feat: replace display_template with link_phrase and reverse_link_phrase

migrations/2018-02-02/down.sql

@@ -0,0 +1,6 @@
+BEGIN;
+
+ALTER TABLE bookbrainz.relationship_type RENAME COLUMN link_phrase TO display_template;
+ALTER TABLE bookbrainz.relationship_type DROP COLUMN reverse_link_phrase;
+
+COMMIT;

migrations/2018-02-02/up.sql

@@ -0,0 +1,10 @@
+BEGIN;
+
+ALTER TABLE bookbrainz.relationship_type RENAME COLUMN display_template TO link_phrase;
+ALTER TABLE bookbrainz.relationship_type ADD COLUMN reverse_link_phrase TEXT CHECK (reverse_link_phrase <> '');
+
+UPDATE bookbrainz.relationship_type SET reverse_link_phrase=' ';
+
+ALTER TABLE bookbrainz.relationship_type ALTER COLUMN reverse_link_phrase SET NOT NULL;
+
+COMMIT;

schemas/bookbrainz.sql

@@ -468,7 +468,8 @@ CREATE TABLE bookbrainz.relationship_type (
 	id SERIAL PRIMARY KEY,
 	label VARCHAR(255) NOT NULL CHECK (label <> ''),
 	description TEXT NOT NULL CHECK (description <> ''),
-	display_template TEXT NOT NULL CHECK (display_template <> ''),
+	link_phrase TEXT NOT NULL CHECK (link_phrase <> ''),
+	reverse_link_phrase TEXT NOT NULL CHECK (reverse_link_phrase <> ''),
 	source_entity_type bookbrainz.entity_type NOT NULL,
 	target_entity_type bookbrainz.entity_type NOT NULL,
 	parent_id INT,