Solr throws an error if an undefined field is used, so make sure to include the correct field names from schema .
Here are a full list of options you can send to the service:
> q = search terms (can be multiple)
> field = field constraints (can be multiple)
> fm = json or xml
> i = number of results per page (default is 10)
> p = page number
> val = facet constrain (eg: you want to search water, and constrain it by the keyword canada – val=KW:"canada")