如果绑定为空/未定义(带过滤器)，Angularjs 模板默认值 [英] Angularjs Template Default Value if Binding Null / Undefined (With Filter)

问题描述

我有一个模板绑定，它使用 Angular 的日期过滤器显示一个名为date"的模型属性，它是一个日期.

I have a template binding that displays a model attribute called 'date' which is a date, using Angular's date filter.

<span class="gallery-date">{{gallery.date | date:'mediumDate'}}</span>

到目前为止一切顺利.但是目前，如果日期字段中没有值，则绑定将不显示任何内容.但是，如果没有日期，我希望它显示字符串各种".

So far so good. However at the moment, if there is no value in the date field, the binding displays nothing. However, I would like it to display the string 'Various' if there is no date.

我可以使用二元运算符获得基本逻辑:

I can get the basic logic using a binary operator:

<span class="gallery-date">{{gallery.date || 'Various'}}</span>

但是我不能让它与日期过滤器一起工作:

However I can't get it to work with the date filter:

<span class="gallery-date">{{gallery.date | date:'mediumDate' || "Various"}}</span>

如何在日期过滤器旁边使用二元运算符?

推荐答案

原来我需要做的就是将表达式的左侧用软括号括起来:

Turns out all I needed to do was wrap the left-hand side of the expression in soft brackets:

<span class="gallery-date">{{(gallery.date | date:'mediumDate') || "Various"}}</span>

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