In this section, we will describe how to create a new page to get data from users.
This section describes how to create a new page with a form for getting data from users.
The page will display a form with a name input field and an email input field.
After getting these data from a user, the page will echo them back to the user for confirmation.
After getting those two pieces of information from the user, the page will echo the entered values back for confirmation.
To achieve this goal, besides creating an [action](structure-controllers.md) and
two [views](structure-views.md), you will also create a [model](structure-models.md).
Through this tutorial, you will learn
Through this tutorial, you will learn how to:
*How to create a [model](structure-models.md) to represent the data entered by a user;
*How to declare rules to validate the data entered by users;
*How to build an HTML form in a [view](structure-views.md).
*Create a [model](structure-models.md) to represent the data entered by a user through a form
*Declare rules to validate the data entered
*Build an HTML form in a [view](structure-views.md)
Creating a Model <a name="creating-model"></a>
----------------
To represent the data entered by a user, create an `EntryForm` model class as shown below and
save the class in the file `models/EntryForm.php`. Please refer to the [Class Autoloading](concept-autoloading.md)
The data to be requested from the user will be represented by an `EntryForm` model class as shown below and
saved in the file `models/EntryForm.php`. Please refer to the [Class Autoloading](concept-autoloading.md)
section for more details about the class file naming convention.
```php
...
...
@@ -44,26 +44,38 @@ class EntryForm extends Model
}
```
The class extends from [[yii\base\Model]], a base class provided by Yii that is commonly used to
The class extends from [[yii\base\Model]], a base class provided by Yii, commonly used to
represent form data.
The class contains two public members, `name` and `email`, which are used to keep
the data entered by the user. It also contains a method named `rules()` which returns a set
of rules used for validating the data. The validation rules declared above state that
> Info: [[yii\base\Model]] is used as a parent for model classes *not* associated with database tables. [[yii\db\ActiveRecord]] is normally the parent for model classes that do correspond to database tables.
* both the `name` and `email` data are required;
* the `email` data must be a valid email address.
The `EntryForm` class contains two public members, `name` and `email`, which are used to store
the data entered by the user. It also contains a method named `rules()`, which returns a set
of rules for validating the data. The validation rules declared above state that
* both the `name` and `email` values are required
* the `email` data must be a syntactically valid email address
If you have an `EntryForm` object populated with the data entered by a user, you may call
its [[yii\base\Model::validate()|validate()]] to trigger the data validation. A data validation
failure will turn on the [[yii\base\Model::hasErrors|hasErrors]] property, and through
[[yii\base\Model::getErrors|errors]] you may learn what validation errors the model has.
its [[yii\base\Model::validate()|validate()]] to trigger the data validation routines. A data validation
failure will set the [[yii\base\Model::hasErrors|hasErrors]] property to true, and you may learn what validation errors occurred through [[yii\base\Model::getErrors|errors]].
```php
<?php
$model=newEntryForm();
$model->name='Qiang';
$model->email='bad';
if($model->validate()){// Good!
}else{// Failure!
// Use $model->getErrors()
}
```
Creating an Action <a name="creating-action"></a>
------------------
Next, create an `entry` action in the `site` controller, like you did in the previous section.
Next, you'll need to create an `entry` action in the `site` controller that will use the new model. The process of creating and using actions was explained in the [Saying Hello](start-hello.md) section.
```php
<?php
...
...
@@ -97,28 +109,26 @@ class SiteController extends Controller
```
The action first creates an `EntryForm` object. It then tries to populate the model
with the data from `$_POST` which is provided in Yii through [[yii\web\Request::post()]].
If the model is successfully populated (i.e., the user has submitted the HTML form),
it will call [[yii\base\Model::validate()|validate()]] to make sure the data entered
are valid.
with the data from `$_POST`, provided in Yii by [[yii\web\Request::post()]].
If the model is successfully populated (i.e., if the user has submitted the HTML form), the action will call [[yii\base\Model::validate()|validate()]] to make sure the values entered are valid.
If everything is fine, the action will render a view named `entry-confirm` to confirm
with the user that the data he has entered is accepted. Otherwise, the `entry` view will
be rendered, which will show the HTML form together with the validation error messages (if any).
If everything is fine, the action will render a view named `entry-confirm` to confirm the data entered
with the user that the data entered. If a problem occurred, the `entry` view will
be rendered, wherein the HTML form will be shown, along with any validation error messages.
> Info: The expression `Yii::$app` represents the [application](structure-applications.md) instance
which is a globally accessible singleton. It is also a [service locator](concept-service-locator.md)
providing components, such as `request`, `response`, `db`, etc. to support specific functionalities.
In the above code, the `request` component is used to access the `$_POST` data.
