I new in java and try to use spring framework. I have a question.
By example, I have table :
employee (id_employee, name)
employee_product (id_employee_product, id_employee, product_name)
if I select an employee data from my Employee table, I can map it in a POJO model User and define the tables structure in that model, like this:
public class Employee {
private final int id_employee;
private final String nama;
public Employee(int id_employee, String nama){
this.id_employee = id_employee;
this.nama = nama;
}
public int getId() {
return id_employee;
}
public String getNama() {
return nama;
}
}
And this is the map from jdbcTemplate:
final String sql = "SELECT id_employee, nama FROM employee";
return jdbcTemplate.query(sql, (resultSet, i) -> {
return new Employee(
resultSet.getInt("id_employee"),
resultSet.getString("nama")
);
});
That is clear example for select data from 1 table.
My question is, how to map data from query if my data is custom query? Such us using join and select custom field from that tables, Am I need to create POJO every query?
Sometimes I need to select only employee.id_employee, and employee.name field from my employee table.
And in another controller I need to select employee.id_employee from my employee table.
In another case, I need only select employee.name, and employee_product.product_name
Is there an alternative to map the data without creating POJO for every case?
Create a one POJO combining two tables like this
public class Employee {
private int id_employee;
private String name;
private int id_employee_product.
private String product_name
//getter and setters
//Don't create a constructor its Entiry
}
Now by using a BeanPropertyRowMapper Doc Link write your repository like
public List<Employee> fetchEmployeeProduct(){
JdbcTemplate jdbcTemplate = new JdbcTemplate("Your_DataSource");
StringBuilder query = new StringBuilder();
query.append("Your Query");
List<Employee> employeeProductList =
jdbcTemplate.query(query.toString(), new BeanPropertyRowMapper<Employee>(Employee.class));
}
Make sure SELECT clause in the query and Employee POJO's filed name is same.
Once if you execute your query it will automatically map to POJO. You no need to write a custom mapper BeanPropertyRowMapperwill take care of mapping.
I have a Spring Boot app with DataTables server-side processing and Oracle database. Actually, I started with implementing one of the tutorials. It worked. The tutorial uses JPA. I want to implement the same using JDBC. I made all the corresponding classes, the repository, the new model with same filds but without jpa. But when I tried to fetch the data, it allowed me to get only the first page without a chance to get to the second page. Below I will post the extracts of the original and added code. So, the original tutorial used these classes:
#Entity
#Table(name = "MYUSERS")
public class User {
#Id
#Column(name = "USER_ID")
private Long id;
#Column(name = "USER_NAME")
private String name;
#Column(name = "SALARY")
private String salary;
...getters and setters
}
And
#Entity
public class UserModel {
#Id
private Long id;
private String name;
private String salary;
private Integer totalRecords;
#Transient
private Integer rn;
...getters and setters
}
And I substituted these two classes with one like this:
public class NewUser {
private Long id;
private String name;
private String salary;
private Integer totalRecords;
private Integer rn;
...getters and setters
}
The table itself has only 3 fields: id, name and salary, the other 2 fields are created and filled later.
The repositiry the original Author has for the user looks like this:
public interface UserRepository extends JpaRepository<User, Long> {
#Query(value = "SELECT * FROM MYUSERS", nativeQuery = true)
List<User> findAllByUsernames(List<String> listOfUsernames);
}
My own repository looks like this:
#Repository
public class NewUserRepoImpl extends JdbcDaoSupport implements NewUserRepo {
private static final String SELECT_ALL_SQL = "SELECT USER_ID as id, USER_NAME as name, SALARY as salary FROM MYUSERS";
private final NamedParameterJdbcTemplate namedParameterJdbcTemplate;
private final JdbcTemplate jdbctemplate;
public NewUserRepoImpl(NamedParameterJdbcTemplate namedParameterJdbcTemplate, JdbcTemplate jdbctemplate, DataSource dataSource) {
this.namedParameterJdbcTemplate = namedParameterJdbcTemplate;
this.jdbctemplate = jdbctemplate;
setDataSource(dataSource);
}
#Override
public List<NewUser> findAll(PaginationCriteria pagination) {
try {
String paginatedQuery = AppUtil.buildPaginatedQueryForOracle(SELECT_ALL_SQL, pagination);
return jdbctemplate.query(paginatedQuery, newUserRowMapper());
} catch (DataAccessException e) {
throw new EntityNotFoundException("No Entities Found");
}
}
#Bean
public RowMapper<NewUser> newUserRowMapper() {
return (rs, i) -> {
final NewUser newUser = new NewUser();
newUser.setId(rs.getLong("ID"));
newUser.setName(rs.getString("NAME"));
newUser.setSalary(rs.getString("SALARY"));
newUser.setTotalRecords(rs.getInt("TOTAL_RECORDS"));
newUser.setTotalRecords(rs.getInt("RN"));
return newUser;
};
}
}
the buildPaginatedQueryForOracle thing transforms my Query and allows it to get the totalRecords and rn. Below I will post the output of it both for the orifinal and my queries (they are the same, I checked).
