如何确定可选函数是否已传递到 Angular 指令中? [英] How to determine if an optional function has been passed into an Angular directive?

问题描述

我有一个显示一些数据的指令，但我希望指令的用户能够控制该数据的显示方式.我希望允许用户使用三个选项之一来控制显示.

1. 传入一个用于显示的字符串
2. 传入一个将被调用以生成字符串的函数
3. 或者只显示原始数据

我无法发布整个指令(NDA 和所有指令)的代码，但它是使用 D3 显示环形图的指令.中间的数字是有问题的数据.因此，假设环形图显示百分比，我可能希望中间的文本显示 55%.因此，假设 myValue 是作用域上的一个属性并设置为 55，这就是我想要做的:

这将显示 55%或者做:

这将显示 ringLabelFunction(value) 返回的任何内容最后可以选择:

它只会显示 55.

在指令中我有

<代码> ...范围: {全部的:"@"，其余的:"@"，值后缀:"@",centerNumberClass: "@",后缀类:"@",剩余颜色:"@",总颜色:"@",图表宽度:"@",图表高度:"@",戒指厚度:"@",labelFunction: "&",标签文本:"@"},链接:函数($scope，元素，属性){var labelContent;如果($scope.labelText){labelContent = $scope.labelText;} else if ($scope.labelFunction) {//<-- 这总是正确的labelContent = $scope.labelFunction({remaining:$scope.remaining});} else {//所以我从来没有遇到过这个labelContent = $scope.remaining;}...}...

所以，简而言之，我正在寻找一种方法来确定 $scope.labelFunction 是否已实际设置.

解决方案

您有链接 attrs.只需检查是否定义了 label-function 并且其值引用了 function

link:function($scope, element, attrs) {if(attrs.labelFunction != undefined && typeof(attrs.onStuff) == 'function'){范围.$eval(attrs.labelFunction);}}

I have a directive that displays some data but I want to user of the directive to be able to control how that data is displayed. I would like to allow a user to be able control the display using one of three options.

1. pass in a string to use for the display
2. pass in a function that will be called to generate the string
3. or just show the raw data

I can't post the code for the entire directive (NDA and all) but it is a directive for showing a ring chart using D3. The number in the middle is the piece of data in question. So assuming the ring chart is showing a percentage, I may want the text in the center to say 55%. So assuming myValue is a property on the scope and is set to 55, here is what I would like to do:

<div ring-chart total="100"
             remaining="{{myValue}}"
             center-number-class="center-number-sm"
             remaining-color="#0F79C0"
             used-color="#C1D3E6"
             chart-width="45"
             chart-height="45"
             ring-thickness="3"
             label-text="{{myValue}}%"></div>

which would show 55% or do:

<div ring-chart total="100"
             remaining="{{myValue}}"
             center-number-class="center-number-sm"
             remaining-color="#0F79C0"
             used-color="#C1D3E6"
             chart-width="45"
             chart-height="45"
             ring-thickness="3"
             label-function="ringLabelFunction(remaining)"></div>

which would show whatever ringLabelFunction(value) returns and finally have the option to do:

<div ring-chart total="100"
             remaining="{{myValue}}"
             center-number-class="center-number-sm"
             remaining-color="#0F79C0"
             used-color="#C1D3E6"
             chart-width="45"
             chart-height="45"
             ring-thickness="3"></div>

which would just show 55.

In the directive I have

    ...
scope: {
    total:"@",
    remaining:"@",
    valueSuffix: "@",
    centerNumberClass: "@",
    suffixClass: "@",
    remainingColor: "@",
    totalColor: "@",
    chartWidth: "@",
    chartHeight: "@",
    ringThickness: "@",
    labelFunction: "&",
    labelText:"@"
},
link:function($scope, element, attrs) {
    var labelContent;
    if ($scope.labelText) {
     labelContent =  $scope.labelText;
    } else if ($scope.labelFunction) { //<-- this is always true
     labelContent = $scope.labelFunction({remaining:$scope.remaining});
    } else { //so I never get to this
     labelContent = $scope.remaining;
    }

   ...
}

...

So, in short I am looking for a way to determine if $scope.labelFunction has actually been set.

解决方案

You have link attrs. Just check if label-function is defined and its value refers to function

link:function($scope, element, attrs) {

   if(attrs.labelFunction != undefined && typeof(attrs.onStuff) == 'function'){
        scope.$eval(attrs.labelFunction);
    }
}

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