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?

• Bjorn: Put your try/except inside the for loop. As written your script will move past this section the first time an error occurs.
• Bjorn: Did you mean to indent your print statement?
• Tom: 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?
• user51332: tableList = [os.path.join(table_workspace, table) for table in arcpy.ListTables("table1w")]

Answer 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.

• user51332: 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: Also it gives the same error when it reaches to the missing dataset in the loop.
• Tom: @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: @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?
• user51332: 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.

Answer 2

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)

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