Importing data and comparing to string-defined field

A CSV import needs to compare a column of data to an indexed string value which are number literals:

The import_csv task

   @model = row[0]
   @article =  Article.where(['model = ?', @model.to_i]).first

is thus attempting to compare the integer from the csv file to a string ad returning.

LINE 1: ...T  "articles".* FROM "articles"  WHERE (model = 1410) LI...
HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts.
: SELECT  "articles".* FROM "articles"  WHERE (model = 1406) LIMIT 1'
01406, ,0,0,1,0,0,RASATO,,408
Error importing row because 'PG::UndefinedFunction: ERROR:  operator does not exist: character varying = integer

Note: comparing string on string

   @article =  Article.where(['model = ?', @model]).first

'Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id'

Is there any way of effecting the comparison, short of saving an indexed value of the string-defined variable?