Node.js |類型錯誤：[...]是不是一個函數

Question

在我的主文件server.js我有以下功能：

server.js

const mongoose = require('mongoose'); 
const SmallRounds = require('./models/smallrounds.js'); 

function initRound(){ 
    logger.info('Initializing round...'); 
    SmallRounds.getLatestRound((err, data) => { 
     [...] 
    }); 
} 

功能getLatestRound（）在得到我的出口貓鼬模型smallrounds.js

smallrounds.js

const mongoose = require('mongoose'); 
const config = require('../config.js'); 

const SmallRoundsSchema = mongoose.Schema({ 
    [...] 
}); 

const SmallRounds = module.exports = mongoose.model('SmallRounds', SmallRoundsSchema); 

module.exports.getLatestRound = function(callback){ 
    SmallRounds.findOne().sort({ created_at: -1 }).exec((err, data) => { 
     if(err) { 
      callback(new Error('Error querying SmallRounds')); 
      return; 
     } 
     callback(null, data) 
    }); 
} 

但是當我打電話initRound（）我得到以下錯誤：

TypeError: SmallRounds.getLatestRound is not a function

at initRound (E:\Projects\CSGOOrb\server.js:393:14)
at Server.server.listen (E:\Projects\CSGOOrb\server.js:372:2)
at Object.onceWrapper (events.js:314:30)
at emitNone (events.js:110:20)
at Server.emit (events.js:207:7)
at emitListeningNT (net.js:1346:10)
at _combinedTickCallback (internal/process/next_tick.js:135:11)
at process._tickCallback (internal/process/next_tick.js:180:9)
at Function.Module.runMain (module.js:607:11)
at startup (bootstrap_node.js:158:16)
at bootstrap_node.js:575:3

這究竟是爲什麼？我不認爲我有循環依賴關係，沒有任何拼寫錯誤。謝謝:)

Answer 1

這不是你如何添加方法到Mongoose模型/模式。

試試這個：

const mongoose = require('mongoose'); 
const config = require('../config.js'); 

const SmallRoundsSchema = mongoose.Schema({ 
    [...] 
}); 

SmallRoundsSchema.statics.getLatestRound = function(callback){ 
    this.findOne().sort({ created_at: -1 }).exec((err, data) => { 
     if(err) { 
      callback(new Error('Error querying SmallRounds')); 
      return; 
     } 
     callback(null, data) 
    }); 
} 

const SmallRounds = module.exports = mongoose.model('SmallRounds', SmallRoundsSchema); 

你可以在這裏閱讀文檔：http://mongoosejs.com/docs/guide.html，在部分 「靜」。還有其他更好的方法來達到同樣的效果，但這會讓你開始。