猫鼬:通过循环模型数组来查找数据 [英] mongoose : find data by looping on an array of models

问题描述

我被异步算法困住了:

我有一系列猫鼬模型:

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一个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，所以我不可能知道哪些模型项目属于

I'd like to grab all items of each collection and put them in an array or something like that. If I do that, the this keyword of the find callback doesn't refer to the current model, so impossible for me to know which model items belong to

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

  });

}

我也试过 async 库没有成功，因为我总是回到同样的问题: 不可能知道哪个模型在回调中执行查找查询.同上 then 如果我使用承诺.

I've also tried async library without success, because I always return to the same issue : impossible to know which model execute the find query inside the callback. Idem in a then if I use promises.

请帮帮我 :) 你会怎么做?

Please help me :) How would you do that ?

编辑model.find 调用 query.find，query.find 调用 mquery.find.在 mquery.find 中，由于丢失了 this 引用而调用了回调: this._collection.find(conds, options, utils.tick(callback));/编辑

EDIT model.find calls query.find, query.find calls mquery.find. In mquery.find, callback is called, by lost the this reference a that time : this._collection.find(conds, options, utils.tick(callback)); /EDIT

推荐答案

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更好地理解.

Please check this code snippet, I have made a working sample of what you need. Please check comments in the code for better understanding.

示例工作代码与您需要的类似.另一个参考问题用于将异步与猫鼬一起使用.

Sample Working code similar to what you required. Another ref ques for using async with mongoose.

/*
 * 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)
});

输出将采用这种格式

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

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