从phantomjs沙盒环境中写入文件系统 [英] Writing to filesystem from within phantomjs sandboxed environment

问题描述

我需要遍历站点上的表单并将中间结果保存到文件中.我正在使用phantomjs的page.evaluate，但是在从page.evaluate的沙盒环境中访问文件系统时遇到问题.我有这样的东西:

I need to traverse forms on a site and save intermediate results to files. I'm using phantomjs' page.evaluate, but I'm having trouble accessing the filesystem from within page.evaluate's sandboxed environment. I have something like this:

for (var i = 0; i<option1.length; i++){
    for (var ii = 0; ii<option2.length; ii++){
        for (var iii = 0; iii<option3.length; iii++){
        ...
            //I found what I want to save
            fs.write("someFileName", someData);
        }
    }
}

很显然，我无法从page.evaluate内部访问nodejs的fs，因此上述操作无效.我似乎有几种选择:

Obviously, I don't have access to nodejs' fs from within page.evaluate, so the above does not work. I seem to have a few options:

• 将我需要写入的所有内容存储到数组中，然后将其从page.evaluate上下文返回到外部的nodejs上下文中，然后从那里保存它.这将需要我没有的内存.
• 将以上逻辑分解为较小的page.evaluate方法，这些方法返回单行数据以保存到文件系统.
• 以某种方式将<魔术>函数传递给page.evaluate以写入文件系统.这似乎是不可能的(例如，如果我尝试传入调用fs.writeFile的函数，即使fs是我传递的函数中的自由变量，我也会得到fs是未定义的?)
• 返回一个迭代器，当该迭代器被拉出时，将产生下一个要写入的数据
• 在本地主机上设置一个简单的Web服务器，该服务器仅接受POST请求并将其内容写入文件系统.然后，page.evaluate代码将向本地主机发出这些请求.我几乎会尝试这样做，但不确定是否会受到原产地政策的影响.

• Store everything I need to write to an array, and return that from the page.evaluate context into the outer, nodejs context, then save it from there. This would require memory I don't have.
• Break up the above logic into smaller page.evaluate methods that return singe pieces of data to save to the filesytem.
• Somehow pass into the page.evaluate a magic function to write to the filesystem. This seems to not be possible (if I try to pass in a function that calls fs.writeFile for example, I get that fs is undefined, even if fs is a free variable in the function I passed?)
• Return an iterator which, when pulled, yields the next piece of data to be written
• Setup a trivial web server on the localhost that simply accepts POST requests and writes their contents into the filesystem. The page.evaluate code would then make those requests to the localhost. I almost try this but I'm not sure I'll be affected by the same-origin policy.

我在这里有什么选择?

推荐答案

您的评价不错，但是您忘记了一种类型:

Your evaluation is sound, but you forgot one type: onCallback. You can register to the event handler in the phantom context and push your data from page context to a file through this callback:

page.onCallback = function(data) {
    if (!data.file) {
        data.file = "defaultFilename.txt";
    }
    if (!data.mode) {
        data.mode = "w";
    }
    fs.write(data.file, data.str, data.mode);
};

...
page.evaluate(function(){
    for (var i = 0; i<option1.length; i++){
        for (var ii = 0; ii<option2.length; ii++){
            for (var iii = 0; iii<option3.length; iii++){
            ...
                // save data
                if (typeof window.callPhantom === 'function') {
                    window.callPhantom({ file: "someFileName", str: someData, mode: "a" }); // append
                }
            }
        }
    }
});

请注意，PhantomJS不在Node.js中运行.虽然，Node.js和PhantomJS之间存在桥梁.另请在此处.

Note that PhantomJS does not run in Node.js. Although, there are bridges between Node.js and PhantomJS. See also my answer here.

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