@Configuration<\/code> class and XML based configuration both.<\/li>\n- Data Access exception hierarchy of Spring is used for translation of exception.<\/li>\n
- Integrated mapping between Java’s POJO and MongoDB’s document.<\/li>\n
MongoTemplate<\/code> class that makes it easy to use common MongoDB operations.<\/li>\n- In Addition to
MongoTemplate<\/code>, MongoReader<\/code> and MongoWriter<\/code> classes for low-level of Mapping.<\/li>\n<\/ol>\nThe best way to understand any technology is by practicing it and we are going to do the same now.<\/p>\n
Let’s now do a simple program to understand Spring Data MongoDB in detail.<\/p>\n
2. Technologies and Tools<\/h2>\n
Let us look at the technologies and tool used for building the program.<\/p>\n
\n- Eclispe\u00a0Oxygen.2 Release (4.7.2)<\/li>\n
- Java – version 9.0.4<\/li>\n
- Gradle – 4.6<\/li>\n
- MongoDB server – 3.6<\/li>\n
- MongoCompass – 3.6<\/li>\n
- SpringDataMongoDB – 2.0.5-RELEASE<\/li>\n<\/ol>\n
3. Project Structure<\/h2>\n
Our project structure will look as shown below.<\/p>\n
![\"\"](\"http:\/\/www.javacodegeeks.com\/wp-content\/uploads\/2018\/03\/ProjectStructure_JCG.jpg\")
<\/a>Project Structure for SpringDataMongoDB<\/figcaption><\/figure><\/p>\nGradle project structure will have above shown project structure. In case of pom.xml the project structure will differ slightly.<\/p>\n
4. The Program<\/h2>\n
As part of this program we will try to accomplish below mentioned objectives.<\/p>\n
\n- Save object to MongoDB<\/li>\n
- Update object in MongoDB<\/li>\n
- Remove object from MongoDB<\/li>\n
- Get all objects from MongoDB<\/li>\n<\/ol>\n
Let’s now understand all the components of the program. First of all we will start with the program dependencies and the jars that are needed for the program.<\/p>\n
4.1 Gradle<\/h3>\n
We are using Gradle for build as part of the program. The build.gradle<\/code> file will look as shown below.<\/p>\nbuild.gradle<\/em><\/span><\/p>\napply plugin: 'java'\nrepositories {\n mavenCentral()\n}\n\ndependencies {\n compile group: 'org.springframework.data', name: 'spring-data-mongodb', version: '2.0.5.RELEASE'\n implementation 'com.google.guava:guava:23.0'\n testImplementation 'junit:junit:4.12'\n}\n\n<\/pre>\nIn the above build.gradle<\/code> file apply plugin: 'java'<\/code> tells us the plugin that needs to be set. For us it is Java plugin.
\nrepositories{}<\/code> lets us know the repository from which the dependency should be pulled. We have chosen mavenCentral<\/code> to pull the dependency jars. We can use jcenter<\/code> also for pulling the respective dependency jars.
\ndependencies {}<\/code> tag is used to provide necessary jar file details that should be pulled for the project.<\/p>\n4.2 Configuration for MongoDB<\/h3>\n
In order to use MongoDB configuration we need to implement\u00a0AbstractMongoConfiguration<\/code> class. The MongoConfig.java<\/code> class will look as shown below. We are using annotations here instead of xml. But, even XML can also be used for the purpose of setting the configuration.<\/p>\nMongoConfig.java class implementation<\/em><\/span><\/p>\npackage com.tutorial.config;\n\nimport org.springframework.context.annotation.Bean;\nimport org.springframework.context.annotation.Configuration;\nimport org.springframework.data.mongodb.config.AbstractMongoConfiguration;\nimport com.mongodb.MongoClient;\n\n@Configuration\npublic class MongoConfig extends AbstractMongoConfiguration {\n\n\t@Override\n\tpublic String getDatabaseName() {\n\t\treturn \"local\";\n\t}\n\n\t@Override\n\t@Bean\n\tpublic MongoClient mongoClient() {\n\t\treturn new MongoClient(\"127.0.0.1\");\n\t}\n}\n<\/pre>\nThe @Configuration<\/code> is used to define the class MongoConfig.java<\/code> as the configuration class. @Bean<\/code> defines the MongoClient<\/code> bean. <\/div> <\/div><\/p>\n4.3 Model class<\/h3>\n
