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python - 赋值前引用的局部变量“all_inf”

问题描述

我是 django 的新手。所以我正在尝试使用 Django 创建一个 CRUD 应用程序，但是我在尝试构建它时收到“分配前引用的局部变量‘all_inf’”这个错误

这是我的观点.py

- - 编码：utf-8 - -

从未来导入 unicode_literals

从 django.shortcuts 导入渲染 从 .forms 导入创建 从注册.模型导入用户

在此处创建您的视图。

def add_show（请求）：

if request.method == 'POST':
    crt = Create(request.POST)
    if crt.is_valid():
        username = crt.cleaned_data['name']
        useremail = crt.cleaned_data['email']
        user_contact = crt.cleaned_data['contact_number']
        save_to_db = User(name=username, email=useremail,
                          contact_number=user_contact)
        save_to_db.save()
        crt = Create()
else:
    crt = Create()
    all_inf = User.object.all()
return render(request, 'index.html', {'form': crt, 'info': all_inf})

我也试图从数据库中获取数据并在表中显示所有数据但它没有显示:(

这是我的示例代码：

div class="col-sm-8">
        <h4 class="text-center alrt alert-info">Showing all results</h4>
        {% if all_inf %}
        <h4>Table Data</h4>
        <table class="table table-dark">
          <thead>
            <tr>
              <th scope="col">ID</th>
              <th scope="col">Name</th>
              <th scope="col">Email</th>
              <th scope="col">Contact Number</th>
              <th scope="col">Actions</th>
            </tr>
          </thead>
          <tbody>
            {% for inf in info %}
            <tr>
              <td>{{inf.id}}dfdf</th>
              <td>{{inf.name}}</td>
              <td>{{inf.email}}}</td>
              <td>{{inf.contact_number}}</td>
            </tr>
            {% endfor %}
          </tbody>
        </table>
        {% else %}
        <h4 class="btn btn-danger">No Records Found Try again</h4>
        {% endif%}
      </div>
    </div>

标签： pythondjango

解决方案

这是因为从句all_inf中没有。if但是，在所有情况下都会执行 return 语句。

all_infSoln -在外部if else块之前放置一些默认值。

要么更改返回语句

if request.method == 'POST':
    crt = Create(request.POST)
    if crt.is_valid():
        username = crt.cleaned_data['name']
        useremail = crt.cleaned_data['email']
        user_contact = crt.cleaned_data['contact_number']
        save_to_db = User(name=username, email=useremail,
                          contact_number=user_contact)
        save_to_db.save()
        crt = Create()
    return render(request, 'index.html', {'form': crt}) #this is not having the ```all_inf```
else:
    crt = Create()
    all_inf = User.object.all()
    return render(request, 'index.html', {'form': crt, 'info': all_inf})

或保持代码相同并根据您的模板代码定义all_infasNone或空列表（[]）

all_inf = None
if request.method == 'POST':
    crt = Create(request.POST)
    if crt.is_valid():
        username = crt.cleaned_data['name']
        useremail = crt.cleaned_data['email']
        user_contact = crt.cleaned_data['contact_number']
        save_to_db = User(name=username, email=useremail,
                          contact_number=user_contact)
        save_to_db.save()
        crt = Create()
else:
    crt = Create()
    all_inf = User.object.all()
return render(request, 'index.html', {'form': crt, 'info': all_inf})

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