在Django模板循环中包含变量

Question

I have a for loop in a Django template, which prints out a list of books, which works well. The issue comes when I try to mark one of the items in the list as selected, based on a value passed in from the views.py file:

<select name="b">
    <option value="1">Book</option>
    {% for book in books %}
        <option {% if book.id == selected_book %} selected {% endif %} value="{{ book.id }}">{{ book.t }}</option>
    {% endfor %}
</select>

The "books" variable is a list, passed in from the views.py file. I can access these variables fine outside of the loop, but if I try to include a seperate variable inside the loop ("selected_book"), I have issues.

The above code does nothing, and if I try to wrap the variable in double brackets

{{ selected_book }}

I get the following error:

TemplateSyntaxError 
Could not parse the remainder: '{{' from '{{'

The variable is being passed into the template, because I can get it to print to the page. I only get an error when I try to use it in the for loop.

If I write "{% if book.id == 2 %}" that works fine.

Answer 1

确保selected_book是整数而不是字符串，否则代码很好