Node.js / Express.js - 如何覆盖/拦截res.render函数？ [英] Node.js / Express.js - How to override/intercept res.render function?
问题描述
app.get（'/ someUrl'，function（req，res）{
res.render = function （view，options，callback）{
view ='testViews /'+ view;
res.prototype.render（view，options，callback）;
};
res.render（'index'，{title：'Hello world'}）;
}）;
它看起来像一个有创意的例子，但它符合我正在构建的整体框架。 / p>
我对于Java的OOP和Prototypal继承知识有点薄弱。我如何做这样的事情？
更新：经过一番实验，我想出了以下：
app.get（'/ someUrl'，function（req，res）{
var response = {};
response.prototype = res;
response.render = function（view，opts，fn，parent，sub）{
view ='testViews /'+ view;
this.prototype.render（view，opts，fn，parent，sub）;
};
response.render（'index '，{title：'Hello world'}）;
}）;
似乎有效。不确定是否是最好的解决方案，因为我正在为每个请求创建一个新的响应包装器对象，这是一个问题吗？
老问题，但发现自己也是一样的问题。如何拦截res渲染？
现在使用express 4.0x。
可以使用/写中间件。这个概念起初对我来说有点令人生畏，但经过一番阅读，这一点更有意义。只是为了阅读这个任何人的某些上下文，覆盖res.render的动机是提供全局视图变量。我希望 session 可以在我的所有模板中使用，而无需在每个res对象中输入。
基本的中间件格式是。
app.use（function （req，res，next）{
// ....
next（）;
}）;
下一个param和函数调用对执行至关重要。 next 是回调函数，允许多个中间件做事情而不阻止。为了更好的此处阅读的解释
然后可以用它来覆盖渲染逻辑
app.use（function req，res，next）{
// grab reference of render
var _render = res.render;
//覆盖逻辑
res.render = function（view，options， fn）{
//做一些自定义逻辑
_.extend（options，{session：true}）;
//继续原始渲染
_render.call（这， view，options，fn）;
}
next（）;
}）;
我已经使用express 3.0.6测试了这段代码。它应该与4.x没有问题。
您还可以使用
app.use（'/ myspcificurl'，function（req，res ， 下一个 ） {...} ）;
I'm building a Node.js app with Connect/Express.js and I want to intercept the res.render(view, option) function to run some code before forwarding it on to the original render function.
app.get('/someUrl', function(req, res) {
res.render = function(view, options, callback) {
view = 'testViews/' + view;
res.prototype.render(view, options, callback);
};
res.render('index', { title: 'Hello world' });
});
It looks like a contrived example, but it does fit in an overall framework I'm building.
My knowledge of OOP and Prototypal inheritance on JavaScript is a bit weak. How would I do something like this?
Update: After some experimentation I came up with the following:
app.get('/someUrl', function(req, res) {
var response = {};
response.prototype = res;
response.render = function(view, opts, fn, parent, sub){
view = 'testViews/' + view;
this.prototype.render(view, opts, fn, parent, sub);
};
response.render('index', { title: 'Hello world' });
});
It seems to work. Not sure if it's the best solution as I'm creating a new response wrapper object for each request, would that be a problem?
Old question, but found myself asking the same thing. How to intercept res render? Using express 4.0x something now.
You can use/write middleware. The concept was a bit daunting to me at first, but after some reading it made a little more sense. And just for some context for anyone else reading this, the motivation for overriding res.render was to provide global view variables. I want session to be available in all my templates without me having to type it in every res object.
The basic middleware format is.
app.use( function( req, res, next ) {
//....
next();
} );
The next param and function call are crucial to execution. next is the callback function, to allow multiple middleware to do their thing without blocking. For a better explanation read here
This can then be used to override render logic
app.use( function( req, res, next ) {
// grab reference of render
var _render = res.render;
// override logic
res.render = function( view, options, fn ) {
// do some custom logic
_.extend( options, {session: true} );
// continue with original render
_render.call( this, view, options, fn );
}
next();
} );
I've tested this code, using express 3.0.6. It should work with 4.x without issue. You can also override specific URLs combos with
app.use( '/myspcificurl', function( req, res, next ) {...} );
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