Google Reader do next loop iteration if tab does not exist

[abiasella]

Hello KNIME community - I’m looking to learn about skipping loop execution.

I am reading a “parent” google sheet and extracting a “child” google sheet ID that is in each row. I pass the child google sheet ID as a variable into another Google Reader node. I want to read the “ABC” tab, if it exists, on every child sheet passed in.

However, not all child sheets have an “ABC” tab, and this is stopping further execution. I’d like to just go on to the next child link from the parent sheet. Please help with ideas to get around this.

Here is a diagram of my workflow.

The error, as expected, is

ERROR Google Sheets Reader 8:329      Execute failed: Could not fetch sheet name for given spreadsheet id: 400 Bad Request
{
  "code" : 400,
  "errors" : [ {
    "domain" : "global",
    "message" : "Unable to parse range: ABC",
    "reason" : "badRequest"
  } ],
  "message" : "Unable to parse range: ABC",
  "status" : "INVALID_ARGUMENT"
}

I’ve tried to think of solutions using GET requests, try/catch, or IF nodes but can’t get something that works.
Thanks in advance for any help!

[armingrudd]

Hi @abiasella,

You can make use of Error Handling nodes in KNIME to prevent workflow failure.
Here, you can put Google sheet reader inside a try-catch construct and pass an empty table in case of failure. You just need to let the Loop End allow different table specifications in each iteration or make sure that you pass the same table structure instead of an empty table.

[mlauber71]

@abiasella maybe you can adapt this example. The collection is done in a temporary database so you would not need to provide a dummy table

This workflow demonstrates how to use the new Excel Reader and path variables...

You might have to provide an empty table at the catch part of you want to collect tables directly.

python problems with input column values, missing values

@sabsab OK it took a minute longer. Maybe there is a more elegant solution but it should work if there is always the same number of Rows with the identical RowID which I understand is the case. If not the try-catch might have to look different. [image]

You could also check the additional links here:

Knime 4.4 Cant merge variable stacks! (likely a loop problem)

@joshuash beside what @Thyme is saying these things come to my mind: (especially) with nested loops it can make sense to use Metanodes in order to make sure what part of the loop will do what and how they are wired. You can check „select sope“ by right clicking on the Loop node and see how KNIME would interpret the wiring. it might very well be necessary to check the logic behind the loop and if it would work in every constellation. It might be necessary to provide a dummy table of the same st…

[abiasella]

Perfect, thank you. The Python problem link was the most helpful. Here is my final working example using the try/catch nodes.