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在 Jinja 2 中包含文件的顶部插入 javascript

发布于 2024-10-04 21:58:01 字数 4757 浏览 0 评论 0原文

在 Jinja2 中，我希望通过运行以下内容来正常工作：

from jinja2 import Environment, FileSystemLoader
env = Environment(loader=FileSystemLoader('.'))
template = env.get_template('x.html')
print template.render()

本质上，目标是使用 aa { 将所有 javascript 合并到 标记中% call js() %} /* 一些 js */ {% endcall %} 宏。

x.html

<html>
<head>
  <script type="text/javascript>
  {% block head_js %}{% endblock %}
  </script>
  </head>
<body>
  {% include "y.html" %}
</body>
</html>

y.html

{% macro js() -%}
    // extend head_js
    {%- block head_js -%}
    {{ super() }}
    try { {{ caller() }} } catch (e) {
       my.log.error(e.name + ": " + e.message);
    }
    {%- endblock -%}
{%- endmacro %}

Some ... <div id="abc">text</div> ...

{% call js() %}
    // jquery parlance:
    $(function () {
        $("#abc").css("color", "red");
    });
{% endcall %}

预期结果

当我通过 jinja2 运行 X.html 时，我预期结果是：

<html>
<head>
  <script type="text/javascript>
  try { {{ $("#abc").css("color", "red"); }} } catch (e) {
       usf.log.error(e.name + ": " + e.message);
    }
  </script>
  </head>
<body>
      Some ... <div id="abc">text</div> ...
</body>
</html>

实际结果

实际结果并不令人鼓舞。我遇到了几种可能具有启发性的错误，例如：

类型错误：宏“js”不接受关键字参数“调用者”

，或者，当我尝试添加另一个基础宏时，例如

{% macro js2() -%}
{%- block head_js -%}
//     ... something
{%- endblock -%}
{%- endmacro %}

我收到以下异常

jinja2.exceptions.TemplateAssertionError：块“head_js”定义了两次

我觉得好像遇到了一个关于 block 标记相对于 macro 标记的优先级的设计问题（即宏似乎没有按照我期望的方式封装块标签）。

我想我的问题很简单：

  1. Jinja2 可以做我正在尝试的事情吗？如果是这样，怎么办？

  2. 如果没有，是否有另一个基于 Python 的模板引擎支持这种模式（例如 mako、genshi 等），并且可以在 Google App Engine 中正常工作

感谢您的阅读 - 我感谢您的意见。

Brian

编辑：

我正在尝试编写一个扩展来解决这个问题。我已经完成了一半——使用以下代码：

from jinja2 import nodes, Environment, FileSystemLoader
from jinja2.ext import Extension

class JavascriptBuilderExtension(Extension):
    tags = set(['js', 'js_content'])

    def __init__(self, environment):
        super(JavascriptBuilderExtension, self).__init__(environment)
        environment.extend(
            javascript_builder_content = [],
        )

    def parse(self, parser):
        """Parse tokens """
        tag = parser.stream.next()
        return getattr(self, "_%s" % str(tag))(parser, tag)

    def _js_content(self, parser, tag):
        """ Return the output """
        content_list = self.environment.javascript_builder_content
        node = nodes.Output(lineno=tag.lineno)
        node.nodes = []

        for o in content_list:
            print "\nAppending node: %s" % str(o)
            node.nodes.extend(o[0].nodes)
        print "Returning node: %s \n" % node
        return node

    def _js(self, parser, tag):
        body = parser.parse_statements(['name:endjs'], drop_needle=True)
        print "Adding: %s" % str(body)
        self.environment.javascript_builder_content.append(body)
        return nodes.Const('<!-- Slurped Javascript -->')

env = Environment(
    loader      = FileSystemLoader('.'),
    extensions  = [JavascriptBuilderExtension],
    )

这使得将 Javascript 添加到模板末尾变得简单...例如

<html>
<head></head>
<body>
    {% js %}
    some javascript {{ 3 + 5 }}
    {% endjs %}
    {% js %}
    more {{ 2 }}
    {% endjs %}
    
<script type="text/javascript">
{% js_content %}
</script>
</body>
</html>

运行 env.get_template('x.html').render() 将产生一些有启发性的评论和预期的输出：

<html>
<head>
  <script type="text/javascript>
  </script>
  </head>
<body>
    <!-- Slurped Javascript -->
    <!-- Slurped Javascript -->
<script type="text/javascript">
    some javascript 8
    more 2
</script>
</body>
</html>

