On Sun, Jan 3, 2010 at 13:22, Vincent Massol <[email protected]> wrote:
> Note that using relative references means that all code that accepts
> an EntityReference must check that it's valid and throw some exception
> if not, whereas before there was no need for any check and no
> exception throwing....
>
> In most cases it's not possible for the code to run the normalizer
> since it wouldn't know which normalizer to use (the default one, the
> current one, etc?). It's the calling code that would know which
> normalizer to use...
We could decide of an arbitrary normalizer like saying when we don't
know we use "current" normalizer same way it's done for a File for
example. We could have a EntityReference#getAbsoluteReference() that
make sure to get a valid full reference (and return this if it's
already a full reference). IMO the code should not throw an exception
but instead document what normalizer it's using when the reference is
not absolute exactly like file system APIs in general.
>
> My status:
> * I have implemented the normalizer code (both Default normalizer and
> current normalizer)
> * I'm now going to start re-implementing the entity reference
> factories and serializers
> * I'm looking at existing code to see how the code would need to be
> adapted and I'm finding that in several cases it's going to be hard.
> Just to illustrate this take this code:
>
> public String getAttachmentURL(AttachmentReference
> attachmentReference, boolean isFullURL)
> {
> String url;
> if (isFullURL) {
> XWikiContext xcontext = getContext();
> url =
> xcontext
> .getURLFactory().createAttachmentURL(attachmentReference.getName(),
>
> attachmentReference
> .getDocumentReference().getLastSpaceReference().getName(),
> attachmentReference.getDocumentReference().getName(),
> "download", null,
> attachmentReference.getDocumentReference().getWikiReference().getName(),
> xcontext).toString();
> } else {
> url =
> getAttachmentURL
> (this
> .entityReferenceSerializer
> .serialize(attachmentReference.getDocumentReference()),
> attachmentReference.getName());
> }
> return url;
> }
>
> There's now no guarantee that the passed reference has a non null
> attachment name, space name or wiki name. The code would need to
> verify this (or createAttachmentURL() would need to check it but
> that's the same). What should it do if it finds a null name? It cannot
> guess if it should use the current normalizer or the default normalizer.
>
> The only solution I can see would be to check if the passed reference
> is absolute (using AttachmentReference.isAbsolute() for ex) and throw
> an InvalidEntityReference exception if it's not absolute.
>
> But that's going to be a pain probably...
>
> I'm still hesitating...
>
> WDYT?
>
> Thanks
> -Vincent
>
> On Dec 31, 2009, at 12:39 PM, Vincent Massol wrote:
>
>> Hi devs,
>>
>> I'm almost done with my entity reference refactoring and I've just
>> realized I have missed something I think. So far the implementation
>> only supports Absolute references (i.e the entity reference factory
>> always return a reference with all parts filled - you choose to use
>> a default factory or a current entity depending on how you wish to
>> resolve the names when they have not been provided in the passed
>> reference string).
>>
>> I now think we must also support relative references (i.e. when some
>> parts can be null) and that it's up to the user of the api to decide
>> if they want to convert a relative reference to an absolute one or
>> not.
>>
>> Here's a use case: renaming of documents. For exemple documents have
>> links specified as a string representing the target doc name. If we
>> don't have relative references then we need to decide if we want to
>> use the default serializer (all parts printed including wiki name)
>> or the compact serializer (only parts different from context
>> reference printed). This doesn't support printing only what the user
>> had decided to fill. For ex a user might have specified voluntarily
>> the space and page name and right now with my implementation he'll
>> get only the page name specified if the new space is the same as the
>> space for the current doc.
>>
>> So here's my proposal:
>>
>> * Entity Reference Factory leaves parts to null when not specified
>> in the string representation.
>> * We add a EntityReference.getAbsoluteReference(EntityReference
>> base) method to return an absolute reference. It's resolved against
>> the passed base reference (i.e. parts not specified are taken from it)
>>
>> WDYT?
>>
>> I'm going to start refactoring my code to do this later today so
>> please let me know if you see any pb with it.
>>
>> Thanks
>> -Vincent
>>
>>
>
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--
Thomas Mortagne
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