Customize queries in toplink

Question

Hi,
I am new to oracle Toplink. I have created objects for few tables in my project. Instead of standard findall, merge queries, I need to write my own query.
Could somebody help me to do this please?

Answer 1

Hi,
You can create Named Queries in Toplink and Define the Query of your requirement.
If you want achieve that using API,below is sample code
SQLCall call = new SQLCall();
call.setSQLString("SELECT * FROM EMPLOYEE where empname=?");
Enumeration employees = getEmployeeHome().findAll(call);
You can define the Named query using the ExpressionBuilder API as given below
ExpressionBuilder exp = new ExpressionBuilder();
ReadAllQuery = new ReadAllQuery();
query.setReferenceClass(Customer.class);
query.setSelectionCriteria(exp.get("city").equal(exp.getParameter("city")));
query.addArgument("city");
// create a query...
event.getSession().getDescriptor(Customer.class).getQueryManager().addQuery("fin
dCustomersInCity", query);
//Add query to Descriptor
descriptor.getQueryManager().addQuery("findCustomersInCity", query);
/* Enumeration findCustomersInCity(String aCity)
Since this finder returns an Enumeration, the type of the query is
ReadAllQuery. The finder is a "NAMED" finder. It's implementation
is a ReadAllQuery that is registered with the QueryManager. */
//1 the query is defined
ReadAllQuery query1 = new ReadAllQuery();
query1.setName("findCustomersInCity");
query1.addArgument("aCity");
query1.setReferenceClass(CustomerBean.class);
//2 an expression is used
ExpressionBuilder builder = new ExpressionBuilder();
query1.setSelectionCriteria
builder.get("city").like(builder.getParameter("aCity";
//3 An option at this point would be to set any desired options on the query,
e.g., queryl.refreshIdentityMapResult();
//4 Finally, the query is registered with the querymanager.
descriptor.getQueryManager().addQuery("findCustomersInCity",query1);
If you want to achieve thru declaratively then follow add the below xml elements to descriptor.xml.For example adding a named query to Dept descriptor in dept.xml
<query type="relational-read-object">
<name>findDeptByName</name>
<parameter-list>
<query-parameter>
<name>name</name>
<type-handle>
<type-name>java.lang.String</type-name>
</type-handle>
</query-parameter>
</parameter-list>
<relational-options>
<format type="expression">
<main-compound-expression type="compound">
<operator-type>AND</operator-type>
<expression-list>
<expression type="basic">
<operator-type>EQUAL</operator-type>
<first-argument type="queryable">
<queryable-argument-element>
<queryable-handle>
<mapping-descriptor-name>testTop.Dept</mapping-descriptor-name>
<queryable-name>dname</queryable-name>
</queryable-handle>
</queryable-argument-element>
</first-argument>
<second-argument type="parm">
<query-parameter-handle>
<class-descriptor-name>testTop.Dept</class-descriptor-name>
<query-signature>findDeptByName(java.lang.String)</query-signature>
<query-parameter-name>name</query-parameter-name>
</query-parameter-handle>
</second-argument>
</expression>
</expression-list>
</main-compound-expression>
</format>
</relational-options>
</query>
You can use JDeveloper to develop the Toplink aplication using Wizards,please refer the below link for more information.
http://download.oracle.com/docs/cd/E15523_01/web.1111/b32441/qryun.htm#CACFBJCI
Regards,
P.Vinay Kumar