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Generate case class from spark DataFrame/Dataset schema.
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| /** | |
| * Generate Case class from DataFrame.schema | |
| * | |
| * val df:DataFrame = ... | |
| * | |
| * val s2cc = new Schema2CaseClass | |
| * import s2cc.implicit._ | |
| * | |
| * println(s2cc.schemaToCaseClass(df.schema, "MyClass")) | |
| * | |
| */ | |
| import org.apache.spark.sql.types._ | |
| class Schema2CaseClass { | |
| type TypeConverter = (DataType) => String | |
| def schemaToCaseClass(schema:StructType, className:String)(implicit tc:TypeConverter):String = { | |
| def genField(s:StructField):String = { | |
| val f = tc(s.dataType) | |
| s match { | |
| case x if(x.nullable) => s" ${s.name}:Option[$f]" | |
| case _ => s" ${s.name}:$f" | |
| } | |
| } | |
| val fieldsStr = schema.map(genField).mkString(",\n ") | |
| s""" | |
| |case class $className ( | |
| | $fieldsStr | |
| |) | |
| """.stripMargin | |
| } | |
| object implicits { | |
| implicit val defaultTypeConverter:TypeConverter = (t:DataType) => { t match { | |
| case _:ByteType => "Byte" | |
| case _:ShortType => "Short" | |
| case _:IntegerType => "Int" | |
| case _:LongType => "Long" | |
| case _:FloatType => "Float" | |
| case _:DoubleType => "Double" | |
| case _:DecimalType => "java.math.BigDecimal" | |
| case _:StringType => "String" | |
| case _:BinaryType => "Array[Byte]" | |
| case _:BooleanType => "Boolean" | |
| case _:TimestampType => "java.sql.Timestamp" | |
| case _:DateType => "java.sql.Date" | |
| case _:ArrayType => "scala.collection.Seq" | |
| case _:MapType => "scala.collection.Map" | |
| case _:StructType => "org.apache.spark.sql.Row" | |
| case _ => "String" | |
| }} | |
| } | |
| } | |
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