diff options
Diffstat (limited to 'guides/source')
| -rw-r--r-- | guides/source/active_record_querying.textile | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/guides/source/active_record_querying.textile b/guides/source/active_record_querying.textile index d16cdd66ee..a9cb424eaa 100644 --- a/guides/source/active_record_querying.textile +++ b/guides/source/active_record_querying.textile @@ -101,7 +101,7 @@ SELECT * FROM clients WHERE (clients.id = 10) LIMIT 1 h5. +take+ -<tt>Model.take</tt> retrieves a record without any implicit ordering. The retrieved record may vary depending on the database engine. For example: +<tt>Model.take</tt> retrieves a record without any implicit ordering. For example: <ruby> client = Client.take @@ -114,11 +114,13 @@ The SQL equivalent of the above is: SELECT * FROM clients LIMIT 1 </sql> -<tt>Model.take</tt> returns +nil+ if no record is found. No exception will be raised. +<tt>Model.take</tt> returns +nil+ if no record is found and no exception will be raised. + +TIP: The retrieved record may vary depending on the database engine. h5. +first+ -<tt>Model.first</tt> finds the first record. If no order is chained it will order by primary key. For example: +<tt>Model.first</tt> finds the first record ordered by the primary key. For example: <ruby> client = Client.first @@ -131,11 +133,11 @@ The SQL equivalent of the above is: SELECT * FROM clients ORDER BY clients.id ASC LIMIT 1 </sql> -<tt>Model.first</tt> returns +nil+ if no matching record is found. No exception will be raised. +<tt>Model.first</tt> returns +nil+ if no matching record is found and no exception will be raised. h5. +last+ -<tt>Model.last</tt> finds the last record. If no order is chained it will order by primary key. For example: +<tt>Model.last</tt> finds the last record ordered by the primary key. For example: <ruby> client = Client.last @@ -148,7 +150,7 @@ The SQL equivalent of the above is: SELECT * FROM clients ORDER BY clients.id DESC LIMIT 1 </sql> -<tt>Model.last</tt> returns +nil+ if no matching record is found. No exception will be raised. +<tt>Model.last</tt> returns +nil+ if no matching record is found and no exception will be raised. h5. +find_by+ @@ -183,11 +185,11 @@ The SQL equivalent of the above is: SELECT * FROM clients LIMIT 1 </sql> -<tt>Model.take!</tt> raises +RecordNotFound+ if no matching record is found. +<tt>Model.take!</tt> raises +ActiveRecord::RecordNotFound+ if no matching record is found. h5(#first_1). +first!+ -<tt>Model.first!</tt> finds the first record. If no order is chained it will order by primary key. For example: +<tt>Model.first!</tt> finds the first record ordered by the primary key. For example: <ruby> client = Client.first! @@ -200,11 +202,11 @@ The SQL equivalent of the above is: SELECT * FROM clients ORDER BY clients.id ASC LIMIT 1 </sql> -<tt>Model.first!</tt> raises +RecordNotFound+ if no matching record is found. +<tt>Model.first!</tt> raises +ActiveRecord::RecordNotFound+ if no matching record is found. h5(#last_1). +last!+ -<tt>Model.last!</tt> finds the last record. If no order is chained it will order by primary key. For example: +<tt>Model.last!</tt> finds the last record ordered by the primary key. For example: <ruby> client = Client.last! @@ -217,18 +219,18 @@ The SQL equivalent of the above is: SELECT * FROM clients ORDER BY clients.id DESC LIMIT 1 </sql> -<tt>Model.last!</tt> raises +RecordNotFound+ if no matching record is found. +<tt>Model.last!</tt> raises +ActiveRecord::RecordNotFound+ if no matching record is found. h5(#find_by_1). +find_by!+ -<tt>Model.find_by!</tt> finds the first record matching some conditions. It raises +RecordNotFound+ if no matching record is found. For example: +<tt>Model.find_by!</tt> finds the first record matching some conditions. It raises +ActiveRecord::RecordNotFound+ if no matching record is found. For example: <ruby> Client.find_by! first_name: 'Lifo' # => #<Client id: 1, first_name: "Lifo"> Client.find_by! first_name: 'Jon' -# => RecordNotFound +# => ActiveRecord::RecordNotFound </ruby> It is equivalent to writing: |