如何在 Django 中执行 PostgreSQL 查询

Question

I am trying to fetch the PostgreSQL table onto HTML using Django, When I execute the spatial query in the query Tool of PostgreSQL I got the perfect results, but When I'm trying to execute the same script from Django getting all rows of data. 感谢您提前提供帮助。

SQL query which is working perfectly

SELECT *
    FROM jhk_schls as point,jhk_urban as polygon
WHERE ST_Within(point.geom, polygon.geom)

Django 脚本

def search(request):
    if request.method == "POST":
        first_layer = request.POST.get('first_layer')
        spati_func = request.POST.get('spa_func')
        second_layer = request.POST.get('secon_layer')
        within_fun = 'select * from' + " " + str(first_layer) + " " + 'as point,' + str(second_layer) + " " + 'as polygon' + " " + 'WHERE' + " " + str(spati_func)+'(point.geom, polygon.geom)'
        cursor = connection.cursor()
        cursor.execute(within_fun)
        data = cursor.fetchall()
        return render(request, 'geoit/search.html',{ 'data':data})
    return render(request,'geoit/search.html')

HTML

<span>Select Layer</span>
      <select name="first_layer">
     <option value="-1" disabled  selected >Please select</option>
     Layer<li><option value="jhk_schls">jhk_schls</option></li>
    </select>
  </br>
  <span>Spatial Functions</span>
<select name="spa_func">
     <option value="-1" disabled  selected >Please select</option>
     Layer<li><option value="ST_Within">ST_Within</option></li>
    </select>
</br>
<span>Select Layer</span>
<select name="secon_layer">

     <option value="-1" disabled  selected >Please select</option>
     Layer<li><option value="jhk_urban">jhk_urban</option></li>
     
    </select>
<input type="submit" value="submit">
          </p>
        </div>
</form>
            <button type="submit" value="submit"><i class="fa fa-search"></i>
            </button>
        </form>
        <p></p>
        <center>
            <table>
    
           
        {% for item in data %}
                  <tr>
                <td>{{ item.0 }}</td>
                <td>{{ item.2 }}</td>
                 
            </tr>
        {% endfor %}
    </table>
        </center>
```

Answer 1

在 Django 中，您可能希望使用 Django ORM 从数据库中获取数据。

在这种情况下，请查看地理查询集的“内部”function：

https://docs.djangoproject.com/en/3.1/ref/contrib/gis/geoquerysets/#within

附带说明一下，您在视图中构造查询的方式，将视图中的参数直接传递到查询中，会为您打开 SQL 注入攻击，并且可能非常危险。 如果您需要使用查询字符串参数的输入创建 SQL，请阅读如何安全地执行此操作： https://realpython.com/prevent-python-sql-injection/#passing-safe-query-parameters