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author | Aaron Patterson <aaron.patterson@gmail.com> | 2011-03-29 17:38:43 -0700 |
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committer | Aaron Patterson <aaron.patterson@gmail.com> | 2011-03-29 17:38:43 -0700 |
commit | 0471fc9f1cf95865a9810b46f1227783fee40ab5 (patch) | |
tree | 50c6a1990e7b97b7960a692c9441e686cbcb4902 /railties/guides/source/active_record_querying.textile | |
parent | 28c73f012328c8386acfc608f0dfb1a459dbf170 (diff) | |
parent | 58becf116580c37c63b89f4a660ebe293f6e7c4e (diff) | |
download | rails-0471fc9f1cf95865a9810b46f1227783fee40ab5.tar.gz rails-0471fc9f1cf95865a9810b46f1227783fee40ab5.tar.bz2 rails-0471fc9f1cf95865a9810b46f1227783fee40ab5.zip |
Merge branch 'master' into zomg
* master: (51 commits)
order is not guaranteed by this select, so add an order and call first!
oracle stores this with microseconds, so convert to seconds before comparing
make sure that active connections are not cleared during test when an exception happens
clearing active connections in the ConnectionManagement middleware if an exception happens
proxy body responses so we close database connections after body is flushed
Pass the proper method_name instead of hardcoding to action_name.
Quote find_in_batches ORDER BY clause [#6620 state:resolved]
Delegate first!, last!, any? and many? to scoped
Dont call authenticate_or_request_with_http_basic twice
Remove 'warning: ambiguous first argument' when running ActionPack tests
Change exists? so that it doesn't instantiate records [#6127 state:resolved]
Move mapper_test to the appropriate location
Update the wildcard route to be non-greedy by default, therefore be able to match the (.:format) segment [#6605 state:resolved]
Fix examples
Added Base.http_basic_authenticate_with to do simple http basic authentication with a single class method call [DHH]
make sure we have an active database connection before running each connection management test
adding active_connections? to the connection pool for finding open connections
adding active_connection? to the connection pool
testing app delegation from the ConnectionManagement middleware
namespacing connection management tests. :heart:
...
Diffstat (limited to 'railties/guides/source/active_record_querying.textile')
-rw-r--r-- | railties/guides/source/active_record_querying.textile | 56 |
1 files changed, 55 insertions, 1 deletions
diff --git a/railties/guides/source/active_record_querying.textile b/railties/guides/source/active_record_querying.textile index 009d541106..f3a10b8b92 100644 --- a/railties/guides/source/active_record_querying.textile +++ b/railties/guides/source/active_record_querying.textile @@ -76,7 +76,7 @@ Primary operation of <tt>Model.find(options)</tt> can be summarized as: h4. Retrieving a Single Object -Active Record lets you retrieve a single object using three different ways. +Active Record lets you retrieve a single object using five different ways. h5. Using a Primary Key @@ -130,6 +130,40 @@ SELECT * FROM clients ORDER BY clients.id DESC LIMIT 1 <tt>Model.last</tt> returns +nil+ if no matching record is found. No exception will be raised. +h5. +first!+ + +<tt>Model.first!</tt> finds the first record. For example: + +<ruby> +client = Client.first! +=> #<Client id: 1, first_name: "Lifo"> +</ruby> + +SQL equivalent of the above is: + +<sql> +SELECT * FROM clients LIMIT 1 +</sql> + +<tt>Model.first!</tt> raises +RecordNotFound+ if no matching record is found. + +h5. +last!+ + +<tt>Model.last!</tt> finds the last record. For example: + +<ruby> +client = Client.last! +=> #<Client id: 221, first_name: "Russel"> +</ruby> + +SQL equivalent of the above is: + +<sql> +SELECT * FROM clients ORDER BY clients.id DESC LIMIT 1 +</sql> + +<tt>Model.last!</tt> raises +RecordNotFound+ if no matching record is found. + h4. Retrieving Multiple Objects h5. Using Multiple Primary Keys @@ -928,6 +962,26 @@ Client.exists? The above returns +false+ if the +clients+ table is empty and +true+ otherwise. +You can also use +any?+ and +many?+ to check for existence on a model or relation. + +<ruby> +# via a model +Post.any? +Post.many? + +# via a named scope +Post.recent.any? +Post.recent.many? + +# via a relation +Post.where(:published => true).any? +Post.where(:published => true).many? + +# via an association +Post.first.categories.any? +Post.first.categories.many? +</ruby> + h3. Calculations This section uses count as an example method in this preamble, but the options described apply to all sub-sections. |