使用groovy DOMBuilder省略空属性 [英] Omit empty attributes with groovy DOMBuilder

问题描述

Groovy的 MarkupBuilder 有一个 omitNullAttributes 和 omitEmptyAttributes 。但 DOMBuilder 没有。这是我的代码

 >>> def xml = DOMBuilder.newInstance（）
>>> def maybeEmpty = null 
>>> println xml.foo（bar：maybeEmpty）
< foo bar =/> 
  

如果空，我想要 bar 。我在 Groovy AntBuilder的答案中找到了解决方法，省略了条件属性.. 。到 findAll 空属性并删除它们。因为我有一个复杂的DOM生成，我正在寻找其他选项。

解决方案

我相信没有内置的，在该选项中，但如果您需要一个DOMBuilder，您可以将其子类化并过滤属性...

  @groovy。 transform.InheritConstructors 
 class DOMBuilderSubclass extends groovy.xml.DOMBuilder {
 @Override 
 protected Object createNode（Object name，Map attributes）{
 super.createNode name，attributes.findAll { it.value！= null} 
} 
} 
  

您可能想按照标准DOMBuilder调整构造，这只是一个例子。

  def factory = groovy.xml.FactorySupport.createDocumentBuilderFactory（） .newDocumentBuilder（）
 def builder = new DOMBuilderSubclass（factory）
 println builder.foo（bar：null，baz：1）
 //<？xml version =1.0encoding = UTF-8 >？; 
 //< foo baz =1/> 
  

标准输出，如你所说...

pre> println groovy.xml.DOMBuilder.newInstance（）。foo（bar：null，baz：1）
//<？xml version =1.0encoding = UTF-8 >？;
//< foo bar =baz =1/>


Groovy's MarkupBuilder has an omitNullAttributes and an omitEmptyAttributes. But DOMBuilder doesn't. This is the code I have

>>> def xml = DOMBuilder.newInstance()
>>> def maybeEmpty = null
>>> println xml.foo(bar: maybeEmpty)
<foo bar=""/>

I want bar to be omitted if empty. I found a workaround in an answer to Groovy AntBuilder, omit conditional attributes... to findAll empty attributes and remove them. Since I have a complex DOM to be generated, I'm looking for other options.

解决方案

I believe there is no built-in option for that, but if you need a DOMBuilder, you could subclass it and filter the attributes...

@groovy.transform.InheritConstructors
class DOMBuilderSubclass extends groovy.xml.DOMBuilder {
    @Override
    protected Object createNode(Object name, Map attributes) {
        super.createNode name, attributes.findAll{it.value != null}
     }
}

You might want to tune the construction as in standard DOMBuilder, this is just an example.

def factory = groovy.xml.FactorySupport.createDocumentBuilderFactory().newDocumentBuilder()
def builder = new DOMBuilderSubclass(factory)
println builder.foo(bar: null, baz: 1)
//<?xml version="1.0" encoding="UTF-8"?>
//<foo baz="1"/>    

standard output as you said was...

println groovy.xml.DOMBuilder.newInstance().foo(bar: null, baz: 1)
//<?xml version="1.0" encoding="UTF-8"?>
//<foo bar="" baz="1"/>

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