ClickHouse: Nullable(DateTime) as time field throwing error in chart UI

[ravikishorer]

ClickHouse: Nullable(DateTime) as time field throwing error in create a new chart UI as the query it is generating contains time fields which have milli second precision and clickhouse couldn't convert them to date time.

Expected results

It should work correctly.

Actual results

Create chart area shows error when time field is present.

Screenshots

The field is identified correctly as a temporal field in the fields section of the chart UI

How to reproduce the bug

1. Clickhouse create table

CREATE TABLE trainingReport
 ( 
Training_ID Int32,
date Nullable(DateTime),
) ENGINE = MergeTree()
 ORDER BY tuple();

2. Try to create a chart with this dataset which contains a temporal field value

Environment

• superset version: 1.1.0
• python version: 3.8.5
• node.js version: 12.18.3

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

Additional context

Query is becoming something like
SELECT COUNT(*) AS count FROM "default"."trainingReport" WHERE "Last_Published_Date__UTC_TimeZone_" >= '2021-05-10 00:00:00.000000' AND "Last_Published_Date__UTC_TimeZone_" < '2021-05-17 00:00:00.000000' ORDER BY count DESC LIMIT 10000;

https://github.com/apache/superset/blob/master/superset/db_engine_specs/clickhouse.py#L66 is the issue as the field type is Nullable(DateTime), no proper conversion is happening for the from and to dates as the function is simply checking for utils.TemporalType.DATE and utils.TemporalType.DATETIME.

[suedschwede]

I would use Datatypes without NULLABLE in Superset

NULLABLE(DateTime) = DateTime

I use as workaround (clickhouse.py)

@classmethod
    def get_datatype(cls, type_code: Any) -> Optional[str]:
        """
        Change column type code from cursor description to string representation.

        :param type_code: Type code from cursor description
        :return: String representation of type code
        """
         
        type_code = type_code.upper()
 
        if (type_code.find('NULLABLE(') != -1): 
          type_code = type_code.replace("NULLABLE(", "")
          type_code = type_code.replace(")", "",1)


        if isinstance(type_code, str) and type_code != "":
            return type_code.upper()
        return None