feat(mcp): views in list_tables, describe_table and sample_rows (#1133)

docs/mcp-server.md

@@ -77,7 +77,7 @@ and most stdio clients:
 | Tool | Arguments | Returns |
 |---|---|---|
 | `list_connections` | — | shared connections: `id`, `name`, `type`, `environment`, `database` |
-| `list_tables` | `connection_id` | tables with their column count |
+| `list_tables` | `connection_id` | tables and views with their column count |
 | `describe_table` | `connection_id`, `table` | columns, types, primary key, foreign key targets, indexes |
 | `sample_rows` | `connection_id`, `table`, `rows` (1-100, default 20) | first rows of the table |
 | `run_query` | `connection_id`, `sql` | `columns`, `rows`, `row_count`, `truncated` |
@@ -97,8 +97,9 @@ can fix its query and retry.
 - **Rows:** at most 1000 per `run_query` (`truncated: true` when cut), 100 per
   `sample_rows`. **Cells** longer than 4 KB are cut with a marker.
 - **Time:** 15 s per statement.
-- **Tables:** base tables of the current schema / database; views are not
-  listed yet.
+- **Tables:** base tables and views of the current schema / database
+  (`kind: "view"`; PostgreSQL materialized views included). A view has no
+  primary key or index information.
 
 ## Activity log
 

lib/core/erd/erd_catalog.dart

@@ -59,6 +59,37 @@ SELECT m.name AS table_name, p.name AS column_name, p.type AS data_type,
   CASE WHEN p."notnull" = 0 THEN 1 ELSE 0 END AS is_nullable
 FROM sqlite_master m JOIN pragma_table_info(m.name) p
 WHERE m.type = 'table' AND m.name NOT LIKE 'sqlite_%'
+ORDER BY m.name, p.cid''',
+      };
+
+  /// Columns of the views (and PostgreSQL materialized views) of the current
+  /// schema or database, in the shape of [columnsSql]: no primary key, every
+  /// column nullable. MCP lists them next to the tables.
+  static String viewColumnsSql(SqlDialect d) => switch (d) {
+        SqlDialect.postgres => '''
+SELECT ${_pgQualified('c', 'ns')} AS table_name, a.attname AS column_name,
+  format_type(a.atttypid, a.atttypmod) AS data_type,
+  0 AS is_pk, 1 AS is_nullable
+FROM pg_catalog.pg_attribute a
+JOIN pg_catalog.pg_class c ON c.oid = a.attrelid
+JOIN pg_catalog.pg_namespace ns ON ns.oid = c.relnamespace
+WHERE ns.nspname = current_schema()
+  AND c.relkind IN ('v', 'm')
+  AND a.attnum > 0 AND NOT a.attisdropped
+ORDER BY table_name, a.attnum''',
+        SqlDialect.mysql => '''
+SELECT c.table_name, c.column_name, c.column_type, 0, 1
+FROM information_schema.columns c
+JOIN information_schema.tables t
+  ON t.table_schema = c.table_schema AND t.table_name = c.table_name
+  AND t.table_type = 'VIEW'
+WHERE c.table_schema = DATABASE()
+ORDER BY c.table_name, c.ordinal_position''',
+        SqlDialect.sqlite => '''
+SELECT m.name AS table_name, p.name AS column_name, p.type AS data_type,
+  0 AS is_pk, 1 AS is_nullable
+FROM sqlite_master m JOIN pragma_table_info(m.name) p
+WHERE m.type = 'view' AND m.name NOT LIKE 'sqlite_%'
 ORDER BY m.name, p.cid''',
       };
 

lib/core/mcp/mcp_query_service.dart

@@ -82,18 +82,22 @@ class McpQueryService {
   }
 
   Future<List<McpTableSummary>> listTables(int connectionId) async {
-    final schema = await _withDelegate(connectionId, _loadSchema);
+    final cat = await _withDelegate(connectionId, _loadCatalog);
     return [
-      for (final t in schema.tables)
-        McpTableSummary(name: t.name, columnCount: t.columns.length),
+      for (final t in cat.schema.tables)
+        McpTableSummary(
+          name: t.name,
+          columnCount: t.columns.length,
+          isView: cat.views.contains(t.name),
+        ),
     ];
   }
 
   /// All tables with columns and keys in one catalog pass (no indexes); backs
   /// the `schema://` resource.
   Future<List<McpTableDescription>> schemaOverview(int connectionId) {
     return _withDelegate(connectionId, (delegate, dialect) async {
-      final schema = await _loadSchema(delegate, dialect);
+      final schema = (await _loadCatalog(delegate, dialect)).schema;
       return [for (final t in schema.tables) _describe(schema, t, const [])];
     });
   }
@@ -103,8 +107,10 @@ class McpQueryService {
     String table,
   ) {
     return _withDelegate(connectionId, (delegate, dialect) async {
-      final schema = await _loadSchema(delegate, dialect);
+      final cat = await _loadCatalog(delegate, dialect);
+      final schema = cat.schema;
       final t = _findTable(schema, table);
+      if (cat.views.contains(t.name)) return _describe(schema, t, const []);
       final indexes = await _run(
         () => delegate.executeQuery(
           _indexesSql(dialect, t.name),
@@ -150,7 +156,8 @@ class McpQueryService {
   }) {
     final n = rows.clamp(1, maxSampleRows);
     return _withDelegate(connectionId, (delegate, dialect) async {
-      final t = _findTable(await _loadSchema(delegate, dialect), table);
+      final t =
+          _findTable((await _loadCatalog(delegate, dialect)).schema, table);
       final result = await _run(
         () => delegate.executeQuery(
           'SELECT * FROM ${quoteIdentifier(t.name, dialect)}',
@@ -227,6 +234,35 @@ class McpQueryService {
     }
   }
 
