在Jinja2中，如何将宏与块标签结合使用？ [英] In Jinja2, how can I use macros in combination with block tags?
问题描述
我是一名前端开发人员，而且我一直在试图有效地使用Jinja2。我想调整一个当前的网站，所以它有多个基础模板使用继承，它完全使用块标签替代内容并覆盖它，并使用宏来支持传递参数。
I'm a front end developer, and I've been trying to get a hang on using Jinja2 effectively. I want to tweak a current site so it has multiple base templates using inheritance, it fully uses block tags to substitute content and override it, and uses macros to support passing of arguments.
我的基本模板包含此代码（为简单起见）：
My base template contains this code (edited for simplicity):
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
{% from "foo.html" import macro1, macro2, macro3 %}
{% macro base_template(title=none, arg2=none, urls={}, arg3=false) %}
<html>
<title>{{ title }} | Site.com</title>
....
{{ caller() }}
....
</html>
{% endmacro %}
{% block content %}{% endblock %}
我扩展的页面如下所示：
And my pages that extend it look like this:
{% extends "base.html" %}
{% block content %}
{% call base_template(title="home", arg2="active", arg3="true") %}
(html code here)
{% endcall %}
{% endblock %}
所以基本上页面扩展基础，他们调用一个宏并将参数传递给该宏。我完全不了解这一切，但主要的一点是，这允许默认值和一定程度的灵活性，不需要重新定义整个块：它提供了一定程度的灵活性和强大功能。再次，这是很大的简化。
So basically all the pages extend base, they call a macro and pass arguments to that macro. I don't quite understand it all, but the main point is that this allows default values and a degree of flexibility that doesn't require redefining an entire block: it gives some degree of flexibility and power. Again this is heavily simplified.
唯一的问题是，这否定了我使用块的能力。宏是灵活的，但是有块，我有能力完全覆盖某些东西，或者使用它的父母内容并添加它，我不能使用宏（至少我不认为）。问题是，我不能用块包装东西，否则他们将看不到宏中的值。例如，这样做：
The only problem is, this negates my ability to use blocks. Macros are for flexibility, but with blocks, I have the ability to override something entirely, or use it's parents contents and add to it, which I can't do with Macros (at least I don't think). The problem is, I can't wrap things in blocks, else they won't see the values in the macro. For instance, doing this:
{% block title %}<title>{{ title }} | Site.com</title>{% endblock %}
将会失败，因为它会说标题未定义。
Will fail because it will say title is undefined.
最终我正在寻找一种利用块的功能和组织方面的方法，但仍然可以利用逻辑和宏的简洁。如果有人可以给我任何关于这个问题的帮助，我真的很感激。
Ultimately I am looking for a way to utilize both the power and organiztional aspects of blocks, but still be able to utilize the logic & terseness of macros. If anyone could give me any help as to how I might go about this problem, I would really appreciate it.
推荐答案
块是只能在模板的顶层定义。如果扩展模板，则使用集标记在子模板中设置的任何值都可以从扩展的模板访问。例如，如果您有一个名为 layout.html 的模板：
Blocks are only definable at a template's top level. If you extend a template, any values set in the child template using a set tag will be accessible from the template it is extending. For example, if you have a template named layout.html:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<title>{{ title }} | Site.com</title>
....
{% block content %}{% endblock content %}
....
</html>
你有这个子模板， index.html ：
{% extends "layout.html" %}
{% set title = 'Homepage' %}
{% block content %}
(html code here)
{% endblock content %}
然后，父项中引用标题将解析为'Homepage'。您可以使用任何类型的变量来执行此操作。对于你在做什么，我认为没有任何宏需要 - 如果你利用这个功能，并且把块放在一起，你可以做很多关于布局所需的一切事情。我将看看 Plurk Solace 使用的一些模板，其中由Jinja2作者之一撰写，如果您想了解何时使用Jinja2的各种功能。
Then the reference to title in the parent would resolve to 'Homepage'. You can do this with any type of variable. For what you're doing, I don't think there is any need for macros - if you take advantage of this feature and place blocks well, you will be able to do pretty much everything you need to do as far as layouts are concerned. I would look at some of the templates used by Plurk Solace, which is written by one of the Jinja2 authors, if you want to get a good idea of when to use various features of Jinja2.
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