Freemarker dataGetter directive

[litvinovg]

Mentioned in VIVO GitHub issue

What does this pull request do?

Adds new Freemarker directive to execute DataGetters with provided parameters and save results as Freemarker variables.

What's new?

• Added new directive to FreemarkerConfiguration
• Fixed substitutions in SparqlQueryDataGetter
• New data properties to specify types of substituted variables
• Added more tests for SparqlQueryDataGetter
• Removed unreachable case in DataGetterBase
• Removed SparqlQueryDataGetterTest.java from checkstyle suppressions

How should this be tested?

SparqlQueryDataGetter improvements covered by tests.
New directive could be tested by calling test data getter in Freemarker template:

<@dataGetter uri = "test:dataGetter" var = "labels" parameters = {"object": "http://purl.org/ontology/bibo/AcademicArticle"} />
<#if labels?has_content><p>Label returned by data getter: ${labels[0].label}</p></#if>

Data getter configuration:

<test:dataGetter>
    a <java:edu.cornell.mannlib.vitro.webapp.utils.dataGetter.SparqlQueryDataGetter> ;
    display:saveToVar "result" ;
    display:uri "object";
    display:query """
    PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
    SELECT ?label
        WHERE {
          ?object rdfs:label ?label .
        } LIMIT 1
     """ .

Interested parties

@VIVO-project/vivo-committers

[chenejac]

@litvinovg great work!!! I really like the implementation. I have added a couple of tiny comments/suggestions. I think it is important in the documentation to explain overriding saveToVar property with var attribute in datagetter directive. I needed some time to understand that in the code.

[chenejac]

@litvinovg I have posted one comment in the review to align a comment with the code.

Regarding testing, I had the issue to test it. It was my fault, but we should consider to clarify that in the documentation. Namely, I defined a datagetter in an n3 file by using a prefix (display), and I also used the prefix in ftl file. So, we should clarify in the documentation that full uri has to be used in the ftl file.

[chenejac]

@litvinovg thanks.

Code reviewed and the usage of new directive tested.