PySpark Convert StructType to MapType

## Convert a StructType to MapType column :
## Useful when you want to move all Dynamic Fields of a Schema within a StructType column into a single MapType Column.

from pyspark.sql.types import *
from pyspark.sql.functions import *
import json

def toMap(d):
    if d:
        return(json.loads(d))  
    else:
        return None
    
# UDF returns a Map of Strings as Key:Value pair
map_udf=udf(lambda d: toMap(d),\
            MapType(StringType(),StringType()))

df = df.withColumn("structtype_json_col", to_json('structtype_col'))
df = df.withColumn("maptype_col", map_udf(df.structtype_json_col)).drop("structtype_json_col")
df.printSchema()