So, the main part, the controller. I left the old and new pieces in it for now for debug purposes and just returning one of the results:
#RequestMapping(value="/users/paginated/orcl", method=RequestMethod.GET)
#ResponseBody
public String listUsersPaginatedForOracle(HttpServletRequest request, HttpServletResponse response, Model model) {
DataTableRequest<User> dataTableInRQ = new DataTableRequest<User>(request);
System.out.println(new Gson().toJson(dataTableInRQ));
DataTableRequest<NewUser> dataTableInRQNew = new DataTableRequest<NewUser>(request);
System.out.println(new Gson().toJson(dataTableInRQNew));
PaginationCriteria pagination = dataTableInRQ.getPaginationRequest();
System.out.println(new Gson().toJson(pagination));
PaginationCriteria paginationNew = dataTableInRQNew.getPaginationRequest();
System.out.println(new Gson().toJson(paginationNew));
String baseQuery = "SELECT USER_ID as id, USER_NAME as name, SALARY as salary FROM MYUSERS";
String paginatedQuery = AppUtil.buildPaginatedQueryForOracle(baseQuery, pagination);
String paginatedQueryNew = AppUtil.buildPaginatedQueryForOracle(baseQuery, paginationNew);
System.out.println(paginatedQuery);
System.out.println(paginatedQueryNew);
Query query = entityManager.createNativeQuery(paginatedQuery, UserModel.class);
System.out.println("Query:");
System.out.println(query);
#SuppressWarnings("unchecked")
List<UserModel> userList = query.getResultList();
System.out.println(new Gson().toJson(userList));
#SuppressWarnings("unchecked")
List<NewUser> userListNew = newUserRepo.findAll(paginationNew);
System.out.println(new Gson().toJson(userListNew));
DataTableResults<UserModel> dataTableResult = new DataTableResults<UserModel>();
DataTableResults<NewUser> dataTableResultNew = new DataTableResults<NewUser>();
dataTableResult.setDraw(dataTableInRQ.getDraw());
dataTableResultNew.setDraw(dataTableInRQNew.getDraw());
dataTableResult.setListOfDataObjects(userList);
dataTableResultNew.setListOfDataObjects(userListNew);
if (!AppUtil.isObjectEmpty(userList)) {
dataTableResult.setRecordsTotal(userList.get(0).getTotalRecords()
.toString());
if (dataTableInRQ.getPaginationRequest().isFilterByEmpty()) {
dataTableResult.setRecordsFiltered(userList.get(0).getTotalRecords()
.toString());
} else {
dataTableResult.setRecordsFiltered(Integer.toString(userList.size()));
}
}
if (!AppUtil.isObjectEmpty(userListNew)) {
dataTableResultNew.setRecordsTotal(userListNew.get(0).getTotalRecords()
.toString());
if (dataTableInRQ.getPaginationRequest().isFilterByEmpty()) {
dataTableResultNew.setRecordsFiltered(userListNew.get(0).getTotalRecords()
.toString());
} else {
dataTableResultNew.setRecordsFiltered(Integer.toString(userListNew.size()));
}
}
System.out.println(new Gson().toJson(dataTableResult));
System.out.println(new Gson().toJson(dataTableResultNew));
return new Gson().toJson(dataTableResult);
}
So, I log out everything possible in the console. Here is the output:
{"uniqueId":"1579786571491","draw":"1","start":0,"length":5,"search":"","regex":false,"columns":[{"index":0,"data":"id","name":"ID","searchable":true,"orderable":true,"search":"","regex":false,"sortDir":"ASC"},{"index":1,"data":"name","name":"Name","searchable":true,"orderable":true,"search":"","regex":false},{"index":2,"data":"salary","name":"Salary","searchable":true,"orderable":true,"search":"","regex":false}],"order":{"index":0,"data":"id","name":"ID","searchable":true,"orderable":true,"search":"","regex":false,"sortDir":"ASC"},"isGlobalSearch":false,"maxParamsToCheck":3}
