Azure移动应用程序node.js后端-自定义查询和传递参数 [英] Azure Mobile App node.js backend - Custom queries and passing parameters

问题描述

我曾经有一个带有JavaScript后端的Azure移动服务.现在，我切换到带有其node.js后端的新Azure移动应用程序. 由于node.js对事情的处理方式不同，所以我想问你如何做一些简单的事情，这些事情以前可以在较旧的后端上使用.

I used to have an Azure Mobile Service with a JavaScript backend. Now I switched to the new Azure Mobile App with its node.js backend. Since things are handled differently with node.js, I want to ask you how to do some simple things that used to work with the older backend.

第一件事是，如何在服务器端修改读取"或插入"请求，例如执行自定义查询.我以前是这样的:

The first thing is, how can I modify a "read" or "insert" request on the server side to, for instance, execute a custom query. I used to do that like this:

function read(query, user, request) {
var visitorID = request.parameters.visitor;
var liked = request.parameters.liked;
var link = request.parameters.link;
if (visitorID && !liked && !link) {
    if (visitorID.indexOf(" ") == -1) {
        var sqlUnique = "SELECT TOP 1 * FROM ........;";
        mssql.query(sqlUnique, {
            success: function(results) {
                if(results.length > 0) {
                    request.respond(statusCodes.OK, results);   
                }
                else {
                    request.respond(statusCodes.BAD_REQUEST, {error: 'An error message.'});
                }
            },
            error: function(err) {
                request.respond(statusCodes.BAD_REQUEST, {error: 'There was a problem with the request.'});
            }
        });
    } else {
        request.respond(statusCodes.BAD_REQUEST, {error: 'Invalid username.'});
    }
}
else {
    // no server-side action needed
    request.execute();
}

}

如您所见，每当客户端从服务器读取时，其他一些事情就会被执行.我的问题是，现在如何使用Azure移动应用程序的node.js后端执行相同的操作.尤其是当客户端在请求内传递某些参数时.如何在node.js中读取这些参数?在请求中执行查询之前，如何执行自定义查询?

As you can see, whenever a client reads from the server, some other things are getting executed. My question is now, how to do that same thing with Azure Mobile App's node.js backend. Especially when a client passes some parameters within the request. How can I read those parameters in node.js? And how can I execute a custom query before executing the query in the request?

如果有人可以帮助我将上述JavaScript代码移植到node.js，我将非常高兴！

If someone can help me port the above JavaScript code to node.js, I would be very happy!

推荐答案

如果我没有误解，您想在Mobile Apps的EasyTables脚本中的表操作中查询一些自定义SQL stmt.

If I don't misunderstand, you want to query some custom SQL stmt in table operations in EasyTables scripts in Mobile Apps.

我们可以利用"use()"自定义中间件来指定针对表的每个请求要执行的中间件，作为对azure-mobile-apps sdk文档的描述，位于

we can leverage "use()" to custom middleware to specify middleware to be executed for every request against the table as the description on the document of azure-mobile-apps sdk at http://azure.github.io/azure-mobile-apps-node/module-azure-mobile-apps_express_tables_table.html#~use.

var queries = require('azure-mobile-apps/src/query');
var readMiddleware = function(req,res,next){
    var table = req.azureMobile.tables('table2'),
    query = queries.create('table2')
            .where({ TestProperty : req.body.testproperty });
    table.read(query).then(function(results) {
        if(results){
            req.someStoreData = somehander(results); //some hander operations here to get what you want to store and will use in next step
            next();
        }else{
            res.send("no data");
        }
    });
};

table.read.use(readMiddleware, table.operation);
table.read(function (context) {
   console.log(context.req.someStoreData);
   return context.execute();
});

您可以在SO上参考类似的问题，

You can refer to the similar question on SO, Query other tables in insert function of Azure Table Storage.

您可以通过context.req.query.someparams在表操作关闭中获取参数，类似于我们在expressjs中处理参数. 您可以参考代码示例在GitHub上.

And you can get the params in table operations closure via context.req.query.someparams similar with we handling params in expressjs. You can refer to the code sample on GitHub.

这篇关于Azure移动应用程序node.js后端-自定义查询和传递参数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！