Better way to write a join query in ormlite
Question
I have two tables CustomerBalance and Customer which are bound with CustomerRefId field. I want the CustomerBalance records that are lets say greater than 100 for a field balance of this tables. I also want to include into my results the name of the particular customer that fulfills that criteria. I created the following method that works!
public List<CustomerBalance> getCustomerBalanceFilter(String filterVal) {
try {
PreparedQuery<CustomerBalance> preparedQuery = mDbHelper.getCustomerBalanceDao().queryBuilder()
.where().gt(CustomerBalance.DB_COL_CUSTOMER_BALANCE, filterVal)
.prepare();
List<CustomerBalance> result = mDbHelper.getCustomerBalanceDao().query(preparedQuery);
for(CustomerBalance alert : result) {
PreparedQuery<Customer> getCustQuery = mDbHelper.getCustomerDao().queryBuilder()
.where().eq(Customer.DB_COL_CUSTOMER_REF_ID, alert.getCustomerID())
.prepare();
List<Customer> customer = mDbHelper.getCustomerDao().query(getCustQuery);
alert.setCustomer(customer.size() == 1 ? customer.get(0) : null);
}
return result;
} catch(Exception ex) {
return null;
}
}
This methods is working, is this the best way to write such a query? or is there a more appropriate approach?
Solution
One improvement to your query is to use ORMLite's SelectArg
to pass in the customer-id instead of a new query each time. Something like:
...
List<CustomerBalance> result = mDbHelper.getCustomerBalanceDao()
.query(preparedQuery);
SelectArg custIdArg = new SelectArg();
PreparedQuery<Customer> getCustQuery = mDbHelper.getCustomerDao().queryBuilder()
.where().eq(Customer.DB_COL_CUSTOMER_REF_ID, custIdArg)
.prepare();
for (CustomerBalance alert : result) {
custIdArg.setValue(alert.getCustomerID());
List<Customer> customer = mDbHelper.getCustomerDao().query(getCustQuery);
alert.setCustomer(customer.size() == 1 ? customer.get(0) : null);
}
Here are the docs for SelectArg
:
FYI, there also is an UpdateBuilder
, but I don't see an easy way to turn your code above into a single UPDATE
statement.