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Diffstat (limited to 'guides/source/active_record_querying.md')
| -rw-r--r-- | guides/source/active_record_querying.md | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md index 9620270141..24f98f68ca 100644 --- a/guides/source/active_record_querying.md +++ b/guides/source/active_record_querying.md @@ -5,13 +5,13 @@ This guide covers different ways to retrieve data from the database using Active After reading this guide, you will know: -* Find records using a variety of methods and conditions. -* Specify the order, retrieved attributes, grouping, and other properties of the found records. -* Use eager loading to reduce the number of database queries needed for data retrieval. -* Use dynamic finders methods. -* Check for the existence of particular records. -* Perform various calculations on Active Record models. -* Run EXPLAIN on relations. +* How to find records using a variety of methods and conditions. +* How to specify the order, retrieved attributes, grouping, and other properties of the found records. +* How to use eager loading to reduce the number of database queries needed for data retrieval. +* How to use dynamic finders methods. +* How to check for the existence of particular records. +* How to perform various calculations on Active Record models. +* How to run EXPLAIN on relations. -------------------------------------------------------------------------------- @@ -505,6 +505,20 @@ This code will generate SQL like this: SELECT * FROM clients WHERE (clients.orders_count IN (1,3,5)) ``` +### NOT, LIKE, and NOT LIKE Conditions + +`NOT`, `LIKE`, and `NOT LIKE` SQL queries can be built by `where.not`, `where.like`, and `where.not_like` respectively. + +```ruby +Post.where.not(author: author) + +Author.where.like(name: 'Nari%') + +Developer.where.not_like(name: 'Tenderl%') +``` + +In other words, these sort of queries can be generated by calling `where` with no argument, then immediately chain with `not`, `like`, or `not_like` passing `where` conditions. + Ordering -------- @@ -1190,7 +1204,7 @@ class Client < ActiveRecord::Base end ``` -### Removing all scoping +### Removing All Scoping If we wish to remove scoping for any reason we can use the `unscoped` method. This is especially useful if a `default_scope` is specified in the model and should not be @@ -1222,9 +1236,7 @@ You can specify an exclamation point (`!`) on the end of the dynamic finders to 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)`. -WARNING: Up to and including Rails 3.1, when the number of arguments passed to a dynamic finder method is lesser than the number of fields, say `Client.find_by_name_and_locked("Ryan")`, the behavior is to pass `nil` as the missing argument. This is **unintentional** and this behavior will be changed in Rails 3.2 to throw an `ArgumentError`. - -Find or build a new object +Find or Build a New Object -------------------------- It's common that you need to find a record or create it if it doesn't exist. You can do that with the `find_or_create_by` and `find_or_create_by!` methods. |