Exceptions in arcpy using specific errors?

Question

I have this code:

... for table in tableList:
...     with arcpy.da.SearchCursor(table, ["qname","tname","query"]) as cur:
...         for row in cur:
...             if row[2] not in ('',None): 
...                 query = row[2]
...                 arcpy.Select_analysis(in_features=row[1],
...      out_feature_class=os.path.join(shapefile_output_folder,row[0]),where_clause=query)

If a certain file that meets at the loop doesn't exist I want to print the name of the file and continue without stopping.

The error when it doesn't find the file is :

Runtime error Traceback (most recent call last): File "", line 8, in File "c:\program files (x86)\arcgis\desktop10.6\arcpy\arcpy\analysis.py", line 90, in Select raise e ExecuteError: ERROR 000732: Input Features: Dataset TA2a does not exist or is not supported

So how should the exception be? I tried:

try
 ... for table in tableList:
    ...     with arcpy.da.SearchCursor(table, ["qname","tname","query"]) as cur:
    ...         for row in cur:
    ...             if row[2] not in ('',None): 
    ...                 query = row[2]
    ...                 arcpy.Select_analysis(in_features=row[1],
    ...      out_feature_class=os.path.join(shapefile_output_folder,row[0]),where_clause=query
)
except arcpy.RuntimeError:
print(table)

Can you suggest corrections?

Put your try/except inside the for loop. As written your script will move past this section the first time an error occurs. — Bjorn
– Bjorn, Commented Nov 5, 2018 at 16:10
You want the try to be at the relevant level. Based on what you've written here, that would be right after for table in tableList:. Out of curiosity, how is tableList being populated? — Tom
– Tom, Commented Nov 5, 2018 at 16:11
tableList = [os.path.join(table_workspace, table) for table in arcpy.ListTables("table1w")] — user51332
– user51332, Commented Nov 6, 2018 at 6:59

Tom · Accepted Answer · 2018-11-05 16:14:23Z

1

You don't need a try statement. You can specifically test whether the table exists prior to starting the cursor:

for table in tableList:
    if not arcpy.Exists(table):
        print('{} does not exist'.format(table))
        continue
    with arcpy.da.SearchCursor(table, ["qname","tname","query"]) as cur:
        for row in cur:
            if row[2] not in ('',None):
                query = row[2]
                arcpy.Select_analysis(in_features=row[1],
    out_feature_class=os.path.join(shapefile_output_folder,row[0]),where_clause=query)

I find a conditional and continue to be cleaner than try/except.

answered Nov 5, 2018 at 16:14

Tom

4,1581 gold badge23 silver badges39 bronze badges

It is better because we know the possible error i may be caused right. If we didn't know what error it could be caused we would do the try approach?

user51332
– user51332

2018-11-06 06:50:07 +00:00
Commented Nov 6, 2018 at 6:50
Also it gives the same error when it reaches to the missing dataset in the loop.

user51332
– user51332

2018-11-06 07:23:25 +00:00
Commented Nov 6, 2018 at 7:23
@user51332, You are correct that if there was some other error, it would raise an Exception, but if you said "If a certain file that meets at the loop doesn't exist..."; this addresses your specific request. Also, if there's another error, you probably want to see the Exception so that you can resolve it rather than printing a misleading message that the dataset doesn't exist and then continuing.

Tom
– Tom

2018-11-06 17:18:13 +00:00
Commented Nov 6, 2018 at 17:18
@user51332, If you're getting the same error, then the issue isn't that the dataset doesn't exist, but that it can't be read by a cursor. I repeat my question from above: how is tableList being populated?

Tom
– Tom

2018-11-06 17:19:13 +00:00
Commented Nov 6, 2018 at 17:19
I have already answered your question below the comment that you asked.In the comments of the question. The way i fixed it with try except was to include only the select analysis line. If you can make it your way to work would be great though.without try except.

user51332
– user51332

2018-11-07 09:29:57 +00:00
Commented Nov 7, 2018 at 9:29

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Emil Brundage · Accepted Answer · 2018-11-06 00:20:34Z

0

You're close. It's actually arcpy.ExecuteError.

try:
 ... for table in tableList:
    ...     with arcpy.da.SearchCursor(table, ["qname","tname","query"]) as cur:
    ...         for row in cur:
    ...             if row[2] not in ('',None): 
    ...                 query = row[2]
    ...                 arcpy.Select_analysis(in_features=row[1],
    ...      out_feature_class=os.path.join(shapefile_output_folder,row[0]),where_clause=query
)
except arcpy.ExecuteError:
    print(table)

answered Nov 6, 2018 at 0:20

Emil Brundage

13.9k3 gold badges29 silver badges64 bronze badges

1

But he said he wants to keep processing the tables that do exist. This will end the loop.

Tom
– Tom

2018-11-06 01:03:04 +00:00
Commented Nov 6, 2018 at 1:03

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