rename `Relation#uniq` to `Relation#distinct`. `#uniq` still works.

The similarity of `Relation#uniq` to `Array#uniq` is confusing. Since our
Relation API is close to SQL terms I renamed `#uniq` to `#distinct`.

There is no deprecation. `#uniq` and `#uniq!` are aliases and will continue
to work. I also updated the documentation to promote the use of `#distinct`.

1 files changed, 11 insertions, 9 deletions

diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index b7960936cf..10a31109d5 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -710,20 +710,22 @@ module ActiveRecord
     #   User.select(:name)
     #   # => Might return two records with the same name
     #
-    #   User.select(:name).uniq
-    #   # => Returns 1 record per unique name
+    #   User.select(:name).distinct
+    #   # => Returns 1 record per distinct name
     #
-    #   User.select(:name).uniq.uniq(false)
+    #   User.select(:name).distinct.distinct(false)
     #   # => You can also remove the uniqueness
-    def uniq(value = true)
-      spawn.uniq!(value)
+    def distinct(value = true)
+      spawn.distinct!(value)
     end
+    alias uniq distinct
 
-    # Like #uniq, but modifies relation in place.
-    def uniq!(value = true) # :nodoc:
-      self.uniq_value = value
+    # Like #distinct, but modifies relation in place.
+    def distinct!(value = true) # :nodoc:
+      self.distinct_value = value
       self
     end
+    alias uniq! distinct!
 
     # Used to extend a scope with additional methods, either through
     # a module or through a block provided.
@@ -814,7 +816,7 @@ module ActiveRecord
 
       build_select(arel, select_values.uniq)
 
-      arel.distinct(uniq_value)
+      arel.distinct(distinct_value)
       arel.from(build_from) if from_value
       arel.lock(lock_value) if lock_value