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CRUD in MongoDB & Spring Data

Now, since we have already been introduced to mongo and its server is setup. We shall now move on to performing basic CRUD operations.
Lets take a use case example of ‘Company’ database that stores employee information. 

We wish to store employee name, email address, age and multiple addresses. Traditionally in RDBMS we would create an Employee table and Address Table having foreign key reference to ‘employee id ‘




Incase of NoSQL, we will be creating Employee documnet which will have store employee information like name, email, age and an array of employes address. Following is a snippet of the schema defined
{
"name" : "",
"email" : "",
"age" : “”,
"address" : [ ... ]
}
Thus to begin with, we will first define the entities. We have employee as an aggregate root entity that stores list of address having 1-M relatioship. Address Entity is represend as @Embeddable as it is embaded in another aggregate root entity. Employee is represented as @Document as the object to presist. The Employees id property is annotated with @Id so that JPA will recognize it as the object’s ID. The id property is also annotated with @GeneratedValue to indicate that the ID should be generated automatically.

Employee.java

Address.java

We have to specify the server host & port in the configuration file here localhost : 27017. Mongo Template offers convenience to create, update, delete and query for MongoDB documents and provides a mapping between your domain objects and MongoDB documents.Here, we will be creating & mapping employee bean which is our domain object.

ApplicationContext.xml

Now creating repository interface with CRUD methods.
 


EmployeeRepository.java
EmployeeRepositoryImpl.java





EmployeeMain.java

We shall also define a web service that would return the list of all employees and also an employee by id


EmployeeWS.java

EmployeeWSImpl.java

You can also find the complete source code at  https://github.com/meta-magic/MongoDB.git

Output
Displaying all Employees [
******************************************************************
     Employee Information :=1, name:=aaa, age:=10, email:= a@y.com
      Employee Address
     Address :=home addr, pin:=22235  
     Address :=ofc addr, pin:=21345    ,
******************************************************************
     Employee Information :=2, name:=bbb, age:=3, email:= b@y.com
      Employee Address
     Address :=home addr 2, pin:=22235  
     Address :=ofc addr 2, pin:=21345    ]
Find Employee with EMPID:1
******************************************************************
     Employee Information :=1, name:=aaa, age:=10, email:= a@y.com
      Employee Address
     Address :=home addr, pin:=22235  
     Address :=ofc addr, pin:=21345  
Displaying all Employees after update EMPID:1[
******************************************************************
     Employee Information :=1, name:=abc, age:=10, email:= a@y.com
      Employee Address
     Address :=home addr, pin:=22235  
     Address :=ofc addr, pin:=21345    ,
******************************************************************
     Employee Information :=2, name:=bbb, age:=3, email:= b@y.com
      Employee Address
     Address :=home addr 2, pin:=22235  
     Address :=ofc addr 2, pin:=21345    ]
Displaying all Employees after deleting EMPID:2 [
******************************************************************
     Employee Information :=1, name:=zzz, age:=10, email:= a@y.com
      Employee Address
     Address :=home addr, pin:=22235  
     Address :=ofc addr, pin:=21345    ]

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