sometime my code run well, but sometime this error occurs

[hehbhehb]

2014-10-29 14:15:35 [111.172.8.83][][-][error][yii\base\ErrorException:8] exception 'yii\base\ErrorException' with message 'Trying to get property of non-object' in /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/ActiveRecord.php:359
Stack trace:
#0 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/ActiveRecord.php(359): yii\base\ErrorHandler->handleError(8, 'Trying to get p...', '/mnt/wwwroot/wx...', 359, Array)
#1 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/ActiveQueryTrait.php(132): yii\db\ActiveRecord::populateRecord(Object(app\models\MItem), Array)
#2 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/ActiveQuery.php(218): yii\db\ActiveQuery->createModels(Array)
#3 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/Query.php(207): yii\db\ActiveQuery->populate(Array)
#4 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/ActiveQuery.php(130): yii\db\Query->all(NULL)
#5 /mnt/wwwroot/wx/controllers/WapController.php(1143): yii\db\ActiveQuery->all()
#6 [internal function]: app\controllers\WapController->actionCardlist()
#7 /mnt/wwwroot/wx/vendor/yiisoft/yii2/base/InlineAction.php(55): call_user_func_array(Array, Array)
#8 /mnt/wwwroot/wx/vendor/yiisoft/yii2/base/Controller.php(151): yii\base\InlineAction->runWithParams(Array)
#9 /mnt/wwwroot/wx/vendor/yiisoft/yii2/base/Module.php(455): yii\base\Controller->runAction('cardlist', Array)
#10 /mnt/wwwroot/wx/vendor/yiisoft/yii2/web/Application.php(83): yii\base\Module->runAction('wap/cardlist', Array)
#11 /mnt/wwwroot/wx/vendor/yiisoft/yii2/base/Application.php(375): yii\web\Application->handleRequest(Object(yii\web\Request))
#12 /mnt/wwwroot/wx/web/index.php(14): yii\base\Application->run()
#13 {main}

Yii is 2.0.0

[hehbhehb]

code fragments:
public function actionCardlist()
{
....
$this->layout ='wapy';
$models = MItem::find()->where(['kind'=>$kind])->orderBy(['price'=>SORT_DESC])->all();
....
}

[mitalcoi]

How many records you have in table associated with MItem?

[hehbhehb]

3 records

[mdmunir]

show your MItem class.

[qiangxue]

Please show the PHP type of the value of MItem::getTableSchema(). What is your database type? Did you enable schema caching?

[hehbhehb]

it is object, mysql, yes, I enabled schema caching

2014-10-31 09:08:52,yii\db\TableSchema Object
(
[schemaName] =>
[name] => wx_item
[fullName] => wx_item
[primaryKey] => Array
(
[0] => iid
)

[sequenceName] =>
[foreignKeys] => Array
    (
    )

[columns] => Array
    (
        [iid] => yii\db\ColumnSchema Object
            (
                [name] => iid
                [allowNull] =>
                [type] => integer
                [phpType] => integer
                [dbType] => int(10) unsigned
                [defaultValue] =>
                [enumValues] =>
                [size] => 10
                [precision] => 10
                [scale] =>
                [isPrimaryKey] => 1
                [autoIncrement] => 1
                [unsigned] => 1
                [comment] =>
            )

        [gh_id] => yii\db\ColumnSchema Object
            (
                [name] => gh_id
                [allowNull] =>
        ....

....
)

CREATE TABLE wx_item (
iid int(10) unsigned NOT NULL AUTO_INCREMENT PRIMARY KEY,
gh_id VARCHAR(32) NOT NULL DEFAULT '',
price int(10) unsigned NOT NULL DEFAULT '0',
price_hint VARCHAR(128) NOT NULL DEFAULT '',
title VARCHAR(128) NOT NULL DEFAULT '',
title_hint VARCHAR(256) NOT NULL DEFAULT '',
pkg_name VARCHAR(128) NOT NULL DEFAULT '',
pkg_name_hint VARCHAR(256) NOT NULL DEFAULT '',
detail text NOT NULL DEFAULT '',
pic_url VARCHAR(256) NOT NULL DEFAULT '',
cid int(10) unsigned NOT NULL DEFAULT '0',
status int(10) unsigned NOT NULL DEFAULT '0',
quantity int(10) unsigned NOT NULL DEFAULT '0',
old_price int(10) unsigned NOT NULL DEFAULT '0',
old_price_hint VARCHAR(128) NOT NULL DEFAULT '',
ctrl_soldout tinyint(3) unsigned NOT NULL DEFAULT '0',
KEY gh_id_idx(gh_id)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

config/db.php:
return [
'class' => 'yii\db\Connection',
'dsn' => 'mysql:host=localhost;dbname=wx',
'username' => 'xxx',
'password' => 'xxx',
'charset' => 'utf8',
'enableSchemaCache' => true,
'schemaCacheDuration' => YII_DEBUG ? 10 : 3600,
];

web.php
...
'cache' => [
'class' => 'yii\caching\MemCache',
'keyPrefix' => 'ya54dee8',
'servers' => [
[
'host' => 'localhost',
'port' => 11211,
'weight' => 100,
],
],
],
...

