发布于 2015-08-21 15:06:46 | 771 次阅读 | 评论: 0 | 来源: 网络整理
To speed up development PhalconMvcModel helps you to query fields and constraints from tables related to models. To achieve this, PhalconMvcModelMetaData is available to manage and cache table meta-data.
Sometimes it is necessary to get those attributes when working with models. You can get a meta-data instance as follows:
<?php
$robot = new Robots();
// Get PhalconMvcModelMetadata instance
$metaData = $robot->getModelsMetaData();
// Get robots fields names
$attributes = $metaData->getAttributes($robot);
print_r($attributes);
// Get robots fields data types
$dataTypes = $metaData->getDataTypes($robot);
print_r($dataTypes);
Once the application is in a production stage, it is not necessary to query the meta-data of the table from the database system each time you use the table. This could be done caching the meta-data using any of the following adapters:
| Adapter | Description | API |
|---|---|---|
| Memory | This adapter is the default. The meta-data is cached only during the request. When the request is completed, the meta-data are released as part of the normal memory of the request. This adapter is perfect when the application is in development so as to refresh the meta-data in each request containing the new and/or modified fields. | PhalconMvcModelMetaDataMemory |
| Session | This adapter stores meta-data in the $_SESSION superglobal. This adapter is recommended only when the application is actually using a small number of models. The meta-data are refreshed every time a new session starts. This also requires the use of session_start() to start the session before using any models. | PhalconMvcModelMetaDataSession |
| Apc | This adapter uses the Alternative PHP Cache (APC) to store the table meta-data. You can specify the lifetime of the meta-data with options. This is the most recommended way to store meta-data when the application is in production stage. | PhalconMvcModelMetaDataApc |
| XCache | This adapter uses XCache to store the table meta-data. You can specify the lifetime of the meta-data with options. This is the most recommended way to store meta-data when the application is in production stage. | PhalconMvcModelMetaDataXcache |
| Files | This adapter uses plain files to store meta-data. By using this adapter the disk-reading is increased but the database access is reduced | PhalconMvcModelMetaDataFiles |
As other ORM’s dependencies, the metadata manager is requested from the services container:
<?php
use PhalconMvcModelMetaDataApc as ApcMetaData;
$di['modelsMetadata'] = function () {
// Create a meta-data manager with APC
$metaData = new ApcMetaData(
array(
"lifetime" => 86400,
"prefix" => "my-prefix"
)
);
return $metaData;
};
As mentioned above the default strategy to obtain the model’s meta-data is database introspection. In this strategy, the information schema is used to know the fields in a table, its primary key, nullable fields, data types, etc.
You can change the default meta-data introspection in the following way:
<?php
use PhalconMvcModelMetaDataApc as ApcMetaData;
$di['modelsMetadata'] = function () {
// Instantiate a meta-data adapter
$metaData = new ApcMetaData(
array(
"lifetime" => 86400,
"prefix" => "my-prefix"
)
);
// Set a custom meta-data introspection strategy
$metaData->setStrategy(new MyIntrospectionStrategy());
return $metaData;
};
This strategy doesn’t require any customization and is implicitly used by all the meta-data adapters.
This strategy makes use of annotations to describe the columns in a model:
<?php
use PhalconMvcModel;
class Robots extends Model
{
/**
* @Primary
* @Identity
* @Column(type="integer", nullable=false)
*/
public $id;
/**
* @Column(type="string", length=70, nullable=false)
*/
public $name;
/**
* @Column(type="string", length=32, nullable=false)
*/
public $type;
/**
* @Column(type="integer", nullable=false)
*/
public $year;
}
Annotations must be placed in properties that are mapped to columns in the mapped source. Properties without the @Column annotation are handled as simple class attributes.
The following annotations are supported:
| Name | Description |
|---|---|
| Primary | Mark the field as part of the table’s primary key |
| Identity | The field is an auto_increment/serial column |
| Column | This marks an attribute as a mapped column |
The annotation @Column supports the following parameters:
| Name | Description |
|---|---|
| type | The column’s type (string, integer, decimal, boolean) |
| length | The column’s length if any |
| nullable | Set whether the column accepts null values or not |
The annotations strategy could be set up this way:
<?php
use PhalconMvcModelMetaDataApc as ApcMetaData;
use PhalconMvcModelMetaDataStrategyAnnotations as StrategyAnnotations;
$di['modelsMetadata'] = function () {
// Instantiate a meta-data adapter
$metaData = new ApcMetaData(
array(
"lifetime" => 86400,
"prefix" => "my-prefix"
)
);
// Set a custom meta-data database introspection
$metaData->setStrategy(new StrategyAnnotations());
return $metaData;
};
Phalcon can obtain the metadata for each model automatically without the developer must set them manually using any of the introspection strategies presented above.
The developer also has the option of define the metadata manually. This strategy overrides any strategy set in the meta-data manager. New columns added/modified/removed to/from the mapped table must be added/modified/removed also for everything to work properly.
The following example shows how to define the meta-data manually:
<?php
use PhalconMvcModel;
use PhalconDbColumn;
use PhalconMvcModelMetaData;
class Robots extends Model
{
public function metaData()
{
return array(
// Every column in the mapped table
MetaData::MODELS_ATTRIBUTES => array(
'id', 'name', 'type', 'year'
),
// Every column part of the primary key
MetaData::MODELS_PRIMARY_KEY => array(
'id'
),
// Every column that isn't part of the primary key
MetaData::MODELS_NON_PRIMARY_KEY => array(
'name', 'type', 'year'
),
// Every column that doesn't allows null values
MetaData::MODELS_NOT_NULL => array(
'id', 'name', 'type'
),
// Every column and their data types
MetaData::MODELS_DATA_TYPES => array(
'id' => Column::TYPE_INTEGER,
'name' => Column::TYPE_VARCHAR,
'type' => Column::TYPE_VARCHAR,
'year' => Column::TYPE_INTEGER
),
// The columns that have numeric data types
MetaData::MODELS_DATA_TYPES_NUMERIC => array(
'id' => true,
'year' => true
),
// The identity column, use boolean false if the model doesn't have
// an identity column
MetaData::MODELS_IDENTITY_COLUMN => 'id',
// How every column must be bound/casted
MetaData::MODELS_DATA_TYPES_BIND => array(
'id' => Column::BIND_PARAM_INT,
'name' => Column::BIND_PARAM_STR,
'type' => Column::BIND_PARAM_STR,
'year' => Column::BIND_PARAM_INT
),
// Fields that must be ignored from INSERT SQL statements
MetaData::MODELS_AUTOMATIC_DEFAULT_INSERT => array(
'year' => true
),
// Fields that must be ignored from UPDATE SQL statements
MetaData::MODELS_AUTOMATIC_DEFAULT_UPDATE => array(
'year' => true
),
// Default values for columns
MetaData::MODELS_DEFAULT_VALUES => array(
'year' => '2015'
),
// Fields that allow empty strings
MetaData::MODELS_EMPTY_STRING_VALUES => array(
'name' => true
)
);
}
}