Check if key type of a map is string when creating structField in R.

Author: Sun Rui

R/pkg/R/schema.R

@@ -131,7 +131,7 @@ checkType <- function(type) {
   if (type %in% primtiveTypes) {
     return()
   } else {
-    # Array type
+    # Check complex types
     firstChar <- substr(type, 1, 1)
     switch (firstChar,
             a = {
@@ -150,8 +150,8 @@ checkType <- function(type) {
               matchedStrings <- regmatches(type, m)
               if (length(matchedStrings[[1]]) >= 3) {
                 keyType <- matchedStrings[[1]][2]
+                stopifnot (keyType == "string" || keyType == "character")
                 valueType <- matchedStrings[[1]][3]
-                checkType(keyType)
                 checkType(valueType)
                 return()
               }

sql/core/src/main/scala/org/apache/spark/sql/api/r/SQLUtils.scala

@@ -65,6 +65,9 @@ private[r] object SQLUtils {
         org.apache.spark.sql.types.ArrayType(getSQLDataType(elemType))
       }
       case r"\Amap<(.*)${keyType},(.*)${valueType}>\Z" => {
+        if (keyType != "string" && keyType != "character") {
+          throw new IllegalArgumentException("Key type of a map must be string or character")
+        }
         org.apache.spark.sql.types.MapType(getSQLDataType(keyType), getSQLDataType(valueType))
       }
       case _ => throw new IllegalArgumentException(s"Invaid type $dataType")