使mongoose.js查询同步运行

问题描述

我有两个猫鼬收藏.第一个存储位置列表，第二个存储对位置的访问.我的节点代码经过检查，并尝试获取对每个地方的访问列表，并构建一个以JSON输出的字符串.第一个查询在第二个查询开始之前完成-有没有办法使它们同步运行?

I have two mongoose collections. The first stores a list of places, the second is visits to the places. My node code goes through and attempts to get the list of visits to each place and build a string that I output as JSON. The first query completes before the second ever starts - is there a way to make them run synchronously?

推荐答案

如果您使用的是node.js，则您应该使用 https://github.com/caolan/async

If you are using node.js then u should use https://github.com/caolan/async

当您必须从多个集合中获取数据时，必须多次链接查询.

when you have to fetch data from multiple collections you have to chain your queries multiple times.

这将使您的代码复杂且难以阅读，并且没有模块化.使用异步创建使用mongodb和node.js进行模块化

It will make your code complex and difficult to read and no modularity. Use async to createmodularity using mongodb and node.js

我的项目中的示例代码:

Example Code from my project :

var async = require('async');

var createGlobalGroup = function(socket, data) {
    async.waterfall(
    [
    /**
     * this function is required to pass data recieved from client
     * @param  {Function} callback To pass data recieved from client
     */

    function(callback) {
        callback(null, socket, data);
    },
    /**
     * Step 1: Verify User
     */
    verifyUser,
    /**
     * Step 2: Check User Access Rights And Roles
     */
    checkUserAccessRightsAndRoles,
    /**
     * Step 3: Create Project
     */
    createNewGlobalGroup], function(err, result) {
        /**
         * function to be called when all functions in async array has been called
         */
        console.log('project created ....')
    });
}
verifyUser = function(socket, data, callback) {
//do your query
    /**
     * call next function in series
     * provide sufficient input to next function
     */
    callback(null, socket, data, {
        "isValidUser": true,
    });
}

checkUserAccessRightsAndRoles = function(socket, data, asyncObj, callback) {
    //do your query
    if(condition) {
        callback(null, socket, data, {
            roles: result,
            "isValidUser": asyncObj.isValidUser,
            "userId": asyncObj.userId,
        });
    } else {
    //no call back
    }
}

var createNewGlobalGroup = function(socket, data, asyncObj, callback) {
//wanna stop then no callback
}

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