Extra Features of Readmulti Operations

TheREADMULTI_MAX option in the model limits the number of records processed by a standard "normal" readmulti operation. It has however no effect when you hand-craft your own operations. As a result none of the overrides for this option (defined in Cúram Configuration Settings) have any effect. To limit the number of records returned within your readmulti subclass you must override the following method:
public int getMaximum();
You can filter out records from the database result set by overriding the following method of your readmulti subclass:
public boolean filter(Object dtls) throws AppException, InformationalException;

Each record is passed to filter before being passed to your operation method. Any record which results in filter returning false is not passed to operation. The default filter always returns true.
If you want to write code that is called before the first row is passed to operation, you can override:
public void pre() throws AppException, InformationalException;

If you want to write code that is called with the first row read from the database, you can override:

public void first(Object dtls) throws AppException, InformationalException;

The same record is also passed to the operation method.

Note: Note that first is called as long as there is at least one row in the result set, regardless of whether or not filter returns true for this row.
If you want to write code that is called after the last call to operation, you can override:
public void post() throws AppException, InformationalException;

Be aware, this function is always called once, regardless of the value returned by the operation method.
An optional third parameter to the execute method of readmulti helper classes is a boolean which specifies whether records read from the database will be updated later in the transaction. This can be used as in:
```
E.newInstance().readmultiHelper(key, op, true);
```
This means that each record read from the database is locked for write access as it is read.

You can use a combination of the above methods, with your own data members, to achieve many common styles readmulti operation. For instance, Extra Features of Readmulti Operations shows a readmulti operation that produces a report grouped by department:

Figure 1. Specialized readmulti example

static class MyReadmultiOperation
       extends curam.util.dataaccess.ReadmultiOperation
{
  // Remember last dept, for grouping
  private String lastDepartment;

  // Department salary accumulator
  private curam.util.type.Money salaryDeptTotal;

  // Total Salary Accumulator
  private curam.util.type.Money salaryGrandTotal;

  public void pre()
    throws AppException, InformationalException {
    // initialization
    lastDepartment = "";
    salaryGrandTotal = 0.0;
  }

  public void first (Object dtls)
  throws AppException, InformationalException {
    // per-department group initialization
    salaryDeptTotal = 0.0;

    // remember last department for grouping.
    lastDepartment = dtls.department;
  }

  public boolean operation(Object dtls)
    throws AppException, InformationalException {

    // Change of department group
    if (!(lastDepartment.equals(dtls.department))) {
      printGroupTotals();

      // redo per-dept initialization
      first(dtls);
    }

    // detail report line
    curam.util.resources.Trace.kTopLevelLogger.info("Emp ");
    curam.util.resources.Trace.kTopLevelLogger.info(
      dtls.employeeId);
     curam.util.resources.Trace.kTopLevelLogger.info(
      " salary: ");
    curam.util.resources.Trace.kTopLevelLogger.info(
      dtls.salary);

    // accumulate dept salary
    salaryDeptTotal += dtls.salary;

    // accumulate total salary
    salaryGrandTotal += dtls.salary;

    return true;
  }

 public void post()
    throws AppException, InformationalException {
    // only if there was at least one department
    if (!(lastDepartment.empty())) {
      printGroupTotals();
      // final group
      // Grand total report line:
      curam.util.resources.Trace.kTopLevelLogger.info(
        "Grand total salary: ");
      curam.util.resources.Trace.kTopLevelLogger.info(
        salaryGrandTotal);
    }
  }

  public int getMaximum() {
    // Explicitly enforce that all matching records are
    // considered.  Any number other than zero would limit
    // the number of records.
    return 0;
  }

  private void printGroupTotals() {
    // group report line
    curam.util.resources.Trace.kTopLevelLogger.info(
      "Department ");
    curam.util.resources.Trace.kTopLevelLogger.info(
      lastDepartment);
    curam.util.resources.Trace.kTopLevelLogger.info(
      " total salary: ");
    curam.util.resources.Trace.kTopLevelLogger.info(
      salaryDeptTotal);
  }
}