Question

这是我的代码：

//server.js
const express = require('express'),
          cors = require('cors'),
          bodyParser = require('body-parser'),
          mongoose = require('mongoose');


const Mate = require('./models/mate');


mongoose.Promise = global.Promise;


const app = express();
const router = express.Router();

app.use(cors());
app.use(bodyParser.json())

mongoose.connect('mongodb://localhost:27018/mate', {useNewUrlParser: true});

const connection = mongoose.connection;

connection.once('open', () => {
    console.log('Mongodb db connection established succ');
})

router.route('/mate').get((req, res) => {
    mongoose.model('Mate').find((err, mate) =>  {
        if (err) 
            console.log(err);
        else
            res.json(mate);
    });
});

router.route('/mate/:id').get((req, res) => {
    mongoose.model('Mate').findById((err, mate) => {
        if(err)
            console.log(err);
        else
            res.json(mate);
    });
});

router.route('/mate/add').post(async (req, res) => {
        try {
            const mate = new Mate(req.body);
            await mate.save();
            res.status(200).json({
                'mate:': 'Added succesfully'
            });
        } catch (err) {
            console.log(err);
            res.status(400).send( 'failed to create' );
        }
}); 

router.route('mate/update/:id').post((req, res) => {
    mongoose.model(Mate).findById(req.params.id, (err, mate) =>{
        if(!mate)
            return next(new Error('couldnt load doc'))
        else {
            mate.title = req.body.title;
            mate.day = req.body.day;
            mate.severity = req.body.severity;
            mate.status = req.body.status;

            mate.save().then(mate => {
                res.json('Update done');
            }).catch(err => {
                res.status(400).send('update failed');
            });
        }
    });
});

router.route('mate/delete/:id').get((req, res) => {
    mongoose.model(Mate).findByIdAndRemove({_id: req.params.id}, (err, mate) => {
        if(err)
            res.json(err);
        else
            res.json('Removed');
    });
});

app.use('/', router);

app.listen(4000, () => console.log('server running on port 4000'));

//mate.js

const mongoose = require('mongoose')

const Schema = mongoose.Schema;

let MateSchema = new Schema({
    title: {
        type: String
    },
    day: {
        type: String
    },
    severity: {
        type: String
    },
    status: {
        type: String, 
        default: 'Open'
    }
});

module.export = mongoose.model('Mate', MateSchema);

所以基本上，问题在于server.js中的添加控制器，该控制器必须使用创建的新json向我的数据库抛出发布请求。好吧，它没有，但是它引发了这个错误：TypeError：Mate不是构造函数；

请帮助我弄清楚为什么会这样。我是代码新手，所以这可能是一个愚蠢的问题，但我对此深感困惑。

Answer 1

使mate.js如下所示

module.exports = function(mongoose) {

    var options = {
    collection: 'mate',
    timestamps: {
      createdAt: 'created_on',
      updatedAt: 'updated_on'
    },
    toObject: {
      virtuals: true
    },
    toJSON: {
      virtuals: true
    }
  };

let MateSchema = new mongoose.Schema({
    title: {
        type: String
    },
    day: {
        type: String
    },
    severity: {
        type: String
    },
    status: {
        type: String, 
        default: 'Open'
    }
});



return MateSchema;
};

Answer 2

在模块导出中进行以下更改：

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference attendanceRef = rootRef.child("Attendance");
ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            String xname = ds.child("xname").getValue(String.class);
            Log.d(TAG, xname);
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
    }
};
attendanceRef.addListenerForSingleValueEvent(valueEventListener);

在CRUD中创建发布请求的问题

2 个答案: