fix empty case

Author: sfc-gh-jrose

src/snowflake/snowpark/types.py

@@ -780,8 +780,13 @@ def json_value(self) -> Dict[str, Any]:
 
     def _fill_ast(self, ast: proto.SpDataType) -> None:
         ast.sp_struct_type.structured = self.structured
-        for field in self.fields or []:
-            field._fill_ast(ast.sp_struct_type.fields.list.add())
+        if self.fields is None:
+            return
+        elif len(self.fields) > 0:
+            for field in self.fields or []:
+                field._fill_ast(ast.sp_struct_type.fields.list.add())
+        else:
+            ast.sp_struct_type.fields.list.extend([])
 
 
 class VariantType(DataType):

tests/ast/data/col_cast.test

@@ -101,9 +101,9 @@ df = df.select(col("A").cast(MapType(StringType(), StringType(), structured=Fals
 
 df = df.select(col("A").cast(VectorType(FloatType(), 42)))
 
-df = df.select(col("A").cast(StructType(structured=False)))
+df = df.select(col("A").cast(StructType([], structured=False)))
 
-df = df.select(col("A").cast(StructType(structured=False)))
+df = df.select(col("A").cast(StructType([], structured=False)))
 
 df = df.select(col("A").cast(StructType([StructField("B", IntegerType(), nullable=True)], structured=False)))
 
@@ -1572,6 +1572,8 @@ body {
             }
             to {
               sp_struct_type {
+                fields {
+                }
               }
             }
           }
@@ -1651,6 +1653,8 @@ body {
             }
             to {
               sp_struct_type {
+                fields {
+                }
               }
             }
           }

tests/ast/data/col_try_cast.test

@@ -93,7 +93,7 @@ df = df.select(col("A").try_cast(MapType(StringType(), StringType(), structured=
 
 df = df.select(col("A").try_cast(VectorType(FloatType(), 42)))
 
-df = df.select(col("A").try_cast(StructType(structured=False)))
+df = df.select(col("A").try_cast(StructType([], structured=False)))
 
 df = df.select(col("A").try_cast(VariantType()))
 
@@ -1478,6 +1478,8 @@ body {
             }
             to {
               sp_struct_type {
+                fields {
+                }
               }
             }
           }

tests/ast/data/sproc.test

@@ -175,11 +175,11 @@ res34 = sproc("select_sp", return_type=StructType([StructField("A", IntegerType(
 
 session.sql("SELECT 1 as A, 2 as B").show()
 
-res38 = sproc("select_sp", return_type=StructType(structured=False), input_types=[IntegerType(), IntegerType()], source_code_display=False, _registered_object_name="\"MOCK_DATABASE\".\"MOCK_SCHEMA\".\"SNOWPARK_TEMP_PROCEDURE_xxx\"")(1, 2)
+res38 = sproc("select_sp", return_type=StructType([], structured=False), input_types=[IntegerType(), IntegerType()], source_code_display=False, _registered_object_name="\"MOCK_DATABASE\".\"MOCK_SCHEMA\".\"SNOWPARK_TEMP_PROCEDURE_xxx\"")(1, 2)
 
 session.sql("SELECT 1 as A, 2 as B").show()
 
-res42 = sproc("select_sp", return_type=StructType(structured=False), input_types=[LongType(), LongType()], _registered_object_name="\"MOCK_DATABASE\".\"MOCK_SCHEMA\".\"SNOWPARK_TEMP_PROCEDURE_xxx\"")(1, 2)
+res42 = sproc("select_sp", return_type=StructType([], structured=False), input_types=[LongType(), LongType()], _registered_object_name="\"MOCK_DATABASE\".\"MOCK_SCHEMA\".\"SNOWPARK_TEMP_PROCEDURE_xxx\"")(1, 2)
 
 session.sql("SELECT 1 as A, 2 as B").show()
 
@@ -1995,6 +1995,8 @@ body {
         parallel: 4
         return_type {
           sp_struct_type {
+            fields {
+            }
           }
         }
         src {
@@ -2140,6 +2142,8 @@ body {
         parallel: 4
         return_type {
           sp_struct_type {
+            fields {
+            }
           }
         }
         source_code_display: true