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Build a master-detail screen

In FDC Pro, the master-detail relationship belongs to the detail dataset. The master dataset remains independent, while the detail dataset declares which master fields constrain which detail fields.

1. Create the master dataset​

final customers = FdcDataSet(
  fields: const [
    FdcIntegerField(name: 'customer_id', isKey: true),
    FdcStringField(name: 'company', size: 120),
  ],
  adapter: customerAdapter,
);

2. Create the detail dataset​

final orders = FdcDataSet(
  fields: const [
    FdcIntegerField(name: 'order_id', isKey: true),
    FdcIntegerField(name: 'customer_id'),
    FdcDateField(name: 'order_date'),
    FdcDecimalField(name: 'amount', precision: 18, scale: 2),
  ],
  adapter: orderAdapter,
  masterDataSet: customers,
  masterRelation: const [
    FdcMasterDetailRelation(
      masterField: 'customer_id',
      detailField: 'customer_id',
    ),
  ],
);

The relation can contain multiple mappings for composite relationships.

3. Open both datasets​

await customers.open();
await orders.open();

When the current master record changes, the detail dataset refreshes its effective query using the master relation.

4. Bind two grids​

Column(
  children: [
    Expanded(
      child: FdcProGrid(
        dataSet: customers,
        columns: customerColumns,
      ),
    ),
    Expanded(
      child: FdcProGrid(
        dataSet: orders,
        columns: orderColumns,
      ),
    ),
  ],
)

The grid is not responsible for master-detail synchronization. The relationship stays at the dataset layer and therefore also works with standalone editors or custom UI.

User filters still compose normally​

A user filter on the detail dataset is combined with the master relation constraint rather than replacing it.

await orders.filter.set(const [
  FdcDataSetFilter(
    fieldName: 'status',
    operator: FdcFilterOperator.equals,
    value: 'open',
  ),
]);

The active master relation remains in effect.

Design rule​

Keep the adapter unaware of master-detail semantics. It should receive an ordinary effective query containing the filters that need to be executed.

This keeps Memory, SQLite, JSON/REST, and custom adapters compatible with the same dataset-level relationship model.