{"uniqueId":"1579786571491","draw":"1","start":0,"length":5,"search":"","regex":false,"columns":[{"index":0,"data":"id","name":"ID","searchable":true,"orderable":true,"search":"","regex":false,"sortDir":"ASC"},{"index":1,"data":"name","name":"Name","searchable":true,"orderable":true,"search":"","regex":false},{"index":2,"data":"salary","name":"Salary","searchable":true,"orderable":true,"search":"","regex":false}],"order":{"index":0,"data":"id","name":"ID","searchable":true,"orderable":true,"search":"","regex":false,"sortDir":"ASC"},"isGlobalSearch":false,"maxParamsToCheck":3}
{"pageNumber":0,"pageSize":5,"sortBy":{"mapOfSorts":{"id":"ASC"}},"filterBy":{"mapOfFilters":{},"globalSearch":false}}
{"pageNumber":0,"pageSize":5,"sortBy":{"mapOfSorts":{"id":"ASC"}},"filterBy":{"mapOfFilters":{},"globalSearch":false}}
SELECT * FROM (SELECT FILTERED_ORDERED_RESULTS.*, COUNT(1) OVER() total_records, ROWNUM AS RN FROM (SELECT BASEINFO.* FROM ( SELECT USER_ID as id, USER_NAME as name, SALARY as salary FROM MYUSERS ) BASEINFO ) FILTERED_ORDERED_RESULTS ORDER BY id ASC ) WHERE RN > (0 * 5) AND RN <= (0 + 1) * 5
SELECT * FROM (SELECT FILTERED_ORDERED_RESULTS.*, COUNT(1) OVER() total_records, ROWNUM AS RN FROM (SELECT BASEINFO.* FROM ( SELECT USER_ID as id, USER_NAME as name, SALARY as salary FROM MYUSERS ) BASEINFO ) FILTERED_ORDERED_RESULTS ORDER BY id ASC ) WHERE RN > (0 * 5) AND RN <= (0 + 1) * 5
Query:
org.hibernate.query.internal.NativeQueryImpl#3ea49a4
[{"id":3,"name":"user3","salary":"300","totalRecords":18},{"id":4,"name":"user4","salary":"400","totalRecords":18},{"id":5,"name":"user5","salary":"500","totalRecords":18},{"id":6,"name":"user6","salary":"600","totalRecords":18},{"id":7,"name":"user7","salary":"700","totalRecords":18}]
[{"id":3,"name":"user3","salary":"300","totalRecords":1},{"id":4,"name":"user4","salary":"400","totalRecords":2},{"id":5,"name":"user5","salary":"500","totalRecords":3},{"id":6,"name":"user6","salary":"600","totalRecords":4},{"id":7,"name":"user7","salary":"700","totalRecords":5}]
{"draw":"1","recordsFiltered":"18","recordsTotal":"18","data":[{"id":3,"name":"user3","salary":"300","totalRecords":18},{"id":4,"name":"user4","salary":"400","totalRecords":18},{"id":5,"name":"user5","salary":"500","totalRecords":18},{"id":6,"name":"user6","salary":"600","totalRecords":18},{"id":7,"name":"user7","salary":"700","totalRecords":18}]}
{"draw":"1","recordsFiltered":"1","recordsTotal":"1","data":[{"id":3,"name":"user3","salary":"300","totalRecords":1},{"id":4,"name":"user4","salary":"400","totalRecords":2},{"id":5,"name":"user5","salary":"500","totalRecords":3},{"id":6,"name":"user6","salary":"600","totalRecords":4},{"id":7,"name":"user7","salary":"700","totalRecords":5}]}
It helped me realize that:
DataTableRequest incoming from the back is the same for both jpa
and jdbc
PaginationCriteria are also the same
paginatedQuery
having been made with the method specified above are the same.
