Row Processors

Row Processors allow you to transform entities during ResultSet parsing in a single pass. This is useful for:

Running calculations (cumulative sums, totals)
Delta calculations (comparing with previous row)
Row numbering
Data enrichment
Security masking

Basic Row Processor


public class RunningSumProcessor implements RowProcessor<Sale> {
    private BigDecimal runningTotal = BigDecimal.ZERO;
    private int rowNumber = 0;
 
    @Override
    public void process(Sale sale, RowContext context) {
        // Update running total
        runningTotal = runningTotal.add(sale.getAmount());
        sale.setRunningTotal(runningTotal);
 
        // Add row number
        rowNumber++;
        sale.setRowNumber(rowNumber);
    }
}
 
// Usage
DevExtremeResult<Sale> result = gridDataProvider
    .query(Sale.class)
    .loadOptions(loadOptions)
    .rowProcessor(new RunningSumProcessor())
    .executeDevExtreme();

Using RowContext State


RowProcessor<Employee> processor = (employee, context) -> {
    // Get previous employee for comparison
    Employee previous = context.getState("previousEmployee", Employee.class).orElse(null);
 
    if (previous != null) {
        // Calculate delta from previous row
        BigDecimal salaryDelta = employee.getSalary().subtract(previous.getSalary());
        employee.setSalaryDelta(salaryDelta);
    }
 
    // Store current as previous for next row
    context.setState("previousEmployee", employee);
};

Using Context Metadata


RowProcessor<Employee> processor = (employee, context) -> {
    boolean isAdmin = context.getMetadata("isAdmin", Boolean.class).orElse(false);
    if (!isAdmin) {
        employee.setSalary(null); // Mask salary for non-admins
    }
};
 
DevExtremeResult<Employee> result = gridDataProvider
    .query(Employee.class)
    .loadOptions(loadOptions)
    .rowProcessor(processor)
    .contextMetadata("userId", currentUser.getId())
    .contextMetadata("isAdmin", currentUser.hasRole("ADMIN"))
    .executeDevExtreme();

Chaining Multiple Processors


RowProcessor<Employee> combined = new CalculatedFieldsProcessor()
    .andThen(new DepartmentEnrichmentProcessor())
    .andThen(new SecurityMaskingProcessor());
 
DevExtremeResult<Employee> result = gridDataProvider
    .query(Employee.class)
    .loadOptions(loadOptions)
    .rowProcessor(combined)
    .executeDevExtreme();

RowContext API

Method	Description
`getConnection()`	Get database connection for data enrichment
`getEntityMetaData()`	Get table name, field mappings, relationships
`getSchema()`	Get current schema being queried
`getMetadata()`	Get custom metadata map
`getMetadata(key, type)`	Get specific metadata value
`setState(key, value)`	Store state for next row
`getState(key, type)`	Get state from previous rows
`hasState(key)`	Check if state key exists
`removeState(key)`	Remove state value
`clearState()`	Clear all state