+  /// Tables and keys, then the views: a name that is already a table stays a
+  /// table. Views have no keys and no indexes.
+  Future<({ErdSchema schema, Set<String> views})> _loadCatalog(
+    SqlQueryRunner delegate,
+    SqlDialect dialect,
+  ) async {
+    final base = await _loadSchema(delegate, dialect);
+    final viewRows = await _run(
+      () => delegate.executeQuery(ErdCatalog.viewColumnsSql(dialect),
+          limit: _catalogRows, timeout: timeout),
+      dialect,
+    );
+    final known = {for (final t in base.tables) t.name};
+    final views = [
+      for (final t in ErdSchema.fromCatalog(
+              columnRows: viewRows.rows, fkRows: const [])
+          .tables)
+        if (!known.contains(t.name)) t,
+    ];
+    return (
+      schema: ErdSchema(
+        tables: [...base.tables, ...views],
+        relations: base.relations,
+        truncated: base.truncated,
+      ),
+      views: {for (final v in views) v.name},
+    );
+  }
+
   Future<ErdSchema> _loadSchema(
     SqlQueryRunner delegate,
     SqlDialect dialect,
@@ -365,12 +401,21 @@ class McpConnectionInfo {
 }
 
 class McpTableSummary {
-  const McpTableSummary({required this.name, required this.columnCount});
+  const McpTableSummary({
+    required this.name,
+    required this.columnCount,
+    this.isView = false,
+  });
 
   final String name;
   final int columnCount;
+  final bool isView;
 
-  Map<String, Object?> toJson() => {'name': name, 'columns': columnCount};
+  Map<String, Object?> toJson() => {
+        'name': name,
+        'columns': columnCount,
+        if (isView) 'kind': 'view',
+      };
 }
 
 class McpColumnInfo {

lib/core/mcp/querya_mcp_server.dart

@@ -107,7 +107,8 @@ base class QueryaMcpServer extends MCPServer with ToolsSupport, ResourcesSupport
 
   static final _listTables = Tool(
     name: 'list_tables',
-    description: 'Lists the tables of a connection with their column count.',
+    description: 'Lists the tables and views of a connection with their column '
+        'count; views carry "kind": "view".',
     inputSchema: Schema.object(
       properties: {'connection_id': _connectionId},
       required: ['connection_id'],

test/core/mcp/mcp_query_service_test.dart

@@ -3,6 +3,7 @@ import 'dart:convert';
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:querya_desktop/core/database/table_mutation_engine.dart';
+import 'package:querya_desktop/core/erd/erd_catalog.dart';
 import 'package:querya_desktop/core/mcp/mcp_access_store.dart';
 import 'package:querya_desktop/core/mcp/mcp_query_service.dart';
 import 'package:querya_desktop/core/security/connection_environment.dart';
@@ -222,6 +223,45 @@ void main() {
       ]);
     });
 
+    group('views', () {
+      setUp(() {
+        db.onExecute = (sql) {
+          if (sql == ErdCatalog.viewColumnsSql(SqlDialect.postgres)) {
+            return const SqlExecutionResult(columns: ['t', 'c', 'ty', 'pk'], rows: [
+              ['active_users', 'id', 'integer', '0'],
+              ['active_users', 'name', 'text', '0'],
+              // Already a table: stays a table.
+              ['users', 'id', 'integer', '0'],
+            ]);
+          }
+          return _catalog(sql);
+        };
+      });
+
+      test('listTables names the views next to the tables', () async {
+        final tables = await service().listTables(1);
+        expect([for (final t in tables) t.toJson()], [
+          {'name': 'users', 'columns': 2},
+          {'name': 'orders', 'columns': 2},
+          {'name': 'active_users', 'columns': 2, 'kind': 'view'},
+        ]);
+      });
+
+      test('describeTable of a view has columns and no index query', () async {
+        final view = await service().describeTable(1, 'active_users');
+        expect(view.columns.map((c) => c.name), ['id', 'name']);
+        expect(view.columns.any((c) => c.primaryKey), isFalse);
+        expect(view.indexes, isEmpty);
+        expect(db.executed.where((s) => s.contains('pg_indexes')), isEmpty);
+      });
+
+      test('sampleRows reads a view through its quoted name', () async {
+        await service().sampleRows(1, 'active_users', rows: 5);
+        expect(
+            db.executed.last, contains('"active_users"'));
+      });
+    });
+
     test('describeTable has keys, references and indexes', () async {
       final users = await service().describeTable(1, 'users');
       expect(users.columns.first.primaryKey, isTrue);