下拉列表在我的更新语法angularjs中传递空值 [英] dropdown is passing blank value in my update syntax angularjs

问题描述

我正在创建一个Web应用程序，其中我在 c＃和 angularjs

I am creating a web app in which i am using c# with angularjs

当前，我正在更新记录，其中有一个名为 zone 的下拉列表，看起来像这样

currently i am updating my records in which i have one dropdownlist called zone which looks like this

<select ng-model="uzone" ng-change="locationupd(c)">
  <option ng-repeat="l in gzone" value="{{l.jzone}}">{{l.jzone}}</option>
</select>

但下拉列表中的第一个字段显示为空白，而不是第一个值区域

but the first field in the dropdown is showing blank instead of the first value of zone

有人可以帮我吗？

推荐答案

昨天我在工作中遇到了类似情况。

我的下拉列表必须列出所有国家/地区的名称。

现在，我可以为下拉列表设置默认值。

请

I dealt with a similar situation yesterday at work.
My drop down list had to list the names of all countries.
I am now able to set a default value for the drop down list.
Please change the code according to your needs.

我要做的是：将CH / Switzerland设置为vm.selectedCountry的默认值。

What I had to do: Set CH/Switzerland as default value for vm.selectedCountry.

代码笔代码（使用选择）：

示例：

CodePen code (using select):
Sample:

<select class="selector" ng-model="vm.selectedCountry" ng-options="country.name for country in vm.countries" ng-init="vm.selectedCountry = {'name': 'Switzerland', 'code': 'CH', 'init': true}">

<!--shows only when ng-init is run-->
    <option value="" ng-show="vm.selectedCountry.init">Switzerland</option>

</select>

下拉列表（AngularJS）：使用select，ng-init和ng-show

CodePen代码添加默认值（使用md- select和Angular Material）：

样本：

CodePen code (using md-select and Angular Material):
Sample:

<md-select ng-model="vm.selectedCountry" ng-init="vm.selectedCountry = vm.selectedCountry?selectedCountry : 'CH';">

                    <md-option ng-value="'CH'" ng-selected="vm.selectedCountry == 'CH'?true:false">Switzerland</md-option>

                    <md-option ng-repeat="country in vm.countries" ng-value="country.code">
                        {{country.name}}
                    </md-option>
</md-select>

下拉列表（AngularJS）：使用md-select，ng-init和ng-selected添加默认值

，默认值是从数组中拼接出来的，然后放在md-select中（否则会发生重复）。

In the above one, the default value is spliced from the array and put first in md-select (else, duplication occurs).

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