1 files changed, 28 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/errors.rb b/activerecord/lib/active_record/errors.rb
index 6464d40c94..7c8be37326 100644
--- a/activerecord/lib/active_record/errors.rb
+++ b/activerecord/lib/active_record/errors.rb
@@ -123,6 +123,34 @@ module ActiveRecord
   class InvalidForeignKey < WrappedDatabaseException
   end
 
+  # Raised when a foreign key constraint cannot be added because the column type does not match the referenced column type.
+  class MismatchedForeignKey < WrappedDatabaseException
+    def initialize(adapter = nil, message: nil, table: nil, foreign_key: nil, target_table: nil, primary_key: nil)
+      @adapter = adapter
+      if table
+        msg = <<-EOM.strip_heredoc
+          Column `#{foreign_key}` on table `#{table}` has a type of `#{column_type(table, foreign_key)}`.
+          This does not match column `#{primary_key}` on `#{target_table}`, which has type `#{column_type(target_table, primary_key)}`.
+          To resolve this issue, change the type of the `#{foreign_key}` column on `#{table}` to be :integer. (For example `t.integer #{foreign_key}`).
+        EOM
+      else
+        msg = <<-EOM
+          There is a mismatch between the foreign key and primary key column types.
+          Verify that the foreign key column type and the primary key of the associated table match types.
+        EOM
+      end
+      if message
+        msg << "\nOriginal message: #{message}"
+      end
+      super(msg)
+    end
+
+    private
+      def column_type(table, column)
+        @adapter.columns(table).detect { |c| c.name == column }.sql_type
+      end
+  end
+
   # Raised when a record cannot be inserted or updated because a value too long for a column type.
   class ValueTooLong < StatementInvalid
   end