当然，这与所希望的将脚本放在头部不同，但至少它可以方便地合并到一个地方。

但是，该解决方案并不完整，因为当您有一个 {% include "y.html" %} 时，其中“y.html”包含一个 {% js %} code> 语句，{% js_content %} 在包含的 {% js %} 语句之前被调用（即 x.html 被完全解析）在 y.html 开始之前）。

我还需要（但尚未）插入具有静态 javascript try/catch 的常量节点，我表示我希望将其插入其中。这不是问题。

我很高兴能取得进步，也很感谢大家的意见。

我已经打开了相关问题： Jinja2 编译扩展包含后

原文

In Jinja2, I would like the following to work as it looks like it should, by running:

from jinja2 import Environment, FileSystemLoader
env = Environment(loader=FileSystemLoader('.'))
template = env.get_template('x.html')
print template.render()

Essentially the objective is to coalesce all the javascript into the <head> tags by using a a {% call js() %} /* some js */ {% endcall %} macro.

x.html

<html>
<head>
  <script type="text/javascript>
  {% block head_js %}{% endblock %}
  </script>
  </head>
<body>
  {% include "y.html" %}
</body>
</html>

y.html

{% macro js() -%}
    // extend head_js
    {%- block head_js -%}
    {{ super() }}
    try { {{ caller() }} } catch (e) {
       my.log.error(e.name + ": " + e.message);
    }
    {%- endblock -%}
{%- endmacro %}

Some ... <div id="abc">text</div> ...

{% call js() %}
    // jquery parlance:
    $(function () {
        $("#abc").css("color", "red");
    });
{% endcall %}

Expected result

When I run X.html through jinja2, I would expect the result to be:

<html>
<head>
  <script type="text/javascript>
  try { {{ $("#abc").css("color", "red"); }} } catch (e) {
       usf.log.error(e.name + ": " + e.message);
    }
  </script>
  </head>
<body>
      Some ... <div id="abc">text</div> ...
</body>
</html>

Actual result

The actual results are not encouraging. I get a couple types of potentially illuminating errors, e.g.:

TypeError: macro 'js' takes no keyword argument 'caller'

or, when I try adding another basis macro such as

{% macro js2() -%}
{%- block head_js -%}
//     ... something
{%- endblock -%}
{%- endmacro %}

I get the following exception

jinja2.exceptions.TemplateAssertionError: block 'head_js' defined twice

I feel as though I am running into a design issue regarding the precedence of the block tags over the macro tags (i.e. macros do not seem to encapsulate block tags in the way I expect).

I suppose my questions are quite simple:

  1. Can Jinja2 do what I am attempting? If so, how?

  2. If not, is there another Python based templating engine that does support this sort of pattern (e.g. mako, genshi, etc.), which would work without issue in Google App Engine

Thank you for reading - I appreciate your input.

Brian

Edit:

I'm trying to write an extension to resolve this problem. I'm halfway there -- using the following code:

from jinja2 import nodes, Environment, FileSystemLoader
from jinja2.ext import Extension

class JavascriptBuilderExtension(Extension):
    tags = set(['js', 'js_content'])

    def __init__(self, environment):
        super(JavascriptBuilderExtension, self).__init__(environment)
        environment.extend(
            javascript_builder_content = [],
        )

    def parse(self, parser):
        """Parse tokens """
        tag = parser.stream.next()
        return getattr(self, "_%s" % str(tag))(parser, tag)

    def _js_content(self, parser, tag):
        """ Return the output """
        content_list = self.environment.javascript_builder_content
        node = nodes.Output(lineno=tag.lineno)
        node.nodes = []

        for o in content_list:
            print "\nAppending node: %s" % str(o)
            node.nodes.extend(o[0].nodes)
        print "Returning node: %s \n" % node
        return node

    def _js(self, parser, tag):
        body = parser.parse_statements(['name:endjs'], drop_needle=True)
        print "Adding: %s" % str(body)
        self.environment.javascript_builder_content.append(body)
        return nodes.Const('<!-- Slurped Javascript -->')

env = Environment(
    loader      = FileSystemLoader('.'),
    extensions  = [JavascriptBuilderExtension],
    )

This makes it simple to add Javascript to the end of a template ... e.g.

<html>
<head></head>
<body>
    {% js %}
    some javascript {{ 3 + 5 }}
    {% endjs %}
    {% js %}
    more {{ 2 }}
    {% endjs %}
    
<script type="text/javascript">
{% js_content %}
</script>
</body>
</html>

Running env.get_template('x.html').render() will result in some illuminating comments and the expected output of:

<html>
<head>
  <script type="text/javascript>
  </script>
  </head>
<body>
    <!-- Slurped Javascript -->
    <!-- Slurped Javascript -->
<script type="text/javascript">
    some javascript 8
    more 2
</script>
</body>
</html>

Of course, this isn't the same as having the script in the head, as hoped, but at least it's conveniently coalesced into one place.

