-
class
atk4\data\
Field
¶
Field¶
Field represents a model property that can hold information about your entity. In Agile Data we call it a Field, to distinguish it from object properties. Fields inside a model normally have a corresponding instance of Field class.
See Model::addField()
on how fields are added. By default,
persistence sets the property _default_seed_addField which should correspond
to a field object that has enough capabilities for performing field-specific
mapping into persistence-logic.
-
class
atk4\data\
Field
Field represents a property of your business entity or column if you think of your data in a tabular way. Once you have defined Field for your Model, you can set and read value of that field:
$model->addField('name');
$model->set('name', 'John');
echo $model->get('name'); // john
Agile Data supports and prefers a ArrayAccess format of interacting with fields:
$model->addField('age');
$model['age'] = 29;
echo $model['age'];
Just like you can reuse Model
to access multiple data records,
Field
object will be reused also.
Purpose of Field¶
Implementation of Field in Agile Data is a very powerful and distinctive feature.
While Model::data
store your field values, the job of Field
is to interpret that value, normalize it, type-cast it, validate it and decide
on how to store or present it.
The implementation of Fields is tightly integrated with Model
and
Persistence
.
Field Type¶
-
property
atk4\data\Field::$
type
¶
Probably a most useful quality of Field is that it has a clear type:
$model->addField('age', ['type'=>'integer']);
$model['age'] = "123";
var_dump($model['age']); // int(123)
Agile Data defines some basic types to make sure that values:
- can be safely stored and manipulated.
- can be saved (Persistence)
- can be presented to user (UI)
A good example would be a date type:
$model->addField('birth', ['type' => 'date']);
$model['birth'] = DateTime::createFromFormat('m/d/Y', '1/10/2014');
$model->save();
When used with SQL persistence the value will be automatically converted into a format preferred by the database 2014-10-01. Because PHP has only a single type for storing date, time and datetime, this can lead to various problems such as handling of timezones or DST. Agile Data takes care of those issues for you automatically.
Conversions between types is what we call Typecasting and there is a documentation section dedicated to it.
Finally, because Field is a class, it can be further extended. For some
interesting examples, check out FieldPassword
. I’ll explain how to
create your own field classes and where they can be beneficial.
Valid types are: string, integer, boolean, datetime, date, time.
You can specify unsupported type too. It will be untouched by Agile Data so you would have to implement your own handling of a new type.
- Persistence implements two methods:
Persistence::typecastSaveRow()
Persistence::typecastLoadRow()
Those are responsible for converting PHP native types to persistence specific formats as defined in fields. Those methods will also change name of the field if needed (see Field::actual)
-
property
atk4\data\Field::$
typecast
¶
This property can be used to override typecasting for your field. See Typecasting
Basic Properties¶
Fields have properties, which define its behaviour. Some properties apply on how
the values are handled or restrictions on interaction, other values can even
help with data vizualization. For example if Field::enum
is used
with Agile UI form, it will be displayed as radio button or a drop-down:
$model->addField('gender', ['enum' => ['F', 'M']]);
// Agile UI code:
$app = new \atk4\ui\App('my app');
$app->initLayout('Centered');
$app->add('Form')->setModel($model);
You will also not be able to set value which is not one of the enum values even if you don’t use UI.
This allows you to define your data fields once and have those rules respected everywhere in your app - in your manual code, in UI and in API.
-
property
atk4\data\Field::$
default
¶
When no value is specified for a field, default value is used when inserting. This value will also appear pre-filled inside a Form.
-
property
atk4\data\Field::$
enum
¶
Specifies array containing all the possible options for the value. You can set only to one of the values (loosely typed comparison is used).
-
property
atk4\data\Field::$
values
¶
Specifies array containing all the possible options for the value. Similar with $enum, but difference is that this array is a hash array so array keys will be used as values and array values will be used as titles for these values.
-
property
atk4\data\Field::$
mandatory
¶
Set this to true if field value must not be NULL. You can set the NULL value to the field, but you won’t be able to save it.
Example:
$model['age'] = 0;
$model->save();
$model['age'] = null;
$model->save(); // exception
-
property
atk4\data\Field::$
required
¶
Set this to true for field that may not contain “empty” value.
You can’t use NULL or any value that is considered empty()
by PHP.
Some examples that are not allowed are:
- empty string “”
- 0 numerical value or 0.00
- boolean false
Example:
$model['age'] = 0;
$model->save(); // exception
$model['age'] = null;
$model->save(); // exception
-
property
atk4\data\Field::$
read_only
¶
Modifying field that is read-only through set() methods (or array access) will
result in exception. Field_SQL_Expression
is read-only by default.
-
property
atk4\data\Field::$
actual
¶
Specify name of the Table Row Field under which field will be persisted.
-
property
atk4\data\Field::$
join
¶
This property will point to Join
object if field is associated
with a joined table row.
-
property
atk4\data\Field::$
system
¶
System flag is intended for fields that are important to have inside hooks
or some core logic of a model. System fields will always be appended to
Model::onlyFields
, however by default they will not appear on forms
or grids (see Model::isVisible
, Model::isEditable
).
Adding condition on a field will also make it system.
-
property
atk4\data\Field::$
never_persist
¶
Field will never be loaded or saved into persistence. You can use this flag for fields that physically are not located in the database, yet you want to see this field in beforeSave hooks.
-
property
atk4\data\Field::$
never_save
¶
This field will be loaded normally, but will not be saved in a database. Unlike “read_only” which has a similar effect, you can still change the value of this field. It will simply be ignored on save. You can create some logic in beforeSave hook to read this value.
-
property
atk4\data\Field::$
ui
¶
This field contains certain arguments that may be needed by the UI layer to know if user should be allowed to edit this field.
-
atk4\data\Field::
set
()¶
Set the value of the field. Same as $model->set($field_name, $value);
-
atk4\data\Field::
get
()¶
Get the value of the field. Same as $model->get($field_name, $value);
UI Presentation¶
Agile Data does not deal directly with formatting your data for the user. There may be various items to consider, for instance the same date can be presented in a short or long format for the user.
The UI framework such as Agile Toolkit can make use of the Field::ui
property to allow user to define default formats or input parsing rules, but
Agile Data does not regulate the Field::ui
property and different
UI frameworks may use it differently.
-
atk4\data\Field::
isEditable
()¶
Returns true if UI should render this field as editable and include inside forms by default.
-
atk4\data\Field::
isVisible
()¶
Returns true if UI should render this field in Grid and other read_only display views by default.
-
atk4\data\Field::
isHidden
()¶
Returns true if UI should not render this field in views.
Password (after 1.5.0 release)¶
-
class
atk4\data\Field\
Password
¶
FieldPassword is a class that implements proper handling of data passwords. Without this class your password will be stored unencrypted. Here is how to use it properly:
$user->addField('mypass', ['Password']);
$user['mypass'] = 'secret';
$user->save();
Password is automatically hashed with password_encrypt before storing. If you attempt to load existing record from database and $user->get(‘mypass’) you will always get NULL.
There is another way to verify passwords using Model::compare
:
$user->loadBy('email', $email);
return $user->compare('password', $password);
This should return true if your supplied password matches the one that is stored. Final example:
// class User extends Model
function changePass($old_pass, $new_pass) {
if (!$this->compare('password', $old_pass)) {
throw new Exception('Old password is incorrect');
}
$this['password'] = $new_pass;
$this->save();
}