diff options
Diffstat (limited to 'railties/guides/source')
| -rw-r--r-- | railties/guides/source/active_record_querying.textile | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/railties/guides/source/active_record_querying.textile b/railties/guides/source/active_record_querying.textile index 6e7ff6d5e0..1b39f91eb1 100644 --- a/railties/guides/source/active_record_querying.textile +++ b/railties/guides/source/active_record_querying.textile @@ -103,7 +103,7 @@ h5. +first+ <ruby> client = Client.first -=> #<Client id: 1, name: => "Lifo"> +=> #<Client id: 1, first_name: => "Lifo"> </ruby> SQL equivalent of the above is: @@ -120,7 +120,7 @@ h5. +last+ <ruby> client = Client.last -=> #<Client id: 221, name: => "Russel"> +=> #<Client id: 221, first_name: => "Russel"> </ruby> SQL equivalent of the above is: @@ -140,7 +140,7 @@ h5. Using Multiple Primary Keys <ruby> # Find the clients with primary keys 1 and 10. client = Client.find(1, 10) # Or even Client.find([1, 10]) -=> [#<Client id: 1, name: => "Lifo">, #<Client id: 10, name: => "Ryan">] +=> [#<Client id: 1, first_name: => "Lifo">, #<Client id: 10, first_name: => "Ryan">] </ruby> SQL equivalent of the above is: @@ -227,7 +227,7 @@ h4. Pure String Conditions If you'd like to add conditions to your find, you could just specify them in there, just like +Client.where("orders_count = '2'")+. This will find all clients where the +orders_count+ field's value is 2. -WARNING: Building your own conditions as pure strings can leave you vulnerable to SQL injection exploits. For example, +Client.where("name LIKE '%#{params[:name]}%'")+ is not safe. See the next section for the preferred way to handle conditions using an array. +WARNING: Building your own conditions as pure strings can leave you vulnerable to SQL injection exploits. For example, +Client.where("first_name LIKE '%#{params[:first_name]}%'")+ is not safe. See the next section for the preferred way to handle conditions using an array. h4. Array Conditions @@ -544,7 +544,7 @@ In order to use optimistic locking, the table needs to have a column called +loc c1 = Client.find(1) c2 = Client.find(1) -c1.name = "Michael" +c1.first_name = "Michael" c1.save c2.name = "should fail" @@ -773,21 +773,21 @@ Even though Active Record lets you specify conditions on the eager loaded associ h3. Dynamic Finders -For every field (also known as an attribute) you define in your table, Active Record provides a finder method. If you have a field called +name+ on your +Client+ model for example, you get +find_by_name+ and +find_all_by_name+ for free from Active Record. If you have also have a +locked+ field on the +Client+ model, you also get +find_by_locked+ and +find_all_by_locked+. +For every field (also known as an attribute) you define in your table, Active Record provides a finder method. If you have a field called +first_name+ on your +Client+ model for example, you get +find_by_first_name+ and +find_all_by_first_name+ for free from Active Record. If you have also have a +locked+ field on the +Client+ model, you also get +find_by_locked+ and +find_all_by_locked+. You can do +find_last_by_*+ methods too which will find the last record matching your argument. You can specify an exclamation point (<tt>!</tt>) on the end of the dynamic finders to get them to raise an +ActiveRecord::RecordNotFound+ error if they do not return any records, like +Client.find_by_name!("Ryan")+ -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_name_and_locked("Ryan", true)+. +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_name(params[: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_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 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")+: <sql> -SELECT * FROM clients WHERE (clients.name = 'Ryan') LIMIT 1 +SELECT * FROM clients WHERE (clients.first_name = 'Ryan') LIMIT 1 BEGIN -INSERT INTO clients (name, updated_at, created_at, orders_count, locked) +INSERT INTO clients (first_name, updated_at, created_at, orders_count, locked) VALUES('Ryan', '2008-09-28 15:39:12', '2008-09-28 15:39:12', 0, '0') COMMIT </sql> @@ -795,10 +795,10 @@ 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: <ruby> -client = Client.find_or_initialize_by_name('Ryan') +client = Client.find_or_initialize_by_first_name('Ryan') </ruby> -will either assign an existing client object with the name "Ryan" to the client local variable, or initialize a new object similar to calling +Client.new(:name => 'Ryan')+. From here, you can modify other fields in client by calling the attribute setters on it: +client.locked = true+ and when you want to write it to the database just call +save+ on it. +will either assign an existing client object with the name "Ryan" to the client local variable, or initialize a new object similar to calling +Client.new(:first_name => 'Ryan')+. From here, you can modify other fields in client by calling the attribute setters on it: +client.locked = true+ and when you want to write it to the database just call +save+ on it. h3. Finding by SQL |