We will now look at the model class. We are using student.java<\/code> as the model class which contains attributes for Student like Name and age. The Student.java<\/code> model class is used for mapping POJO to the MongoDB collection.<\/p>\nModel class for Student<\/em><\/span><\/p>\npackage com.tutorial.model;\n\nimport org.springframework.data.annotation.Id;\nimport org.springframework.data.mongodb.core.mapping.Document;\n\n@Document(collection = \"students\")\npublic class Student {\n\tpublic Student(String studentName, int studentAge) {\n\t\tthis.studentName = studentName;\n\t\tthis.studentAge = studentAge;\n\t}\n\t@Id\n\tprivate String id;\n\tString studentName;\n\tint studentAge;\n\n public String getStudentName() {\n\t\treturn studentName;\n\t}\n\n\tpublic void setStudentName(String studentName) {\n\t\tthis.studentName = studentName;\n\t}\n\n\tpublic int getStudentAge() {\n\t\treturn studentAge;\n\t}\n\n\tpublic void setStudentAge(int studentAge) {\n\t\tthis.studentAge = studentAge;\n\t}\n\n\t@Override\n public String toString() {\n return String.format(\n \"Student[id=%s, studentName='%s', studentAge=\"+studentAge+\"]\",\n id, studentName);\n } \n}\n<\/pre>\n@Document<\/code>\u00a0 defines the document. The property collection<\/code> defines the collection which will be used for mapping with the collection. All the attributes that are mentioned as part of the collection should be available in the POJO class. @Id<\/code>\u00a0defines the id of the collection.<\/p>\n4.4 CRUD operations<\/h3>\n
To perform CRUD operations like saving data, updating data, removing data and getting the data from MongoDB we will use MongoOperations<\/code>.<\/p>\nNow let’s look at the MongoDBPOperations.java<\/code> class. This class contains implementation for all the methods for CRUD operations.<\/p>\nMongoDBPOperations class which will be used for performing CRUD operations<\/em><\/span><\/p>\npackage com.tutorial;\n\nimport java.util.List;\n\nimport org.springframework.data.mongodb.core.MongoOperations;\nimport org.springframework.data.mongodb.core.query.Criteria;\nimport org.springframework.data.mongodb.core.query.Query;\nimport org.springframework.data.mongodb.core.query.Update;\n\nimport com.tutorial.model.Student;\n\npublic class MongoDBPOperations {\n\npublic void saveStudent(MongoOperations mongoOperation, Student student) {\n\t\t\n\t\tmongoOperation.save(student);\n\t\tSystem.out.println(\"Student saved successfully\");\n\t\t\/\/ student object got created with id.\n\t\tSystem.out.println(\"student : \" + student);\n\t}\n\t\n\tpublic void searchStudent(MongoOperations mongoOperation, String critera,String value) {\n\t\t\/\/ query to search student\n\t\tQuery searchStudent = new Query(Criteria.where(critera).is(value));\n\n\t\t\/\/ find student based on the query\n\t\tStudent resultStudent = mongoOperation.findOne(searchStudent, Student.class);\n\t\tSystem.out.println(\"Student found!!\");\n\t\tSystem.out.println(\"Student details: \" + resultStudent);\n\t}\n\t\n\tpublic void updateStudent(MongoOperations mongoOperation, String critera,String value, String updateCriteria, String updateValue) {\n\t\t\/\/ query to search student\n\t\tQuery searchStudent = new Query(Criteria.where(critera).is(value));\n\t\tmongoOperation.updateFirst(searchStudent, Update.update(updateCriteria, updateValue),\n\t\t\t\tStudent.class);\n\t\tSystem.out.println(\"Student got updated successfully\");\n\t}\n\tpublic void getAllStudent(MongoOperations mongoOperation) {\n\t\tList listStudent = mongoOperation.findAll(Student.class);\n\t\tfor(Student student:listStudent) {\n\t\tSystem.out.println(\"Student = \" + student);\n\t\t}\n\t}\n\tpublic void removeStudent(MongoOperations mongoOperation, String critera,String value) {\n\t\tQuery searchStudent = new Query(Criteria.where(critera).is(value));\n\t\tmongoOperation.remove(searchStudent, Student.class);\n\t\tSystem.out.println(\"Student removed successfully!! \");\n\t}\n}\n<\/pre>\nThe most important class of a Java program is the class that contains the main method.
