Merge branch 'develop' into delightful-queries

docs/_includes/content/getting_started.md

@@ -27,7 +27,7 @@ part 'filename.g.dart';
 // be represented by a class called "Todo".
 class Todos extends Table {
   IntColumn get id => integer().autoIncrement()();
-  TextColumn get title => text().withLength(min: 6, max: 10)();
+  TextColumn get title => text().withLength(min: 6, max: 32)();
   TextColumn get content => text().named('body')();
   IntColumn get category => integer().nullable()();
 }

moor/example/example.g.dart

@@ -64,6 +64,7 @@ class $CategoriesTable extends Categories
   final GeneratedDatabase _db;
   final String _alias;
   $CategoriesTable(this._db, [this._alias]);
+  final VerificationMeta _idMeta = const VerificationMeta('id');
   GeneratedIntColumn _id;
   @override
   GeneratedIntColumn get id => _id ??= _constructId();
@@ -71,6 +72,8 @@ class $CategoriesTable extends Categories
     return GeneratedIntColumn('id', $tableName, false, hasAutoIncrement: true);
   }
 
+  final VerificationMeta _descriptionMeta =
+      const VerificationMeta('description');
   GeneratedTextColumn _description;
   @override
   GeneratedTextColumn get description =>
@@ -92,9 +95,14 @@ class $CategoriesTable extends Categories
   @override
   final String actualTableName = 'categories';
   @override
-  bool validateIntegrity(Category instance, bool isInserting) =>
+  VerificationContext validateIntegrity(Category instance, bool isInserting) =>
-      id.isAcceptableValue(instance.id, isInserting) &&
+      VerificationContext()
-      description.isAcceptableValue(instance.description, isInserting);
+        ..handle(
+            _idMeta, id.isAcceptableValue(instance.id, isInserting, _idMeta))
+        ..handle(
+            _descriptionMeta,
+            description.isAcceptableValue(
+                instance.description, isInserting, _descriptionMeta));
   @override
   Set<GeneratedColumn> get $primaryKey => {id};
   @override
@@ -199,6 +207,7 @@ class $RecipesTable extends Recipes with TableInfo<$RecipesTable, Recipe> {
   final GeneratedDatabase _db;
   final String _alias;
   $RecipesTable(this._db, [this._alias]);
+  final VerificationMeta _idMeta = const VerificationMeta('id');
   GeneratedIntColumn _id;
   @override
   GeneratedIntColumn get id => _id ??= _constructId();
@@ -206,6 +215,7 @@ class $RecipesTable extends Recipes with TableInfo<$RecipesTable, Recipe> {
     return GeneratedIntColumn('id', $tableName, false, hasAutoIncrement: true);
   }
 
+  final VerificationMeta _titleMeta = const VerificationMeta('title');
   GeneratedTextColumn _title;
   @override
   GeneratedTextColumn get title => _title ??= _constructTitle();
@@ -213,6 +223,8 @@ class $RecipesTable extends Recipes with TableInfo<$RecipesTable, Recipe> {
     return GeneratedTextColumn('title', $tableName, false, maxTextLength: 16);
   }
 
+  final VerificationMeta _instructionsMeta =
+      const VerificationMeta('instructions');
   GeneratedTextColumn _instructions;
   @override
   GeneratedTextColumn get instructions =>
@@ -225,6 +237,7 @@ class $RecipesTable extends Recipes with TableInfo<$RecipesTable, Recipe> {
     );
   }
 
