Read CSV File Using Apex

Hello friends, In this post you will see a code example that helps you to parse CSV file using apex code. With the help of this code you can easily read data from CSV file and stored in salesforce. so let's get started.

Read csv file using apex

I used the following csv file to parse using apex. Simply upload this file in document and from there i read and parse it using apex class.

To read above file we have to create an apex class and replace the following code.

CSVReader.apxc

 public class CSVReader {
    public static final String ParserCOMMA = String.fromCharArray(new List<Integer>{44});
    public static final String ParserCR = '\r';
    public static final String ParserDQUOTE = '\"';
    public static final String ParserLF = '\n';
    public static final String ParserCRLF = ParserCR + ParserLF;
    public static final String ParserLFCR = ParserLF + ParserCR;
    public static final String ParserDQUOTEDQUOTE = ParserDQUOTE + ParserDQUOTE;
    
    public static List<List<String>> doParse(Blob file) {
        String fileString = file.toString();        
        if (!fileString.endsWith(ParserCRLF)) {
            fileString = fileString + ParserCRLF;
        }        
        List<List<String>> fileValues = new List<List<String>>();
        List<String> rowValues = new List<String>();
        CSVValue csvValue = new CSVValue();        
        Boolean eod = false; 
        while (!eod) {
            System.debug(fileString);
            csvValue = ParseStringValue(fileString);            
            rowValues.add(csvValue.value);            
            if (csvValue.delimiter == ParserCRLF) {
                fileValues.add(rowValues);                
                System.debug(rowValues);                
                if (fileValues.size() > 0) {
                    System.assertEquals(fileValues.get(0).size(),rowValues.size());
                }                
                rowValues = new List<String>();
            }
            
            if (csvValue.biteSize() == fileString.length()) {
                eod = true;
            }
            else {
                fileString = fileString.substring(csvValue.biteSize());
            }
        }        
        return fileValues;
    } 
   
    public static CSVValue ParseStringValue(String data) {
        System.assert(data.endsWith(ParserCRLF));        
        CSVValue csvValue = new CSVValue();        
        if (data.startsWith(ParserDQUOTE)){
            csvValue.enclosed = true;            
            Integer searchIndex = 1;     
            Integer dquoteIndex = -1;    
            Integer dquotesIndex = -1;             
            Boolean closerFound = false;            
            while (!closerFound) {
                dquoteIndex = data.indexOf(ParserDQUOTE, searchIndex);                
                dquotesIndex = data.indexOf(ParserDQUOTEDQUOTE,searchIndex);                
                System.assert(dquoteIndex != -1);                
                if (dquoteIndex == dquotesIndex) {
                    searchIndex = dquotesIndex+ParserDQUOTEDQUOTE.length();
                }
                else {
                    closerFound = true;
                }
            }            
            csvValue.value = data.substring(ParserDQUOTE.length(), dquoteIndex).replaceAll(ParserDQUOTEDQUOTE, ParserDQUOTE);            
            Integer commaIndex = data.indexOf(ParserCOMMA, dquoteIndex);
            Integer crlfIndex = data.indexOf(ParserCRLF, dquoteIndex);            
            if (commaIndex != -1 && commaIndex < crlfIndex) {
                csvValue.delimiter = ParserCOMMA;
            }
            else {
                csvValue.delimiter = ParserCRLF;
            }
        }
        else {
            csvValue.enclosed = false;            
            Integer commaIndex = data.indexOf(ParserCOMMA);
            Integer crlfIndex = data.indexOf(ParserCRLF);            
            if (commaIndex != -1 && commaIndex < crlfIndex) {
                csvValue.value = data.substring(0, commaIndex);
                csvValue.delimiter = ParserCOMMA;
            }
            else {
                csvValue.value = data.substring(0, crlfIndex);
                csvValue.delimiter = ParserCRLF;
            }
        }        
        System.debug('Returning: ' + csvValue);        
        return csvValue;
    }       
    
    private class CSVValue {        
        public String value;       
        public Boolean enclosed;      
        public String delimiter;
        
        public CSVValue() {
            this(null, null, null);
        }
        
        public CSVValue(String value, Boolean enclosed, String delimiter) {
            this.value = value;
            this.enclosed = enclosed;
            this.delimiter = delimiter;
        }        
        
        public Integer biteSize() {
            Integer biteSize = value.replaceAll(ParserDQUOTE, ParserDQUOTEDQUOTE).length()+delimiter.length();            
            if (enclosed) {
                biteSize += ParserDQUOTE.length() * 2;
            }            
            System.debug('biteSize: ' + biteSize);            
            return biteSize;
        }        
        
        public Boolean equals(CSVValue compCSVValue) {
            return this.value.equals(compCSVValue.value)
                && this.enclosed == compCSVValue.enclosed
                && this.delimiter == compCSVValue.delimiter;
        }
        
        public void assertEquals(CSVValue compCSVValue) {
            System.assertEquals(value, compCSVValue.value);
            System.assertEquals(enclosed, compCSVValue.enclosed);
            System.assertEquals(delimiter, compCSVValue.delimiter);
        }
    } 
 }

To see the output we read csv file that we uploaded in document, using following code snippet.

 Document docs = [SELECT Id,Body FROM Document WHERE Name='DemoCSV'];
 List<List<String>> fileValues = CSVReader.doParse(docs.Body);
 Map<integer, List<string>> rowMap = new Map<integer, List<string>>();
 for(integer i = 1; i < fileValues.size(); i++) {
    rowMap.put(i, fileValues[i]);
 }
 System.debug('rowMap^^^** '+rowMap);

Output:

 

Hope you like this post, for any feedback or suggestions please feel free to comment. I would appreciate your feedback and suggestions.
Thank you.