[jira] [Resolved] (SPARK-22212) Some SQL functions in Python fail with string column name

["Jakub Nowacki (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-22212?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jakub Nowacki resolved SPARK-22212.
-----------------------------------
    Resolution: Later

Keeping the resolution on-hold until API unification consensus will be reached. 

> Some SQL functions in Python fail with string column name 
> ----------------------------------------------------------
>
>                 Key: SPARK-22212
>                 URL: https://issues.apache.org/jira/browse/SPARK-22212
>             Project: Spark
>          Issue Type: Bug
>          Components: PySpark, SQL
>    Affects Versions: 2.2.0
>            Reporter: Jakub Nowacki
>            Priority: Minor
>
> Most of the functions in {{pyspark.sql.functions}} allow usage of both column name string and {{Column}} object. But there are some functions, like {{trim}}, that require to pass only {{Column}}. See below code for explanation.
> {code}
> >>> import pyspark.sql.functions as func
> >>> df = spark.createDataFrame([tuple(l) for l in "abcde"], ["text"])
> >>> df.select(func.trim(df["text"])).show()
> +----------+
> |trim(text)|
> +----------+
> |         a|
> |         b|
> |         c|
> |         d|
> |         e|
> +----------+
> >>> df.select(func.trim("text")).show()
> [...]
> Py4JError: An error occurred while calling z:org.apache.spark.sql.functions.trim. Trace:
> py4j.Py4JException: Method trim([class java.lang.String]) 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:748)
> {code}
> This is because most of the Python function calls map column name to Column in the Python function mapping, but functions created via {{_create_function}} pass them as is, if they are not {{Column}}.
> I am preparing PR with the proposed fix.



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