Output values not available in Apex Action when I run a Flow

Question

I am writing a sample class to split a fields into several fields depending on the separator character '\\|!\\|'.

My problem is when I ran the flow, it's not possible to me to retrieve the values returned from the Apex Action.

It's maybe a problem of the method declaration with a List of List and/or the size of the List returned in the output that don't match the size of the List entered?

public class ImplementCrossCellSolution3 {

    @InvocableMethod(label='Parse Comments into Fields Version 3')
    public static List<List<OutputVariables>> parseComments(List<InputVariables> recordComments){

        String comments = recordComments[0].recordComments;

        HubSpotCommentsInfo HubInfo = new HubSpotCommentsInfo();
        List<List<OutputVariables>> outputHubSpotCommentsInfo = new List<List<OutputVariables>>(); //===============
        
        List<OutputVariables> outputresults = new List<OutputVariables>();
        OutputVariables outputresult = new OutputVariables();
 
        List<String> parts = comments.split('\\|!\\|');

                Integer index = 0;
                for(String part : parts) {
                    part = part.trim();

                    switch on index {
                        when 0 {
                            HubInfo.fields1 = part;
                            outputresult.fields1 = part;
                            system.debug(HubInfo.fields1);
                            system.debug(outputresult.fields1);
                            }
                        when 1 {
                            HubInfo.fields2 = part;
                            outputresult.fields2 = part;
                            system.debug(HubInfo.fields2);
                            system.debug(outputresult.fields2);
                            }
                        when 2 {
                            HubInfo.fields3 = part;
                            outputresult.fields3 = part;
                            //system.debug(HubInfo.fields3);
                            //system.debug(outputresult.fields3);
                            }
                        when 3 {
                            HubInfo.fields4 = part;
                            outputresult.fields4 = part;
                            //system.debug(HubInfo.fields4);
                            //system.debug(outputresult.fields4);
                            }
                    }
                    index++;
                    outputresults.add(outputresult);
                    }
                //return outputresults;
                outputHubSpotCommentsInfo.add(outputresults); // ===================
                return outputHubSpotCommentsInfo; // ====================

    }
    
    public class InputVariables {  //=====================
        @InvocableVariable 
        public String recordComments;
        
    }

    public class OutputVariables {
        @InvocableVariable
        public String fields1;
        @InvocableVariable
        public String fields2; 
        @InvocableVariable
        public String fields3;
        @InvocableVariable
        public String fields4; 
    }
}

Answer 1

The input size and output size must match. That means your code must iterate over all of the InputVariables, like this:

public class ImplementCrossCellSolution3 {

    @InvocableMethod(label='Parse Comments into Fields Version 3')
    public static List<List<OutputVariables>> parseComments(List<InputVariables> recordComments){
        List<List<OutputVariables>> outputHubSpotCommentsInfo = new List<List<OutputVariables>>();
        for(InputVariables recordComment: recordComments) {
            List<OutputVariables> output = new List<OutputVariables>();
            String comments = recordComment.recordComments;
            List<String> parts = comments.split('\\|!\\|');
            OutputVariables outputresult = new OutputVariables();
            for(Integer index = 0; index < parts.size(); index++) {
                switch on Math.mod(index, 4) {
                    when 0 {
                        outputresult.fields1 = parts[index].trim();
                    }
                    when 1 {
                        outputresult.fields2 = parts[index].trim();
                    }
                    when 2 {
                        outputresult.fields3 = parts[index].trim();
                    }
                    when 3 {
                        outputresult.fields4 = parts[index].trim();
                        output.add(outputresult);
                        outputresult = new OutputVariables();
                    }
                }
            }
            if(Math.mod(parts.size(), 4) != 0) {
                outputresults.add(outputresult);
            }
            outputHubSpotCommentsInfo.add(outputresults);
        }
        return outputHubSpotCommentsInfo;
    }
    
    public class InputVariables {  //=====================
        @InvocableVariable 
        public String recordComments;
        
    }

    public class OutputVariables {
        @InvocableVariable
        public String fields1;
        @InvocableVariable
        public String fields2; 
        @InvocableVariable
        public String fields3;
        @InvocableVariable
        public String fields4; 
    }
}