node.js - Mongoose : find data by looping on an array of models

Question

我陷入了异步算法的困境:

我有一系列 Mongoose 模型:

var allRefDatasSchemas = {
  RefAllotement: mongoose.model('RefAllotement', RefDataSchema),
  RefModeleConstructeur: mongoose.model('RefModeleConstructeur', RefDataSchema),
  RefTypeKit: mongoose.model('RefTypeKit', RefDataSchema),
  RefTypeUtilisation: mongoose.model('RefTypeUtilisation', RefDataSchema),
};

我想获取每个集合的所有项目并将它们放入数组或类似的东西中。如果我这样做，find 回调的 this 关键字不会引用当前模型，我不可能知道哪些模型项目属于

var results = {};

for (var model in allRefDatasSchemas) {

  allRefDatasSchemas[model].find(function(err, data) {

    // I'd like to do something like that :
    // but this.modelName is null, because it isn't the model
    // on which the find is done.
    results[this.modelName] = data;

    // if I use "model" variable, it doesn't work, because asynchronous callback

  });

}

我也尝试过async库没有成功，因为我总是返回相同的问题:不可能知道哪个模型在回调中执行查找查询。如果我使用 Promise，则同上 then 。

请帮助我:)你会怎么做？

编辑model.find 调用 query.find，query.find 调用 mquery.find。在 mquery.find 中，通过丢失 this 引用来调用回调: this._collection.find(conds, options, utils.tick(callback));/编辑

Answer 1

请检查此代码片段，我已经制作了您需要的工作示例。请检查代码中的注释以便更好地理解。

Sample Working code与您所要求的类似。另ref ques用于将异步与 Mongoose 一起使用。

/*
 * Object to store all models
 */
var allRefDatasSchemas = {
  RefAllotement: mongoose.model('RefAllotement', RefDataSchema),
  RefModeleConstructeur: mongoose.model('RefModeleConstructeur', RefDataSchema),
  RefTypeKit: mongoose.model('RefTypeKit', RefDataSchema),
  RefTypeUtilisation: mongoose.model('RefTypeUtilisation', RefDataSchema),
};
/*
 * need an array to run all queries one by one in a definite order using async waterfall mwthod
 */
var arr = [];
for(each in allRefDatasSchemas) {
    arr.push(each);
}

/*
 * Callback function for initiation of waterfall
 */
var queue = [
    function(callback) {
        // pass the ref array and run first query by passing starting index - 0
        callback(null, arr, 0)
    }
];

/*
 * Object to store result of all queries
 */
var finalResult = {};

/*
 * Generic Callback function for every dynamic query
 */
var callbackFunc = function(prevModelData, currentIndex, callback) {
    allRefDatasSchemas[arr[currentIndex]].find(function(err, result) {
        if(err) {
            console.log(err)
        } else {

            // Your Query
            // 
            // I'd like to do something like that :
            // but this.modelName is null, because it isn't the model
            // on which the find is done.

            // arr[currentIndex] will point to 
            // RefAllotement, RefModeleConstructeur etc. as you required
            finalResult[arr[currentIndex]] = result

            // send current result to next interation if required or you can skip
            // and increment the currentIndex to call next query 
            callback(null, result, currentIndex + 1)
        }
    })
}

/*
 * Add callback function for every dynamic query
 */
for(each in allRefDatasSchemas) {
    queue.push(callbackFunc);
}

/*
 * Run all dynamic queries one by one using async.js waterfall method
 */
async.waterfall(queue, function (err, result) {
    // Final object with result of all the queries
    console.log('finish', finalResult)
});

输出将采用此格式

finish { RefAllotement:[
        // Result of RefAllotement query
    ],
    RefModeleConstructeur:[
        // Result of RefModeleConstructeur query
    ],
    RefTypeKit:[
        // Result of RefTypeKit query
    ],
  RefTypeUtilisation:[
        // Result of RefTypeUtilisation query
    ]
}