+  final VerificationMeta _categoryMeta = const VerificationMeta('category');
   GeneratedIntColumn _category;
   @override
   GeneratedIntColumn get category => _category ??= _constructCategory();
@@ -245,11 +258,20 @@ class $RecipesTable extends Recipes with TableInfo<$RecipesTable, Recipe> {
   @override
   final String actualTableName = 'recipes';
   @override
-  bool validateIntegrity(Recipe instance, bool isInserting) =>
+  VerificationContext validateIntegrity(Recipe instance, bool isInserting) =>
-      id.isAcceptableValue(instance.id, isInserting) &&
+      VerificationContext()
-      title.isAcceptableValue(instance.title, isInserting) &&
+        ..handle(
-      instructions.isAcceptableValue(instance.instructions, isInserting) &&
+            _idMeta, id.isAcceptableValue(instance.id, isInserting, _idMeta))
-      category.isAcceptableValue(instance.category, isInserting);
+        ..handle(_titleMeta,
+            title.isAcceptableValue(instance.title, isInserting, _titleMeta))
+        ..handle(
+            _instructionsMeta,
+            instructions.isAcceptableValue(
+                instance.instructions, isInserting, _instructionsMeta))
+        ..handle(
+            _categoryMeta,
+            category.isAcceptableValue(
+                instance.category, isInserting, _categoryMeta));
   @override
   Set<GeneratedColumn> get $primaryKey => {id};
   @override
@@ -349,6 +371,7 @@ class $IngredientsTable extends Ingredients
   final GeneratedDatabase _db;
   final String _alias;
   $IngredientsTable(this._db, [this._alias]);
+  final VerificationMeta _idMeta = const VerificationMeta('id');
   GeneratedIntColumn _id;
   @override
   GeneratedIntColumn get id => _id ??= _constructId();
@@ -356,6 +379,7 @@ class $IngredientsTable extends Ingredients
     return GeneratedIntColumn('id', $tableName, false, hasAutoIncrement: true);
   }
 
+  final VerificationMeta _nameMeta = const VerificationMeta('name');
   GeneratedTextColumn _name;
   @override
   GeneratedTextColumn get name => _name ??= _constructName();
@@ -367,6 +391,8 @@ class $IngredientsTable extends Ingredients
     );
   }
 
+  final VerificationMeta _caloriesPer100gMeta =
+      const VerificationMeta('caloriesPer100g');
   GeneratedIntColumn _caloriesPer100g;
   @override
   GeneratedIntColumn get caloriesPer100g =>
@@ -388,10 +414,17 @@ class $IngredientsTable extends Ingredients
   @override
   final String actualTableName = 'ingredients';
   @override
-  bool validateIntegrity(Ingredient instance, bool isInserting) =>
+  VerificationContext validateIntegrity(
-      id.isAcceptableValue(instance.id, isInserting) &&
+          Ingredient instance, bool isInserting) =>
-      name.isAcceptableValue(instance.name, isInserting) &&
+      VerificationContext()
-      caloriesPer100g.isAcceptableValue(instance.caloriesPer100g, isInserting);
+        ..handle(
+            _idMeta, id.isAcceptableValue(instance.id, isInserting, _idMeta))
+        ..handle(_nameMeta,
+            name.isAcceptableValue(instance.name, isInserting, _nameMeta))
+        ..handle(
+            _caloriesPer100gMeta,
+            caloriesPer100g.isAcceptableValue(
+                instance.caloriesPer100g, isInserting, _caloriesPer100gMeta));
   @override
   Set<GeneratedColumn> get $primaryKey => {id};
   @override
@@ -492,6 +525,7 @@ class $IngredientInRecipesTable extends IngredientInRecipes
   final GeneratedDatabase _db;
   final String _alias;
   $IngredientInRecipesTable(this._db, [this._alias]);
+  final VerificationMeta _recipeMeta = const VerificationMeta('recipe');
   GeneratedIntColumn _recipe;
   @override
   GeneratedIntColumn get recipe => _recipe ??= _constructRecipe();
@@ -503,6 +537,7 @@ class $IngredientInRecipesTable extends IngredientInRecipes
     );
   }
 
+  final VerificationMeta _ingredientMeta = const VerificationMeta('ingredient');
   GeneratedIntColumn _ingredient;
   @override
   GeneratedIntColumn get ingredient => _ingredient ??= _constructIngredient();
@@ -514,6 +549,8 @@ class $IngredientInRecipesTable extends IngredientInRecipes
     );
   }
 
