How to check type of PyRow

Ignition
1

I'm trying to do some parameter validation checking and I have a parameter that could be a string or it could be a row from a dataset. Printing the type of object gives me:

<type 'com.inductiveautomation.ignition.common.script.builtin.DatasetUtilities$PyDataSet$PyRow'>

But if I try to check it within a script via:


from com.inductiveautomation.ignition.common.script.builtin.DatasetUtilities import PyDataset

if type(myParam) is DatasetUtilities.PyDataSet.PyRow:

, I get an error saying:

AttributeError: type object 'com.inductiveautomation.ignition.common.script.bui' has no attribute 'PyRow'

Does type() not go only 1 level deep? Is there any other method to check if a dataset row was passed as a parameter?

2 
... import PyDataset
if type(myParam) is DatasetUtilities.PyDataSet.PyRow:

Should be:

... import PyDataset
if type(myParam) is PyDataSet.PyRow:

Though I'd argue this is a bit of an antipattern - you should probably check if it's explicitly a string first, then check it's iterable in any form, and then bail if you can't handle it, to be more "Pythonic".

Or you could import and use com.inductiveautomation.ignition.common.PyUtilities.isSequence - which will return True for sequence-like things but not Python strings.

1 Like
3

I still get the same error. I tried different combinations of the import and the comparison of the type. no dice.

4

I do check if string first, but also wanted to explicitly check if it was a row. Let me try doing the isSequence to see if that works.

Update: the isSequence worked.

However, is there a way to check the type of object all the way down to the PyRow level?

5

This (surprisingly to me) seems to not be possible. It's probably due to the weird nature of PyRow - it's a Java nested, inner class of a static nested class of a regular class. You can import PyDataSet directly, but it seems like PyRow, even though it's public, is not visible to Jython at all.

EDIT:
Actually, I think it's because PyDataSet now explicitly tells Jython it's a "Python object", so it's not exposed to further reflection from Jython, and PyDataSet doesn't attempt to expose PyRow explicitly.

6

Perhaps consider ditching PyDataset for v8.3, and instead supplying a deliberate adapter that just wraps all Dataset implementations with the desired jythonic functionality. Similar to the way jython wraps all java.util.Map<> implementations with dictionary-like behaviors. Registered with the interpreter so it always works.

Then every Dataset is always a Dataset, back and forth through all .py2java() and .java2py() implicit operations, but always has the jythonic behaviors in jython. PyRow can then be a top-level class instantiated as needed by the adapter.

4 Likes
7

It's on my list of things to do. My concern is that it might end up breaking behaviors in some subtle way, but I definitely prefer it to the current split approach.

1 Like
8

Another approach would be to have the Dataset interface implement List<DatasetRow> via default methods, then have the new DatasetRow class implement List<Object>, plus inject the item getters (and maybe attribute getters) to mimic current PyRow behavior.

Then PyDataset could be deprecated.

9

Shouldn't it be isinstance(myParam, PyDataSet.PyRow) ?
I was always told that using type(x) to check for types is a bad practice.

Also, if you do "reunite" datasets and pyDatasets for 8.3 I'll be very happy :smiley:

1 Like
10

I tried isinstance() but it gave the same error regarding PyRow.