一、为什么使用过滤器?
在实际操作中,我们需要对统一数据源进行多次转换,比如我的货币单位,在不同的国家我们将用不同的符号表示。因此,你可能会想到在控制器中判断国家以显示不同的结果,但是过滤器却可以更好的帮助我们做到同样的效果。
过滤器将数据在被指令处理并显示到视图之前进行转换,而不必修改作用域中原有的数据,这样能够允许同一份数据在应用中的不同部分以不同形式得以展示。
接下来,我们详细讨论有关过滤器的用法
二、过滤单个数据的值
下表展示用于单个数据的内置过滤器
先来看看我们的准备案例,待会我们将在这个案例的基础上来使用内容过滤器
<!DOCTYPE> <!-- use module --> <html ng-app="exampleApp"> <head> <title>Angluar test</title> <meta charset="utf-8"/> <link rel="stylesheet" type="text/css" href="css/bootstrap.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > <link rel="stylesheet" type="text/css" href="css/bootstrap-theme.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > </head> <body> <dlv class="panel panel-default" ng-controller="defaultCtrl"> <div class="panel panel-header"> Products <span class="label label-primary">{{products.length}}</span> </div> <div class="panel panel-body"> <table class="table table-striped table-bordered table-hover"> <thead> <tr><th>Name</th><th>Category</th><th>Expiry</th><th>Price</th></tr> </thead> <tbody> <tr ng-repeat="p in products"> <td>{{p.name}}</td> <td>{{p.category}}</td> <td>{{p.expiry}}</td> <td>{{p.price}}</td> </tr> </tbody> </table> </div> </dlv> <script type="text/javascript" src="/UploadFiles/2021-04-02/angular.min.js">就是一个表格的形式来展示产品的详细情况的案例
1.格式化货币值
<tr ng-repeat="p in products"> <td>{{p.name}}</td> <td>{{p.category}}</td> <td>{{p.expiry}}</td> <!-- 使用currency --> <td>{{p.price | currency}}</td> </tr>2.格式化数字值
<tr ng-repeat="p in products"> <td>{{p.name}}</td> <td>{{p.category}}</td> <td>{{p.expiry}}</td> <!-- 保留小数点后3位 --> <td>{{p.price | number : 3}}</td> </tr>3.格式化日期
// 在控制器中添加 $scope.getExpiryDate = function (days) { var now = new Date(); return now.setDate(now.getDate() + days); }<tr ng-repeat="p in products"> <td>{{p.name}}</td> <td>{{p.category}}</td> <!-- 在视图中使用--> <td>{{getExpiryDate(p.expiry) | date : 'yyyy/MM/dd'}}</td> <!-- 货币单位本地化 --> <td>{{p.price}}</td> </tr>4.改变字符串大小写
<tr ng-repeat="p in products"> <!-- 字母大小写 --> <td>{{p.name | uppercase}}</td> <td>{{p.category | lowercase}}</td> <td>{{getExpiryDate(p.expiry) | date : 'yyyy/MM/dd'}}</td> <!-- 货币单位本地化 --> <td>{{p.price}}</td> </tr>5.生成JSON
<tr ng-repeat="p in products"> <!-- 生成JSON数据 --> <td>{{p.name | json}}</td> <td>{{p.category}}</td> <td>{{getExpiryDate(p.expiry) | date : 'yyyy/MM/dd'}}</td> <!-- 货币单位本地化 --> <td>{{p.price}}</td> </tr>6.本地化过滤器输出
需要移入本地化JS文件
<!-- 引入本地化文件 --> <script type="text/javascript" src="/UploadFiles/2021-04-02/angular-locale_zh-cn.js"><tr ng-repeat="p in products"> <td>{{p.name}}</td> <td>{{p.category}}</td> <td>{{p.expiry}}</td> <!-- 货币单位本地化 --> <td>{{p.price | currency}}</td> </tr>三、过滤集合
1.限制项目的数量—limitTo过滤器
<!DOCTYPE> <!-- use module --> <html ng-app="exampleApp"> <head> <title>Angluar test</title> <meta charset="utf-8"/> <link rel="stylesheet" type="text/css" href="css/bootstrap.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > <link rel="stylesheet" type="text/css" href="css/bootstrap-theme.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > </head> <body> <dlv class="panel panel-default" ng-controller="defaultCtrl"> <div class="panel panel-header"> Products <span class="label label-primary">{{products.length}}</span> </div> <div class="panel panel-body"> Limit: <select ng-model="limitVal" ng-options="item for item in limitRange"></select> </div> <div class="panel panel-body"> <table class="table table-striped table-bordered table-hover"> <thead> <tr><th>Name</th><th>Category</th><th>Expiry</th><th>Price</th></tr> </thead> <tbody> <!-- 只显示limitVal行 --> <tr ng-repeat="p in products | limitTo : limitVal"> <td>{{p.name}}</td> <td>{{p.category}}</td> <td>{{p.expiry}}</td> <td>{{p.price | number : 2}}</td> </tr> </tbody> </table> </div> </dlv> <script type="text/javascript" src="/UploadFiles/2021-04-02/angular.min.js">单击下拉列表,根据提示显示不同的条数,负数表示从后往前取
