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| author | Gonçalo Silva <goncalossilva@gmail.com> | 2011-03-30 03:24:20 +0100 |
|---|---|---|
| committer | Gonçalo Silva <goncalossilva@gmail.com> | 2011-03-30 03:24:20 +0100 |
| commit | b8f9a4515682f2722dc6e8ff9c106f5f774e703b (patch) | |
| tree | 4c8f2cdc516374b1856963d57dfdaeb212bb2153 /railties/guides/source/active_record_querying.textile | |
| parent | 6212749bd48d84e79b728b128bc8a0eabb572106 (diff) | |
| parent | 58becf116580c37c63b89f4a660ebe293f6e7c4e (diff) | |
| download | rails-b8f9a4515682f2722dc6e8ff9c106f5f774e703b.tar.gz rails-b8f9a4515682f2722dc6e8ff9c106f5f774e703b.tar.bz2 rails-b8f9a4515682f2722dc6e8ff9c106f5f774e703b.zip | |
Merge branch 'master' of https://github.com/rails/rails into performance_test
Diffstat (limited to 'railties/guides/source/active_record_querying.textile')
| -rw-r--r-- | railties/guides/source/active_record_querying.textile | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/railties/guides/source/active_record_querying.textile b/railties/guides/source/active_record_querying.textile index 2c5d9e67e3..f3a10b8b92 100644 --- a/railties/guides/source/active_record_querying.textile +++ b/railties/guides/source/active_record_querying.textile @@ -962,6 +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. |