Sitecore 9.2 problem with Solr query for single-reference fields

Question

I've upgraded from sc90 to sc92 and faced the following problem with field types in solr:

sc90:

sitecore field type: DropLink
solr doc: "accommodation_type_s":"6f75a5e4380448c7b95820e14b4bab12"
predicate.Or(i => i["accommodation_type_s"] == value)
=> solr query: accommodation_type_s:(6f75a5e4380448c7b95820e14b4bab12)

sc92

sitecore field type: DropLink
solr doc: "accommodation_type_sm":["6f75a5e4380448c7b95820e14b4bab12"]
predicate.Or(i => i["accommodation_type_sm"] == value)
=> solr query: ERROR Solr Error : ["undefined field accommodation_type"] - Query attempted: accommodation_type:(6f75a5e4380448c7b95820e14b4bab12)...

Looks like all single-link field types became list of guids instead of string guid in solr documents.

I can't use strongly typed objects to make query like i.AccommodationType.Contains(guid) or == guid because all queries are dynamically built and I don't know what field will be used to make it.

I've seen suggestions from other similar issues here that recommend:

by patching the returnType to string

But the main problem for me is why does the query i["accommodation_type_sm"] == value ignore the _sm postfix and raise an error in the search logs?

Answer 1

Finally found the reason (thanks Sitecore support).

I use a custom search index that does not include the /sitecore/templates sub-tree.

Solution if you are not able to use POCO objects with field types and field names definition you should include this section in your index config (normally sitecore_master/web_index as value) and use exact field name without any transformations (f.e. don't use "accommodation_type_sm" but use "Accommodation type" to build the predicate).

The last section from this doc actually describes this problem: https://doc.sitecore.com/developers/93/platform-administration-and-architecture/en/using-solr-field-name-resolution.html