+  final VerificationMeta _amountInGramsMeta =
+      const VerificationMeta('amountInGrams');
   GeneratedIntColumn _amountInGrams;
   @override
   GeneratedIntColumn get amountInGrams =>
@@ -535,10 +572,19 @@ class $IngredientInRecipesTable extends IngredientInRecipes
   @override
   final String actualTableName = 'recipe_ingredients';
   @override
-  bool validateIntegrity(IngredientInRecipe instance, bool isInserting) =>
+  VerificationContext validateIntegrity(
-      recipe.isAcceptableValue(instance.recipe, isInserting) &&
+          IngredientInRecipe instance, bool isInserting) =>
-      ingredient.isAcceptableValue(instance.ingredient, isInserting) &&
+      VerificationContext()
-      amountInGrams.isAcceptableValue(instance.amountInGrams, isInserting);
+        ..handle(_recipeMeta,
+            recipe.isAcceptableValue(instance.recipe, isInserting, _recipeMeta))
+        ..handle(
+            _ingredientMeta,
+            ingredient.isAcceptableValue(
+                instance.ingredient, isInserting, _ingredientMeta))
+        ..handle(
+            _amountInGramsMeta,
+            amountInGrams.isAcceptableValue(
+                instance.amountInGrams, isInserting, _amountInGramsMeta));
   @override
   Set<GeneratedColumn> get $primaryKey => {recipe, ingredient};
   @override

moor/lib/moor.dart

@@ -21,6 +21,7 @@ export 'package:moor/src/runtime/statements/select.dart';
 export 'package:moor/src/runtime/statements/insert.dart';
 export 'package:moor/src/runtime/statements/delete.dart';
 export 'package:moor/src/runtime/structure/columns.dart';
+export 'package:moor/src/runtime/structure/error_handling.dart';
 export 'package:moor/src/runtime/structure/table_info.dart';
 export 'package:moor/src/runtime/data_class.dart';
 export 'package:moor/src/runtime/database.dart';

moor/lib/src/runtime/statements/insert.dart

@@ -116,9 +116,7 @@ class InsertStatement<DataClass> {
       throw InvalidDataException(
           'Cannot writee null row into ${table.$tableName}');
     }
-    if (!table.validateIntegrity(d, true)) {
+
-      throw InvalidDataException(
+    table.validateIntegrity(d, true).throwIfInvalid(d);
-          'Invalid data: $d cannot be written into ${table.$tableName}');
-    }
   }
 }

moor/lib/src/runtime/statements/update.dart

@@ -56,10 +56,7 @@ class UpdateStatement<T extends Table, D> extends Query<T, D>
   /// See also: [replace], which does not require [where] statements and
   /// supports setting fields back to null.
   Future<int> write(D entity) async {
-    if (!table.validateIntegrity(entity, false)) {
+    table.validateIntegrity(entity, false).throwIfInvalid(entity);
-      throw InvalidDataException(
-          'Invalid data: $entity cannot be written into ${table.$tableName}');
-    }
 
     _updatedFields = table.entityToSql(entity)
       ..remove((_, value) => value == null);
@@ -93,10 +90,7 @@ class UpdateStatement<T extends Table, D> extends Query<T, D>
     // because all the fields from the entity will be written (as opposed to a
     // regular update, where only non-null fields will be written). If isInserted
     // was false, the null fields would not be validated.
-    if (!table.validateIntegrity(entity, true)) {
+    table.validateIntegrity(entity, true).throwIfInvalid(entity);
-      throw InvalidDataException('Invalid data: $entity cannot be used to '
-          'replace another row as some required fields are null or invalid.');
-    }
     assert(
         whereExpr == null,
         'When using replace on an update statement, you may not use where(...)'

moor/lib/src/runtime/structure/columns.dart

@@ -9,6 +9,12 @@ import 'package:moor/src/runtime/expressions/variables.dart';
 import 'package:moor/src/types/sql_types.dart';
 import 'package:moor/sqlite_keywords.dart';
 