However, the solution is not complete because when you have a {% include "y.html" %} in there, where "y.html" includes a {% js %} statement, the {% js_content %} gets called before the include's {% js %} statement (i.e. x.html is fully parsed before y.html starts).

I also need to, but have not yet, inserted constant nodes that would have the static javascript try/catch, which I indicated I wanted to have in there. This is not an issue.

I'm pleased to be making progress, and I'm grateful for input.

I have opened the related question: Jinja2 compile extension after includes

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评论（5）

哀由 2024-10-11 21:58:01

从我的评论来看：

如果您想使用扩展而不是
包括你能做到。但因为
之间的完全分离
你不会的解析和渲染步骤
能够改变上下文
父范围，直到为时已晚。
此外，Jinja 上下文应该
是不可变的。

示例：

base.html

<html>
   <head>
      {% block head %}

      <title>{% block title %}This is the main template{% endblock %}</title>

      <script type="text/javascript">
      {% block head_js %}
      $(function () {
        $("#abc").css("color", "red");
      });
      {% endblock %}
      </script>

      {% endblock head_js %}
   </head>
   <body>
      {% block body %}
      <h1>{% block body_title %}This is the main template{% endblock body_title %}</h1>

      {% endblock body %}
   </body>
 </html>

some_page.html

{% block title %}This is some page{% endblock title %}

{% block head_js %}
{{ super() }}
try { {{ caller() }} } catch (e) {
   my.log.error(e.name + ": " + e.message);
}        // jquery parlance:
{% endblock head_js %}

From my comment:

If you would use extend instead of
include you could do it. But because
of the full separation between the
parse and render step you won't be
able to change the context of the
parent scope till after it's too late.
Also, the Jinja context is supposed to
be immutable.

Example:

base.html

<html>
   <head>
      {% block head %}

      <title>{% block title %}This is the main template{% endblock %}</title>

      <script type="text/javascript">
      {% block head_js %}
      $(function () {
        $("#abc").css("color", "red");
      });
      {% endblock %}
      </script>

      {% endblock head_js %}
   </head>
   <body>
      {% block body %}
      <h1>{% block body_title %}This is the main template{% endblock body_title %}</h1>

      {% endblock body %}
   </body>
 </html>

some_page.html

{% block title %}This is some page{% endblock title %}

{% block head_js %}
{{ super() }}
try { {{ caller() }} } catch (e) {
   my.log.error(e.name + ": " + e.message);
}        // jquery parlance:
{% endblock head_js %}
回复 原文
夜声 2024-10-11 21:58:01

您可以将其概括为在宏中工作的通用捕获扩展。这是我写的：

from jinja2 import nodes
from jinja2.ext import Extension

class CaptureExtension(Extension):
    """
    Generic HTML capture, inspired by Rails' capture helper

    In any template, you can capture an area of content and store it in a global
    variable:

    {% contentfor 'name_of_variable' %}
        blah blah blah 
    {% endcontentfor %}

    To display the result
    {{ name_of_variable }}

    Multiple contentfor blocks will append additional content to any previously 
    captured content.  

    The context is global, and works within macros as well, so it's useful for letting macros define
    javascript or <head> tag content that needs to go at a particular position
    on the base template.

    Inspired by http://stackoverflow.com/questions/4292630/insert-javascript-at-top-of-including-file-in-jinja-2
    and http://api.rubyonrails.org/classes/ActionView/Helpers/CaptureHelper.html
    """
    tags = set(['contentfor'])

    def __init__(self, environment):
        super(CaptureExtension, self).__init__(environment)

    def parse(self, parser):
        """Parse tokens """
        tag = parser.stream.next()
        args = [parser.parse_expression()]
        body = parser.parse_statements(['name:endcontentfor'], drop_needle=True)
        return nodes.CallBlock(self.call_method('_capture', args),[], [], body).set_lineno(tag.lineno)

    def _capture(self, name, caller):
        if name not in self.environment.globals:
            self.environment.globals[name] = ''
        self.environment.globals[name] += caller()
        return ""

You can generalize this into a generic capture extension that works within macros. Here's one I wrote:

from jinja2 import nodes
from jinja2.ext import Extension

class CaptureExtension(Extension):
    """
    Generic HTML capture, inspired by Rails' capture helper

    In any template, you can capture an area of content and store it in a global
    variable:

    {% contentfor 'name_of_variable' %}
        blah blah blah 
    {% endcontentfor %}

    To display the result
    {{ name_of_variable }}

    Multiple contentfor blocks will append additional content to any previously 
    captured content.  