2.选取项—filter过滤器
<!DOCTYPE> <!-- use module --> <html ng-app="exampleApp"> <head> <title>Angluar test</title> <meta charset="utf-8"/> <link rel="stylesheet" type="text/css" href="css/bootstrap.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > <link rel="stylesheet" type="text/css" href="css/bootstrap-theme.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > </head> <body> <dlv class="panel panel-default" ng-controller="defaultCtrl"> <div class="panel panel-header"> Products <span class="label label-primary">{{products.length}}</span> </div> <div class="panel panel-body"> <table class="table table-striped table-bordered table-hover"> <thead> <tr><th>Name</th><th>Category</th><th>Expiry</th><th>Price</th></tr> </thead> <tbody> <!-- 自定义过滤 --> <tr ng-repeat="p in products | filter : selectItems"> <td>{{p.name}}</td> <td>{{p.category}}</td> <td>{{p.expiry}}</td> <td>{{p.price | number : 2}}</td> </tr> </tbody> </table> </div> </dlv> <script type="text/javascript" src="/UploadFiles/2021-04-02/angular.min.js">仅仅保留类别为Fish或者name=='Beer'的行
3.对项目进行排序—orderBy过滤器
<!DOCTYPE> <!-- use module --> <html ng-app="exampleApp"> <head> <title>Angluar test</title> <meta charset="utf-8"/> <link rel="stylesheet" type="text/css" href="css/bootstrap.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > <link rel="stylesheet" type="text/css" href="css/bootstrap-theme.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > </head> <body> <dlv class="panel panel-default" ng-controller="defaultCtrl"> <div class="panel panel-header"> Products <span class="label label-primary">{{products.length}}</span> </div> <div class="panel panel-body"> <table class="table table-striped table-bordered table-hover"> <thead> <tr><th>Name</th><th>Category</th><th>Expiry</th><th>Price</th></tr> </thead> <tbody> <!-- 通过价格按照升序排列 --> <!-- <tr ng-repeat="p in products | orderBy : 'price'"> --> <!-- price前加-表示按照降序排列 --> <!-- <tr ng-repeat="p in products | orderBy : '-price'"> --> <!-- 自定义排序 --> <!-- <tr ng-repeat="p in products | orderBy : customOrder"> --> <!-- 组合排序,保质期<5的降序排列,其他的按照价格升序排序 --> <tr ng-repeat="p in products | orderBy : [customOrder, '-price']"> <td>{{p.name}}</td> <td>{{p.category}}</td> <td>{{p.expiry}}</td> <td>{{p.price | number : 2}}</td> </tr> </tbody> </table> </div> </dlv> <script type="text/javascript" src="/UploadFiles/2021-04-02/angular.min.js">
四、链式过滤器
就是将过滤器串联起来综合使用
<!DOCTYPE> <!-- use module --> <html ng-app="exampleApp"> <head> <title>Angluar test</title> <meta charset="utf-8"/> <link rel="stylesheet" type="text/css" href="css/bootstrap.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > <link rel="stylesheet" type="text/css" href="css/bootstrap-theme.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > </head> <body> <dlv class="panel panel-default" ng-controller="defaultCtrl"> <div class="panel panel-header"> Products <span class="label label-primary">{{products.length}}</span> </div> <div class="panel panel-body"> <table class="table table-striped table-bordered table-hover"> <thead> <tr><th>Name</th><th>Category</th><th>Expiry</th><th>Price</th></tr> </thead> <tbody> <!-- 过滤链条,通过orderBy和limitTo共同作用 --> <tr ng-repeat="p in products | orderBy : [customOrder, '-price'] | limitTo : 5"> <td>{{p.name}}</td> <td>{{p.category}}</td> <td>{{p.expiry}}</td> <td>{{p.price | number : 2}}</td> </tr> </tbody> </table> </div> </dlv> <script type="text/javascript" src="/UploadFiles/2021-04-02/angular.min.js"><tr ng-repeat="p in products | orderBy : [customOrder, '-price'] | limitTo : 5">五、自定义过滤器
