获取量角器中的元素属性值 [英] get element attribute value in Protractor

问题描述

我正在编写一个量角器测试，该测试必须等待element属性具有非空值，然后要将其返回给调用方函数。事实证明，这比我想象的要难写！

I'm writing a Protractor test that has to wait for an element attribute to have a non-empty value and then I want to return that value to the caller function. This has proven to be more difficult to write than I expected!

我能够正确安排 browser.wait（）命令等待element属性具有非空值，并且我已经验证了该值实际上是我期望在回调函数中获得的值，但是由于某些原因，我无法返回该值

I am able to correctly schedule a browser.wait() command to wait for the element attribute to have a non-empty value and I have verified that this value is in fact what I am expecting to get inside the callback function, but for some reason, I am not able to return that value outside of the callback function and onto the rest of the test code.

这是我的代码的样子：

function test() {
    var item = getItem();
    console.log(item);
}

function getItem() {
    var item;
    browser.wait(function() {
        return element(by.id('element-id')).getAttribute('attribute-name').then(function(value) {
            item = value;
            // console.log(item);
            return value !== '';
        });
    });
    return item;
}

我可以说执行顺序不符合我的预期，因为当我取消注释回调函数中的 console.log（）调用时，我看到了预期值。但是，在 test（）函数中的同一调用将显示未定义。

I can tell that the order of execution is not as I expect it to be, because when I uncomment the console.log() call inside the callback function, I see the expected value printed out. However, the same call in the test() function prints 'undefined'.

这是怎么回事？我想念什么？如何从回调函数中正确获取属性值？

What is going on here? What am I missing? How can I get the attribute value out of the callback function properly?

感谢您的帮助。

推荐答案

我不会将等待和获取属性部分结合在一起-逻辑上这是两个分开的东西，将它们分开：

I would not combine the wait and the getting attribute parts - logically these are two separate things, keep them separate:

browser.wait(function() {
    return element(by.id('element-id')).getAttribute("attribute").then(function(value) {
        item = value;
        // console.log(item);
        return value !== '';
    });
});

element(by.id('element-id')).getAttribute("attribute").then(function (value) {
    console.log(value);
});

请注意，您可以通过以下方式简化等待条件：

Note that, you may simplify the wait condition this way:

var EC = protractor.ExpectedConditions;
var elm = $('#element-id[attribute="expected value"]');

browser.wait(EC.presenceOf(elm), 5000);
elm.getAttribute("attribute").then(function (value) {
    console.log(value);
});

---

仅供参考，您可能已经解决了当前的问题与 递延 ：

function test() {
    getItem().then(function (value) {
        console.log(value);
    });
}

function getItem() {
    var item = protractor.promise.defer();
    browser.wait(function() {
        return element(by.id('element-id')).getAttribute('attribute').then(function(value) {
            var result = value !== '';
            if (result) {
                item.fulfill(value);
            }
            return result;
        });
    });
    return item.promise;
}

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