如何从Mongo中的数组中删除元素

Question

我完全坚持使用Mongoose并删除方法。我有一个带有注释和表单的页面，带有按钮Delete。我的目标是仅删除被点击的评论。下面是我的MongoDB文件（顺便说一下，我使用override库的方法express来处理请求发布和删除）。

{
    "_id": {
        "$oid": "5a455cf460414f548f3d1afb"
    },
    "title": "Tets",
    "body": "tes",
    "user": {
        "$oid": "5a440bae124b7e4626aeeb70"
    },
    "date": {
        "$date": "2017-12-28T21:07:00.194Z"
    },
    "comments": [
        {
          "commentBody": "ets",
          "commentUser": {
                "$oid": "5a440bae124b7e4626aeeb70"
            },
            "_id": {
                "$oid": "5a455cf660414f548f3d1afc"
            },
            "commentDate": {
                "$date": "2017-12-28T21:07:02.143Z"
            }
        }
    ],
    "allowComments": true,
    "status": "public",
    "__v": 1
}

我的架构

        const mongoose = require('mongoose')
        const Schema = mongoose.Schema;

        //Create Schema
        const StorySchema = new Schema({
        title: {
            type: String,
            required: true
        },
        body: {
            type: String,
            required: true
        },
        status: {
            type: String,
            default: 'public'
        },
        allowComments: {
            type: Boolean,
            default: true
        },
        comments: [{
            commentBody: {
                type: String,
                required: true
            },
            commentDate: {
                type: Date,
                default: Date.now
            },
            commentUser: {
                type: Schema.Types.ObjectId,
                ref: 'users'
            }
        }],
        user: {
            type: Schema.Types.ObjectId,
            ref: 'users'
        },
        date: {
            type: Date,
            default: Date.now
        }
    });

        mongoose.model('stories',StorySchema, 'stories');

而我的JS文件，我的post方法完全按照我的意愿工作，但删除根本不起作用（无法读取未定义的属性'comments'）

    router.post('/comment/:id' , (req , res) => {
    Story.findOne({
        _id: req.params.id
    })
    .then(story => {
        const newComment = {
            commentBody: req.body.commentBody,
            commentUser: req.user.id
        }

        //Push to comments array
        story.comments.unshift(newComment);

        story.save()
        .then(story => {
            res.redirect(`/stories/show/${story.id}`)
        })
    });
    })

    router.delete('/comment/:id', (req, res) => {
    Story.remove({
        _id: req.body.id.comments
    })
    .then(() => {
        req.flash('success_msg', 'Comments Removed!');
        res.redirect('/dashboard');
    })
    });

这是我的车把文件与表格

{{#e story story.comments}}

<form action="/stories/comment/{{id}}?_method=DELETE" method="post" id="delete-form">
<input type="hidden" name="_method" value="DELETE">
<button type="submit" class="btn red"><i class="fa fa-remove"></i> Delete</button>
</form>

{{/each}}

我得到的错误

TypeError: Cannot read property 'comments' of undefined
at router.delete (/Users/ar2z/Desktop/fierce-caverns-70427/routes/stories.js:197:20)

请帮帮我。我完全迷失了。

Answer 1

我最近遇到了同样的错误。我发现你需要这样做：

router.delete("/comments/:id", function(req,res){
   var Model = require("myModel");
   //Run a find and update query to delete the comment
   Model.findOne({_id:req.params.id}, function(err,doc){
      if(doc && !err){
         doc.comments = doc.comments.filter(function(comment){
            //This will filter out the comment you want to delete
            return comment._id != req.body.commentId
         })
      }
      res.redirect("/comments/")
   })
}

Answer 2

我的错是从我开始尝试使用数组元素开始，就像我使用Mongo对象一样

    Story.remove({
            _id: req.body.id.comments
        })

上面的代码不适用于使用对象的数组元素但是对于数组中的删除元素我使用：

Story.update( { }, { $pull: { comments: { _id: req.params.id }}}, { multi: true } )

此代码从文档数组中删除项目

$pull MongoDb documentation