mongoose can't save data - mongodb

Question

I meet some trouble need your help ~~ thx
I am use mongoose + superAgent + feedparser + eventProxy to get Rss and save these datas
now I can get and finish parse these dataes however I can't save them with moogose
I have 3 module are dao.js , app.js and service.js
I configure dao as this codes
var mongoose = require("mongoose"),
db,
modelName = "news"; // 设定操作的collections
mongoose.connect("mongodb://localhost:27017/test");
db = mongoose.connection;
db
.on("error", function (err) {
console.log("Connection Error!!! this's some prompts: ");
console.log(err);
})
.once("open", function () {
console.log("Open DataBase Successfully!!!");
});
// 设置
var newsSchema = mongoose.Schema({
"category": String,
"data": [{
"title": String,
"link": String,
"pubDate": String,
"source": String,
"author": String
}]
});
console.log(newsSchema.ObjectId);
newsSchema.pre("save", function (next) {
if( !this.title ) {
this.title = "未知标题";
}
next();
})
var newsModel = mongoose.model(modelName, newsSchema);
module.exports = {
model: newsModel,
schema: newsSchema,
mongoose,
db
}
and save data as these codes:
saveData(callback) {
var $self = this;
for(var i = 0; i<$self.result.length; i++) {
new model($self.result[i]).save(function (err) {
if(err) {
console.log(err)
} else {
console.log("数据存储成功!")
}
});
}
callback && callback();
db.close();
}
Now the data can't save successfully meanwhile the save callback func don't run
Could you give me some advise?