Question

我尝试从帖子中获取所有内容和媒体，然后附加到新帖子以发送到响应以便于访问数据。问题是每当我运行呼叫时，都会在获取内容和媒体之前发送响应。

module.exports.getPosts = function(req,res){
var resultPosts = [];
Post.findAll({where:{UserUsername:req.headers.x_username}}).then(function(posts){
    posts.forEach(function(post){
        Db.getContent(post.id,function(foundContent){
            Db.getMedia(post.id,function(foundMedia){
                console.log('creating new post');
                var newPost = {
                    id:post.id,
                    time:post.time,
                    username:post.UserUsername,
                    content: foundContent,
                    media:foundMedia
                };
                resultPosts.push(newPost);
            });
        });
    });//foreach
    console.log('sending');
    res.send({posts:resultPosts});
});//end query

};

Answer 1

记住你使用异步代码，正如你所说，你在getMedia回调完成工作之前调用res.send。将res.send移动到该回调，以确保在完成推送到resultPosts数组后调用它

module.exports.getPosts = function(req,res){
var resultPosts = [];
Post.findAll({where:{UserUsername:req.headers.x_username}}).then(function(posts){
    posts.forEach(function(post){
        Db.getContent(post.id,function(foundContent){
            Db.getMedia(post.id,function(foundMedia){
                console.log('creating new post');
                var newPost = {
                    id:post.id,
                    time:post.time,
                    username:post.UserUsername,
                    content: foundContent,
                    media:foundMedia
                };
                resultPosts.push(newPost);
                console.log('sending');
                res.send({posts:resultPosts});
            });
        });
    });//foreach

});//end query

Answer 2

您必须使整个功能异步。在这种情况下，您必须先forEach通过所有结果，然后输出到res。您可以使用async.forEach（）方法解决此问题：https://codeburst.io/javascript-async-await-with-foreach-b6ba62bbf404

我将使用迭代器执行一个简单的异步递归函数，使其完全保持本机状态，而无需任何额外的库。

var resultPosts = []
        Post.findAll({where:{UserUsername:req.headers.x_username}}).then(function(posts) 
        {
                getPost(posts[Symbol.iterator]())
                function getPost(iter) {
                        var cursor = iter.next()
                        if(cursor.done)
                           return res.send({posts:resultPosts})
                  Db.getContent(post.id,function(foundContent){
                     Db.getMedia(post.id,function(foundMedia){
                         var post = cursor.value
                        resultPosts.push({
                          id:post.id,
                          time:post.time,
                           username:post.UserUsername,
                             content: foundContent,
                          media:foundMedia
                         })
                  getPost(iter)
               }
           })
         })

Sequelize Foreach循环在更新数据之前发送响应

2 个答案: