Sådan løses com.mongodb.spark.exceptions.MongoTypeConversionException:Kan ikke caste... Java Spark

Jeg havde det samme problem og sampleSize løser delvist dette problem, men løser det ikke, hvis du har mange data.

Her er løsningen, hvordan du kan løse dette. Brug denne tilgang sammen med øget sampleSize (i mit tilfælde er det 100.000):

def fix_schema(schema: StructType) -> StructType:
    """Fix spark schema due to inconsistent MongoDB schema collection.

    It fixes such issues like:
        Cannot cast STRING into a NullType
        Cannot cast STRING into a StructType

    :param schema: a source schema taken from a Spark DataFrame to be fixed
    """
    if isinstance(schema, StructType):
        return StructType([fix_schema(field) for field in schema.fields])
    if isinstance(schema, ArrayType):
        return ArrayType(fix_schema(schema.elementType))
    if isinstance(schema, StructField) and is_struct_oid_obj(schema):
        return StructField(name=schema.name, dataType=StringType(), nullable=schema.nullable)
    elif isinstance(schema, StructField):
        return StructField(schema.name, fix_schema(schema.dataType), schema.nullable)
    if isinstance(schema, NullType):
        return StringType()
    return schema


def is_struct_oid_obj(struct_field: StructField) -> bool:
    """
    Checks that our schema has StructType field with single oid name inside

    :param struct_field: a StructField from Spark schema
    :return bool
    """
    return (isinstance(struct_field.dataType, StructType)
            and len(struct_field.dataType.fields) == 1
            and struct_field.dataType.fields[0].name == "oid")