Ruby on Rails 2.1 - The Finders
Following are the ways to find out records with and without conditions −
The following code will find an author with ID 50.
The following code will find authors with ID 20, 30 and 40.
The following code will find all the authors −
The following code will find all the authors with first name alam.
Author.find :all :condition => ["first_name =?", "alam" ]
The following code will find the first record of the authors with first name alam.
Author.find :first :condition => ["first_name =?", "alam" ]
Options for Finders
You can use the following options along with the find function.
:order => 'name DESC' Use this option to sort the result in ascending or descending order.
:offset => 20 Starts fetching records from offset 20.
:limit => 20 Returns only 20 records.
:group => 'name' This is equivalent to SQL fragment GROUP BY.
:joins => LEFT JOIN ...' Additional LEFT JOIN (rarely used).
:include => [:account, :friends] This is LEFT OUTER JOIN with these model.
:select => [:name, :address] Use this instead of SELECT * FROM.
:readonly => true Use this to make objects write protected.
Dynamic Attribute-based Finders
You can use more dynamic functions to fetch values.
If there is a field user_name, then you can use the following to find records by username.
If there is a field last_name, then you can use the following to find records by last name.
If there are fields user_name and password, then you can use the following to find a record for a given username and password.