+import 'error_handling.dart';
+
+const VerificationResult _invalidNull = VerificationResult.failure(
+    "This column is not nullable and doesn't have a default value. "
+    "Null fields thus can't be inserted.");
+
 /// Base class for the implementation of [Column].
 abstract class GeneratedColumn<T, S extends SqlType<T>> extends Column<T, S> {
   /// The sql name of this column.
@@ -84,9 +90,14 @@ abstract class GeneratedColumn<T, S extends SqlType<T>> extends Column<T, S> {
   /// method should check whether the value is valid for an update. Null values
   /// should always be accepted for updates, as the describe a value that should
   /// not be replaced.
-  bool isAcceptableValue(T value, bool duringInsert) {
+  VerificationResult isAcceptableValue(
+      T value, bool duringInsert, VerificationMeta meta) {
     final nullOk = !duringInsert || $nullable || defaultValue != null;
-    return nullOk || value != null;
+    if (!nullOk && value == null) {
+      return _invalidNull;
+    } else {
+      return const VerificationResult.success();
+    }
   }
 }
 
@@ -114,15 +125,22 @@ class GeneratedTextColumn extends GeneratedColumn<String, StringType>
   final String typeName = 'VARCHAR';
 
   @override
-  bool isAcceptableValue(String value, bool duringInsert) {
+  VerificationResult isAcceptableValue(
+      String value, bool duringInsert, VerificationMeta meta) {
     // handle nullability check in common column
-    if (value == null) return super.isAcceptableValue(null, duringInsert);
+    if (value == null) return super.isAcceptableValue(null, duringInsert, meta);
 
     final length = value.length;
-    if (minTextLength != null && minTextLength > length) return false;
+    if (minTextLength != null && minTextLength > length) {
-    if (maxTextLength != null && maxTextLength < length) return false;
+      return VerificationResult.failure(
+          'Must at least be $minTextLength characters long.');
+    }
+    if (maxTextLength != null && maxTextLength < length) {
+      return VerificationResult.failure(
+          'Must at most be $maxTextLength characters long.');
+    }
 
-    return true;
+    return const VerificationResult.success();
   }
 }
 
@@ -171,8 +189,13 @@ class GeneratedIntColumn extends GeneratedColumn<int, IntType>
   }
 
   @override
-  bool isAcceptableValue(int value, bool duringInsert) =>
+  VerificationResult isAcceptableValue(
-      hasAutoIncrement || super.isAcceptableValue(value, duringInsert);
+      int value, bool duringInsert, VerificationMeta meta) {
+    if (hasAutoIncrement) {
+      return const VerificationResult.success();
+    }
+    return super.isAcceptableValue(value, duringInsert, meta);
+  }
 }
 
 class GeneratedDateTimeColumn extends GeneratedColumn<DateTime, DateTimeType>

moor/lib/src/runtime/structure/error_handling.dart

@@ -0,0 +1,48 @@
+import 'package:moor/moor.dart';
+
+/// Additional information that is passed to [GeneratedColumn]s when verifying
+/// data to provide more helpful error messages.
+class VerificationMeta {
+  /// The dart getter name of the property being validated.
+  final String dartGetterName;
+
+  const VerificationMeta(this.dartGetterName);
+}
+
+/// Returned by [GeneratedColumn.isAcceptableValue] to provide a description
+/// when a valid is invalid.
+class VerificationResult {
+  final bool success;
+  final String message;
+
+  const VerificationResult(this.success, this.message);
+  const VerificationResult.success()
+      : success = true,
+        message = null;
+  const VerificationResult.failure(this.message) : success = false;
+}
+
+class VerificationContext {
+  final Map<VerificationMeta, VerificationResult> _errors = {};
+
+  bool get dataValid => _errors.isEmpty;
+
+  void handle(VerificationMeta meta, VerificationResult result) {
+    if (!result.success) {
+      _errors[meta] = result;
+    }
+  }
+
+  void throwIfInvalid(dynamic dataObject) {
+    if (dataValid) return;
+
+    final messageBuilder =
+        StringBuffer('Sorry, $dataObject cannot be used for that because: \n');
+
+    _errors.forEach((meta, result) {
+      messageBuilder.write('• ${meta.dartGetterName}: ${result.message}\n');
+    });
+
+    throw InvalidDataException(messageBuilder.toString());
+  }
+}

