Re: [Simple-support] Element/Attribute Default Values
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Re: [Simple-support] Element/Attribute Default Values
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From: Keith B. <ka...@gm...> - 2007-06-14 16:16:09
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Thanks, this is great. I look forward to the support the @Element
annotations.
On 6/13/07, Niall Gallagher <gal...@ya...> wrote:
>
> Hi,
>
> Simple 1.3.1 has been release with support for null @Attribute and @Text
> values. This means that within the XML document the Java null value can be
> represented in a textual manner within the XML document. For example take
> the following:
>
> @Root
> public class Example {
>
> @Attribute(empty="NULL")
> private String name;
>
> @Text(empty="NO TEXT HERE")
> private String value;
>
> public Example() {
> super();
> }
>
> public Example(String name, String value) {
> this.name = name;
> this.value = value;
> }
> }
>
> So if Persister.write was used on various instances of the Example class
> the output would look like follows:
>
> 1) new Example(null, null)
>
> <example name="NULL>NO TEXT HERE</example>
>
> 2) new Example("Some Name", null)
>
> <example name="Some Name">NO TEXT HERE</example>
>
> 3) new Example("Some Name", "Some Description")
>
> <example name="Some Name">Some Description</example>
>
> Deserialization will ensure that fields with the null text value will be
> assigned null. I have not yet had time to add support for null @Element,
> @ElementArray, or @ElementList.
>
> Niall
>
> ----- Original Message ----
> From: Niall Gallagher <gal...@ya...>
> To: Niall Gallagher <gal...@ya...>; Keith Byrne <
> ka...@gm...>; sim...@li...
> Sent: Tuesday, June 12, 2007 10:36:56 AM
> Subject: Re: [Simple-support] Element/Attribute Default Values
>
> Hi,
>
> In future I hope to add an "empty" attribute to all of the annotations
> such that empty values can be inserted without having to bend over backwards
> to cope with null values. Ill be implementing something like
>
> @Root
> public class MyClass {
>
> @Attribute(empty="NULL")
> private String example;
> }
>
> Such that if the field "example" had a null value it would be written as
> follows:
>
> <myClass example="NULL"/>
>
> The deserialization process will know to substitute the specified value
> with null when reconstituting the object. For the @Element, @ElementList,
> and @ElementArray annotations the field will be a boolean like so:
>
> @Root
> public class MyOtherClass {
>
> @ElementList(empty=true)
> private Collection<String> list;
> }
>
> The above annotation tells the persister to serialize the empty value such
> that the result of having a null list would be:
>
> <myOtherClass>
> <list/>
> </myOtherClass>
>
> Where as if the annotation was set not to write an empty value the
> resulting XML would be:
>
> <myOtherClass/>
>
> This requires only very minor changes, so will probably make it in soon
> enough.
>
> Niall
>
> ----- Original Message ----
> From: Niall Gallagher <gal...@ya...>
> To: Keith Byrne <ka...@gm...>; sim...@li...
> Sent: Monday, June 11, 2007 10:38:52 PM
> Subject: Re: [Simple-support] Element/Attribute Default Values
>
> Hi,
>
> Yes there is a way to intercept, for example:
>
> public class MyExample {
>
> private static final DEFAULT_VALUE = "[[NULL]]";
> @Element
> private String webAddress
>
> @Commit
> private void resolveMyDefault() {
> if(webAddress.equals(DEFAULT_VALUE)) {
> webAddress = null;
> }
> }
>
> @Persist
> private void fixMyObject() {
> if(webAddress == null){
> webAddress = DEFAULT_VALUE:
> }
> }
>
> @Complete
> private void backToNormal() {
> resolveMyDefault();
> }
> }
>
> This should do the trick, as @Persist gets called just before the object
> is persisted, and @Complete gets called when its been serialized to the XML
> document. The @Commit gets called after deserialization so the object values
> will be reverted to a proper working runtime value.
>
> Hope this helps.
> Niall
>
> ----- Original Message ----
> From: Keith Byrne <ka...@gm...>
> To: sim...@li...
> Sent: Monday, June 11, 2007 10:33:16 AM
> Subject: [Simple-support] Element/Attribute Default Values
>
>
> I have a situation where a field isn't required, but when it's null and is
> serialized, the tag still needs to show up empty. Specifically, there is a
> String field (webAddress) that has an Attribute annotation, that went it's
> null should be serialized to <webAddress/>, instead of not showing up. Is
> there a way to intercept the serializing of an Element/Attribute, and based
> upon it's type, serialize a default value?
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