feat: added Express request handler (#7)

packages/backend/package.json

@@ -33,6 +33,7 @@
         "sql-formatter": "^15.0.2"
     },
     "devDependencies": {
+        "@types/express": "^4.17.21",
         "@types/node": "^20.10.5",
         "@types/pg": "^8.10.9",
         "@vitest/coverage-v8": "^1.2.2",

packages/backend/src/index.ts

@@ -1,4 +1,10 @@
 export { collectLast } from './util/generators/collectLast';
+export {
+    type ExpressSynthqlHandler,
+    type ExpressSynthqlHandlerRequest,
+    type ExpressSynthqlHandlerResponse,
+    createExpressSynthqlHandler,
+} from './util/handlers/createExpressSynthqlHandler';
 
 export type * from './types/QueryPlan';
 export * from './QueryEngine';

packages/backend/src/util/handlers/createExpressSynthqlHandler.test.ts

@@ -0,0 +1,23 @@
+import { describe, test } from 'vitest';
+import { query } from '@synthql/queries';
+
+import { DB } from '../../tests/db';
+const from = query<DB>().from;
+
+describe('createExpressSynthqlHandler', () => {
+    test(`Query execution is successful`, async () => {
+        const q = from('actor')
+            .columns('actor_id', 'first_name', 'last_name')
+            .groupingId('actor_id')
+            .where({ actor_id: { in: [1] } })
+            .one();
+    });
+
+    test(`Query execution is successful with returnLastOnly passed`, async () => {
+        const q = from('actor')
+            .columns('actor_id', 'first_name', 'last_name')
+            .groupingId('actor_id')
+            .where({ actor_id: { in: [1] } })
+            .maybe();
+    });
+});

packages/backend/src/util/handlers/createExpressSynthqlHandler.ts

@@ -0,0 +1,63 @@
+import { QueryEngine, collectLast } from '../..';
+import type { Request, Response } from 'express';
+
+export type ExpressSynthqlHandlerRequest = Pick<Request, 'body' | 'headers'>;
+
+export type ExpressSynthqlHandlerResponse = Pick<
+    Response,
+    'statusCode' | 'write' | 'setHeader' | 'end'
+>;
+
+export type ExpressSynthqlHandler = (
+    req: ExpressSynthqlHandlerRequest,
+    res: ExpressSynthqlHandlerResponse,
+) => void;
+
+export function createExpressSynthqlHandler<T>(
+    queryEngine: QueryEngine<T>,
+): ExpressSynthqlHandler {
+    return async (req, res) => {
+        try {
+            const headers = req.headers;
+            const query = await JSON.parse(req.body);
+            const returnLastOnly = headers['x-return-last-only'] === 'true';
+
+            if (returnLastOnly) {
+                try {
+                    const result = await collectLast(
+                        queryEngine.execute(query, {
+                            returnLastOnly,
+                        }),
+                    );
+
+                    res.statusCode = 200;
+                    res.setHeader('Content-Type', 'application/json');
+                    res.write(JSON.stringify(result));
+                    res.end();
+                } catch (error) {
+                    res.statusCode = 500;
+                    res.setHeader('Content-Type', 'application/json');
+                    res.write(JSON.stringify({ error: String(error) }));
+                    res.end();
+                }
+            } else {
+                res.statusCode = 200;
+                res.setHeader('Content-Type', 'application/x-ndjson');
+
+                for await (const intermediateResult of queryEngine.execute(
+                    query,
+                )) {
+                    res.write(JSON.stringify(intermediateResult));
+                    res.write('\n');
+                }
+
+                res.end();
+            }
+        } catch (error) {
+            res.statusCode = 400;
+            res.setHeader('Content-Type', 'application/json');
+            res.write(JSON.stringify({ error: 'Invalid JSON body' }));
+            res.end();
+        }
+    };
+}