moor/lib/src/runtime/structure/table_info.dart

@@ -38,7 +38,7 @@ mixin TableInfo<TableDsl extends Table, DataClass> {
   /// that it respects all constraints (nullability, text length, etc.).
   /// During insertion mode, fields that have a default value or are
   /// auto-incrementing are allowed to be null as they will be set by sqlite.
-  bool validateIntegrity(DataClass instance, bool isInserting);
+  VerificationContext validateIntegrity(DataClass instance, bool isInserting);
 
   /// Maps the given data class to a [Map] that can be inserted into sql. The
   /// keys should represent the column name in sql, the values the corresponding

moor/test/data/tables/todos.g.dart

@@ -102,6 +102,7 @@ class $TodosTableTable extends TodosTable
   final GeneratedDatabase _db;
   final String _alias;
   $TodosTableTable(this._db, [this._alias]);
+  final VerificationMeta _idMeta = const VerificationMeta('id');
   GeneratedIntColumn _id;
   @override
   GeneratedIntColumn get id => _id ??= _constructId();
@@ -109,6 +110,7 @@ class $TodosTableTable extends TodosTable
     return GeneratedIntColumn('id', $tableName, false, hasAutoIncrement: true);
   }
 
+  final VerificationMeta _titleMeta = const VerificationMeta('title');
   GeneratedTextColumn _title;
   @override
   GeneratedTextColumn get title => _title ??= _constructTitle();
@@ -117,6 +119,7 @@ class $TodosTableTable extends TodosTable
         minTextLength: 4, maxTextLength: 16);
   }
 
+  final VerificationMeta _contentMeta = const VerificationMeta('content');
   GeneratedTextColumn _content;
   @override
   GeneratedTextColumn get content => _content ??= _constructContent();
@@ -128,6 +131,7 @@ class $TodosTableTable extends TodosTable
     );
   }
 
+  final VerificationMeta _targetDateMeta = const VerificationMeta('targetDate');
   GeneratedDateTimeColumn _targetDate;
   @override
   GeneratedDateTimeColumn get targetDate =>
@@ -140,6 +144,7 @@ class $TodosTableTable extends TodosTable
     );
   }
 
+  final VerificationMeta _categoryMeta = const VerificationMeta('category');
   GeneratedIntColumn _category;
   @override
   GeneratedIntColumn get category => _category ??= _constructCategory();
@@ -161,12 +166,24 @@ class $TodosTableTable extends TodosTable
   @override
   final String actualTableName = 'todos';
   @override
-  bool validateIntegrity(TodoEntry instance, bool isInserting) =>
+  VerificationContext validateIntegrity(TodoEntry instance, bool isInserting) =>
-      id.isAcceptableValue(instance.id, isInserting) &&
+      VerificationContext()
-      title.isAcceptableValue(instance.title, isInserting) &&
+        ..handle(
-      content.isAcceptableValue(instance.content, isInserting) &&
+            _idMeta, id.isAcceptableValue(instance.id, isInserting, _idMeta))
-      targetDate.isAcceptableValue(instance.targetDate, isInserting) &&
+        ..handle(_titleMeta,
-      category.isAcceptableValue(instance.category, isInserting);
+            title.isAcceptableValue(instance.title, isInserting, _titleMeta))
+        ..handle(
+            _contentMeta,
+            content.isAcceptableValue(
+                instance.content, isInserting, _contentMeta))
+        ..handle(
+            _targetDateMeta,
+            targetDate.isAcceptableValue(
+                instance.targetDate, isInserting, _targetDateMeta))
+        ..handle(
+            _categoryMeta,
+            category.isAcceptableValue(
+                instance.category, isInserting, _categoryMeta));
   @override
   Set<GeneratedColumn> get $primaryKey => {id};
   @override
@@ -259,6 +276,7 @@ class $CategoriesTable extends Categories
   final GeneratedDatabase _db;
   final String _alias;
   $CategoriesTable(this._db, [this._alias]);
+  final VerificationMeta _idMeta = const VerificationMeta('id');
   GeneratedIntColumn _id;
   @override
   GeneratedIntColumn get id => _id ??= _constructId();
@@ -266,6 +284,8 @@ class $CategoriesTable extends Categories
     return GeneratedIntColumn('id', $tableName, false, hasAutoIncrement: true);
   }
 
