将嵌套循环查询合并到父数组结果-pg-promise

将嵌套循环查询合并到父数组结果-pg-promise

我是pg-promise的作者;）

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con.task(t => {    const a = post => t.any('SELECt * FROM comment WHERe idPost = ', post.id)        .then(comments => { post.comments = comments; return post;        });    return t.map('SELECt *, avatar FROM post, users WHERe user =  AND user = alias ORDER BY time DESC LIMIT 10 OFFSET ', [username, pos], a)        .then(t.batch);})    .then(posts => {        res.send(posts);    })    .catch(error => {        console.log(error);    });

更新

如果您不想一路使用JSON查询方法，那么以下方法将比原始解决方案更好地扩展，因为我们将所有子查询连接起来，然后将它们作为一个查询执行：

con.task(async t => {    const posts = await t.any('SELECt *, avatar FROM post, users WHERe user =  AND user = alias ORDER BY time DESC LIMIT 10 OFFSET ', [username, pos]);    const a = post => ({query: 'SELECt * FROM comment WHERe idPost = ${id}', values: post});    const queries = pgp.helpers.concat(posts.map(a));    await t.multi(queries)        .then(comments => { posts.forEach((p, index) => {     p.comments = comments[index]; });        });    return posts;})    .then(posts => {        res.send(posts);    })    .catch(error => {        console.log(error);    });

查看API：

• helpers.concat
• 多数据库