Move sortField to relationship setup (#4304)

* Add migration

* Add sort field to relation types

* Remove sortfield options in favor of relationship

* Add sort field configuration to relational setup

* Save m2a sortfield on the correct row

* Add default sort field to system data

api/src/database/migrations/20210225A-add-relations-sort-field.ts

@@ -0,0 +1,33 @@
+import Knex from 'knex';
+
+export async function up(knex: Knex) {
+	await knex.schema.alterTable('directus_relations', (table) => {
+		table.string('sort_field');
+	});
+
+	const fieldsWithSort = await knex
+		.select('collection', 'field', 'options')
+		.from('directus_fields')
+		.whereIn('interface', ['one-to-many', 'm2a-builder', 'many-to-many']);
+
+	for (const field of fieldsWithSort) {
+		const options = typeof field.options === 'string' ? JSON.parse(field.options) : field.options ?? {};
+
+		if ('sortField' in options) {
+			await knex('directus_relations')
+				.update({
+					sort_field: options.sortField,
+				})
+				.where({
+					one_collection: field.collection,
+					one_field: field.field,
+				});
+		}
+	}
+}
+
+export async function down(knex: Knex) {
+	await knex.schema.alterTable('directus_relations', (table) => {
+		table.dropColumn('sort_field');
+	});
+}