Python |使用django进行表单验证-yiteyi-C++库

先决条件 : Django安装 | Django简介 Django使用MVT模式。因此需要创建数据模型（或表）。对于每个表，都会创建一个模型类。假设有一种形式 用户名 , 性别和文本作为用户的输入，任务是验证数据并保存它。在django，可以这样做，如下所示：

null

python

                           from                                        django.db                                        import                                        models                         
            
                           # model named Post                         
                           class                                        Post(models.Model):                         
                                                     Male                                        =                                        'M'                         
                                                     FeMale                                        =                                        'F'                         
                                                     GENDER_CHOICES                                        =                                        (                         
                                                     (Male,                                        'Male'                                        ),                         
                                                     (FeMale,                                        'Female'                                        ),                         
                                                     )                         
            
                                                     # define a username filed with bound  max length it can have                         
                                                     username                                        =                                        models.CharField( max_length                                        =                                        20                                        , blank                                        =                                        False                                        ,                         
                                                     null                                        =                                        False                                        )                         
                                      
                                                     # This is used to write a post                         
                                                     text                                        =                                        models.TextField(blank                                        =                                        False                                        , null                                        =                                        False                                        )                         
                                      
                                                     # Values for gender are restricted by giving choices                         
                                                     gender                                        =                                        models.CharField(max_length                                        =                                        6                                        , choices                                        =                                        GENDER_CHOICES,                         
                                                     default                                        =                                        Male)                         
                                      
                                                     time                                        =                                        models.DateTimeField(auto_now_add                                        =                                        True                                        )                         

创建数据模型后，更改需要反映在数据库中才能执行此操作，请运行以下命令：

python manage.py makemigrations

这样做会编译模型，如果没有发现任何错误，就会在迁移文件夹中创建一个文件。稍后运行下面给出的命令，最终将保存到迁移文件中的更改反映到数据库中。

python manage.py migrate

现在可以创建一个表单。假设用户名长度不应小于5，帖子长度应大于10。然后我们定义类 PostForm 符合以下要求的验证规则：

python

                           from                                        django.forms                                        import                                        ModelForm                         
                           from                                        django                                        import                                        forms                         
                           from                                        formValidationApp.models                                        import                                        *                         
            
                           # define the class of a form                         
                           class                                        PostForm(ModelForm):                         
                                                     class                                        Meta:                         
                                                     # write the name of models for which the form is made                         
                                                     model                                        =                                        Post                         
            
                                                     # Custom fields                         
                                                     fields                                        =                                        [                                        "username"                                        ,                                        "gender"                                        ,                                        "text"                                        ]                         
            
                                                     # this function will be used for the validation                         
                                                     def                                        clean(                                        self                                        ):                         
            
                                                     # data from the form is fetched using super function                         
                                                     super                                        (PostForm,                                        self                                        ).clean()                         
                                      
                                                     # extract the username and text field from the data                         
                                                     username                                        =                                        self                                        .cleaned_data.get(                                        'username'                                        )                         
                                                     text                                        =                                        self                                        .cleaned_data.get(                                        'text'                                        )                         
            
                                                     # conditions to be met for the username length                         
                                                     if                                        len                                        (username) <                                        5                                        :                         
                                                     self                                        ._errors[                                        'username'                                        ]                                        =                                        self                                        .error_class([                         
                                                     'Minimum 5 characters required'                                        ])                         
                                                     if                                        len                                        (text) <                                        10                                        :                         
                                                     self                                        ._errors[                                        'text'                                        ]                                        =                                        self                                        .error_class([                         
                                                     'Post Should Contain a minimum of 10 characters'                                        ])                         
            
                                                     # return any errors if found                         
                                                     return                                        self                                        .cleaned_data                         

到目前为止，数据模型和表单类都已定义。现在重点将放在如何实际使用上面定义的这些模块上。首先，通过以下命令在localhost上运行

python manage.py runserver

打开 http://localhost:8000/ 在浏览器中，然后它将在 网址。py 文件，正在查找“”路径 网址。py 文件如下所示：

python

                           from                                        django.contrib                                        import                                        admin                         
                           from                                        django.urls                                        import                                        path, include                         
                           from                                        django.conf.urls                                        import                                        url                         
                           from                                        django.shortcuts                                        import                                        HttpResponse                         
                           from                                        .                                        import                                        views                         
            
            
                           urlpatterns                                        =                                        [                         
                                                     path('                                        ', views.home, name ='                                        index'),                         
                           ]                         

