DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports
Events Video Library
Refcards
Trend Reports

Events

View Events Video Library

Zones

Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks

Related

  • How to Identify the Underlying Causes of Connection Timeout Errors for MongoDB With Java
  • Achieving Inheritance in NoSQL Databases With Java Using Eclipse JNoSQL
  • Powering Enterprise Applications: Unleashing the Java-MongoDB Synergy
  • Java and MongoDB Integration: A CRUD Tutorial [Video Tutorial]

Trending

  • How to Submit a Post to DZone
  • The Death of REST? Why gRPC and GraphQL Are Taking Over
  • Squid Game: The Clean Code Trials — A Java Developer's Survival Story
  • Docker Model Runner: Running AI Models Locally Made Simple
  1. DZone
  2. Data Engineering
  3. Databases
  4. Generic Search in MongoDB With Java

Generic Search in MongoDB With Java

There is no need to put a Service Class for every collection — one method could do that!

By 
Anis Hajri user avatar
Anis Hajri
·
Dec. 17, 18 · Tutorial
Likes (2)
Comment
Save
Tweet
Share
18.9K Views

Join the DZone community and get the full member experience.

Join For Free

In this post, we will create a generic method to search data in MongoDB database via MongoDB driver API. There is no need to put specific Service Class for every collection; one method could do that

  •  QueryParam: Class to specify field name, value, and operator (equal, greather than, etc.)
package com.ahajri.mongo.queries;

public class QueryParam{

  //collection field name
private String fieldName;
//Operator name 
private String operator;
//value 
private Object value;


public QueryParam(String fieldName, String operator, Object value) {
super();
this.fieldName = fieldName;
this.operator = operator;
this.value = value;
}

public String getFieldName() {
return fieldName;
}

public void setFieldName(String fieldName) {
this.fieldName = fieldName;
}

public String getOperator() {
return operator;
}

public void setOperator(String operator) {
this.operator = operator;
}

public Object getValue() {
return value;
}

public void setValue(Object value) {
this.value = value;
}



}


Operators are grouped in a Java enum, as shown below:

package com.ahajri.mongo.enums;

/**
 * 
 * @author ahajri
 * 
 * 
 *         <p>
 *         $eq Matches values that are equal to a specified value.
 *         </p>
 *         <p>
 *         $gt Matches values that are greater than a specified value.
 *         </p>
 *         <p>
 *         $gte Matches values that are greater than or equal to a specified
 *         value.
 *         </p>
 *         <p>
 *         $in Matches any of the values specified in an array.
 *         </p>
 *         <p>
 *         $lt Matches values that are less than a specified value.
 *         </p>
 *         <p>
 *         $lte Matches values that are less than or equal to a specified value.
 *         </p>
 *         <p>
 *         $ne Matches all values that are not equal to a specified value.
 *         </p>
 *         <p>
 *         $nin Matches none of the values specified in an array.
 *         </p>
 *
 */
public enum OperatorEnum {
EQ, GT, GTE, IN, LT, LTE, NE, NIN;
}


Now, let's explore our Mongo service accessor class; our database is supposed to be hosted on MLab, and application.yml contains the required information, as shown below:

mlab:
  db.host: ${MLAB_DB_HOST}
  db.name: ${MLAB_DB_NAME}
  db.user: ${MLAB_DB_USER}
  db.port: ${MLAB_DB_PORT}
  db.password: ${MLAB_DB_PASSWORD}
  api.key: ${MLAB_API_KEY}

spring:
  data.mongodb.uri: mongodb://${MLAB_DB_USER}:${MLAB_DB_PASSWORD}@${MLAB_DB_HOST}:${MLAB_DB_PORT}/${MLAB_DB_NAME}
  servlet.multipart.enabled: true
  servlet.multipart.file-size-threshold: 2KB
  servlet.multipart.max-file-size: 200MB
  servlet.multipart.max-request-size: 215MB