packages/react/src/test/appendBody.ts

@@ -0,0 +1,46 @@
+import { IncomingMessage, ServerResponse } from 'http';
+import {
+    ExpressSynthqlHandler,
+    ExpressSynthqlHandlerRequest,
+    ExpressSynthqlHandlerResponse,
+} from '@synthql/backend';
+
+function readBody(req: IncomingMessage): Promise<string> {
+    return new Promise((resolve, reject) => {
+        let body = '';
+
+        req.on('data', (chunk) => {
+            body += chunk;
+        });
+
+        req.on('end', () => {
+            resolve(body);
+        });
+
+        req.on('error', (e) => {
+            reject(e);
+        });
+    });
+}
+
+export type IncomingMessageWithBody = IncomingMessage &
+    ExpressSynthqlHandlerRequest;
+
+export type ServerResponseWithEnd = ServerResponse &
+    ExpressSynthqlHandlerResponse;
+
+export function appendBody(expressHandler: ExpressSynthqlHandler) {
+    return async (req: IncomingMessage, res: ServerResponse) => {
+        const body = await readBody(req);
+
+        const newReq = {
+            ...req,
+            headers: req.headers,
+            body: body,
+        } as IncomingMessageWithBody;
+
+        const newRes = res as ServerResponseWithEnd;
+
+        expressHandler(newReq, newRes);
+    };
+}

packages/react/src/test/createPagilaServer.ts

@@ -1,7 +1,9 @@
-import { QueryEngine } from '@synthql/backend';
-import { DB } from './db';
+import { QueryEngine, createExpressSynthqlHandler } from '@synthql/backend';
 import http from 'http';
 
+import { DB } from './db';
+import { appendBody } from './appendBody';
+
 export interface PagilaServer {
     url: string;
     server: http.Server;
@@ -13,42 +15,15 @@ export function createPagilaServer({
     queryEngine: QueryEngine<DB>;
 }): Promise<PagilaServer> {
     return new Promise((resolve, reject) => {
-        const server = http.createServer((req, res) => {
-            let body = '';
-
-            req.on('data', (chunk) => {
-                body += chunk;
-            });
-
-            req.on('end', async () => {
-                const headers = req.headers;
+        const handler = createExpressSynthqlHandler<DB>(queryEngine);
 
-                const json = JSON.parse(body);
+        const nodeHandler = appendBody(handler);
 
-                res.writeHead(200, { 'Content-Type': 'application/json' });
-
-                try {
-                    for await (const intermediateResult of queryEngine.execute(
-                        json,
-                        {
-                            returnLastOnly:
-                                headers['x-return-last-only'] === 'true',
-                        },
-                    )) {
-                        res.write(JSON.stringify(intermediateResult) + '\n');
-                    }
-
-                    res.end();
-                } catch (error) {
-                    res.write(JSON.stringify({ error: String(error) }) + '\n');
-
-                    res.end();
-                }
-            });
-        });
+        const server = http.createServer(nodeHandler);
 
         server.listen(() => {
             const address = server.address();
+
             if (typeof address === 'string' || address === null) {
                 reject('Failed to get server address: ' + address);
             } else {

yarn.lock

@@ -2833,9 +2833,9 @@
     "@types/range-parser" "*"
     "@types/send" "*"
 
-"@types/express@*", "@types/express@^4.17.13":
+"@types/express@*", "@types/express@^4.17.13", "@types/express@^4.17.21":
   version "4.17.21"
-  resolved "https://registry.npmjs.org/@types/express/-/express-4.17.21.tgz"
+  resolved "https://registry.yarnpkg.com/@types/express/-/express-4.17.21.tgz#c26d4a151e60efe0084b23dc3369ebc631ed192d"
   integrity sha512-ejlPM315qwLpaQlQDTjPdsUFSc6ZsP4AN6AlWnogPjQ7CVi7PYF3YVz+CY3jE2pwYf7E/7HlDAN0rV2GxTG0HQ==
   dependencies:
     "@types/body-parser" "*"