Class JSchemaChangeitem

Each object represents one query, which is one line from a DDL SQL query. This class is used to check the site's database to see if the DDL query has been run. If not, it provides the ability to fix the database by re-running the DDL query. The queries are parsed from the update files in the folder administrator/components/com_admin/sql/updates/<database>. These updates are run automatically if the site was updated using com_installer. However, it is possible that the program files could be updated without udpating the database (for example, if a user just copies the new files over the top of an existing installation).

This is an abstract class. We need to extend it for each database and add a buildCheckQuery() method that creates the query to check that a DDL query has been run.

Direct known subclasses

JSchemaChangeitemMysql, JSchemaChangeitemPostgresql, JSchemaChangeitemSqlsrv

Abstract
Package: Joomla\Libraries\Schema
Copyright: Copyright (C) 2005 - 2017 Open Source Matters, Inc. All rights reserved.
License: General Public License version 2 or later; see LICENSE.txt
Since: 2.5
Located at cms/schema/changeitem.php

Methods summary

`public`	# `__construct( JDatabaseDriver $db, string $file, string $query )` Constructor: builds check query and message from $updateQuery Constructor: builds check query and message from $updateQuery Parameters `$db` `JDatabaseDriver` - $db Database connector object `$file` `string` - $file Full path name of the sql file `$query` `string` - $query Text of the sql query (one line of the file) Since 2.5
`public static JSchemaChangeitem`	# `getInstance( JDatabaseDriver $db, string $file, string $query )` Returns a reference to the JSchemaChangeitem object. Returns a reference to the JSchemaChangeitem object. Parameters `$db` `JDatabaseDriver` - $db Database connector object `$file` `string` - $file Full path name of the sql file `$query` `string` - $query Text of the sql query (one line of the file) Returns `JSchemaChangeitem` - instance based on the database driver Throws `RuntimeException` - if class for database driver not found Since 2.5
`abstract protected`	# `buildCheckQuery( )` Checks a DDL query to see if it is a known type If yes, build a check query to see if the DDL has been run on the database. If successful, the $msgElements, $queryType, $checkStatus and $checkQuery fields are populated. The $msgElements contains the text to create the user message. The $checkQuery contains the SQL query to check whether the schema change has been run against the current database. The $queryType contains the type of DDL query that was run (for example, CREATE_TABLE, ADD_COLUMN, CHANGE_COLUMN_TYPE, ADD_INDEX). The $checkStatus field is set to zero if the query is created Checks a DDL query to see if it is a known type If yes, build a check query to see if the DDL has been run on the database. If successful, the $msgElements, $queryType, $checkStatus and $checkQuery fields are populated. The $msgElements contains the text to create the user message. The $checkQuery contains the SQL query to check whether the schema change has been run against the current database. The $queryType contains the type of DDL query that was run (for example, CREATE_TABLE, ADD_COLUMN, CHANGE_COLUMN_TYPE, ADD_INDEX). The $checkStatus field is set to zero if the query is created If not successful, $checkQuery is empty and , and $checkStatus is -1. For example, this will happen if the current line is a non-DDL statement. Since 2.5
`public boolean`	# `check( )` Runs the check query and checks that 1 row is returned If yes, return true, otherwise return false Runs the check query and checks that 1 row is returned If yes, return true, otherwise return false Returns `boolean` - true on success, false otherwise Since 2.5
`public`	# `fix( )` Runs the update query to apply the change to the database Runs the update query to apply the change to the database Since 2.5

Magic methods summary

Properties summary

`public string`	`$file`	# Update file: full path file name where query was found Update file: full path file name where query was found Since 2.5
`public string`	`$updateQuery`	# Update query: query used to change the db schema (one line from the file) Update query: query used to change the db schema (one line from the file) Since 2.5
`public string`	`$checkQuery`	# Check query: query used to check the db schema Check query: query used to check the db schema Since 2.5
`public string`	`$checkQueryExpected`	# Check query result: expected result of check query if database is up to date Check query result: expected result of check query if database is up to date Since 2.5
`public JDatabaseDriver`	`$db`	# JDatabaseDriver object JDatabaseDriver object Since 2.5
`public string`	`$queryType`	# Query type: To be used in building a language key for a message to tell user what was checked / changed Possible values: ADD_TABLE, ADD_COLUMN, CHANGE_COLUMN_TYPE, ADD_INDEX Query type: To be used in building a language key for a message to tell user what was checked / changed Possible values: ADD_TABLE, ADD_COLUMN, CHANGE_COLUMN_TYPE, ADD_INDEX Since 2.5
`public array`	`$msgElements`	# Array with values for use in a JText::sprintf statment indicating what was checked Array with values for use in a JText::sprintf statment indicating what was checked Tells you what the message should be, based on which elements are defined, as follows: For ADD_TABLE: table For ADD_COLUMN: table, column For CHANGE_COLUMN_TYPE: table, column, type For ADD_INDEX: table, index Since 2.5
`public integer`	`$checkStatus`	# Checked status Checked status Since 2.5
`public integer`	`$rerunStatus`	# Rerun status Rerun status Since 2.5

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Class JSchemaChangeitem

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