Tuesday, February 10, 2015

Custom Sql in Liferay

Today we will discuss Custom Sql/Sql query in Liferay


Liferay Service Builder create basic CRUD method but there are some scenarios when we have to write SQL query. For writing native SQL query we use the concept of Custom Query in Liferay. Before Reading this blog it is highly recommended to read my previous blog on  Service Builder in Detail.


Lets Start this step by step:-

Step 1:-Create service.xml
You can create service as mention in my previous article Service Builder in Detail .

service.xml




Step 2:-Create xml files for sql Query

Now create a folder custom-sql inside src and create default.xml in it.

default.xml(/WEB-INF/src/custom-sql/default.xml)

here we can write our sql query but for good maintanability we create seperate file student-custom-sql.xml and include in default.xml.

student-custom-sql.xml

  • Here we use sql id this is unique for each query.This id is used to fetch the query in method.
  • No need to write semicolon(;).
  • You can create one xml file for one entity and then include in default.xml.

Step 3:-Create xxxFinderImpl Class
Now create xxxFinderImpl class inside persistence in our case create StudentFinderImpl that extends BasePersistenceImpl and implements StudentFinder.

StudentFinderImpl.java

Initally it shows error because there is no StudentFinder interface.

Run Service builder

After this error is gone and StudentFinder interface is created which is blank.


StudentFinder.java
One more class StudentFinderUtil is also created .

StudentFinderUtil.java

Step 4:-Create method in xxxFinderImpl Class
Create method in this class and provide implementation.This is the main task where we fire query and get the result.

StudentFinderImpl.java

Explanation:-

1)CustomSQLUtil.get("studentBetweenQuery");
Here we fetch the sql query from xml file with the help of sql id. For different queries different id and method in this class.

2)queryObject.addEntity("Student", StudentImpl.class);
Here we add our entity to queryObject. If sql query belong to multiple tables than we have to add all the entities to query object.

3)return (List<Student>) queryObject.list();
Here we return List<Student> because our query return all records belong to Student table but if our query contain two or more table like in case of join then we return List<Object[]>.

Step 5:-Expose method to LocalServiceUtil Class
We can't directly call method from StudentFinderImpl or StudentFinderUtil . All method are call from xxxLocalServiceUtil
Class so first we create method in xxxLocalServiceImpl 

StudentLocalServiceImpl.java

Here this show error because StudentFinderUtil has not contain getStudentBetweenStudentId(start, end).

Run Service builder

Now error is gone coz this will create method in StudentFinder interface and StudentFinderUtil  Class also.Now StudentFinder and StudentFinderUtil become:-

StudentFinder.java

StudentFinderUtil.java

Now Both Contain  getStudentBetweenStudentId(int start, int end).

Note:-
Normally we first create method in interface then provide implementation in Impl class but in Liferay we provide implementation in xxxLocalServiceImpl first and Run service builder which create method in Inteface.

Step 6:-Call method from LocalServiceUtil Class
Now from your doView() or from jsp call your method as:-


You can download source code from Custom Sql in Liferay





Hope this will help....

Related Post:-

Liferay Service Builder in Detail

Custom Sql with two table in Liferay

Finder Method for Service Builder in Liferay

Many To Many Relationship mapping in Liferay Services

Liferay Service Builder in Detail

How to install Maven

Creating Portlet/Services using Maven







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