基本上，这会将“”url与函数相关联家定义如下： 意见。py 文件 意见。py文件 :

python

                           from                                        .models                                        import                                        Post                         
                           from                                        .forms                                        import                                        PostForm                         
                           from                                        .                                        import                                        views                         
                           from                                        django.shortcuts                                        import                                        HttpResponse, render, redirect                         
            
            
                           def                                        home(request):                         
            
                                                     # check if the request is post                         
                                                     if                                        request.method                                        =                                        =                                        'POST'                                        :                         
            
                                                     # Pass the form data to the form class                         
                                                     details                                        =                                        PostForm(request.POST)                         
            
                                                     # In the 'form' class the clean function                         
                                                     # is defined, if all the data is correct                         
                                                     # as per the clean function, it returns true                         
                                                     if                                        details.is_valid():                         
            
                                                     # Temporarily make an object to be add some                         
                                                     # logic into the data if there is such a need                         
                                                     # before writing to the database                         
                                                     post                                        =                                        details.save(commit                                        =                                        False                                        )                         
            
                                                     # Finally write the changes into database                         
                                                     post.save()                         
            
                                                     # redirect it to some another page indicating data                         
                                                     # was inserted successfully                         
                                                     return                                        HttpResponse(                                        "data submitted successfully"                                        )                         
                                      
                                                     else                                        :                         
                                      
                                                     # Redirect back to the same page if the data                         
                                                     # was invalid                         
                                                     return                                        render(request,                                        "home.html"                                        , {                                        'form'                                        :details})                         
                                                     else                                        :                         
            
                                                     # If the request is a GET request then,                         
                                                     # create an empty form object and                         
                                                     # render it into the page                         
                                                     form                                        =                                        PostForm(                                        None                                        )                         
                                                     return                                        render(request,                                        'home.html'                                        , {                                        'form'                                        :form})                         

家html 模板文件

html

                           {% load bootstrap3 %}                         
                           {% bootstrap_messages %}                         
                           <!DOCTYPE html>                         
                           <                                        html                                        lang                                        =                                        "en"                                        >                         
            
                           <                                        head                                        >                         
            
                                                     <                                        title                                        >Basic Form</                                        title                                        >                         
                                      
                                                     <                                        meta                                        charset                                        =                                        "utf-8"                                        />                         
                                      
                                                     <                                        meta                                        name                                        =                                        "viewport"                                        content                                        =                                        "width=device-width, initial-scale=1, shrink-to-fit=no"                                        >                         
            
                           <                                        link                                        rel                                        =                                        "stylesheet"                                        href                                        =                                        "                             https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css                            "                                        >                         
                           <                                        script                                        src                                        =                                        "                             https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js                            "                                        >                         
                           </                                        script                                        >                         
                           <                                        script                                        src                                        =                                        "                             https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js                            "                                        >                         
                           </                                        script                                        >                         
                           </                                        head                                        >                         
            
                           <                                        body                                        style                                        =                                        "padding-top: 60px;background-color: #f5f7f8 !important;"                                        >                         
                                                     <                                        div                                        class                                        =                                        "container"                                        >                         
                                                     <                                        div                                        class                                        =                                        "row"                                        >                         
                                                     <                                        div                                        class                                        =                                        "col-md-4 col-md-offset-4"                                        >                         
                                                     <                                        h2                                        >Form</                                        h2                                        >                         
                                                     <                                        form                                        action                                        =                                        ""                                        method                                        =                                        "post"                                        ><                                        input                                        type                                        =                                        'hidden'                                        />                         
                                                     {%csrf_token %}                         
            
                                                     {% bootstrap_form form %}                         
                           <!-This is the form variable which we are passing from the function                         
                           of home in views.py file. That's the beauty of Django we                         
                           don't need to write much codes in this it'll automatically pass                         
                           all the form details in here                         
                           ->                         
                                                     <                                        div                                        class                                        =                                        "form-group"                                        >                         
                                                     <                                        button                                        type                                        =                                        "submit"                                        class                                        =                                        "btn btn-default "                                        >                         
                                                     Submit                         
                                                     </                                        button                                        >                         
            
                                                     </                                        div                                        >                         
            
                                                     </                                        form                                        >                         
                                                     </                                        div                                        >                         
                                                     </                                        div                                        >                         
                           </                                        div                                        >                         
            
                           </                                        body                                        >                         
            
                           </                                        html                                        >                         

开放 http://localhost:8000/ 在浏览器中显示以下内容：，

图片[1]-Python |使用django进行表单验证-yiteyi-C++库

如果提交了用户名长度小于5的表单，则在提交时会给出一个错误，同样，对于填写的帖子文本也会给出一个错误。下图显示了表单在提交无效表单数据时的行为。

图片[2]-Python |使用django进行表单验证-yiteyi-C++库

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