\n[ulp id=’c4qGwqz2zZ7CesZd’]
\n <\/p>\n
4.5 Application class<\/h3>\n
The main class which contains the main method is the Application.java<\/code> class. We will use this class to call methods from MongoDBPOperations<\/code> class.<\/p>\nApplication class for calling methods of MongoDBPOperations class<\/em><\/span><\/p>\npackage com.tutorial;\n\nimport org.springframework.context.ApplicationContext;\nimport org.springframework.context.annotation.AnnotationConfigApplicationContext;\nimport org.springframework.data.mongodb.core.MongoOperations;\nimport com.tutorial.config.MongoConfig;\nimport com.tutorial.model.Student;\n\n\npublic class Application {\n\t\n\tpublic static void main (String[] args) {\n\t\t\n \t \t\n\t\t\/\/ For Annotation\n\t\t\t\tApplicationContext ctx = new AnnotationConfigApplicationContext(MongoConfig.class);\n\t\t\t\tMongoOperations mongoOperation = (MongoOperations) ctx.getBean(\"mongoTemplate\");\n\t\t\t\tMongoDBPOperations ops = new MongoDBPOperations();\n\n\t\t\t\tStudent student = new Student(\"John\", 15);\n\t\t\t\t\n\t\t\t\t\/\/save student\n\t\t\t\tops.saveStudent(mongoOperation, student);\n\n\t\t\t\t\/\/ get student based on search criteria\n\t\t\t\tops.searchStudent(mongoOperation, \"studentName\", \"John\");\n\t\t\t\t\n\t\t\t\t\/\/update student based on criteria\n\t\t\t\tops.updateStudent(mongoOperation, \"StudentName\", \"John\", \"studentAge\", \"18\");\n\t\t\t\t\/\/ get student based on search criteria\n\t\t\t\tops.searchStudent(mongoOperation, \"studentName\", \"John\");\n\t\t\t\t\n\t\t\t\t\/\/ get all the students\n\t\t\t\tops.getAllStudent(mongoOperation);\n\t\t\t\t\n\t\t\t\t\/\/remove student based on criteria\n\t\t\t\tops.removeStudent(mongoOperation, \"studentName\", \"John\");\n\t\t\t\t\/\/ get all the students\n\t\t\t\tops.getAllStudent(mongoOperation);\n\t\t\t\t\n\n }\n\t\n\t\n\n}\n<\/pre>\nLet us look a step by step operation that are performed in the Application.java<\/code> class:<\/p>\n\n- We are creating
ApplicationContext<\/code>. This is due to the need of loading the configuration.<\/li>\n- In addition,
MongoOperations<\/code> object is created to load MongoTemplate<\/code> bean.<\/li>\nMongoDBOperations<\/code> object provides access to the methods to perform different MongoOperation<\/code> methods.<\/li>\n- Furthermore Create a Student object with Name John and Age as 15.<\/li>\n
- We are calling the
saveMethod<\/code> of\u00a0MongoDBOperations<\/code> and we will pass the necessary parameters for saving the object in the Database.<\/li>\n- Similarly we are calling different methods of
MongoDBOperations<\/code> one by one.<\/li>\n<\/ol>\n4.6 Run the program<\/h3>\n
Finally let us now run the program as a java application. Right click on the Application.java -> Run as -> Java Application.<\/p>\n
Following result will appear on the console.<\/p>\n
![\"\"](\"http:\/\/www.javacodegeeks.com\/wp-content\/uploads\/2018\/03\/Console_JCG.jpg\")
<\/a>Console output after running the program<\/figcaption><\/figure><\/p>\nNow let us comment the command for removing object. MongoDB will store data successfully.<\/p>\n
Furthermore let us comment the line for removing the object as shown below.<\/p>\n
Application class after commenting remove methods<\/em><\/span><\/p>\npackage com.tutorial;\n\nimport org.springframework.context.ApplicationContext;\nimport org.springframework.context.annotation.AnnotationConfigApplicationContext;\nimport org.springframework.data.mongodb.core.MongoOperations;\nimport com.tutorial.config.MongoConfig;\nimport com.tutorial.model.Student;\n\n\npublic class Application {\n\t\n\tpublic static void main (String[] args) {\n\t\t\n \t \t\n\t\t\/\/ For Annotation\n\t\t\t\tApplicationContext ctx = new AnnotationConfigApplicationContext(MongoConfig.class);\n\t\t\t\tMongoOperations mongoOperation = (MongoOperations) ctx.getBean(\"mongoTemplate\");\n\t\t\t\tMongoDBPOperations ops = new MongoDBPOperations();\n\n\t\t\t\tStudent student = new Student(\"John\", 15);\n\t\t\t\t\n\t\t\t\t\/\/save student\n\t\t\t\tops.saveStudent(mongoOperation, student);\n\n\t\t\t\t\/\/ get student based on search criteria\n\t\t\t\tops.searchStudent(mongoOperation, \"studentName\", \"John\");\n\t\t\t\t\n\t\t\t\t\/\/update student based on criteria\n\t\t\t\tops.updateStudent(mongoOperation, \"StudentName\", \"John\", \"studentAge\", \"18\");\n\t\t\t\t\/\/ get student based on search criteria\n\t\t\t\tops.searchStudent(mongoOperation, \"studentName\", \"John\");\n\t\t\t\t\n\t\t\t\t\/\/ get all the students\n\t\t\t\tops.getAllStudent(mongoOperation);\n\t\t\t\t\n\t\t\t\t\/\/remove student based on criteria\n\t\t\t\t\/\/ops.removeStudent(mongoOperation, \"studentName\", \"John\");\n\t\t\t\t\/\/ get all the students\n\t\t\t\t\/\/ops.getAllStudent(mongoOperation);\n\t\t\t\t\n\n }\n\t\n\t\n\n}\n<\/pre>\nAs a result of change in the program let us re-run the program. The following will appear on the console.<\/p>\n