异步节点，猫鼬插入数据

Question

我有一个要读取的CSV文件，其中包含数百行。 基于CSV文件中的一行，我正在创建一个“项目”并将其存储到我的项目集合中。 每个项目也都有一个类别，这是它自己的模型。 如此多的项目可以具有相同的类别。 这两个集合一开始都没有，我需要根据CSV文件填充这两个集合。 我遇到的问题是，由于很多行都包含相同的类别，通常是一个接一个地接一个地创建，因为所有事情都是异步发生的，所以会创建相同类型的多个类别文档。 我有这样的代码：

    exports.upload = function(req, res) {
var reader = csv.createCsvFileReader("test.csv", {columnsFromHeader:true, nestedQuotes:true});
reader.addListener('data', function(data) {        
    projectService.findCategory(data.Category, function(id){
        var Project = mongoose.model('Project');
        var project = new Project();
        project.name = data.Name;
        project.narrative = data.Narrative;
        project.address = data.address;
        project.category = id;
        project.lat = data.Lat;
        project.lng = data.Lng;
        project.save(function(err){
            console.log(project);
            if(err){
                console.log("There was an error in saving your project");
                console.log(err);
                return;
            }
        });
    });
});

}

和

    exports.findCategory = function(projectCategory, callback) {
var Category = mongoose.model('Category');
Category.findOne({ name: projectCategory }, function(err, categoryReturned){
    if (err) {
        console.log("Could not return a category");
        console.log(err);
        return;
    }
    if(categoryReturned == null){ //If category does not exist create a new category. 
        category = new Category({name : projectCategory});
        console.log(category);
        category.save(function(err, categoryCreated){
            console.log('New Category Created');
            callback(categoryCreated._id);
        });
    }else{
        callback(categoryReturned._id);
    }
});

}

这是一些示例输入：

    "Name","Narrative","Address","Category","Lat","Lng","Year_Completed","Sponsors"
    "Raymond Avenue Neighborhood Garden Construction","","","3",34.0317141377768,-118.297777175903,"2010","??? (City of Los Angeles, The Garden Council)"
    "El Cariso Smart Garden Construction","","","3",34.3169450092985,-118.419291973114,"2010","L.A. County Parks and Recreation"
    "Central Basin Friendly Native Plants Garden","","","2",33.9955722580013,-118.144440650939,"2010","Central Basin Municipal Water District"

这将创建两个“ 3”类别条目。 我知道为什么。 我不知道如何解决它。

Answer 1

var dataArray = new Array(YOUR DATA);
var index = 0;
(function(data) {
    var presentFunction = argument.callee;
    projectService.findCategory(data.Category, function(id){
        var Project = mongoose.model('Project');
        var project = new Project();
        project.name = data.Name;
        project.narrative = data.Narrative;
        project.address = data.address;
        project.category = id;
        project.lat = data.Lat;
        project.lng = data.Lng;
        project.save(function(err){
           console.log(project);
           if(err){
               console.log("There was an error in saving your project");
            console.log(err);
            return;
           }
           if (index > dataArray.length - 1) {
               return;
           } else {
               index++;
               presentFunction(dataArray[index]);
           }
        });
    });
})(dataArray[index]);

这应该做到。 解决方案是粗略的，有很多改进的余地，但是您知道了。