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So I have a Windows Forms project up and running. It uses the Lucene.Net library and I made a Lucene index with it. The program takes user requests, runs them through some algorithms and displays the resultsets in a DataGridView.

Afterwards I installed XAMPP, using the Tomcat service for setting up Solr 3.6.1. I configured the schema.xml as following (thanks to Can a raw Lucene index be loaded by Solr?):

<fieldType name="tdouble" class="solr.TrieDoubleField" precisionStep="0" omitNorms="true" positionIncrementGap="0"/>
[...]
<field name="LuminaireId" type="string" indexed="true" stored="true"/>
<field name="LampCount" type="tdouble" multiValued="true" indexed="true" stored="true" required="false"/>
[...]

I searched for some examples for how to setup all the stuff and came up with a Product-Class for mapping the values (there are some more values, but for getting the picture this will be sufficient, I think) like this:

public class SolrProduct
{
      [SolrUniqueKey("LuminaireId")]
      public string LuminaireId { get; set; }

      [SolrField("LampCount")]
      public ICollection<double> LampCount { get; set; }
}

A simple test-query (using this method)

internal override List<KeyValuePair<Int64, Double>> CalculateRanking(List<T> checkedAttributes)
{
    Startup.Init<SolrProduct>("http://localhost:8983/solr/");
    var solr = ServiceLocator.Current.GetInstance<ISolrOperations<SolrProduct>>();
    var results = solr.Query("LampCount:1");
    // as is: no mapping for result-return for now, returning "null" instead
    return(null);
}

produces an ArgumentException, telling me that the object of type "System.Collections.ArrayList" cannot be converted to type "System.String". Even after searching for that problem on the internet and debugging the program, I still don't understand the Exception. "LampCount" is an multiValued-Field (former NumericField in the Lucene index), with the schema.xml and mapping in the Product.cs it should work.

It works when using the webinterface on localhost:8983/solr/admin/, I can shoot a query as "LampCount:1" and it returns a bunch of correctly found documents. This might be another problem, but with all "setup as is", the resultset XML of the Solr webinterface shows (in every found document):

<arr name="LampCount">
<str>ERROR:SCHEMA-INDEX-MISMATCH,stringValue=1</str>
</arr>

I indexed the LampCount-field for Lucene index documents with

 var valueField = new NumericField(internalname, Field.Store.YES, true);
 valueField.SetDoubleValue(value);
 doc.Add(valueField);

Can this be the problem, for I cannot see the big picture at the moment and feel totally lost. Much appreciated if you can untie my brainknot. ;-)

Thanks in advance!

Community
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Petra Lehrmann
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1 Answers1

0

There is a mismatch between your schema and POCO. Basically Solr is trying to convert that "tdouble" field type into your collection. Best thing you can do is execute, your query in the admin control panel and observer what is coming back, and then ask yourself how you think it will handle the typing back into your POCO.

Shaun Kiesewetter
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