Use field key instead of ID for group value (#8349)

* Add migration to replace group ID with group name

* Replace group IDs with field names

* Tweak group interfaces

* Ignore schema export

api/src/database/migrations/20210927A-replace-fields-group.ts

@@ -0,0 +1,63 @@
+import { Knex } from 'knex';
+import { uniq } from 'lodash';
+
+export async function up(knex: Knex): Promise<void> {
+	const groupsInUse = await knex.select('id', 'group').from('directus_fields').whereNotNull('group');
+
+	if (groupsInUse.length === 0) return;
+
+	const groupIDs: number[] = uniq(groupsInUse.map(({ group }) => group));
+
+	const groupFields = await knex.select('id', 'field').from('directus_fields').whereIn('id', groupIDs);
+
+	const groupMap = new Map();
+
+	for (const { id, field } of groupFields) {
+		groupMap.set(id, field);
+	}
+
+	await knex.schema.alterTable('directus_fields', (table) => {
+		table.dropColumn('group');
+	});
+
+	await knex.schema.alterTable('directus_fields', (table) => {
+		table.string('group', 64);
+	});
+
+	for (const { id, group } of groupsInUse) {
+		await knex('directus_fields')
+			.update({ group: groupMap.get(group) })
+			.where({ id });
+	}
+}
+
+export async function down(knex: Knex): Promise<void> {
+	const fieldsThatUseAGroup = await knex
+		.select('id', 'collection', 'group')
+		.from('directus_fields')
+		.whereNotNull('group');
+
+	if (fieldsThatUseAGroup.length === 0) return;
+
+	const groupMap = new Map();
+
+	for (const { collection, group } of fieldsThatUseAGroup) {
+		const { id } = await knex.select('id').from('directus_fields').where({ collection, field: group }).first();
+
+		groupMap.set(group, id);
+	}
+
+	await knex.schema.alterTable('directus_fields', (table) => {
+		table.dropColumn('group');
+	});
+
+	await knex.schema.alterTable('directus_fields', (table) => {
+		table.integer('group').references('id').inTable('directus_fields');
+	});
+
+	for (const { id, group } of fieldsThatUseAGroup) {
+		await knex('directus_fields')
+			.update({ group: groupMap.get(group) })
+			.where({ id });
+	}
+}