SOURCE

function aticleInsert(dbname,collection,document,callback){
    var db = mongoClient.db(dbname);
    db.collection(collection).insertOne(document).then((data)=>{
        callback(data)
    },(err) => {
        callback(err)
    })
}

function articleDelete(dbname,collection,sql,callback){
    var db = mongoClient.db(dbname);
    db.collection(collection).removeOne(sql).then(data => {
        callback(data)
    }).catch(error => {
        callback(error)
    })
}

function articleUpdate(dbname,collection,sql,update,callback){
    var db = mongoClient.db(dbname);
    db.collection(collection).updateOne(sql,update).then(data => {
        callback(data)
    }).catch(error => {
        callback(error)
    })
}


function handleInsert(req,res){
    if(!req.body) return res.sendStatus(400);
    let document = req.body.document;
    let collection = '';
    if(req.url === '/preview'){
        collection = previewCollection;
    }else if(req.url === '/article'){
        collection = detailCollection
    }
    aticleInsert(dbname,collection,document,(data) => {
        res.send(data)
        return
    })
}

function handleDelete(req,res){
    if(!req.body) return res.sendStatus(400);
    let document = req.body.document;
    let sql = document['sql'],
        collection = '';
    if(req.url === '/preview'){
        collection = previewCollection;
    }else if(req.url === '/article'){
        collection = detailCollection
    }
    articleDelete(dbname,collection,sql,(data) => {
            res.send(data)
            return
    })
}

function handleUpdate(req,res){
    if(!req.body) return res.sendStatus(400);
    let document = req.body.document;
    let sql = document['sql'],
        update = document['update'],
        collection = '';
    if(req.url === '/preview'){
        collection = previewCollection;
    }else if(req.url === '/article'){
        collection = detailCollection
    }
    articleUpdate(dbname,collection,sql,update,(data) => {
        res.send(data)
        return
    })
}


app.post(/^\/preview$|^\/article$/,jsonParser,handleInsert)

app.delete(/^\/preview$|^\/article$/,jsonParser,handleDelete)

app.put(/^\/preview$|^\/article$/,jsonParser,handleUpdate)