Differences are already seen in the Lists: where the Jpa list
retrieved with native Query has totalRecords as 18 for every row,
the JDBC repo with the same query returns 1,2,3... for every
subsequent row.
It made me think that I should look at the Query made for JPA. But, as you see in the log, System.out.println wasn't able to decipher it for some reason.
Any advice on how to decipher it and more importantly how to get the right total result for each row would be greatly appreciated!!!
I have one method which must return data in DAO.
Department model:
public class Department implements Serializable {
private Long id;
private String departmentName;
private List<Employees> employeesInThisDepartment;
// getters and setters...
}
Employees model:
public class Employees implements Serializable {
private Long id;
private String department;
private String fullName;
private Date birthday;
private int salary;
// getters and setters...
}
And method in DAO:
#Override
public Department findByDepartmentNameWithEmployees(String departmentName) {
String sql = "select d.id, d.departmentName, e.id, e.fullName, e.department, e.birthday" +
", e.salary from department as d left join employees as e on d.departmentName = e.department " +
"where lower(d.departmentName) = lower(:departmentName)";
Map<String, Object> map = new HashMap<>();
map.put("departmentName", departmentName);
return jdbcTemplate.queryForObject(sql, map, (rs, rowNum) -> {
Department department = new Department();
department.setId(rs.getLong("department.id"));
department.setDepartmentName(rs.getString("department.departmentName"));
department.setEmployeesInThisDepartment(new ArrayList<>());
while (rs.next()){
Employees employees = new Employees();
employees.setId(rs.getLong("employees.id"));
employees.setFullName(rs.getString("employees.fullName"));
employees.setDepartment(rs.getString("employees.department"));
employees.setBirthday(rs.getDate("employees.birthday"));
employees.setSalary(rs.getInt("employees.salary"));
department.getEmployeesInThisDepartment().add(employees);
}
return department;
});
}
This method must return one department with list of all employees who works in this department, but it misses the first employee in the list.
Why is this happening? (SQL part is working correctly, I think that the problem is with the loop?)
Right, problem in the loop. According to docs:
Implementations must implement this method to map each row of data in
the ResultSet.
So you do not need to invoke rs.next(), just remove this loop wrapper and move block
Department department = new Department();
department.setEmployeesInThisDepartment(new ArrayList<>());
outside return jdbcTemplate.queryForObject(sql, map, (rs, rowNum) -> { ... }. I.e.:
Department department = new Department();
department.setEmployeesInThisDepartment(new ArrayList<>());
jdbcTemplate.queryForObject(sql, map, (rs, rowNum) -> {
department.setId(rs.getLong("department.id"));
department.setDepartmentName(rs.getString("department.departmentName"));
Employees employees = new Employees();
employees.setId(rs.getLong("employees.id"));
employees.setFullName(rs.getString("employees.fullName"));
employees.setDepartment(rs.getString("employees.department"));
employees.setBirthday(rs.getDate("employees.birthday"));
employees.setSalary(rs.getInt("employees.salary"));
department.getEmployeesInThisDepartment().add(employees);
});
return department;
I am using Spring MVC with JdbcTemplate and a MySQL database.
Say I have the following 2 tables :
table_school
ID NAME
table_students
ID NAME ADDRESS SCHOOL_ID
I have a School POJO that has the following class variables :
int id, String name, List<Student> students
Is there a way of retrieving a List with each School object containing the appropriate List of Student objects using JdbcTemplate in one query? I know this is easily achievable using Hibernate but I would like to use JdbcTemplate ..
Many thanks !
Yes, you can fetch all data in 1 query.