> Info: The expression `Yii::$app` represents the [application](structure-applications.md) instance,
which is a globally accessible singleton. It is also a [service locator](concept-service-locator.md) that
provides components such as `request`, `response`, `db`, etc. to support specific functionality.
In the above code, the `request` component of the application instance is used to access the `$_POST` data.
Creating Views <a name="creating-views"></a>
--------------
Finally, create two views named `entry-confirm` and `entry` that are rendered by the `entry` action,
as described in the last subsection.
Finally, create two view files named `entry-confirm` and `entry`. These will be rendered by the `entry` action,
as just described.
The `entry-confirm` view simply displays the name and email data. It should be stored as the file `views/site/entry-confirm.php`.
The `entry-confirm` view simply displays the name and email data. It should be stored in the file `views/site/entry-confirm.php`.
```php
<?php
...
...
@@ -132,7 +142,7 @@ use yii\helpers\Html;
</ul>
```
The `entry` view displays an HTML form. It should be stored as the file `views/site/entry.php`.
The `entry` view displays an HTML form. It should be stored in the file `views/site/entry.php`.
```php
<?php
...
...
@@ -153,10 +163,10 @@ use yii\widgets\ActiveForm;
```
The view uses a powerful [widget](structure-widgets.md) called [[yii\widgets\ActiveForm|ActiveForm]] to
build the HTML form. The `begin()` and `end()` methods of the widget render the opening and close
build the HTML form. The `begin()` and `end()` methods of the widget render the opening and closing
form tags, respectively. Between the two method calls, input fields are created by the
[[yii\widgets\ActiveForm::field()|field()]] method. The first input field is about the "name" data,
and the second the "email" data. After the input fields, the [[yii\helpers\Html::submitButton()]] method
[[yii\widgets\ActiveForm::field()|field()]] method. The first input field is for the "name" data,
and the second for the "email" data. After the input fields, the [[yii\helpers\Html::submitButton()]] method
is called to generate a submit button.
...
...
@@ -169,10 +179,8 @@ To see how it works, use your browser to access the following URL:
http://hostname/index.php?r=site/entry
```
You will see a page displaying a form with two input fields. In front of each input field, a label
is also displayed indicating what data you need to enter. If you click the submit button without
entering anything, or if you do not provide a valid email address, you will see an error message that
is displayed next to each problematic input field.
You will see a page displaying a form with two input fields. In front of each input field, a label indicates what data is to be entered. If you click the submit button without
entering anything, or if you do not provide a valid email address, you will see an error message displayed next to each problematic input field.
...
...
@@ -189,14 +197,18 @@ You may wonder how the HTML form works behind the scene, because it seems almost
display a label for each input field and show error messages if you do not enter the data correctly
without reloading the page.
Yes, the data validation is actually done on the client side using JavaScript as well as on the server side.
Yes, the data validation is initially done on the client side using JavaScript, and secondarily performed on the server side via PHP.
[[yii\widgets\ActiveForm]] is smart enough to extract the validation rules that you have declared in `EntryForm`,
turn them into JavaScript code, and use the JavaScript to perform data validation. In case you have disabled
turn them into executable JavaScript code, and use the JavaScript to perform data validation. In case you have disabled
JavaScript on your browser, the validation will still be performed on the server side, as shown in
the `actionEntry()` method. This ensures data validity in all circumstances.
The labels for input fields are generated by the `field()` method based on the model property names.
For example, the label `Name` will be generated for the `name` property. You may customize a label by
> Warning: Client-side validation is a conveniences that provides for a better user experience. Server-side validation is always required, whether or not client-side validation is in place.
The labels for input fields are generated by the `field()` method, using the property names from the model.
For example, the label `Name` will be generated for the `name` property.
You may customize a label within a view using
the following code:
```php
...
...
@@ -205,18 +217,18 @@ the following code:
```
> Info: Yii provides many such widgets to help you quickly build complex and dynamic views.
As you will learn later, writing a new widget is also extremely easy. You may turn much of your
As you will learn later, writing a new widget is also extremely easy. You may want to turn much of your
view code into reusable widgets to simplify view development in future.
Summary <a name="summary"></a>
-------
In this section, you have touched every part in the MVC design pattern. You have learned how
to create a model class to represent the user data and validate them.
In this section of the guide, you have touched every part in the MVC design pattern. You have learned how
to create a model class to represent the user data and validate said data.
You have also learned how to get data from users and how to display them back. This is a task that
could take you a lot of time when developing an application. Yii provides powerful widgets
You have also learned how to get data from users and how to display data back in the browser. This is a task that
could take you a lot of time when developing an application, but Yii provides powerful widgets
to make this task very easy.
In the next section, you will learn how to work with databases which are needed in nearly every application.
In the next section, you will learn how to work with databases, which are needed in nearly every application.
