From 3766e1b22f5144800dbd5efe15dae5e26df584b9 Mon Sep 17 00:00:00 2001 From: Larry Ullman Date: Mon, 26 Aug 2013 13:50:55 -0400 Subject: [PATCH] Edited the first half --- docs/guide/active-record.md | 52 +++++++++++++++++++-------------------------- 1 file changed, 22 insertions(+), 30 deletions(-) diff --git a/docs/guide/active-record.md b/docs/guide/active-record.md index bb39115..0c93fad 100644 --- a/docs/guide/active-record.md +++ b/docs/guide/active-record.md @@ -1,17 +1,15 @@ Active Record ============= -ActiveRecord implements the [Active Record design pattern](http://en.wikipedia.org/wiki/Active_record). -The idea is that an [[ActiveRecord]] object is associated with a row in a database table and its attributes are mapped -to the columns of the corresponding table columns. Reading an ActiveRecord attribute is equivalent to accessing -the corresponding table column. For example, a `Customer` object is associated with a row in the -`tbl_customer` table, and its `name` attribute is mapped to the `name` column in the `tbl_customer` table. -To get the value of the `name` column in the table row, you can simply use the expression `$customer->name`, -just like reading an object property. - -Instead of writing raw SQL statements to perform database queries, you can call intuitive methods provided -by ActiveRecord to achieve the same goals. For example, calling [[ActiveRecord::save()|save()]] would -insert or update a row in the associated table of the ActiveRecord class: +Active Record implements the [Active Record design pattern](http://en.wikipedia.org/wiki/Active_record). +The premise behind Active Record is that an individual [[ActiveRecord]] object is associated with a specific row in a database table. The object's attributes are mapped to the columns of the corresponding table. Therefore, referencing an Active Record attribute is equivalent to accessing +the corresponding table column for that record. + +For example, say that the `Customer` ActiveRecord class is associated with the +`tbl_customer` table. This would mean that the class's `name` attribute is automatically mapped to the `name` column in `tbl_customer`. +Thanks to Active Record, assuming the variable `$customer` is an object of type `Customer`, to get the value of the `name` column for the table row, you can simply use the expression `$customer->name`. In this example, Active Record is providing an object-oriented way to access data stored in the database, just as you would access any object property. But Active Record provides much more functionality than this. + +With Active Record, instead of writing raw SQL statements to perform database queries, you can call intuitive methods to achieve the same goals. For example, calling [[ActiveRecord::save()|save()]] would perform an INSERT or UPDATE query, creating or updating a row in the associated table of the ActiveRecord class: ```php $customer = new Customer(); @@ -24,7 +22,7 @@ Declaring ActiveRecord Classes ------------------------------ To declare an ActiveRecord class you need to extend [[\yii\db\ActiveRecord]] and -implement the `tableName` method like the following: +implement the `tableName` method: ```php use yii\db\ActiveRecord; @@ -41,13 +39,12 @@ class Customer extends ActiveRecord } ``` -Connecting to Database +Connecting to the Database ---------------------- ActiveRecord relies on a [[Connection|DB connection]] to perform the underlying DB operations. -By default, it assumes that there is an application component named `db` which gives the needed -[[Connection]] instance. Usually this component is configured via application configuration -like the following: +By default, ActiveRecord assumes that there is an application component named `db` which provides the needed +[[Connection]] instance. Usually this component is configured in application configuration file: ```php return array( @@ -65,13 +62,10 @@ return array( Please read the [Database basics](database-basics.md) section to learn more on how to configure and use database connections. -> Tip: To use a different database connection, you may override the [[ActiveRecord::getDb()]] method. -You may create a base ActiveRecord class and override its [[ActiveRecord::getDb()]] method. You -then extend from this base class for all those ActiveRecord classes that need to use the same -DB connection. +> Tip: To use a different database connection, you need to override the [[ActiveRecord::getDb()]] method. To do that, create a base class that extends ActiveRecord. In the base class, override the [[ActiveRecord::getDb()]] method. Then extend your new base class for all of your ActiveRecord classes that need to use the same alternative database connection. -Querying Data from Database +Querying Data from the Database --------------------------- There are two ActiveRecord methods for querying data from database: @@ -79,8 +73,8 @@ There are two ActiveRecord methods for querying data from database: - [[ActiveRecord::find()]] - [[ActiveRecord::findBySql()]] -They both return an [[ActiveQuery]] instance which extends from [[Query]] and thus supports -the same set of flexible and powerful DB query methods. The followings are some examples, +Both methods return an [[ActiveQuery]] instance, which extends from [[Query]] thus supporting +the same set of flexible and powerful DB query methods. The followings examples demonstrate some of the possibilities. ```php // to retrieve all *active* customers and order them by their ID: @@ -122,10 +116,10 @@ Accessing Column Data --------------------- ActiveRecord maps each column of the corresponding database table row to an *attribute* in the ActiveRecord -object. An attribute is like a regular object property whose name is the same as the corresponding column -name and is case-sensitive. +object. The attribute behaves like any regular object public property. The attribute's name will be the same as the corresponding column +name, and is case-sensitive. -To read the value of a column, you can use the following expression: +To read the value of a column, you can use the following syntax: ```php // "id" is the name of a column in the table associated with $customer ActiveRecord object @@ -141,7 +135,7 @@ $values = $customer->attributes; ``` -Manipulating Data in Database +Manipulating Data in the Database ----------------------------- ActiveRecord provides the following methods to insert, update and delete data in the database: @@ -157,9 +151,7 @@ ActiveRecord provides the following methods to insert, update and delete data in Note that [[ActiveRecord::updateAll()|updateAll()]], [[ActiveRecord::updateAllCounters()|updateAllCounters()]] and [[ActiveRecord::deleteAll()|deleteAll()]] are static methods and apply to the whole database -table, while the rest of the methods only apply to the row associated with the ActiveRecord object. - -The followings are some examples: +table, while the other methods only apply to the row associated with the ActiveRecord object through which the method is being called. ```php // to insert a new customer record