How to upload and retrieve file in mongodb in spring boot application without using GridFSTemplate?

Question

I want to upload files and retrieve them from mongodb in spring boot application. But I don't want to use GridFSTemplate because my file size will not be greater than 16 MB. I am not choosing GridFSTemplate because none of the requirements mentioned in link https://docs.mongodb.com/manual/core/gridfs/#faq-developers-when-to-use-gridfs do not meet my requirements. Is working with Document to save files and retrieve them using MongoTemplate a good approach? MyDocument definition will look like

@Document
public class MyDocument {
    @Id
    private String id;
    private String emailId;
    private String docType;
    @CreatedDate
    private DateTime created;
    @LastModifiedDate
    private DateTime modified;
    private File document;
}

Storing file

MyDocument document = new MyDocument();
document.setEmailId("[email protected]");
document.setDocType("passport");
document.setDocument(file);
mongoTemplate.insert(document);

I want to store file along with some information like email. Later I will retrieve this file based on email parameter. Please suggest if this approach is good or any other better solution is appreciated.

Answer 1

I could finally figure out the way to store files without using GridFS in mongodb. First thing you have to note that we have to store byte[] representation of file.

import org.bson.types.Binary;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;
import org.springframework.data.mongodb.core.mapping.Field;
@Document
public class DemoDocument {
    @Id
    @Field
    private String id;

    @Field
    private String emailId;

    @Field
    private String docType;

    @Field
    private Binary file;
}

Make sure your file object is org.bson.types.Binary. Following is my controller code to save object in monogodb.

@PostMapping("/upload")
public String singleFileUpload(@RequestParam("file") MultipartFile multipart, @RequestParam("email") String email) {
    try {
        DemoDocument demoDocument = new DemoDocument();
        demoDocument.setEmailId(email);
        demoDocument.setDocType("pictures");
        demoDocument.setDocument(new Binary(BsonBinarySubType.BINARY, multipart.getBytes()));
        mongoTemplate.insert(demoDocument);
        System.out.println(demoDocument);
    } catch (Exception e) {
        e.printStackTrace();
        return "failure";
    }
    return "success";
}

You can retrieve this object from mongodb as following.

@PostMapping("/retrieve")
public String retrieveFile(@RequestParam("email") String email){
    DemoDocument demoDocument = mongoTemplate.findOne(new BasicQuery("{emailId : \""+email+"\", docType : \"pictures\"}"), DemoDocument.class);
    System.out.println(demoDocument);
    Binary document = demoDocument.getDocument();
    if(document != null) {
        FileOutputStream fileOuputStream = null;
        try {
            fileOuputStream = new FileOutputStream(RETRIEVE_FOLDER + "prof_pic.jpg");
            fileOuputStream.write(document.getData());
        } catch (Exception e) {
            e.printStackTrace();
            return "failure";
        } finally {
            if (fileOuputStream != null) {
                try {
                    fileOuputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                    return "failure";
                }
            }
        }
    }
    return "success";
}

Please note this is just sample working code for understanding. It can be written in fully object oriented way keeping design principles in mind.