How to detect and add a missing columns?

[hops650]

Hi all, I’m running into an issue with the Java Snippet. If I run a workflow with a POST Request or PATCH Request, the column Status is automatically created. However sometimes I do not have any rows to update, so the POST/PATCH Request don’t run. When 1 of them does not run, the Status column is not created and my Java Snippet fails, this eventually results in my entire workflow failing because I depend on a concatenation to summarize my results via email.

What’s the best way to detect and add a missing column? Here’s an example workflow…
POST and PATCH Test.knwf (16.8 KB)

[ipazin]

Hello @hops650,

there are Table Validator nodes to ensure certain table structure. (Including adding missing columns.)

Table Validator (Reference)

Table Validator

I prefer reference node but it’s up to you which you want to use

Br,
Ivan

[mlauber71]

To deal with a missing column there is this thread:

Add column if doesn't exist

Hi @TigerCole yes 5 years later there are better solutions for this I would now use the Table Validator for this. You can in the dialog define what happens if certain columns are missing, and add them with Missing Values in case they are not there. The Missing Value can than add you a fixed value into these missing values. [image] If you have a second reference table, you can also use the Table Validator (Reference) Than you do not have to take care of configuring the node…

You could use a Java snippet to detect a missing column.

Use Java Snippet to check if Column is there, fill a FlowVariable and then...

Also you might adapt this example:

Skip DB table if a column is not there – mlauber71

[Daniel_Weikert]

Thanks Ivan,
maybe I missed it but is there a detailed explanation what “out of domain” actually means?
Thanks

[ipazin]

Hello @Daniel_Weikert,

domain is the “list of possible values” for a column. If you click the “Spec” tab in an output table, you’ll see the data types of the columns and the domain of the values in the columns. For numerical values, only the range of the values in the data is shown. For string values, the different values appearing in the data are shown (by default up to 60 values but this can be changed; see here how).

This forum topic regarding domain and it’s refreshing is also useful:

Color Manager after Row Filter shows filtered values too...

Hello, I observed an unexpected behaviour of “Color Manager”: In my workflow I read data from database, filter via “Row Filter” for a special entry (in my case [NULL]), filtered data after Row Filter is ok (exclude these entries). But in the following Color Manager node I still see the (excluded) filtered entries with “[NULL]”. If I filter the entries direct in the also used “DB Query Reader” then everything it’s ok. Can anyone explain why Color Manager seems to ignore filtered rows via Row…

Br,
Ivan