+  final VerificationMeta _descriptionMeta =
+      const VerificationMeta('description');
   GeneratedTextColumn _description;
   @override
   GeneratedTextColumn get description =>
@@ -284,9 +304,14 @@ class $CategoriesTable extends Categories
   @override
   final String actualTableName = 'categories';
   @override
-  bool validateIntegrity(Category instance, bool isInserting) =>
+  VerificationContext validateIntegrity(Category instance, bool isInserting) =>
-      id.isAcceptableValue(instance.id, isInserting) &&
+      VerificationContext()
-      description.isAcceptableValue(instance.description, isInserting);
+        ..handle(
+            _idMeta, id.isAcceptableValue(instance.id, isInserting, _idMeta))
+        ..handle(
+            _descriptionMeta,
+            description.isAcceptableValue(
+                instance.description, isInserting, _descriptionMeta));
   @override
   Set<GeneratedColumn> get $primaryKey => {id};
   @override
@@ -413,6 +438,7 @@ class $UsersTable extends Users with TableInfo<$UsersTable, User> {
   final GeneratedDatabase _db;
   final String _alias;
   $UsersTable(this._db, [this._alias]);
+  final VerificationMeta _idMeta = const VerificationMeta('id');
   GeneratedIntColumn _id;
   @override
   GeneratedIntColumn get id => _id ??= _constructId();
@@ -420,6 +446,7 @@ class $UsersTable extends Users with TableInfo<$UsersTable, User> {
     return GeneratedIntColumn('id', $tableName, false, hasAutoIncrement: true);
   }
 
+  final VerificationMeta _nameMeta = const VerificationMeta('name');
   GeneratedTextColumn _name;
   @override
   GeneratedTextColumn get name => _name ??= _constructName();
@@ -428,6 +455,7 @@ class $UsersTable extends Users with TableInfo<$UsersTable, User> {
         minTextLength: 6, maxTextLength: 32);
   }
 
+  final VerificationMeta _isAwesomeMeta = const VerificationMeta('isAwesome');
   GeneratedBoolColumn _isAwesome;
   @override
   GeneratedBoolColumn get isAwesome => _isAwesome ??= _constructIsAwesome();
@@ -436,6 +464,8 @@ class $UsersTable extends Users with TableInfo<$UsersTable, User> {
         defaultValue: const Constant(true));
   }
 
+  final VerificationMeta _profilePictureMeta =
+      const VerificationMeta('profilePicture');
   GeneratedBlobColumn _profilePicture;
   @override
   GeneratedBlobColumn get profilePicture =>
@@ -448,6 +478,8 @@ class $UsersTable extends Users with TableInfo<$UsersTable, User> {
     );
   }
 
