Merge pull request #432 from jaggernod/throw-meaningful-error-on-prepared-statement

Handling exceptional case when executing Prepared Statement

moor_ffi/lib/src/bindings/bindings.dart

@@ -67,6 +67,7 @@ class _SQLiteBindings {
   int Function(Pointer<Database> db) sqlite3_changes;
   int Function(Pointer<Database> db) sqlite3_last_insert_rowid;
 
+  int Function(Pointer<Database> db) sqlite3_extended_errcode;
   Pointer<CBlob> Function(int code) sqlite3_errstr;
   Pointer<CBlob> Function(Pointer<Database> database) sqlite3_errmsg;
 
@@ -165,6 +166,10 @@ class _SQLiteBindings {
     sqlite3_finalize = sqlite
         .lookup<NativeFunction<sqlite3_finalize_native_t>>('sqlite3_finalize')
         .asFunction();
+    sqlite3_extended_errcode = sqlite
+        .lookup<NativeFunction<sqlite3_extended_errcode_native_t>>(
+            'sqlite3_extended_errcode')
+        .asFunction();
     sqlite3_errstr = sqlite
         .lookup<NativeFunction<sqlite3_errstr_native_t>>('sqlite3_errstr')
         .asFunction();

moor_ffi/lib/src/bindings/signatures.dart

@@ -36,6 +36,9 @@ typedef sqlite3_reset_native_t = Int32 Function(Pointer<Statement> statement);
 typedef sqlite3_finalize_native_t = Int32 Function(
     Pointer<Statement> statement);
 
+typedef sqlite3_extended_errcode_native_t = Int32 Function(
+    Pointer<Database> database);
+
 typedef sqlite3_errstr_native_t = Pointer<CBlob> Function(Int32 error);
 
 typedef sqlite3_errmsg_native_t = Pointer<CBlob> Function(

moor_ffi/lib/src/impl/errors.dart

@@ -16,7 +16,12 @@ class SqliteException implements Exception {
 
     String explanation;
     if (code != null) {
-      explanation = bindings.sqlite3_errstr(code).readString();
+      // Getting hold of more explanatory error code as SQLITE_IOERR error group
+      // has an extensive list of extended error codes
+      final extendedCode = bindings.sqlite3_extended_errcode(db);
+      final errStr = bindings.sqlite3_errstr(extendedCode).readString();
+
+      explanation = '$errStr (code $extendedCode)';
     }
 
     return SqliteException(dbMessage, explanation);

moor_ffi/lib/src/impl/prepared_statement.dart

@@ -45,10 +45,15 @@ class PreparedStatement {
       names[i] = bindings.sqlite3_column_name(_stmt, i).readString();
     }
 
-    while (_step() == Errors.SQLITE_ROW) {
+    int resultCode;
+    while ((resultCode = _step()) == Errors.SQLITE_ROW) {
       rows.add([for (var i = 0; i < columnCount; i++) _readValue(i)]);
     }
 
+    if (resultCode != Errors.SQLITE_OK && resultCode != Errors.SQLITE_DONE) {
+      throw SqliteException._fromErrorCode(_db._db, resultCode);
+    }
+
     return Result(names, rows);
   }
 

moor_ffi/test/database/prepared_statements_test.dart

@@ -1,3 +1,4 @@
+import 'dart:ffi';
 import 'dart:typed_data';
 
 import 'package:moor_ffi/database.dart';
@@ -85,4 +86,38 @@ void main() {
 
     db.close();
   });
+
+  test('throws an exception when iterating over result rows', () {
+    final db = Database.memory()
+      ..createFunction(
+        'raise_if_two',
+        1,
+        Pointer.fromFunction(_raiseIfTwo),
+      );
+
+    db.execute(
+        'CREATE TABLE tbl (a INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT)');
+    // insert with a = 1..3
+    for (var i = 0; i < 3; i++) {
+      db.execute('INSERT INTO tbl DEFAULT VALUES');
+    }
+
+    final statement = db.prepare('SELECT raise_if_two(a) FROM tbl ORDER BY a');
+
+    expect(
+      statement.select,
+      throwsA(isA<SqliteException>()
+          .having((e) => e.message, 'message', contains('was two'))),
+    );
+  });
+}
+
+void _raiseIfTwo(Pointer<FunctionContext> ctx, int argCount,
+    Pointer<Pointer<SqliteValue>> args) {
+  final value = args[0].value;
+  if (value == 2) {
+    ctx.resultError('parameter was two');
+  } else {
+    ctx.resultNull();
+  }
 }

moor_ffi/test/ffi/extended_error_codes_test.dart

@@ -0,0 +1,24 @@
+import 'package:moor_ffi/database.dart';
+import 'package:test/test.dart';
+
+void main() {
+  Database database;
+
+  setUp(() => database = Database.memory());
+
+  tearDown(() => database.close());
+
+  test('violating constraint throws exception with extended error code', () {
+    database.execute('CREATE TABLE tbl(a INTEGER NOT NULL)');
+
+    final statement = database.prepare('INSERT INTO tbl DEFAULT VALUES');
+
+    expect(
+      statement.execute,
+      throwsA(
+        isA<SqliteException>().having(
+            (e) => e.explanation, 'explanation', endsWith(' (code 1299)')),
+      ),
+    );
+  });
+}