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javascript - 节点/猫鼬 - 从数组中删除 ObjectId

问题描述

我正在构建的网站上有一个具有评论功能的页面。该网站就像露营地的 Yelp，mongo db 中集合中的每个露营地都有一个字段 - 评论 - 存储在该露营地上发布的每条评论的 id，并且 id 指的是另一个名为评论的集合中的对象。除了删除评论之外，添加、编辑、查看和删除评论都有效，该评论的 id 不会从其关联营地的评论数组中删除。

以下是当前一个露营地的记录示例：

{ 
     "_id" : ObjectId("5b18331953b9811c54ddc4cd"),
          "contact" : { 
          "phone" : "403-748-4066", 
          "email" : "", 
          "website" : "https://www.albertaparks.ca/parks/central/aspen-beach-pp/information-facilities/camping/lakeview/" 
     }, 
     "author" : { 
          "id" : ObjectId("5a998953342cbc7fe8521ef5"), 
          "username" : "Adam" 
     }, 
     "createdAt" : ISODate("2018-06-06T19:04:25.418Z"), 
     "comments" : [ 
          ObjectId("5b1bf59f8f21e152cce41b49") 
     ], 
     "name" : "Lakeview", 
     "cost" : "40", 
     "location" : "Range Rd 284, Bentley, AB T0C 0J0, Canada", 
     "image" : "https://c1.staticflickr.com/9/8620/16612167676_6418f1b470_b.jpg",
      "description" : "Open, pull-through sites are well-suited to RVs. There are unserviced, power, and power/water options. Trees provide some shade from the summer sun. There are many amenities available including a boat launch, playground, sewage disposal, flush toilets and showers. Camp along Gull Lake and enjoy swimming, boating, and the beach. Explore the trails and boardwalks for walking, biking, bird and wildlife watching. ", 
     "lat" : 52.4357744, 
     "__v" : 1, 
     "long" : -113.9873582 
}

如您所见，露营地对象当前引用了一条评论，但如果我要通过 UI 删除评论，它将停止显示评论，因为它将从评论集合中删除，但露营地对象中对评论的引用会保持。这是我目前删除评论的代码：

app.delete("/campgrounds/:id/comments/:comment_id", middleware.checkCommentOwnership, function(req, res){
    // RESTful - DESTROY
    Comment.findByIdAndRemove(req.params.comment_id, function(err){
        if(err){
            req.flash("error", "Uh Oh! Something went wrong.");
            res.redirect("/campgrounds");
        }
        Campground.findById(req.params.id, function(err, campground){
            if(err){
                req.flash("error", "Uh Oh! Something went wrong.");
                res.redirect("/campgrounds");
            }
            campground.comments.remove(req.params.comment_id);
            req.flash("success", "Comment has been deleted!");
            res.redirect("back");
        });
    });
});

然而线

campground.comments.remove(req.params.comment_id);

似乎不起作用。我也（粗鲁地）尝试过

campground.comments.remove("ObjectId(\"" + req.params.comment_id + "\")")

尝试在 comments 数组中镜像存储 id 的格式，但这会引发此错误：

CastError: Cast to ObjectId failed for value "ObjectId("5b1bf4215f319752ab28ba49")" at path "comments"

我主要使用 Mongoose 与数据库交互。

抱歉，如果这是冗长的或重复的，我试图研究解决方案但一无所获 - 至少没有我能理解的！

谢谢。

标签： javascriptarraysnode.jsmongodbmongoose

解决方案

您需要使用 mongodb $pull运算符才能comment_id从数组中删除...

Campground.update({ _id: req.params.id }, { $pull: { comments: req.params.comment_id } }, function(err, campground){
    if(err){
        req.flash("error", "Uh Oh! Something went wrong.");
        return res.redirect("/campgrounds");
    }
    req.flash("success", "Comment has been deleted!");
    return res.redirect("back");
});

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