I am converting my custom index fields from Sitecore 8.1.
Previously, I would declare them like this:
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:set="http://www.sitecore.net/xmlconfig/set/">
<sitecore>
<contentSearch>
<indexConfigurations>
<myCustomIndexConfiguration type="Sitecore.ContentSearch.SolrProvider.SolrIndexConfiguration, Sitecore.ContentSearch.SolrProvider">
<documentOptions>
<fields hint="raw:AddComputedIndexField">
<field fieldName="parsed_content_keywords" returnType="customStringCol" storageType="yes" multiValued="true">
MyProject.Search.ComputedFields.ParsedContentKeywords, MyProject.Search
</field>
</fields>
</documentOptions>
</myCustomIndexConfiguration>
</indexConfigurations>
</contentSearch>
</sitecore>
</configuration>
And customStringCol is declared like this:
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
<sitecore>
<contentSearch>
<indexConfigurations>
<myCustomIndexConfiguration type="Sitecore.ContentSearch.SolrProvider.SolrIndexConfiguration, Sitecore.ContentSearch.SolrProvider">
<fieldMap type="Sitecore.ContentSearch.SolrProvider.SolrFieldMap, Sitecore.ContentSearch.SolrProvider">
<typeMatches hint="raw:AddTypeMatch">
<typeMatch typeName="customStringCol" type="System.Collections.Generic.List`1[System.String]" fieldNameFormat="{0}_csm" multiValued="true" indexed="true" settingType="Sitecore.ContentSearch.SolrProvider.SolrSearchFieldConfiguration, Sitecore.ContentSearch.SolrProvider"/>
</typeMatches>
</fieldMap>
</myCustomIndexConfiguration>
</indexConfigurations>
</contentSearch>
</sitecore>
</configuration>
In Sitecore 8.1 and Solr 4.10x, this configuration results in the index working correctly. In Sitecore 9.1 and Solr 7.2.1, this results in the Solr log outputting the following SolrException:
ERROR: [doc=sitecore://web/{c6ccedd5-28a9-4707-8717-7482a48b538f}?lang=en&ver=1&ndx=sitecore_web_index] unknown field 'parsed_content_keywords_csm'
Question
How do I create a custom index in Sitecore 9.1 and Solr 7.2.1? Could someone share a sample config similar to the one I posted above that works in this scenario?