fix: truncate query aliases generated by the table relation class use…

…d for joins and sub queries.

packages/serverpod/lib/src/database/table_relation.dart

@@ -2,21 +2,42 @@ import 'package:collection/collection.dart';
 import 'package:meta/meta.dart';
 import 'package:serverpod/src/database/columns.dart';
 import 'package:serverpod/src/database/expressions.dart';
+import 'package:serverpod_shared/serverpod_shared.dart';
+
+typedef _TruncateFunction = String Function(String identifier);
 
 /// Records the relation between two tables.
+/// All query aliases generated by [TableRelation] are truncated by the
+/// [truncateFunction].
 /// This is typically only used internally by the serverpod framework.
 @internal
 class TableRelation {
   /// Records the relationship between multiple tables.
   /// Order is important, as it determines the order of joins in the query.
   final List<TableRelationEntry> _tableRelationEntries;
 
+  // Default initialized to truncate to Postgres max name length.
+  _TruncateFunction _truncateFunction = (String identifier) =>
+      truncateIdentifier(identifier, DatabaseConstants.pgsqlMaxNameLimitation);
+
   /// Creates a new [TableRelation].
   /// Throws [ArgumentError] if [tableRelationEntries] is empty.
-  TableRelation(this._tableRelationEntries) {
+  ///
+  /// [truncateFunction] is used to truncate query aliases generated by
+  /// [TableRelation].
+  /// If [truncateFunction] is not provided, the query aliases are truncated
+  /// to Postgres max name length.
+  TableRelation(
+    this._tableRelationEntries, {
+    _TruncateFunction? truncateFunction,
+  }) {
     if (_tableRelationEntries.isEmpty) {
       throw ArgumentError('TableRelation must have at least one entry.');
     }
+
+    if (truncateFunction != null) {
+      _truncateFunction = truncateFunction;
+    }
   }
 
   /// Builds all table relations required to join the tables.
@@ -51,7 +72,7 @@ class TableRelation {
 
   /// The field name query alias including table.
   String get fieldQueryAlias {
-    return _tableRelationEntries.last.field.queryAlias;
+    return _truncateFunction(_tableRelationEntries.last.field.queryAlias);
   }
 
   /// Field column that is joined on.
@@ -61,12 +82,13 @@ class TableRelation {
 
   /// The query alias for field name to be joined on including all joins.
   String get fieldQueryAliasWithJoins {
-    return '${_fromRelationQueryAlias()}.${_tableRelationEntries.last.field.columnName}';
+    return _truncateFunction(
+        '${_fromRelationQueryAlias()}.${_tableRelationEntries.last.field.columnName}');
   }
 
   /// The field name to be joined on including all joins.
   String get fieldNameWithJoins {
-    return '"${_fromRelationQueryAlias()}"."${_tableRelationEntries.last.field.columnName}"';
+    return '"${_truncateFunction(_fromRelationQueryAlias())}"."${_tableRelationEntries.last.field.columnName}"';
   }
 
   /// The foreign field name joined on.
@@ -81,12 +103,14 @@ class TableRelation {
 
   /// The foreign field name to be joined on including all joins.
   String get foreignFieldNameWithJoins {
-    return '"${_buildRelationQueryAlias()}"."${_tableRelationEntries.last.foreignField.columnName}"';
+    return '"${_truncateFunction(_buildRelationQueryAlias())}"."${_tableRelationEntries.last.foreignField.columnName}"';
   }
 
   /// The field name query alias including table.
   String get foreignFieldQueryAlias {
-    return _tableRelationEntries.last.foreignField.queryAlias;
+    return _truncateFunction(
+      _tableRelationEntries.last.foreignField.queryAlias,
+    );
   }
 
   /// Create a new [TableRelation] with only one entry for the last table
@@ -101,7 +125,8 @@ class TableRelation {
   }
 
   /// Retrieves the name of the table with the query prefix applied.
-  String get relationQueryAlias => _buildRelationQueryAlias();
+  String get relationQueryAlias =>
+      _truncateFunction(_buildRelationQueryAlias());
 
   /// Builds the relation query alias including [TableRelationEntries]
   /// up until [end] index.

packages/serverpod/test/database/database_query/long_relation_field_name/join_test.dart

@@ -0,0 +1,47 @@
+import 'package:serverpod/database.dart';
+import 'package:serverpod/src/database/database_query.dart';
+import 'package:serverpod/test_util/table_relation_builder.dart';
+import 'package:test/test.dart';
+
+void main() {
+  var citizenTable = Table(tableName: 'citizen');
+  var companyTable = Table(tableName: 'company');
+  var relationTable = TableRelationBuilder(companyTable).withRelationsFrom([
+    BuilderRelation(
+      citizenTable,
+      'thisFieldIsExactly61CharactersLongAndIsThereforeValidAsNameFo',
+    ),
+  ]).build();
+
+  group('Given SelectQueryBuilder', () {
+    group('when filtering causes a long join name.', () {
+      var query = SelectQueryBuilder(table: citizenTable)
+          .withWhere(relationTable.id.equals(1))
+          .build();
+
+      test('then join query name is truncated.', () {
+        expect(
+          query,
+          contains(
+              'LEFT JOIN "company" AS "citizen_thisFieldIsExactly61CharactersLongAndIsThereforeVale9b4"'),
+        );
+      });
+
+      test('then join query uses the truncated join name.', () {
+        expect(
+          query,
+          contains(
+              '"citizen"."id" = "citizen_thisFieldIsExactly61CharactersLongAndIsThereforeVale9b4"."id"'),
+        );
+      });
+
+      test('then uses truncated name in where statements in for join.', () {
+        expect(
+          query,
+          contains(
+              '"citizen_thisFieldIsExactly61CharactersLongAndIsThereforeVale9b4"."id" = 1'),
+        );
+      });
+    });
+  });
+}