+  final VerificationMeta _creationTimeMeta =
+      const VerificationMeta('creationTime');
   GeneratedDateTimeColumn _creationTime;
   @override
   GeneratedDateTimeColumn get creationTime =>
@@ -467,12 +499,24 @@ class $UsersTable extends Users with TableInfo<$UsersTable, User> {
   @override
   final String actualTableName = 'users';
   @override
-  bool validateIntegrity(User instance, bool isInserting) =>
+  VerificationContext validateIntegrity(User instance, bool isInserting) =>
-      id.isAcceptableValue(instance.id, isInserting) &&
+      VerificationContext()
-      name.isAcceptableValue(instance.name, isInserting) &&
+        ..handle(
-      isAwesome.isAcceptableValue(instance.isAwesome, isInserting) &&
+            _idMeta, id.isAcceptableValue(instance.id, isInserting, _idMeta))
-      profilePicture.isAcceptableValue(instance.profilePicture, isInserting) &&
+        ..handle(_nameMeta,
-      creationTime.isAcceptableValue(instance.creationTime, isInserting);
+            name.isAcceptableValue(instance.name, isInserting, _nameMeta))
+        ..handle(
+            _isAwesomeMeta,
+            isAwesome.isAcceptableValue(
+                instance.isAwesome, isInserting, _isAwesomeMeta))
+        ..handle(
+            _profilePictureMeta,
+            profilePicture.isAcceptableValue(
+                instance.profilePicture, isInserting, _profilePictureMeta))
+        ..handle(
+            _creationTimeMeta,
+            creationTime.isAcceptableValue(
+                instance.creationTime, isInserting, _creationTimeMeta));
   @override
   Set<GeneratedColumn> get $primaryKey => {id};
   @override
@@ -563,6 +607,7 @@ class $SharedTodosTable extends SharedTodos
   final GeneratedDatabase _db;
   final String _alias;
   $SharedTodosTable(this._db, [this._alias]);
+  final VerificationMeta _todoMeta = const VerificationMeta('todo');
   GeneratedIntColumn _todo;
   @override
   GeneratedIntColumn get todo => _todo ??= _constructTodo();
@@ -574,6 +619,7 @@ class $SharedTodosTable extends SharedTodos
     );
   }
 
+  final VerificationMeta _userMeta = const VerificationMeta('user');
   GeneratedIntColumn _user;
   @override
   GeneratedIntColumn get user => _user ??= _constructUser();
@@ -594,9 +640,13 @@ class $SharedTodosTable extends SharedTodos
   @override
   final String actualTableName = 'shared_todos';
   @override
-  bool validateIntegrity(SharedTodo instance, bool isInserting) =>
+  VerificationContext validateIntegrity(
-      todo.isAcceptableValue(instance.todo, isInserting) &&
+          SharedTodo instance, bool isInserting) =>
-      user.isAcceptableValue(instance.user, isInserting);
+      VerificationContext()
+        ..handle(_todoMeta,
+            todo.isAcceptableValue(instance.todo, isInserting, _todoMeta))
+        ..handle(_userMeta,
+            user.isAcceptableValue(instance.user, isInserting, _userMeta));
   @override
   Set<GeneratedColumn> get $primaryKey => {todo, user};
   @override
@@ -686,6 +736,8 @@ class $TableWithoutPKTable extends TableWithoutPK
   final GeneratedDatabase _db;
   final String _alias;
   $TableWithoutPKTable(this._db, [this._alias]);
+  final VerificationMeta _notReallyAnIdMeta =
+      const VerificationMeta('notReallyAnId');
   GeneratedIntColumn _notReallyAnId;
   @override
   GeneratedIntColumn get notReallyAnId =>
@@ -698,6 +750,7 @@ class $TableWithoutPKTable extends TableWithoutPK
     );
   }
 
+  final VerificationMeta _someFloatMeta = const VerificationMeta('someFloat');
   GeneratedRealColumn _someFloat;
   @override
   GeneratedRealColumn get someFloat => _someFloat ??= _constructSomeFloat();
@@ -718,9 +771,17 @@ class $TableWithoutPKTable extends TableWithoutPK
   @override
   final String actualTableName = 'table_without_p_k';
   @override
-  bool validateIntegrity(TableWithoutPKData instance, bool isInserting) =>
+  VerificationContext validateIntegrity(
-      notReallyAnId.isAcceptableValue(instance.notReallyAnId, isInserting) &&
+          TableWithoutPKData instance, bool isInserting) =>
-      someFloat.isAcceptableValue(instance.someFloat, isInserting);
+      VerificationContext()
+        ..handle(
+            _notReallyAnIdMeta,
+            notReallyAnId.isAcceptableValue(
+                instance.notReallyAnId, isInserting, _notReallyAnIdMeta))
+        ..handle(
+            _someFloatMeta,
+            someFloat.isAcceptableValue(
+                instance.someFloat, isInserting, _someFloatMeta));
   @override
   Set<GeneratedColumn> get $primaryKey => <GeneratedColumn>{};
   @override

