Maciej Szymkiewicz created SPARK-19165:
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Summary: UserDefinedFunction should verify call arguments and
provide readable exception in case of mismatch
Key: SPARK-19165
URL: https://issues.apache.org/jira/browse/SPARK-19165
Project: Spark
Issue Type: Sub-task
Components: PySpark, SQL
Affects Versions: 2.1.0, 2.0.0, 1.6.0, 2.2.0
Reporter: Maciej Szymkiewicz
Invalid arguments to UDF call fail with a bit cryptic Py4J errors:
{code}
In [5]: g = udf(lambda x: x)
In [6]: df.select(f([]))
---------------------------------------------------------------------------
Py4JError Traceback (most recent call last)
<ipython-input-10-5fb48a5d66d2> in <module>()
----> 1 df.select(f([]))
....
Py4JError: An error occurred while calling
z:org.apache.spark.sql.functions.col. Trace:
py4j.Py4JException: Method col([class java.util.ArrayList]) does not exist
at py4j.reflection.ReflectionEngine.getMethod(ReflectionEngine.java:318)
at py4j.reflection.ReflectionEngine.getMethod(ReflectionEngine.java:339)
at py4j.Gateway.invoke(Gateway.java:274)
at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
at py4j.commands.CallCommand.execute(CallCommand.java:79)
at py4j.GatewayConnection.run(GatewayConnection.java:214)
at java.lang.Thread.run(Thread.java:745)
{code}
It is pretty easy to perform basic input validation:
{code}
In [8]: f = udf(lambda x: x)
In [9]: f(1)
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
...
TypeError: All arguments should be Columns or strings representing column
names. Got 1 of type <class 'int'>
{code}
This can be further extended to check for expected number of arguments or even,
with some type of annotations, SQL types.
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