带有默认选项的AngularJS指令 [英] AngularJS directive with default options

问题描述

我只是从angularjs开始，并且正在努力将一些旧的JQuery插件转换为Angular指令.我想为我的(元素)指令定义一组默认选项，可以通过在属性中指定选项值来覆盖这些默认选项.

I'm just starting with angularjs, and am working on converting a few old JQuery plugins to Angular directives. I'd like to define a set of default options for my (element) directive, which can be overridden by specifying the option value in an attribute.

我已经了解了其他人的操作方式，在 angular-ui 库中， ui.bootstrap.pagination 似乎在做类似的事情.

I've had a look around for the way others have done this, and in the angular-ui library the ui.bootstrap.pagination seems to do something similar.

首先，所有默认选项都在一个常量对象中定义:

First all default options are defined in a constant object:

.constant('paginationConfig', {
  itemsPerPage: 10,
  boundaryLinks: false,
  ...
})

然后将getAttributeValue实用程序功能附加到指令控制器:

Then a getAttributeValue utility function is attached to the directive controller:

this.getAttributeValue = function(attribute, defaultValue, interpolate) {
    return (angular.isDefined(attribute) ?
            (interpolate ? $interpolate(attribute)($scope.$parent) :
                           $scope.$parent.$eval(attribute)) : defaultValue);
};

最后，它在链接功能中用于读取属性为

Finally, this is used in the linking function to read in attributes as

.directive('pagination', ['$parse', 'paginationConfig', function($parse, config) {
    ...
    controller: 'PaginationController',
    link: function(scope, element, attrs, paginationCtrl) {
        var boundaryLinks = paginationCtrl.getAttributeValue(attrs.boundaryLinks,  config.boundaryLinks);
        var firstText = paginationCtrl.getAttributeValue(attrs.firstText, config.firstText, true);
        ...
    }
});

对于标准东西来说，这似乎是一个相当复杂的设置，因为它想要替换一组默认值.还有其他通用的方法吗?还是总是以这种方式定义诸如getAttributeValue之类的实用程序函数并解析选项是正常的吗?我有兴趣找出人们对于这项共同任务有哪些不同的策略.

This seems like a rather complicated setup for something as standard as wanting to replace a set of default values. Are there any other ways to do this that are common? Or is it normal to always define a utility function such as getAttributeValue and parse options in this way? I'm interested to find out what different strategies people have for this common task.

此外，作为奖励，我不清楚为什么需要interpolate参数.

Also, as a bonus, I'm not clear why the interpolate parameter is required.

推荐答案

您可以使用compile函数-如果未设置属性，则读取属性-将其填充为默认值.

You can use compile function - read attributes if they are not set - fill them with default values.

.directive('pagination', ['$parse', 'paginationConfig', function($parse, config) {
    ...
    controller: 'PaginationController',
    compile: function(element, attrs){
       if (!attrs.attrOne) { attrs.attrOne = 'default value'; }
       if (!attrs.attrTwo) { attrs.attrTwo = 42; }
    },
        ...
  }
});

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