1.创建格式化数据值的过滤器
<!DOCTYPE> <!-- use module --> <html ng-app="exampleApp"> <head> <title>Angluar test</title> <meta charset="utf-8"/> <link rel="stylesheet" type="text/css" href="css/bootstrap.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > <link rel="stylesheet" type="text/css" href="css/bootstrap-theme.min.css" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" > </head> <body> <dlv class="panel panel-default" ng-controller="defaultCtrl"> <div class="panel panel-header"> Products <span class="label label-primary">{{products.length}}</span> </div> <div class="panel panel-body"> <table class="table table-striped table-bordered table-hover"> <thead> <tr><th>Name</th><th>Category</th><th>Expiry</th><th>Price</th></tr> </thead> <tbody> <tr ng-repeat="p in products"> <!-- 使用自定义过滤器 --> <td>{{p.name | labelCase}}</td> <td>{{p.category | labelCase : true}}</td> <td>{{p.expiry}}</td> <td>{{p.price | number : 2}}</td> </tr> </tbody> </table> </div> </dlv> <script type="text/javascript" src="/UploadFiles/2021-04-02/angular.min.js">自定义过滤器,labelCase反转字符串
// js/createFilters.js文件 angular.module("exampleApp") .filter("labelCase", function () { return function (value, reverse) { if (angular.isString(value)) { var inter = reverse "" alt="这里写图片描述" src="/UploadFiles/2021-04-02/2017042614100122.png">2.创建集合过滤器
在createFilter中定义一个skip过滤函数
angular.module("exampleApp") .filter("labelCase", function () { return function (value, reverse) { if (angular.isString(value)) { var inter = reverse "skip", function () { return function (value, count) { if (angular.isArray(value) && angular.isNumber(count)){ if (count > value.length || count < 0) { return value; } else { // 跳过数组前两项 return value.slice(count); } } else { return value; } } })在视图中使用
<tr ng-repeat="p in products | skip : 2"> <!-- 使用自定义过滤器 --> <td>{{p.name | labelCase}}</td> <td>{{p.category | labelCase : true}}</td> <td>{{p.expiry}}</td> <td>{{p.price | number : 2}}</td> </tr>移除前两项Apples和Bananas,然后显示
3.在已有的过滤器上搭建新的过滤器
在createFilter中添加take过滤器返回,将skip和limitTo两个过滤器方法综合起来
angular.module("exampleApp") .filter("labelCase", function () { return function (value, reverse) { if (angular.isString(value)) { var inter = reverse "skip", function () { return function (value, count) { if (angular.isArray(value) && angular.isNumber(count)){ if (count > value.length || count < 0) { return value; } else { // 跳过数组前两项 return value.slice(count); } } else { return value; } } }) // 在已有过滤器的基础上建立新的过滤器 // 将上述的skip和limit两个过滤器合并 .filter("take", function ($filter) { return function (data, skipCount, limitCount) { // 先跳过数组的前skipCount项 var skipData = $filter("skip")(data, skipCount); // 接着只取limitCount行 return $filter("limitTo")(skipData, limitCount); } })在视图中使用:
<tr ng-repeat="p in products | take : 2 : 5"> <!-- 使用自定义过滤器 --> <td>{{p.name | labelCase}}</td> <td>{{p.category | labelCase : true}}</td> <td>{{p.expiry}}</td> <td>{{p.price | number : 2}}</td> </tr>先移除两项,然后值取5条数据
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