How I can make dynamic header column and dynamic data to export to Excel/CSV/PDF using MongoDB, Spring Boot, and apache poi - mongodb

Question

I want to make export function using Spring Boot, I have data on MongoDB NoSQL, and then want to export my document on MongoDB Dynamically using Apache POI ( If any better dependency you can recommend to me).
I don't want to declare header column, entity model, etc., I want to export data dynamically as shown as in my Document database, any one can give me an example for it?

Answer 1

Please try these code may be help for you.
->add Gson Depandencies in porm.xml
Controller code
MasterController.java
#Autowired
MasterServiceImpl masterServiceImpl;
#GetMapping(value="/dynamicfile/{flag}/{fileType}/{fileName}")
public ResponseEntity<InputStreamResource> downloadsFiles(#PathVariable("flag") int flag,#PathVariable("fileType") String fileType,#PathVariable("fileName") String fileName) throws IOException{
List<?> objects=new ArrayList<>();
if(flag==1) {
objects=masterServiceImpl.getData();
}
ByteArrayInputStream in = masterServiceImpl.downloadsFiles(objects,fileType);
HttpHeaders headers = new HttpHeaders();
if(fileType.equals("Excel")) {
headers.add("Content-Disposition", "attachment; filename="+fileName+".xlsx");
}else if(fileType.equals("Pdf")){
headers.add("Content-Disposition", "attachment; filename="+fileName+".pdf");
}else if(fileType.equals("Csv")) {
headers.add("Content-Disposition", "attachment; filename="+fileName+".csv");
}
return ResponseEntity.ok().headers(headers).body(new InputStreamResource(in));
}
Service code :
MasterServiceImpl.java
public static List<HashMap<Object, Object>> getListOfObjectToListOfHashMap(List<?> objects) {
List<HashMap<Object,Object>> list=new ArrayList<>();
for(int i=0;i<objects.size();i++) {
HashMap<Object,Object> map=new HashMap<>();
String temp=new Gson().toJson(objects.get(i)).toString();
String temo1= temp.substring(1, temp.length()-1);
String[] temp2=temo1.split(",");
for(int j=-1;j<temp2.length;j++) {
if(j==-1) {
map.put("SrNo",i+1);
}else {
String tempKey=temp2[j].toString().split(":")[0].toString();
String tempValue=temp2[j].toString().split(":")[1].toString();
char ch=tempValue.charAt(0);
if(ch=='"') {
map.put(tempKey.substring(1, tempKey.length()-1), tempValue.substring(1, tempValue.length()-1));
}else {
map.put(tempKey.substring(1, tempKey.length()-1), tempValue);
}
}
}
list.add(map);
}
return list;
}
public static ByteArrayInputStream downloadsFiles(List<?> objects,String fileType) throws IOException {
ByteArrayOutputStream out = new ByteArrayOutputStream();
List<HashMap<Object, Object>> list = getListOfObjectToListOfHashMap(objects);
String[] COLUMNs = getColumnsNameFromListOfObject(objects);
try{
if(fileType.equals("Excel")) {
generateExcel(list, COLUMNs,out);
}else if(fileType.equals("Pdf")) {
generatePdf(list, COLUMNs,out);
}else if(fileType.equals("Csv")) {
generatePdf(list, COLUMNs,out);
}
}catch(Exception ex) {
System.out.println("Error occurred:"+ ex);
}
return new ByteArrayInputStream(out.toByteArray());
}
public static final String[] getColumnsNameFromListOfObject(List<?> objects) {
String strObjects=new Gson().toJson(objects.get(0)).toString();
String[] setHeader= strObjects.substring(1, strObjects.length()-1).split(",");
String header="SrNo";
for(int i=0;i<setHeader.length;i++) {
String str=setHeader[i].toString().split(":")[0].toString();
header=header+","+str.substring(1, str.length()-1);
}
return header.split(",");
}
public static final void generateExcel(List<HashMap<Object, Object>> list, String[] COLUMNs,ByteArrayOutputStream out) throws IOException {
Workbook workbook = new XSSFWorkbook();
Sheet sheet = workbook.createSheet("Excelshit");
Font headerFont = workbook.createFont();
headerFont.setBold(true);
headerFont.setColor(IndexedColors.BLUE.getIndex());
CellStyle headerCellStyle = workbook.createCellStyle();
headerCellStyle.setFont(headerFont);
Row headerRow = sheet.createRow(0);
for (int col = 0; col < COLUMNs.length; col++) {
Cell cell = headerRow.createCell(col);
cell.setCellValue(COLUMNs[col]);
cell.setCellStyle(headerCellStyle);
}
int rowIdx = 1;
for(int k = 0; k < list.size(); k++){
Row row =sheet.createRow(rowIdx++);
for (Map.Entry<Object, Object> entry : list.get(k).entrySet()){
Object key = entry.getKey();
Object value = entry.getValue();
for (int col = 0; col < COLUMNs.length; col++) {
if(key.toString().equals(COLUMNs[col].toString())) {
row.createCell(col).setCellValue(value.toString());
}
}
}
}
workbook.write(out);
System.out.println(workbook);
}
private static final void generatePdf(List<HashMap<Object, Object>> list, String[] COLUMNs,ByteArrayOutputStream out) throws DocumentException {
Document document = new Document();
com.itextpdf.text.Font headerFont =FontFactory.getFont(FontFactory.HELVETICA_BOLD,8);
com.itextpdf.text.Font dataFont =FontFactory.getFont(FontFactory.TIMES_ROMAN,8);
PdfPCell hcell=null;
PdfPTable table = new PdfPTable(COLUMNs.length);
for (int col = 0; col < COLUMNs.length; col++) {
hcell = new PdfPCell(new Phrase(COLUMNs[col], headerFont));
hcell.setHorizontalAlignment(Element.ALIGN_CENTER);
table.addCell(hcell);
}
for(int index = 0; index < list.size(); index++){
PdfPCell cell = null;
for (Map.Entry<Object, Object> entry : list.get(index).entrySet()){
Object key = entry.getKey();
Object value = entry.getValue();
for (int col = 0; col < COLUMNs.length; col++) {
if(key.toString().equals(COLUMNs[col].toString())) {
cell = new PdfPCell(new Phrase(value.toString(),dataFont));
cell.setVerticalAlignment(Element.ALIGN_MIDDLE);
cell.setHorizontalAlignment(Element.ALIGN_CENTER);
}
}
table.addCell(cell);
}
}
PdfWriter.getInstance(document, out);
document.open();
document.add(table);
document.close();
}
public List<TblDepartment> getData() {
List<TblDepartment> list = new ArrayList<>();
departmentRepository.findAll().forEach(list::add);
return list;
}