    The context is global, and works within macros as well, so it's useful for letting macros define
    javascript or <head> tag content that needs to go at a particular position
    on the base template.

    Inspired by http://stackoverflow.com/questions/4292630/insert-javascript-at-top-of-including-file-in-jinja-2
    and http://api.rubyonrails.org/classes/ActionView/Helpers/CaptureHelper.html
    """
    tags = set(['contentfor'])

    def __init__(self, environment):
        super(CaptureExtension, self).__init__(environment)

    def parse(self, parser):
        """Parse tokens """
        tag = parser.stream.next()
        args = [parser.parse_expression()]
        body = parser.parse_statements(['name:endcontentfor'], drop_needle=True)
        return nodes.CallBlock(self.call_method('_capture', args),[], [], body).set_lineno(tag.lineno)

    def _capture(self, name, caller):
        if name not in self.environment.globals:
            self.environment.globals[name] = ''
        self.environment.globals[name] += caller()
        return ""
回复 原文
淡水深流 2024-10-11 21:58:01

Lee Semel 的解决方案对我不起作用。我认为全局变量现在在运行时不受这种修改的影响。

from jinja2 import nodes
import jinja2
from jinja2.ext import Extension

class CaptureExtension(Extension):
    """
    Generic HTML capture, inspired by Rails' capture helper

    In any template, you can capture an area of content and store it in a global
    variable:

    {% capture 'name_of_variable' %}
        blah blah blah 
    {% endcapture %}
    {% capture 'a'  %}panorama{% endcapture %}

    To display the result
    {{ captured['name_of_variable'] }}
    {{ captured['a'] }}

    The context is global, and works within macros as well, so it's useful for letting macros define
    javascript or <head> tag content that needs to go at a particular position
    on the base template.

    Inspired by http://stackoverflow.com/questions/4292630/insert-javascript-at-top-of-including-file-in-jinja-2
    and http://api.rubyonrails.org/classes/ActionView/Helpers/CaptureHelper.html
    """
    tags = set(['capture'])

    def __init__(self, environment):
        super(CaptureExtension, self).__init__(environment)
        assert isinstance(environment, jinja2.Environment)
        self._myScope = {}
        environment.globals['captured'] = self._myScope

    def parse(self, parser):
        """Parse tokens """
        assert isinstance(parser, jinja2.parser.Parser)
        tag = parser.stream.next()
        args = [parser.parse_expression()]
        body = parser.parse_statements(['name:endcapture'], drop_needle=True)
        return nodes.CallBlock(self.call_method('_capture', args),[], [], body).set_lineno(tag.lineno)

    def _capture(self, name, caller):
        self._myScope[name] = caller()
        return ""

The solution by Lee Semel did not work for me. I think globals are protected from this kind of modification at runtime now.

from jinja2 import nodes
import jinja2
from jinja2.ext import Extension

class CaptureExtension(Extension):
    """
    Generic HTML capture, inspired by Rails' capture helper

    In any template, you can capture an area of content and store it in a global
    variable:

    {% capture 'name_of_variable' %}
        blah blah blah 
    {% endcapture %}
    {% capture 'a'  %}panorama{% endcapture %}

    To display the result
    {{ captured['name_of_variable'] }}
    {{ captured['a'] }}

    The context is global, and works within macros as well, so it's useful for letting macros define
    javascript or <head> tag content that needs to go at a particular position
    on the base template.

    Inspired by http://stackoverflow.com/questions/4292630/insert-javascript-at-top-of-including-file-in-jinja-2
    and http://api.rubyonrails.org/classes/ActionView/Helpers/CaptureHelper.html
    """
    tags = set(['capture'])

    def __init__(self, environment):
        super(CaptureExtension, self).__init__(environment)
        assert isinstance(environment, jinja2.Environment)
        self._myScope = {}
        environment.globals['captured'] = self._myScope

    def parse(self, parser):
        """Parse tokens """
        assert isinstance(parser, jinja2.parser.Parser)
        tag = parser.stream.next()
        args = [parser.parse_expression()]
        body = parser.parse_statements(['name:endcapture'], drop_needle=True)
        return nodes.CallBlock(self.call_method('_capture', args),[], [], body).set_lineno(tag.lineno)

    def _capture(self, name, caller):
        self._myScope[name] = caller()
        return ""
回复 原文
风吹雪碎 2024-10-11 21:58:01

