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From "Jukka Zitting (JIRA)" <j...@apache.org>
Subject [jira] Updated: (JCR-325) docview roundtripping does not work with multivalue non-string properties
Date Sun, 19 Mar 2006 12:44:59 GMT
     [ http://issues.apache.org/jira/browse/JCR-325?page=all ]

Jukka Zitting updated JCR-325:
------------------------------

    Attachment: xml-refactoring.patch

I've gone through the importer code and come up with a plan on how to implement the interpretation
described above. The current importer design makes it quite hard to postpone the value parsing
decisions until the applicable property definitions are known, which effectively prevents
form implementing the proposed heuristics. To make this easier and to simplify overall code
I'd like to encapsulate the value parsing rules to the PropInfo instances so that the SessionImporter
or WorkspaceImporter classes wouldn't need to know anything about where the values came from
(sys view or doc view) and how they should be parsed. I could then create separate SysViewPropInfo
and DocViewPropInfo subclasses to encapsulate the different value parsing rules of the system
view and document view XML encodings. Doing this however requires quite extensive refactoring
of the current code, so I'd like to get a confirmation on this plan before I proceed.

The attached patch represents the first steps of this refactoring. Unless I've made a mistake,
the patch doesn't yet change any of the existing behaviour (except for the location where
some exceptions and log messages are generated), it just refactors the code structure so that
it is easier to implement the SysViewPropInfo and DocViewPropInfo classes. The reason for
publishing the patch at this point is to separate the structural changes from the behavioural
changes and thus make the changes easier to review. I will continue with the behavioural changes
if this structural change is approved.

Below is a breakdown of the refactoring steps included in this patch. I did almost all of
these changes using the automatic refactoring tools in Eclipse to minimize the chance of accidentally
introducing errors in the code. The patched source also passes all unit tests and seems to
import both system view and document view files just as before, which makes me quite confident
in the quality of the refactoring.

1) Move the following internal classes and interfaces to new files to make the class structure
easier to manage:

   * Importer.TextValue -> TextValue
   * Importer.PropInfo -> PropInfo
   * Importer.NodeInfo -> NodeInfo
   * TargetImportHandler.AppendableValue -> AppendableValue
   * TargetImportHandler.BufferedStringValue -> BufferedStringValue
   * TargetImportHandler.StringValue -> StringValue

2) Remove the NodeInfo and PropInfo setters and make the member fields "private final" to
enforce their immutability

3) Refactor the TargetImportHandler.disposePropertyValues(PropInfo) method into PropInfo.dispose()
to improve encapsulation

4) Move the AppendableValue.dispose() method up to TextValue and implement it as a null method
in StringValue to avoid type casts in PropInfo.dispose()

5) Remove the AppendableValue interface to make the class structure more simple as the SysViewImportHandler
can just as well use the BufferedStringValue class directly

6) Add a TextValue.getNamespaceContext() method and corresponding "private final NamespaceResolver
nsContext;" fields in StringValue and BufferedStringValue to associate the value instances
with the namespace context in which they should be parsed. Remove the "nsContext" argument
from Importer.startNode() and use the TextValue.getNamespaceContext() method in SessionImporter
and WorkspaceImporter to access the correct namespace context.

7) Refactor the contents of the property iterator loop in WorkspaceImporter.startNode() into
PropInfo.apply(NodeState, BatchedItemOperations, NodeTypeRegistry, ReferenceChangeTracker)
and the contents of the similar loop in SessionImporter.startNode() into PropInfo.apply(NodeImpl,
NamespaceResolver, ReferenceChangeTracker) to simplify the huge startNode() methods and to
encapsulate the value parsing logic into PropInfo. This also allows the methods to easily
share code through extracted getTargetType() and getApplicablePropertyDef() methods and enables
other structural simplifications.

8) Remove the now unneeded PropInfo getters.

9) Refactor the contents of the value iterator loops in the PropInfo.apply() methods to TextValue.getValue(int
type, NamespaceResolver resolver) and TextValue.getInternalValue(int type) methods and copy
the implementation to StringValue and BufferedStringValue to increase encapsulation. In both
cases the implementation can be simplified thanks to local access to the value details.

10) Remove the length(), retrieve(), reader(), and getNamespaceContext() methods from the
TextValue interface to ensure proper encapsulation. Those methods can also be fully removed
from StringValue, but in BufferedStringValue they still have a purpose due to the more complex
storage model. Refactor the JCR_MIXINTYPES branch in DocViewImportContentHandler to use TextValue.getValue()
instead of StringValue.retrieve() to get the mixin type names.

Overall these structural changes improve a number of quality metrics. The encapsulation level
is higher, the method and class bodies are shorter, and even the total amount of code is slightly
lower.

> docview roundtripping does not work with multivalue non-string properties
> -------------------------------------------------------------------------
>
>          Key: JCR-325
>          URL: http://issues.apache.org/jira/browse/JCR-325
>      Project: Jackrabbit
>         Type: Improvement
>   Components: xml
>     Versions: 0.9
>  Environment: jackrabbit r379292
>     Reporter: Tobias Bocanegra
>     Assignee: Jukka Zitting
>  Attachments: xml-refactoring.patch
>
> when exporting a multivalue property with docview, the property values are serialized
to a space delimited list in the xml attributes:
> for example:
> <?xml version="1.0" encoding="UTF-8"?>
> .
> .
> <testNode 
>     jcr:primaryType="refTest" 
>     refs="b5c12524-5446-4c1a-b024-77f623680271 7b4d4e6f-9515-47d8-a77c-b4beeaf469bc"
> />
> the refTest nodetype was:
> [refTest] 
> - refs (reference) multiple 
> importing this docview fails with: javax.jcr.ValueFormatException: not a valid UUID format
> this is due to the fact, that the space delimited list is not exploded anymore. actually
this code is commented:
> org.apache.jackrabbit.core.xml.DocViewImportHandler, lines 191 - 200:
> /*
>                 // @todo should attribute value be interpreted as LIST type (i.e. multi-valued
property)?
>                 String[] strings = Text.explode(attrValue, ' ', true);
>                 propValues = new Value[strings.length];
>                 for (int j = 0; j < strings.length; j++) {
>                     // decode encoded blanks in value
>                     strings[j] = Text.replace(strings[j], "_x0020_", " ");
>                     propValues[j] = InternalValue.create(strings[j]);
>                 }
> */
> i haven't tested, but i assume this also fails for all other non-string property types.

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