moor/test/error_handling_test.dart

@@ -0,0 +1,42 @@
+import 'package:moor/moor.dart';
+import 'package:test_api/test_api.dart';
+
+import 'data/tables/todos.dart';
+import 'data/utils/mocks.dart';
+
+// the content is set to non-null and the title must be between 4 and 16 chars
+// long
+final nullContent = TodoEntry(title: 'Test', content: null);
+final shortTitle = TodoEntry(title: 'A', content: 'content');
+final longTitle = TodoEntry(title: 'A ${'very' * 5} long title', content: 'hi');
+final valid = TodoEntry(title: 'Test', content: 'Some content');
+
+void main() {
+  TodoDb db;
+  MockExecutor executor;
+
+  setUp(() {
+    executor = MockExecutor();
+    db = TodoDb(executor);
+  });
+
+  test('detects errors on insert', () {
+    expect(
+      () => db.into(db.todosTable).insert(nullContent),
+      throwsA(predicate<InvalidDataException>(
+          (e) => e.message.contains('not nullable'))),
+    );
+    expect(
+      () => db.into(db.todosTable).insert(shortTitle),
+      throwsA(predicate<InvalidDataException>(
+          (e) => e.message.contains('Must at least be'))),
+    );
+    expect(
+      () => db.into(db.todosTable).insert(longTitle),
+      throwsA(predicate<InvalidDataException>(
+          (e) => e.message.contains('Must at most be'))),
+    );
+
+    expect(db.into(db.todosTable).insert(valid), completes);
+  });
+}

moor_generator/lib/src/writer/table_writer.dart

@@ -34,6 +34,7 @@ class TableWriter {
 
     // Generate the columns
     for (var column in table.columns) {
+      _writeColumnVerificationMeta(buffer, column);
       _writeColumnGetter(buffer, column);
     }
 
@@ -147,22 +148,42 @@ class TableWriter {
     );
   }
 
+  void _writeColumnVerificationMeta(
+      StringBuffer buffer, SpecifiedColumn column) {
+    // final VerificationMeta _targetDateMeta = const VerificationMeta('targetDate');
+    buffer
+      ..write('final VerificationMeta ${_fieldNameForColumnMeta(column)} = ')
+      ..write("const VerificationMeta('${column.dartGetterName}');\n");
+  }
+
   void _writeValidityCheckMethod(StringBuffer buffer) {
     final dataClass = table.dartTypeName;
 
-    buffer.write(
+    buffer.write('@override\nVerificationContext validateIntegrity'
-        '@override\nbool validateIntegrity($dataClass instance, bool isInserting) => ');
+        '($dataClass instance, bool isInserting) => VerificationContext()');
 
-    final validationCode = table.columns.map((column) {
+    /*
+    return VerificationContext()
+      ..handle(
+          _categoryMeta,
+          category.isAcceptableValue(
+              instance.category, isInserting, _categoryMeta));
+     */
+
+    for (var column in table.columns) {
       final getterName = column.dartGetterName;
+      final metaName = _fieldNameForColumnMeta(column);
 
-      // generated columns have a isAcceptableValue(T value, bool duringInsert)
+      // ..handle(_meta, c.isAcceptableValue(instance.c, insert, _meta))
-      // method
+      buffer.write('..handle($metaName, $getterName.isAcceptableValue('
+          'instance.$getterName, isInserting, $metaName))');
+    }
 
-      return '$getterName.isAcceptableValue(instance.$getterName, isInserting)';
+    buffer.write(';\n');
-    }).join('&&');
+  }
 
-    buffer..write(validationCode)..write(';\n');
+  String _fieldNameForColumnMeta(SpecifiedColumn column) {
+    return '_${column.dartGetterName}Meta';
   }
 
   void _writePrimaryKeyOverride(StringBuffer buffer) {