From 981258cf5e3c4ae8e3e2fa93327e2ac325e9b4b3 Mon Sep 17 00:00:00 2001 From: Michael Hutchinson Date: Wed, 14 Jul 2010 01:39:00 -0700 Subject: Active Record Query Interface Guide: Fixed minor typos. --- railties/guides/source/active_record_querying.textile | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'railties/guides/source/active_record_querying.textile') diff --git a/railties/guides/source/active_record_querying.textile b/railties/guides/source/active_record_querying.textile index f5e70aef41..a8d86659d1 100644 --- a/railties/guides/source/active_record_querying.textile +++ b/railties/guides/source/active_record_querying.textile @@ -337,7 +337,7 @@ Just like in Ruby. If you want a shorter syntax be sure to check out the "Hash C h4. Hash Conditions -Active Record also allows you to pass in a hash conditions which can increase the readability of your conditions syntax. With hash conditions, you pass in a hash with keys of the fields you want conditionalised and the values of how you want to conditionalise them: +Active Record also allows you to pass in hash conditions which can increase the readability of your conditions syntax. With hash conditions, you pass in a hash with keys of the fields you want conditionalised and the values of how you want to conditionalise them: NOTE: Only equality, range and subset checking are possible with Hash conditions. @@ -473,7 +473,7 @@ SELECT * FROM clients LIMIT 5, 5 h4. Group -To apply +GROUP BY+ clause to the SQL fired by the finder, you can specify the +group+ method on the find. +To apply a +GROUP BY+ clause to the SQL fired by the finder, you can specify the +group+ method on the find. For example, if you want to find a collection of the dates orders were created on: @@ -527,7 +527,9 @@ client.save h4. Locking Records for Update -Locking is helpful for preventing the race conditions when updating records in the database and ensuring atomic updated. Active Record provides two locking mechanism: +Locking is helpful for preventing race conditions when updating records in the database and ensuring atomic updates. + +Active Record provides two locking mechanisms: * Optimistic Locking * Pessimistic Locking @@ -569,7 +571,7 @@ end h5. Pessimistic Locking -Pessimistic locking uses locking mechanism provided by the underlying database. Passing +:lock => true+ to +Model.find+ obtains an exclusive lock on the selected rows. +Model.find+ using +:lock+ are usually wrapped inside a transaction for preventing deadlock conditions. +Pessimistic locking uses a locking mechanism provided by the underlying database. Passing +:lock => true+ to +Model.find+ obtains an exclusive lock on the selected rows. +Model.find+ using +:lock+ are usually wrapped inside a transaction for preventing deadlock conditions. For example: @@ -601,7 +603,7 @@ end h3. Joining Tables -Model.find provides a +:joins+ option for specifying +JOIN+ clauses on the resulting SQL. There multiple different ways to specify the +:joins+ option: +Model.find provides a +:joins+ option for specifying +JOIN+ clauses on the resulting SQL. There are multiple ways to specify the +:joins+ option: h4. Using a String SQL Fragment @@ -782,7 +784,7 @@ You can specify an exclamation point (!) on the end of the dynamic find If you want to find both by name and locked, you can chain these finders together by simply typing +and+ between the fields for example +Client.find_by_first_name_and_locked("Ryan", true)+. -There's another set of dynamic finders that let you find or create/initialize objects if they aren't found. These work in a similar fashion to the other finders and can be used like +find_or_create_by_first_name(params[:first_name])+. Using this will firstly perform a find and then create if the find returns +nil+. The SQL looks like this for +Client.find_or_create_by_first_name("Ryan")+: +There's another set of dynamic finders that let you find or create/initialize objects if they aren't found. These work in a similar fashion to the other finders and can be used like +find_or_create_by_first_name(params[:first_name])+. Using this will first perform a find and then create if the find returns +nil+. The SQL looks like this for +Client.find_or_create_by_first_name("Ryan")+: SELECT * FROM clients WHERE (clients.first_name = 'Ryan') LIMIT 1 @@ -792,7 +794,7 @@ INSERT INTO clients (first_name, updated_at, created_at, orders_count, locked) COMMIT -+find_or_create+'s sibling, +find_or_initialize+, will find an object and if it does not exist will act similar to calling +new+ with the arguments you passed in. For example: ++find_or_create+'s sibling, +find_or_initialize+, will find an object and if it does not exist will act similarly to calling +new+ with the arguments you passed in. For example: client = Client.find_or_initialize_by_first_name('Ryan') -- cgit v1.2.3