default.xml file and put these lines
site/views/helloworld/tmpl/default.xml
<?xml version="1.0" encoding="utf-8"?>
<metadata>
<layout title="COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_TITLE">
<message>COM_HELLOWORLD_HELLOWORLD_VIEW_DEFAULT_DESC</message>
</layout>
<fields
name="request"
addfieldpath="/administrator/components/com_helloworld/models/fields"
>
<fieldset name="request">
<field
name="id"
type="helloworld"
label="COM_HELLOWORLD_HELLOWORLD_FIELD_GREETING_LABEL"
description="COM_HELLOWORLD_HELLOWORLD_FIELD_GREETING_DESC"
/>
</fieldset>
</fields>
</metadata>
It introduces a new field type and tells Joomla to look for the field definition in the /administrator/components/com_helloworld/models/fields folder.
In order to learn more on database queries, selecting data from a database table and retrieving it in several formats click here. With your favourite file manager and editor put a file admin/models/fields/helloworld.php containing:
admin/models/fields/helloworld.php
<?php
/**
* @package Joomla.Administrator
* @subpackage com_helloworld
*
* @copyright Copyright (C) 2005 - 2018 Open Source Matters, Inc. All rights reserved.
* @license GNU General Public License version 2 or later; see LICENSE.txt
*/
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
JFormHelper::loadFieldClass('list');
/**
* HelloWorld Form Field class for the HelloWorld component
*
* @since 0.0.1
*/
class JFormFieldHelloWorld extends JFormFieldList
{
/**
* The field type.
*
* @var string
*/
protected $type = 'HelloWorld';
/**
* Method to get a list of options for a list input.
*
* @return array An array of JHtml options.
*/
protected function getOptions()
{
$db = JFactory::getDBO();
$query = $db->getQuery(true);
$query->select('id,greeting');
$query->from('#__helloworld');
$db->setQuery((string) $query);
$messages = $db->loadObjectList();
$options = array();
if ($messages)
{
foreach ($messages as $message)
{
$options[] = JHtml::_('select.option', $message->id, $message->greeting);
}
}
$options = array_merge(parent::getOptions(), $options);
return $options;
}
}
The new field type displays a drop-down list of messages to choose from. You can see the result of this change in the menu manager section for the helloworld item.
顯示選擇的訊息
When a menu item of this component is created/updated, Joomla stores the identifier of the message. The HelloWorldModelHelloWorld model has now to compute the message according to this identifier and the data stored in the database. To do this is uses the JTable functionality, which is an alternative to JDatabase if only CRUD operations on single records are required.
修改 site/models/helloworld.php 檔案：
site/models/helloworld.php
<?php
/**
* @package Joomla.Administrator
* @subpackage com_helloworld
*
* @copyright Copyright (C) 2005 - 2018 Open Source Matters, Inc. All rights reserved.
* @license GNU General Public License version 2 or later; see LICENSE.txt
*/
// No direct access to this file
defined('_JEXEC') or die('Restricted access');
/**
* HelloWorld Model
*
* @since 0.0.1
*/
class HelloWorldModelHelloWorld extends JModelItem
{
/**
* @var array messages
*/
protected $messages;
/**
* Method to get a table object, load it if necessary.
*
* @param string $type The table name. Optional.
* @param string $prefix The class prefix. Optional.
* @param array $config Configuration array for model. Optional.
*
* @return JTable A JTable object
*
* @since 1.6
*/
public function getTable($type = 'HelloWorld', $prefix = 'HelloWorldTable', $config = array())
{
return JTable::getInstance($type, $prefix, $config);
}
/**
* Get the message
*
* @param integer $id Greeting Id
*
* @return string Fetched String from Table for relevant Id
*/
public function getMsg($id = 1)
{
if (!is_array($this->messages))
{
$this->messages = array();
}
if (!isset($this->messages[$id]))
{
// Request the selected id
$jinput = JFactory::getApplication()->input;
$id = $jinput->get('id', 1, 'INT');
// Get a TableHelloWorld instance
$table = $this->getTable();
// Load the message
$table->load($id);
// Assign the message
$this->messages[$id] = $table->greeting;
}
return $this->messages[$id];
}
}
The model now asks the TableHelloWorld to get the message. This table class has to be defined in admin/tables/helloworld.php file
admin/tables/helloworld.php
<?php
/**
* @package Joomla.Administrator
* @subpackage com_helloworld
*
* @copyright Copyright (C) 2005 - 2018 Open Source Matters, Inc. All rights reserved.
* @license GNU General Public License version 2 or later; see LICENSE.txt
*/
// No direct access
defined('_JEXEC') or die('Restricted access');
/**
* Hello Table class
*
* @since 0.0.1
*/
class HelloWorldTableHelloWorld extends JTable
{
/**
* Constructor
*
* @param JDatabaseDriver &$db A database connector object
*/
function __construct(&$db)
{
parent::__construct('#__helloworld', 'id', $db);
}
}
您應該不會察覺到任何的變更，但是如果您檢查資料庫，您會看到一個名為 jos_helloworld 的資料表，當中有兩個欄位： id 和 greeting。另有兩筆資料：Hello World! 和 Good bye World 。
包裝元件
您的程式碼路徑中的內容
- helloworld.xml
- site/helloworld.php
- site/index.html
- site/controller.php
- site/views/index.html
- site/views/helloworld/index.html
- site/views/helloworld/view.html.php
- site/views/helloworld/tmpl/index.html
- site/views/helloworld/tmpl/default.xml
- site/views/helloworld/tmpl/default.php
- site/models/index.html
- site/models/helloworld.php
- admin/index.html
- admin/helloworld.php
- admin/sql/index.html
- admin/sql/install.mysql.utf8.sql
- admin/sql/uninstall.mysql.utf8.sql
- admin/sql/updates/index.html
- admin/sql/updates/mysql/index.html
- admin/sql/updates/mysql/0.0.1.sql
- admin/sql/updates/mysql/0.0.6.sql
- admin/models/index.html
- admin/models/fields/index.html
- admin/models/fields/helloworld.php
- admin/tables/index.html
- admin/tables/helloworld.php
Create a compressed file of this directory or directly download the archive and install it using the extension manager of Joomla. You can add a menu item of this component using the menu manager in the backend.
請建立一個PR(pull request )，或是到此 https://github.com/joomla/Joomla-3.2-Hello-World-Component 建立一個issue，如果本頁有什麼程式碼方面的差異或是編輯的需要。