Passing string constants to functions

[Grant Ingersoll]

Any idea on how to pass string constants to a function?

When I do I get:
java.lang.RuntimeException: Exception during query
        at 
org.apache.solr.util.AbstractSolrTestCase.assertQ(AbstractSolrTestCase.java:218)
        at 
org.apache.solr.util.AbstractSolrTestCase.assertQ(AbstractSolrTestCase.java:201)
        at 
org.apache.solr.search.function.distance.DistanceFunctionTest.testHaversine(DistanceFunctionTest.java:55)
Caused by: org.apache.solr.common.SolrException: undefined field tv8nj9qj92me
        at org.apache.solr.schema.IndexSchema.getField(IndexSchema.java:1077)
        at 
org.apache.solr.search.FunctionQParser.parseValueSource(FunctionQParser.java:249)
        at 
org.apache.solr.search.FunctionQParser.parseValueSource(FunctionQParser.java:173)
        at 
org.apache.solr.search.ValueSourceParser$20.parse(ValueSourceParser.java:341)
        at 
org.apache.solr.search.FunctionQParser.parseValueSource(FunctionQParser.java:245)
        at 
org.apache.solr.search.FunctionQParser.parseValueSource(FunctionQParser.java:173)
        at org.apache.solr.search.FunctionQParser.parse(FunctionQParser.java:40)
        at org.apache.solr.search.QParser.getQuery(QParser.java:131)
        at 
org.apache.solr.handler.component.QueryComponent.prepare(QueryComponent.java:89)
        at 
org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:174)
        at 
org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:131)

FWIW, tv8nj9qj92me is a geohash.

The code in question is:
protected ValueSource parseValueSource(boolean doConsumeDelimiter) throws 
ParseException {
    ValueSource valueSource;
    
    int ch = sp.peek();
    if (ch>='0' && ch<='9'  || ch=='.' || ch=='+' || ch=='-') {
      valueSource = new ConstValueSource(sp.getFloat());
    }
    else {
      String id = sp.getId();
      if (sp.opt("(")) {
        // a function... look it up.
        ValueSourceParser argParser = req.getCore().getValueSourceParser(id);
        if (argParser==null) {
          throw new ParseException("Unknown function " + id + " in 
FunctionQuery(" + sp + ")");
        }
        valueSource = argParser.parse(this);
        sp.expect(")");
      }
      else {
        SchemaField f = req.getSchema().getField(id);     //  
<<<<<<<<<<<<<<<<<<<   Exception here.
        valueSource = f.getType().getValueSource(f, this);
      }
    }
    
    if (doConsumeDelimiter)
      consumeArgumentDelimiter();
    
    return valueSource;
  }


Seems like we could change this to allow the id to be a constant and pass it 
along if it isn't a field and wrap it in a literal (new function) or constant.  
Thoughts?

-Grant