Our search method open and close the connection in an atomic way where we only give the collection name and array of the QueryParam class. It looks like this:

package com.ahajri.hc.mongo.cloud;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import javax.annotation.PostConstruct;

import org.bson.Document;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

import com.ahajri.mongo.enums.ErrorMessageEnum;
import com.ahajri.mongo.exception.MyException;
import com.ahajri.mongo.enums.QueryParam;
import com.ahajri.mongo.utils.JsonUtils;
import com.mongodb.MongoClient;
import com.mongodb.MongoClientURI;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.FindOneAndReplaceOptions;

/**
 * @author ahajri
 */
@Service
public class MLabMongoService {

private String cloudMongUrl;

private MongoDatabase db;

private MongoClient client;

@Value("${mlab.api.key}")
protected String apiKey;

@Value("${mlab.db.user}")
protected String dbUser;

@Value("${mlab.db.password}")
protected String dbPwd;

@Value("${mlab.db.name}")
protected String dbName;

@Value("${mlab.db.port}")
protected String dbPort;

@Value("${mlab.db.host}")
protected String dbHost;

public MLabMongoService() {
}

@PostConstruct
public void init() {
      //create MLab url connection 
  cloudMongUrl = "mongodb://" + dbUser + ":" + dbPwd + "@" + dbHost + ":" + dbPort + "/" + dbName;
}

/**
 * Open Mongo Connection
 */
private void begin() {
MongoClientURI uri = new MongoClientURI(cloudMongUrl);
client = new MongoClient(uri);
db = client.getDatabase(uri.getDatabase());
}



/**
 * 
 * Search document
 * 
 * @param collectionName:
 *            Collection name
 * @param qp
 *            : Query Parameters
 * @return list of found documents
 * @throws BusinessException
 */
public List<Document> search(String collectionName, QueryParam... qp) throws BusinessException {
try {
      begin();
      MongoCollection<Document> collection = db.getCollection(collectionName);
      List<Document> result = new ArrayList<>();
      Document query = new Document();
      Arrays.asList(qp).stream().forEach(p -> {
          String operator = p.getOperator();
          String fieldName = p.getFieldName();
          Object value = p.getValue();
          switch (operator) {
          case "EQ":
          query.append(fieldName, new Document().append("$eq", value));
          break;
          case "NE":
          query.append(fieldName, new Document().append("$ne", value));
          break;
          case "GT":
          query.append(fieldName, new Document().append("$gt", value));
          break;
          case "GTE":
          query.append(fieldName, new Document().append("$gte", value));
          break;
          case "LT":
          query.append(fieldName, new Document().append("$lt", value));
          break;
          case "LTE":
          query.append(fieldName, new Document().append("$lte", value));
          break;
          case "IN":
          query.append(fieldName, new Document().append("$in", value));
          break;
          case "NIN":
          query.append(fieldName, new Document().append("$nin", value));
          break;
          default:
          break;
          }

});

  FindIterable<Document> iterable = collection.find(query);
    if (iterable.first() == null) {
    throw new Exception(ErrorMessageEnum.FIND_DOCUMENT_KO.getMessage());
    }
    for (Document document : iterable) {
    result.add(document);
    }

close();
return result;

  } catch (Exception e) {
          throw new MyException(e, ErrorMessageEnum.FIND_DOCUMENT_KO.getMessage());
  }
}


  private void close() {
      if (client != null) {
          client.close();
      }
  }

}


To test the method,QueryParams must be provided in a programmatically. For example:

QueryParam[] qps = new QueryParam[1];

qps[0] = new QueryParam("email", OperatorEnum.EQ.name(), "[email protected]");


Hope this was helpful!

MongoDB Java (programming language)

Opinions expressed by DZone contributors are their own.

Related

  • How to Identify the Underlying Causes of Connection Timeout Errors for MongoDB With Java
  • Achieving Inheritance in NoSQL Databases With Java Using Eclipse JNoSQL
  • Powering Enterprise Applications: Unleashing the Java-MongoDB Synergy
  • Java and MongoDB Integration: A CRUD Tutorial [Video Tutorial]

Partner Resources

×

Comments

The likes didn't load as expected. Please refresh the page and try again.

ABOUT US

  • About DZone
  • Support and feedback
  • Community research
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Core Program
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 3343 Perimeter Hill Drive
  • Suite 100
  • Nashville, TN 37211
  • [email protected]

Let's be friends: