prepareImport method

Future<OrmImportPlan<T>> prepareImport(Iterable<T> entities, { required List<Column<T, dynamic>> conflictOn, required List<Column<T, dynamic>> update, OrmImportDuplicates duplicates = OrmImportDuplicates.reject, OrmImportEmptyValues emptyValues = OrmImportEmptyValues.overwrite, String? validate(T entity)?, })

Callers parse/map CSV/JSON/etc to entities. Null or empty text preserves stored fields on conflict only when keepExisting is explicitly selected. NOCASE/RTRIM duplicate identity is resolved by SQLite, not Dart equality.

Implementation

Future<OrmImportPlan<T>> prepareImport(Iterable<T> entities,
    {required List<Column<T, dynamic>> conflictOn,
    required List<Column<T, dynamic>> update,
    OrmImportDuplicates duplicates = OrmImportDuplicates.reject,
    OrmImportEmptyValues emptyValues = OrmImportEmptyValues.overwrite,
    String? Function(T entity)? validate}) {
  try {
    _writeType(type);
    final keys = _projection(type, conflictOn),
        fields = _projection(type, update);
    if (keys.isEmpty ||
        fields.isEmpty ||
        fields.any((c) =>
            c.keyOrder != null ||
            c.generated ||
            c.version ||
            keys.contains(c))) {
      throw const OrmMappingException(
          'Import requires conflict keys and writable non-key/non-version update fields');
    }
    context._checkTrackingMutable();
    final rows = <int, Map<String, Object?>>{};
    final issues = <OrmImportIssue>[];
    var count = 0;
    for (final entity in entities) {
      final index = count++;
      if (count > 10000 || count * keys.length > 20000) {
        throw RangeError('Import exceeds 10000 rows / 20000 key binds');
      }
      try {
        final reason = validate?.call(entity);
        if (reason != null) {
          issues.add(OrmImportIssue(index, 'validation', reason));
          continue;
        }
        final row = _copyOrmRow(type.encode(entity));
        if (keys.any((c) => row[c.sqlName] == null)) {
          issues.add(OrmImportIssue(
              index, 'nullKey', 'Conflict keys cannot be NULL'));
        } else {
          rows[index] = row;
        }
      } catch (error) {
        issues.add(OrmImportIssue(index, 'invalidValue',
            'Validation/encoding failed: ${error.runtimeType}'));
      }
    }
    return context._run(() async {
      final collations = await context._uniqueTarget(type, keys);
      if (rows.length > 1) {
        final parameters = <Object?>[];
        final values = [
          for (final entry in rows.entries)
            '(${entry.key},${keys.map((c) {
              parameters.add(copyOrmValue(entry.value[c.sqlName]));
              return '?';
            }).join(',')})'
        ];
        final names = [
          for (var i = 0; i < keys.length; i++) quoteIdentifier('_k$i')
        ];
        final groups = [
          for (var i = 0; i < keys.length; i++)
            '${names[i]} COLLATE ${quoteIdentifier(collations[i])}'
        ];
        final repeated = await context.connection.query(
            'WITH ${quoteIdentifier('_import')} (${quoteIdentifier('_i')},${names.join(',')}) AS (VALUES ${values.join(',')}) SELECT group_concat(${quoteIdentifier('_i')}) FROM ${quoteIdentifier('_import')} GROUP BY ${groups.join(',')} HAVING count(*)>1',
            parameters);
        for (final raw in repeated.rows) {
          final indices = (raw.single as String)
              .split(',')
              .map(int.parse)
              .toList()
            ..sort();
          final kept = duplicates == OrmImportDuplicates.keepFirst
              ? indices.first
              : indices.last;
          for (final i in indices) {
            if (duplicates != OrmImportDuplicates.reject && i == kept) {
              continue;
            }
            rows.remove(i);
            issues.add(OrmImportIssue(
                i, 'duplicate', 'Repeated input conflict key',
                error: duplicates == OrmImportDuplicates.reject));
          }
        }
      }
      issues.sort((a, b) => a.inputIndex.compareTo(b.inputIndex));
      return OrmImportPlan._(this, count, rows.values.toList(), keys, fields,
          emptyValues, collations, issues);
    });
  } catch (error, stack) {
    return Future.error(error, stack);
  }
}