[hibernate-issues] [Hibernate-JIRA] Created: (HSEARCH-618) BridgeFactory should pass along the field type to the field bridge constructor (if an appropriate constructor exists)

[I D (JIRA)]

BridgeFactory should pass along the field type to the field bridge constructor (if an appropriate constructor exists)
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                 Key: HSEARCH-618
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HSEARCH-618
             Project: Hibernate Search
          Issue Type: Improvement
    Affects Versions: 3.3.0.Beta2
         Environment: Hibernate Core 3.6.0
            Reporter: I D
            Priority: Minor


Currently, only the built in EnumBridge is getting access to the field type via its constructor.

That's a shame, since the field type is very useful information, and may be necessary for certainy types of bridges, plus it's readily available to the BridgeFactory.

Here's one use case:

Suppose I want to create a bridge named EnumOrdinalBridge, similar to EnumBridge but saving the constants' ordinals to the index (instead of their names/values). This bridge would need to know the Enum type, so the only way this could be done presently is to make it a ParameterizedBridge and then to pass the enum's class name via the "params" param of the @FieldBridge annotation.

Here is how an invokation of such a bridge would look:

{code}
public enum Gender {MALE,FEMALE}
{code}
{code}
@Field(index = Index.UN_TOKENIZED)
@FieldBridge(impl = EnumOrdinalBridge.class, params = {@Parameter(name="class", value="package.name.Gender")})
public Gender getGender() {
	return gender;
}
{code}

Note the problematic use of qualified class name as a string literal - this is neither portable nor refactoring-proof. What if I wanted to change the name of the enum or move it to another package (or what if I simply misspell the qualified class name)? These will all lead to runtime (rather than compile-time) errors. Also, repetition's bad (m'kay?), so there's no reason to have to explicitly pass along information to the bridge when that information is already implicitly available to the BridgeFactory.

I suggest you use reflection in BridgeFactory to detect whether the constructed FieldBridge has a constructor with one argument of type Class. If so - that constructor will be used (instead of the no-args constructor, currently used for all non-built-in field bridges), and the type of the field will be passed as its argument.

With this behavior implemented, the above example can be nicely reduced to the following, and we'll have achieved code portability and enhanced compile-time safety:

{code}
public enum Gender {MALE,FEMALE}
{code}
{code}
@Field(index = Index.UN_TOKENIZED)
@FieldBridge(impl = EnumOrdinalBridge.class)
public Gender getGender() {
	return gender;
}
{code}

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