feat: handle aggregate queries

Author: eEQK

src/app.ts

@@ -181,7 +181,7 @@ ${query.text.trim()}`,
 			}
 
 			let argIface = undefined;
-			let returnIface = undefined;
+			let returnIface: string | undefined;
 			if (query.params.length > 0) {
 				argIface = `${nameWithoutFileNs}Args`;
 				nodesToPush.push(argsDecl(argIface, driver, query.params));
@@ -190,6 +190,9 @@ ${query.text.trim()}`,
 				returnIface = driver.parseDatabaseType(
 					query.columns[0].type?.name ?? "",
 				);
+				if (query.columns[0].isArray) {
+					returnIface += "[]";
+				}
 			} else if (query.columns.length > 1) {
 				returnIface = `${nameWithoutFileNs}Row`;
 				nodesToPush.push(rowDecl(returnIface, driver, query.columns, embeds));

test/cases/aggregate.test.ts

@@ -0,0 +1,18 @@
+import { expect, it, describe } from "bun:test";
+import { db, prepare, sql } from "../case";
+import { aggEmails } from "./aggregate_sql";
+
+await prepare(sql`
+    -- name: AggEmails :one
+    SELECT array_agg(e.id::text)::text[] AS emails FROM emails e;
+`);
+
+describe("aggregation", () => {
+	it("returns an array type", async () => {
+		// this should not have any LSP error
+		const result = (await aggEmails(db)) as string[];
+
+		expect(result).toHaveLength(3);
+		expect(Array.isArray(result)).toBe(true);
+	});
+});