[qiangxue]

Please replace line 359 in yii\db\ActiveRecord with the following code and show the exception message when it happens:

$schema = static::getTableSchema();
if (!$schema instanceof TableSchema) {
    throw new Exception("Unexpected type: " . gettype($schema));
}
$columns = $schema->columns;

[hehbhehb]

type is string

2014-10-31 13:19:34 [171.82.160.72][][-][error][yii\db\Exception] exception 'yii\db\Exception' with message 'Unexpected type: string' in /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/ActiveRecord.php:370
Stack trace:
#0 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/ActiveQueryTrait.php(132): yii\db\ActiveRecord::populateRecord(Object(app\models\MUser), Array)
#1 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/ActiveQuery.php(218): yii\db\ActiveQuery->createModels(Array)
#2 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/ActiveQuery.php(287): yii\db\ActiveQuery->populate(Array)
#3 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/ActiveRecord.php(180): yii\db\ActiveQuery->one()
#4 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/BaseActiveRecord.php(101): yii\db\ActiveRecord::findByCondition(Array, true)
#5 /mnt/wwwroot/wx/controllers/WapController.php(499): yii\db\BaseActiveRecord::findOne(Array)
#6 [internal function]: app\controllers\WapController->actionG2048()
#7 /mnt/wwwroot/wx/vendor/yiisoft/yii2/base/InlineAction.php(55): call_user_func_array(Array, Array)
#8 /mnt/wwwroot/wx/vendor/yiisoft/yii2/base/Controller.php(151): yii\base\InlineAction->runWithParams(Array)
#9 /mnt/wwwroot/wx/vendor/yiisoft/yii2/base/Module.php(455): yii\base\Controller->runAction('g2048', Array)
#10 /mnt/wwwroot/wx/vendor/yiisoft/yii2/web/Application.php(83): yii\base\Module->runAction('wap/g2048', Array)
#11 /mnt/wwwroot/wx/vendor/yiisoft/yii2/base/Application.php(375): yii\web\Application->handleRequest(Object(yii\web\Request))
#12 /mnt/wwwroot/wx/web/index.php(14): yii\base\Application->run()
#13 {main}

[qiangxue]

What is the value of $schema when it is a string? It seems your memcache may have some problem.

[hehbhehb]

it is string type, and its value is some number, such as "0.83963800 1415176883". yes, i will check my memcached

[hehbhehb]

i replace the memcache with apc, and got new errors
2014-11-07 13:17:19 [-][-][-][error][yii\base\ErrorException:2] exception 'yii\base\ErrorException' with message 'array_keys() expects parameter 1 to be array, boolean given' in /mnt/wwwroot/wx/vendor/yiisoft/yii2/caching/ApcCache.php:83
Stack trace:
#0 [internal function]: yii\base\ErrorHandler->handleError(2, 'array_keys() ex...', '/mnt/wwwroot/wx...', 83, Array)
#1 /mnt/wwwroot/wx/vendor/yiisoft/yii2/caching/ApcCache.php(83): array_keys(false)
#2 /mnt/wwwroot/wx/vendor/yiisoft/yii2/caching/Cache.php(235): yii\caching\ApcCache->setValues(Array, 0)
#3 /mnt/wwwroot/wx/vendor/yiisoft/yii2/caching/TagDependency.php(87): yii\caching\Cache->mset(Array)
#4 /mnt/wwwroot/wx/vendor/yiisoft/yii2/caching/TagDependency.php(43): yii\caching\TagDependency::touchKeys(Object(yii\caching\ApcCache), Array)
#5 /mnt/wwwroot/wx/vendor/yiisoft/yii2/caching/Dependency.php(54): yii\caching\TagDependency->generateDependencyData(Object(yii\caching\ApcCache))
#6 /mnt/wwwroot/wx/vendor/yiisoft/yii2/caching/Cache.php(193): yii\caching\Dependency->evaluateDependency(Object(yii\caching\ApcCache))
#7 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/Schema.php(129): yii\caching\Cache->set(Array, Object(yii\db\TableSchema), 3600, Object(yii\caching\TagDependency))
#8 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/Connection.php(709): yii\db\Schema->getTableSchema('wx_order', false)
#9 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/QueryBuilder.php(236): yii\db\Connection->getTableSchema('wx_order')
#10 /mnt/wwwroot/wx/vendor/yiisoft/yii2/db/Command.php(470): yii\db\QueryBuilder->update('wx_order', Array, 'status=:status ...', Array)

[qiangxue]

The APC issue was already fixed in master.
The original schema issue was also fixed in a separate commit.