上面的答案几乎回答了我的查询（我想将不同的 JavaScript 部分全部放在一个地方 - 底部），接受使用“+=”变量，它将捕获相互附加，导致刷新问题。捕获最终会产生所有内容的多个副本，并导致各种问题，具体取决于刷新的次数。

我通过使用字典中标签的行号来解决这个问题，以确保捕获只完成一次。这种方法的一个小缺点是每次遇到捕获标记时都需要重建全局。

不过对我来说效果很好。

from jinja2 import Markup, nodes
from jinja2.ext import Extension

class CaptureExtension(Extension):
    tags = set(['capture'])

    def __init__(self, environment):
        super(CaptureExtension, self).__init__(environment)
        environment.globals['captured'] = {}
        self._captured = {}

    def parse(self, parser):
        lineno = next(parser.stream).lineno
        args = [parser.parse_expression(), nodes.Const(lineno)]
        body = parser.parse_statements(['name:endcapture'], drop_needle=True)
        return nodes.CallBlock(self.call_method('_capture', args), [], [], body).set_lineno(lineno)

    def _capture(self, name, lineno, caller):
        if name not in self._captured:
            self._captured[name] = {}
        self._captured[name][lineno] = caller()
        markup = Markup(''.join(s for s in self._captured[name].values()))
        self.environment.globals['captured'][name] = markup
        return ''

The answers above nearly answered my query (I wanted to put disparate bits of JavaScript all in one place - the bottom), accept using the '+=' variety which appends captures to each other caused problems on refresh. The capture would end up with multiple copies of everything and caused all sorts of issues depending on how many times refresh was hit.

I worked around this by using the line number of the tag in a dictionary to ensure captures are only done once. The one minor disadvantage of this approach is the global needs to be rebuilt every time a capture tage is encountered.

Works well for me though.

from jinja2 import Markup, nodes
from jinja2.ext import Extension

class CaptureExtension(Extension):
    tags = set(['capture'])

    def __init__(self, environment):
        super(CaptureExtension, self).__init__(environment)
        environment.globals['captured'] = {}
        self._captured = {}

    def parse(self, parser):
        lineno = next(parser.stream).lineno
        args = [parser.parse_expression(), nodes.Const(lineno)]
        body = parser.parse_statements(['name:endcapture'], drop_needle=True)
        return nodes.CallBlock(self.call_method('_capture', args), [], [], body).set_lineno(lineno)

    def _capture(self, name, lineno, caller):
        if name not in self._captured:
            self._captured[name] = {}
        self._captured[name][lineno] = caller()
        markup = Markup(''.join(s for s in self._captured[name].values()))
        self.environment.globals['captured'][name] = markup
        return ''
回复 原文
随遇而安 2024-10-11 21:58:01
class JavascriptBuilderExtension(Extension):
    tags = set(['js'])

    def __init__(self, environment):
        super(JavascriptBuilderExtension, self).__init__(environment)
        environment.extend(jbc = "",)

    def parse(self, parser):
        """Parse tokens """
        tag = parser.stream.next()
        body = parser.parse_statements(['name:endjs'], drop_needle=True)
        return nodes.CallBlock(
            self.call_method('_jbc', [], [], None, None),
            [], [], body
        ).set_lineno(tag.lineno)

    def _jbc(self, caller=None):
        self.environment.jbc += "\ntry { %s } catch (e) { ; };" % caller()
        return "<!-- Slurped -->"

完成后，环境将包含一个变量jbc，其中包含所有Javascript。我可以通过例如 string.Template 插入它。

此答案是作为问题编辑发布的questions/4292630/insert-javascript-at-top-of-include-file-in-jinja-2">在 Jinja 2 中包含文件的顶部插入 javascript 由 OP Brian M. Hunt 根据 CC BY-SA 2.5。

class JavascriptBuilderExtension(Extension):
    tags = set(['js'])

    def __init__(self, environment):
        super(JavascriptBuilderExtension, self).__init__(environment)
        environment.extend(jbc = "",)

    def parse(self, parser):
        """Parse tokens """
        tag = parser.stream.next()
        body = parser.parse_statements(['name:endjs'], drop_needle=True)
        return nodes.CallBlock(
            self.call_method('_jbc', [], [], None, None),
            [], [], body
        ).set_lineno(tag.lineno)

    def _jbc(self, caller=None):
        self.environment.jbc += "\ntry { %s } catch (e) { ; };" % caller()
        return "<!-- Slurped -->"

After completed, the environment will contain a variable jbc that has all the Javascript. I can insert this via, for example, string.Template.

This answer was posted as an edit to the question Insert javascript at top of including file in Jinja 2 by the OP Brian M. Hunt under CC BY-SA 2.5.

回复 原文
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