Simple example:
class Student {
int id;
String name;
String addr;
Student(int id, String name, String addr) {
this.addr = addr;
this.id = id;
this.name = name;
}
}
class School {
int id;
String name;
List<Student> students = new ArrayList<>();
School(int id, String name) {
this.id = id;
this.name = name;
}
void addStudent(Student s) {
students.add(s);
}
}
/*
* helper method that gets school from map or create if not present
*/
private School getSchool(Map<Integer, School> schoolMap, int id, String name) {
School school = schoolMap.get(id);
if (school == null) {
school = new School(id, name);
schoolMap.put(id, school);
}
return school;
}
// RUN QUERY
String sql =
" select st.ID, st.NAME, st.ADDRESS. s.id, s.name" +
" from table_students st" +
" inner join table_school s on st.school_id = s.id";
final Map<Integer, School> schoolMap = new HashMap<>();
jdbcTemplate.query(sql, new RowCallbackHandler() {
#Override
public void processRow(ResultSet rs) throws SQLException {
int studentId = rs.getInt(1);
String studentName = rs.getString(2);
String studentAddr = rs.getString(3);
int schoolId = rs.getInt(4);
String schoolName = rs.getString(5);
Student student = new Student(studentId, studentName, studentAddr);
getSchool(schoolMap, schoolId, schoolName).addStudent(student);
}
});
One final point regarding fetching performance:
If you expect many records to fetch it is nearly always a good idea to increase jdbc fetch size parameter. So before run query set it on your jdbcTemplate:
jdbcTemplate.setFetchSize(200); // you can experiment with this value
or if you are using spring's JdbcDaoSupport you can use such pattern:
public class MyDao extends JdbcDaoSupport {
....
#Override
protected void initTemplateConfig() {
getJdbcTemplate().setFetchSize(200);
}
}
I'm trying to execute a simple stored procedure with Spring/Hibernate using Annotations.
Here are my code snippets:
DAO class:
public class UserDAO extends HibernateDaoSupport {
public List selectUsers(final String eid){
return (List) getHibernateTemplate().execute(new HibernateCallback() {
public Object doInHibernate(Session session) throws
HibernateException, SQLException
{
Query q = session.getNamedQuery("SP_APPL_USER");
System.out.println(q);
q.setString("eid", eid);
return q.list();
}
});
}
}
my entity class:
#Entity
#Table(name = "APPL_USER")
#Inheritance(strategy = InheritanceType.SINGLE_TABLE)
#DiscriminatorFormula(value = "SUBSCRIBER_IND")
#DiscriminatorValue("N")
#NamedQuery(name = "req.all", query = "select n from Requestor n")
#org.hibernate.annotations.NamedNativeQuery(name = "SP_APPL_USER",
query = "call SP_APPL_USER(?, :eid)", callable = true, readOnly = true, resultClass = Requestor.class)
public class Requestor {
#Id
#Column(name = "EMPL_ID")
public String getEmpid() {
return empid;
}
public void setEmpid(String empid) {
this.empid = empid;
}
#Column(name = "EMPL_FRST_NM")
public String getFirstname() {
return firstname;
}
...
}
public class Test {
public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext(
"applicationContext.xml");
APFUser user = (APFUser)ctx.getBean("apfUser");
List selectUsers = user.getUserDAO().selectUsers("EMP456");
System.out.println(selectUsers);
}
}
and the stored procedure:
create or replace PROCEDURE SP_APPL_USER (p_cursor out sys_refcursor, eid in varchar2)
as
empId varchar2(8);
fname varchar2(50);
lname varchar2(50);
begin
empId := null;
fname := null;
lname := null;
open p_cursor for
select l.EMPL_ID, l.EMPL_FRST_NM, l.EMPL_LST_NM
into empId, fname, lname
from APPL_USER l
where l.EMPL_ID = eid;
end;
If i enter invalid EID, its returning empty list which is OK.
But when record is there, following exception is thrown:
Exception in thread "main" org.springframework.jdbc.BadSqlGrammarException: Hibernate operation: could not execute query; bad SQL grammar [call SP_APPL_USER(?, ?)]; nested exception is java.sql.SQLException: Invalid column name
Do I need to modify the entity(Requestor.class) ?
How will the REFCURSOR be converted to the List?
The stored procedure is expected to return more than one record.
That's because of the bug in the hibernate.
I've modified the stored procedure to fetch all the columns and it worked well.