[Go SDK]: Retrieve element type from input PCollection in parquetio.Write

CHANGES.md

@@ -73,6 +73,7 @@
 
 * Removed fastjson library dependency for Beam SQL. Table property is changed to be based on jackson ObjectNode (Java) ([#24154](https://github.com/apache/beam/issues/24154)).
 * Removed TensorFlow from Beam Python container images [PR](https://github.com/apache/beam/pull/28424). If you have been negatively affected by this change, please comment on [#20605](https://github.com/apache/beam/issues/20605).
+* Removed the parameter `t reflect.Type` from `parquetio.Write`. The element type is derived from the input PCollection (Go) ([#28490](https://github.com/apache/beam/issues/28490))
 
 ## Deprecations
 

sdks/go/pkg/beam/io/parquetio/parquetio.go

@@ -96,7 +96,7 @@ func (a *parquetReadFn) ProcessElement(ctx context.Context, file fileio.Readable
 }
 
 // Write writes a PCollection<parquetStruct> to .parquet file.
-// Write expects a type t of struct with parquet tags
+// Write expects elements of a struct type with parquet tags
 // For example:
 //
 //	type Student struct {
@@ -108,7 +108,8 @@ func (a *parquetReadFn) ProcessElement(ctx context.Context, file fileio.Readable
 //	  Day     int32   `parquet:"name=day, type=INT32, convertedtype=DATE"`
 //	  Ignored int32   //without parquet tag and won't write
 //	}
-func Write(s beam.Scope, filename string, t reflect.Type, col beam.PCollection) {
+func Write(s beam.Scope, filename string, col beam.PCollection) {
+	t := col.Type().Type()
 	s = s.Scope("parquetio.Write")
 	filesystem.ValidateScheme(filename)
 	pre := beam.AddFixedKey(s, col)

sdks/go/pkg/beam/io/parquetio/parquetio_test.go

@@ -95,7 +95,7 @@ func TestWrite(t *testing.T) {
 	}
 	p, s, sequence := ptest.CreateList(studentList)
 	parquetFile := "./write_student.parquet"
-	Write(s, parquetFile, reflect.TypeOf(Student{}), sequence)
+	Write(s, parquetFile, sequence)
 	t.Cleanup(func() {
 		os.Remove(parquetFile)
 	})