doc: Warn against having uniqueness validator when create_or_find_by is used

sobstel · p8 · sobstel · commit a42eda12dab1 · 2024-02-13T07:23:58.000+01:00
Co-authored-by: Petrik de Heus &lt;petrik@deheus.net&gt;
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
@@ -255,6 +255,8 @@ def find_or_create_by!(attributes, &block)
     #   the problem of running out of integers, if the underlying table is still stuck on a primary
     #   key of type int (note: All \Rails apps since 5.1+ have defaulted to bigint, which is not liable
     #   to this problem).
+    # * Columns with unique database constraints should not have uniqueness validations defined,
+    #   otherwise #create will fail due to validation errors and #find_by will never be called.
     #
     # This method will return a record if all given attributes are covered by unique constraints
     # (unless the INSERT -> DELETE -> SELECT race condition is triggered), but if creation was attempted

Original file line number	Diff line number	Diff line change
`@@ -255,6 +255,8 @@ def find_or_create_by!(attributes, &block)`
`255`	`255`	`# the problem of running out of integers, if the underlying table is still stuck on a primary`
`256`	`256`	`# key of type int (note: All \Rails apps since 5.1+ have defaulted to bigint, which is not liable`
`257`	`257`	`# to this problem).`
	`258`	`+ # * Columns with unique database constraints should not have uniqueness validations defined,`
	`259`	`+ # otherwise #create will fail due to validation errors and #find_by will never be called.`
`258`	`260`	`#`
`259`	`261`	`# This method will return a record if all given attributes are covered by unique constraints`
`260`	`262`	`# (unless the INSERT -> DELETE -> SELECT race condition is triggered), but if creation was attempted`