Validate each filed against multiple constraints using CSV Parser

Question

I am working on a requirement where I need to parse CSV record fields against multiple validations. I am using supercsv which has support for field level processors to validate data.

My requirement is to validate each record/row field against multiple validations and save them to the database with success/failure status. for failure records I have to display all the failed validations using some codes.

Super CSV is working file but it is checking only first validation for a filed and if it is failed , ignoring second validation for the same field.Please look at below code and help me on this.

package com.demo.supercsv;

import java.io.FileReader;
import java.io.IOException;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;

import org.supercsv.cellprocessor.Optional;
import org.supercsv.cellprocessor.constraint.NotNull;
import org.supercsv.cellprocessor.constraint.StrMinMax;
import org.supercsv.cellprocessor.constraint.StrRegEx;
import org.supercsv.cellprocessor.constraint.UniqueHashCode;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.exception.SuperCsvCellProcessorException;
import org.supercsv.io.CsvBeanReader;
import org.supercsv.io.CsvBeanWriter;
import org.supercsv.io.ICsvBeanReader;
import org.supercsv.io.ICsvBeanWriter;
import org.supercsv.prefs.CsvPreference;

public class ParserDemo {

    public static void main(String[] args) throws IOException {

        List<Employee> emps = readCSVToBean();
        System.out.println(emps);
        System.out.println("******");
        writeCSVData(emps);
    }

    private static void writeCSVData(List<Employee> emps) throws IOException {
        ICsvBeanWriter beanWriter = null;
        StringWriter writer = new StringWriter();
        try{
            beanWriter = new CsvBeanWriter(writer, CsvPreference.STANDARD_PREFERENCE);
            final String[] header = new String[]{"id","name","role","salary"};
            final CellProcessor[] processors = getProcessors();

            // write the header
            beanWriter.writeHeader(header);

            //write the beans data
            for(Employee emp : emps){
                beanWriter.write(emp, header, processors);
            }
        }finally{
            if( beanWriter != null ) {
                beanWriter.close();
            }
        }
        System.out.println("CSV Data\n"+writer.toString());
    }

    private static List<Employee> readCSVToBean() throws IOException {
        ICsvBeanReader beanReader = null;
        List<Employee> emps = new ArrayList<Employee>();
        try {
            beanReader = new CsvBeanReader(new FileReader("src/employees.csv"),
                    CsvPreference.STANDARD_PREFERENCE);

            // the name mapping provide the basis for bean setters 
            final String[] nameMapping = new String[]{"id","name","role","salary"};
            //just read the header, so that it don't get mapped to Employee object
            final String[] header = beanReader.getHeader(true);
            final CellProcessor[] processors = getProcessors();

            Employee emp;

            while ((emp = beanReader.read(Employee.class, nameMapping,
                    processors)) != null) {
                emps.add(emp);


                if (!CaptureExceptions.SUPPRESSED_EXCEPTIONS.isEmpty()) {
                    System.out.println("Suppressed exceptions for row "
                                        + beanReader.getRowNumber() + ":");
                    for (SuperCsvCellProcessorException e :
                        CaptureExceptions.SUPPRESSED_EXCEPTIONS) {
                        System.out.println(e);
                    }
                    // for processing next row clearing validation list
                    CaptureExceptions.SUPPRESSED_EXCEPTIONS.clear();
                }

            }

        } finally {
            if (beanReader != null) {
                beanReader.close();
            }
        }
        return emps;
    }

    private static CellProcessor[] getProcessors() {

        final CellProcessor[] processors = new CellProcessor[] { 

                new CaptureExceptions(new NotNull(new StrRegEx("\\d+",new StrMinMax(0, 2)))),//id must be in digits and should not be more than two charecters
                new CaptureExceptions(new Optional()), 
                new CaptureExceptions(new Optional()), 
                new CaptureExceptions(new NotNull()), 
                 // Salary
        };
        return processors;
    }

}

Exception Handler:

package com.demo.supercsv;

import java.util.ArrayList;
import java.util.List;
import org.supercsv.cellprocessor.CellProcessorAdaptor;
import org.supercsv.cellprocessor.ift.CellProcessor;
import org.supercsv.exception.SuperCsvCellProcessorException;
import org.supercsv.util.CsvContext;

public class CaptureExceptions extends CellProcessorAdaptor {

    public static List<SuperCsvCellProcessorException> SUPPRESSED_EXCEPTIONS = 
            new ArrayList<SuperCsvCellProcessorException>();

    public CaptureExceptions(CellProcessor next) {
        super(next);
    }

    public Object execute(Object value, CsvContext context) {
        try {
            return next.execute(value, context);

        } catch (SuperCsvCellProcessorException e) {
            // save the exception
            SUPPRESSED_EXCEPTIONS.add(e);
            if(value!=null)
                return value.toString();
                else
                    return "";
        }
    }
}

sample csv file

ID,Name,Role,Salary
a123,kiran,CEO,"5000USD"
2,Kumar,Manager,2000USD
3,David,developer,1000USD

when I run my program supercsv exception handler displaying this message for the ID value in the first row

Suppressed exceptions for row 2:
org.supercsv.exception.SuperCsvConstraintViolationException: 'a123' does not match the regular expression '\d+'
processor=org.supercsv.cellprocessor.constraint.StrRegEx
context={lineNo=2, rowNo=2, columnNo=1, rowSource=[a123, kiran, CEO, 5000USD]}
[com.demo.supercsv.Employee@23bf011e, com.demo.supercsv.Employee@50e26ae7, com.demo.supercsv.Employee@40d88d2d]

for field Id length should not be null and more than two and it should be neumeric...I have defined field processor like this.

new CaptureExceptions(new NotNull(new StrRegEx("\\d+",new StrMinMax(0, 2))))

but super csv ignoring second validation (maxlenght 2) if given input is not neumeric...if my input is 100 then its validating max lenght..but how to get two validations for wrong input.plese help me on this

Answer 1

SuperCSV cell processors will work in sequence. So, if it passes the previous constraint validation then it will check next one.

To achieve your goal, you need to write a custom CellProcessor, which will check whether the input is a number (digit) and length is between 0 to 2. So, that both of those checks are done in a single step.