Drop down value with Nested CDT

Hello, 

I have a record table and a nested funding type table. The record has typical information but I normalized the database to have some sections in their own tables and nested them according to documentation. For the drop down, the choices are populated by a expression rule that grabs the names of the funding types. I then have a index on the front end {index(rule!RP_GETfundDropDown().data, "fundTypeName", null)} grabbing the names. I then added the primary key of the fundtype table as well and listed those as the choice values. The goal was that I would just need to insert the id of the funding type into the record record type and it would be a reference fk. Instead, it is requiring the whole array of objects. See image. I am not entirely sure what I am doing wrong or why its expecting me to pass the whole row when it's referenced as a fk. 

Get_FundType

a!queryEntity(
entity: cons!FundTypeNames,
query: a!query(
selection: a!querySelection(
columns: {
a!queryColumn(
field: "fundTypeId"
),
a!queryColumn(
field: "fundTypeName"
)
}
),
pagingInfo: a!pagingInfo(
startIndex: 1,
batchSize: 50
)
),
fetchTotalCount: false
)