Unable to set empty XML field i.e. <somefield/> without a value or without xsi:null=true

[jamienich]

Description/Steps to reproduce

The xmlHandler equality operator "==" evaluates undefined and null values as true as follows:

xmlHandler.js, Lines 165-173

      if (val == null) {
        if (descriptor.isNillable) {
          // Set xsi:nil = true
          declareNamespace(nsContext, element, 'xsi', helper.namespaces.xsi);
          if (typeof element.attribute === 'function') {
            element.attribute('xsi:nil', true);
          }
        }
      }

It would be preferable to set the xsi:nil = true only for null values and not undefined values. If we exclude undefined values from the block above undefined values are shown in the XML as follows:

<some_attribute/>

Suggest using the type safe equality operator so it only evaluates null as true:

      if (val === null) { 
        if (descriptor.isNillable) { 
          // Set xsi:nil = true
          declareNamespace(nsContext, element, 'xsi', helper.namespaces.xsi);
          if (typeof element.attribute === 'function') {
            element.attribute('xsi:nil', true);
          }
        }
      }

The new code still allows strong-soap to set a xsi:nil=true when null value is passed, for undefined values however it will not do this. Seems like a fairly major impact if users are used to xsi:null=true being set if they pass through undefined currently, thoughts on this?

Link to reproduction sandbox

Expected result

Additional information

[achrinza]

undefined and null semantics strike again! :-)

I think your proposal makes sense, I'd be happy to review and merge your PR for this.

Seems like a fairly major impact if users are used to xsi:null=true being set if they pass through undefined currently, thoughts on this?

Could we add an entry to options, maybe name it attributesIgnoreUndefined (though open to suggestions).

[jamienich]

thanks @achrinza I've done a PR feat: wsdl option ignoreAttributesUndefined#904 first time, hopefully that looks okay. Modified the option slightly to ignoreAttributesUndefined to align with another option named ignore first.