Flink Java API - Pojo Type to Tuple Datatype

Question

I am creating a small utility on JAVA flink API to learn the functionalities. I am trying to read csv file and just print it and I have developed a POJO class for the structure of the data. When I executed the code, I dont see the right values.(Integers values are replaced with zeros and null values for String. How do I map the datatype for the attributes

My Main Class:

package org.karthick.flinkLab;

import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;

import javax.xml.crypto.Data;

public class CSVFileRead {
    public static void main(String[] args) throws Exception {
        System.out.println("--CSV File Reader using Flink's Data Set API--");
        ExecutionEnvironment execEnv = ExecutionEnvironment.getExecutionEnvironment();
        DataSet<DataModel> csvInput = execEnv.readCsvFile("C:\\Flink\\Data\\IndividualDetails.csv")
                    .pojoType(DataModel.class);
        csvInput.print();

    }
}

My Pojo class (DataModel.class)

package org.karthick.flinkLab;

import org.apache.flink.api.java.tuple.Tuple;
import org.apache.flink.api.java.tuple.Tuple12;

import java.io.Serializable;
import java.util.Date;

public class DataModel<T extends Tuple>
            extends Tuple12<Integer,String,Date,Integer,String,String,String,String,String,String,Date,String>
            implements Serializable
    {
        public Integer id;
        public String government_id;
        public Date diagnosed_date;
        public Integer age;
        public String detected_city;
        public String detected_district;
        public String detected_state;
        public String nationality;
        public String current_status;
        public Date status_change_date;
        public String notes;

        public DataModel() {};

        public String getNotes() {
            return notes;
        }

        public Date getStatus_change_date() {
            return status_change_date;
        }

        public String getCurrent_status() {
            return current_status;
        }

        public String getNationality() {
            return nationality;
        }

        public String getDetected_state() {
            return detected_state;
        }

        public String getDetected_district() {
            return detected_district;
        }

        public String getDetected_city() {
            return detected_city;
        }

        public String gender    ;

        public Date getDiagnosed_date() {
            return diagnosed_date;
        }

        public String getGender() {
            return gender;
        }

        public Integer getAge() {
            return age;
        }

        public Integer getId() {
            return id;
        }

        public void setId(Integer id) {
            this.id = id;
        }

        public String getGovernment_id() {
            return government_id;
        }

        public void setGovernment_id(String government_id) {
            this.government_id = government_id;
        }
}

When I executed the main method, I dont see the proper values. Sample result

(0,,Tue May 19 16:50:38 IST 2020,0,,,,,,,Tue May 19 16:50:38 IST 2020,)

where as I expect something like

(2777,AP,Tue May 19 16:50:38 IST 2020,0,A,B,C,D,E,F,Tue May 19 16:50:38 IST 2020,G)

What could be missing here?

Answer 1

You are missing the column mapping from CSV to POJO. Adding the mapping will work. The mapping of the column names must follow the following two rules:

• The column names should be exactly the same names as in POJO.
• The order of the columns in the mapping should be exactly the same as in the CSV file.

You can define the mapping as follows:

DataSet<DataModel> csvInput = execEnv.readCsvFile("C:\\Flink\\Data\\IndividualDetails.csv")
                    .pojoType(DataModel.class, "id", "age",.........);

It should have thrown error but it hasn't. It could be a bug