Creating a phrase match feature in LTR

[krishan goyal]

Hi,

I am trying to create a phrase match feature (what "pf" does in
dismax/edismax parsers)

I've tried various ways to set it up

{
  "name": "phraseMatch",
  "class": "org.apache.solr.ltr.feature.SolrFeature",
  "params": {
    "q": "{!complexphrase inOrder=true}query(fieldName:${input})"
  },
  "store": "_DEFAULT_"
}

This fails with the exception

Exception from createWeight for SolrFeature [name=phraseMatch,
params={q={!complexphrase inOrder=true}query(fieldName:${input})}] null

But similar query works when used in the query reranking construct with
these params

rqq: "{!complexphrase inOrder=true v=$v1}",
v1: "query(fieldName:"some text"~2^1.0,0)",

What is the problem in the LTR configuration for the feature ?