创建树类别并在帖子中设置的哪种结构更好?并在MERN中按选定类别查找帖子 [英] What structure for create tree category and set in posts is better? and find posts by selected category in MERN

问题描述

我正在使用MERN来开发我的项目，我具有这种结构的树类别:

I'm using MERN to develop my project, I have tree category with this structure:

{id: {
    type: Number
},
parent_id: {
    type: Number
},
name: {
    type: String
},
sub: {
    type: Boolean
}}

例如:

 {
    "_id": "5dfa22dbb04cee3960868fd8",
    "id": 1,
    "name": "Code",
    "parent_id": 0,
    "sub": true,
    "__v": 0
},
{
    "_id": "5dfa2358b04cee3960868fda",
    "id": 101,
    "parent_id": 1,
    "name": "JavaScript",
    "sub": true,
    "__v": 0
},
{
    "_id": "5dfa68735dc1004134b259ab",
    "id": 1001,
    "parent_id": 101,
    "name": "React",
    "sub": false,
    "__v": 0
},

对于每个帖子，我都具有以下结构:

and for each post I have this structure:

    {
    "_id": "5dfd3b918937d40b98afd3f8",
    "user": "5deea38cfc84f42590e01942",
    "title": "test",
    "description": "description test",
    "category":
        {
            "0": "1",
            "1": "101"
        },
    "phone": "+1",
    "country": "USA",
    "city": "NY",
    "options": {
        "transaction_type": ""
    },
    "date": "2019-12-20T21:22:25.940Z",
    "__v": 0
}

例如，我们将ID为1的类别作为父项，将ID 101作为其子项作为1的类别101的孩子像树一样是1001

for example we have category with id 1 as parent and category with id 101 as child of 1 and child of 101 is 1001 like a tree

现在我有一个类别为1001的帖子，因此我为该帖子设置了类别，如底部:

now i have a post that category is 1001 so I set category for this post like bottom:

        "category": [
        {
            "0": "1",
            "1": "101",
            "2": "1001"
        }
    ]

，其他帖子类别为101，因此我将其设置为:

and other post category is 101 so i set like this:

            "category": [
        {
            "0": "1",
            "1": "101",
        }
    ]

当用户从菜单中选择ID为1的类别时，我希望返回所有帖子的类别分别为1、101和1001，因此我使用类似顶部代码的结构来为帖子类别设置父ID和子ID

I want when user select category with id 1 from menu, return all posts have category 1, 101 and 1001 so i use structure like top code to set parent id and child id for post category

此方法正确还是您建议一种更好的方法?

在后端中，我使用底层代码在每个类别中查找帖子，但不起作用我该怎么做?

and in backend with express I using bottom code for find posts in each category but not working what I should to do?

router.get('/category/:category', async (req, res) => {
try {
    const posts = await Post.find({'category': {$all: req.params.category}}).sort({ date: -1 });
    if (!posts) {
        return res.status(404).json({ msg: 'Ads not found' });
    }
        const resultPosts = posts.slice(req.query.start, req.query.count)
        res.json(resultPosts);


} catch (err) {
    console.error(err.message);
    if (err.kind === 'ObjectId') {
        return res.status(404).json({ msg: 'Ads not found' });
    }
    res.status(500).send('Server Error!');
}});

推荐答案

此问题已通过以下方式解决:

The problem was solved this way: link

但是我仍然很乐意分享您有关内容分类的经验

But I'm still happy to share your experiences about content categorization

所以我最终获得的按类别分类的帖子是:

so my final get posts by category is:

router.get('/category/:category', async (req, res) => {
try {
    const posts = await Post.find({category: {$elemMatch: {cat_name: 'req.params.category'}}})
    if (!posts) {
        return res.status(404).json({ msg: 'Ads not found' });
    }
    console.log(posts)
    res.json(posts);

} catch (err) {
    console.error(err.message);
    if (err.kind === 'ObjectId') {
        return res.status(404).json({ msg: 'Ads not found' });
    }
    res.status(500).send('Server Error!');
}

});

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