ResultFieldMatchFinder / Support |+lang= filter in PrintRequests

[mwjames]

This PR is made in reference to: #1344, #594

This PR addresses or contains:

• |+lang= is to support filtering of results that match a specific language and is applied during query post-processing after the condition has retrieved matchable entities. (The PrintRequest and hereby the DV may match text in different languages and unless the query condition was designed in a way that would made them reducible, it would display them all)
• Using the post-filtering mechanism allows that a query condition can be indifferent towards possible language matches, yet enables to only select the one that match the denoted lang value
• |+lang= filtering is only applied to instances of type Monolingual text

This PR includes:

• Tests (unit/integration)
• CI build passed

[mwjames]

@kghbln FYI

{{#ask: [[Has alternative label::+]]
 |?Has alternative label|+lang=en
}}

http://sandbox.semantic-mediawiki.org/wiki/Issue/2037

[kghbln]

|+lang= filtering is only applied to instances of type Monolingual text

Does this also make sense, though in a reduced degree to "Has property description"? like e.g. here on sandbox

Going further I think it will be nice to use this feature it in conjunction with a variable which is providing the language code from the users preference setting. I will have a look if there is an extension for this around.

[kghbln]

I will have a look if there is an extension for this around.

Great, found it: MyVariables

[mwjames]

Does this also make sense, though in a reduced degree to "Has property description"?

Lucky us, Has property description and Has preferred property label are defined as Monolingual text type hence |+lang= can be applied here as well.

[kghbln]

Lucky us, Has property description and Has preferred property label are defined as Monolingual text type hence |+lang= can be applied here as well.

I have the feeling that this does not just work by chance. ;)

Great, found it: MyVariables

Now also available on sandbox.

[kghbln]

@mwjames

Hmm, I did a field test with "Has property description" While it works for "fr" i.e. showing nothing is only works for the first property "Foaf:homepage" and not for "Foaf:knows" or "Foaf:name" when using "en" and "de". The latter two show both languages.

[mwjames]

... not for "Foaf:knows" or "Foaf:name" when using "en" and "de". The latter two show both languages.

This happens when you only test half a meal and declare it as delicious. Should be fixed with #2048 containing a similar test case.

[kghbln]

Should be fixed with #2048 containing a similar test case.

It works! Perfect! 👍

[kghbln]

Now documented.