如何有条件地禁用表单输入字段 [英] How to conditionally disable a form input field

问题描述

假设我有一个具有两个字段的Domain对象Teacher名称，TeacherType teacherType，其中TeacherType是一个包含AssitantProfessor，AssociateProfessor，Professor的枚举。

使用grails run-target generate-all Teacher的视图，它会生成一个_form.gsp，用于创建和编辑Teacher。在编辑视图中，我只希望名称是可编辑的，但TeacherType一旦创建就不可修改（这只是一个示例，它是创建后无法更新某些字段的要求）。在创建视图中，TeacherType和name都应该是可编辑的。

既然create.gsp和edit.gsp呈现_form模板，那么这里的首选方法是什么？

1. 创建两个单独的模板，即_formCreate.gsp，_formEdit.gsp;或


2. 在create.gsp和edit.gsp中传入模型映射，并在_form.gsp中使用它们以有条件地渲染视图？
   例如

在create.gsp中：

 < fieldset class =form> 
 < / fieldset> 
  

在edit.gsp中

 < fieldset class =form> 
 < / fieldset> b 
 
 
 $ b 
在_form.gsp中> < g：if test =$ {mode =='edit'}> 
 < / g：if> 
< g：else> 
 < / g：其他> 
  

方法2可行，但我想如果条件语句的数量增加，那么遵循方法可能会更好1和拆分表单。

是否还有另一种我不知道的方法？

解决方案

< g：select> （以及许多其他< g：...> 表单字段标记）可以是一个布尔值表达式：

 < g：select name =teacherTypefrom =$ {TeacherType？.values（）}
 keys =$ {TeacherType.values（）*。name（）} required =
 value =$ {teacherInstance？.teacherType？.name（）}
 disabled =$ {mode =='edit'}/> 
  

这将呈现为 disabled =disabled如果表达式的计算结果为真，并且缺少禁用的属性（即该字段不会被禁用），如果表达式为false。您甚至可以在模型中使用布尔条目，例如使用

  model =[teacherInstance：teacherInstance，editing：true]渲染模板
  

（或编辑：false 分别），然后说禁用= < g：select> 。


=$ {editing}

Say I have a Domain object Teacher with two fields String name, TeacherType teacherType, where TeacherType is an enum containing AssitantProfessor, AssociateProfessor, Professor.

After I generate the views using grails run-target generate-all Teacher, it produces an _form.gsp that is used for both create and edit of Teacher. In the edit view I want only the name to be editable but the TeacherType to be unmodifiable once created (this is just an example, it is a requirement that certain fields can't be updated after creation). In the create view, both TeacherType and name should be editable.

Since both create.gsp and edit.gsp render the _form template, what is the preferred approach here?

1. Create two separate templates i.e. _formCreate.gsp , _formEdit.gsp; Or
2. Pass in a model map within create.gsp and edit.gsp and use them in _form.gsp to conditionally render the view? e.g.

In create.gsp:

    <fieldset class="form">
        <g:render template="form" model="[teacherInstance: teacherInstance, 'mode':'create']"/>
    </fieldset>

In edit.gsp

    <fieldset class="form">
        <g:render template="form" model="[teacherInstance: teacherInstance, 'mode':'edit']"/>
    </fieldset>

In _form.gsp

    <g:if test="${mode == 'edit'}">
        <g:select name="teacherType" from="${TeacherType?.values()}" keys="${TeacherType.values()*.name()}" required="" value="${teacherInstance?.teacherType?.name()}" disabled="disabled"/>
    </g:if>
    <g:else>
        <g:select name="teacherType" from="${TeacherType?.values()}" keys="${TeacherType.values()*.name()}" required="" value="${teacherInstance?.teacherType?.name()}" disabled="false"/>
    </g:else>

Approach 2 works but I suppose if the number of conditional statements increase it may just be better to follow approach 1 and split the forms.

Is there another approach that I'm not aware of?

解决方案

The disabled attribute of <g:select> (and many other <g:...> form field tags) can be a boolean-valued expression:

<g:select name="teacherType" from="${TeacherType?.values()}"
  keys="${TeacherType.values()*.name()}" required=""
  value="${teacherInstance?.teacherType?.name()}"
  disabled="${mode == 'edit'}"/>

This will render as disabled="disabled" if the expression evaluates to true, and as the absence of a disabled attribute (i.e. the field will not be disabled) if the expression is false. You could even use a boolean entry in the model, e.g. render the template with

model="[teacherInstance: teacherInstance, editing:true]"

(or editing:false respectively) and then say disabled="${editing}" on the <g:select>.

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