Jinja2 equivalent of python multi line strings

Question

So I have this really long URL in my template:

<a href="/route?var1={{ var1 }}&var2={{ var2 }}&var3={{ var3 }}&var4={% for var in var4 %}{{ var }}{% if var != some_value %},{% endif %}{% endfor %}">
  thing
</a>

I'm trying to keep my code lines < 120 chars but I can't figure out how to break this string up across multiple lines without adding newlines or breaking the template. How can I do something like this (as I would in python).

<a href="/route?"
  "var1={{ var1 }}"
  "&var2={{ var2 }}"
  "&var3={{ var3 }}"
  "&var4={% for var in var4 %}"
    "{{ var }}"
    "{% if var != some_value %}"
      ","
    "{% endif %}"
  "{% endfor %}"
>
  thing
</a>

Answer 1

If it weren't for that embedded loop you would do it pretty much exactly how you would do it in Python:

<a href="{{
  "/route"
  "?var1={}"
  "&var2={}"
  "&var3={}"
  "&var4={}"
  "".format(var1, var2, var3, var4)
  }}">
thing
</a>

For your embedded loop...

  "&var4={% for var in var4 %}"
    "{{ var }}"
    "{% if var != some_value %}"
      ","
    "{% endif %}"
  "{% endfor %}"

...assuming that what you meant is "join together all the elements of var4 that are not equal to the value in some_value", we can replace it with a reject filter; take a look at the following example:

import jinja2

t = jinja2.Template(
    """
<a href="{{
  "/route"
  "?var1={}"
  "&var2={}"
  "&var3={}"
  "&var4={}"
  "".format(var1, var2, var3, (var4|reject('eq', some_value)|join(',')))
  }}">
thing
</a>
"""
)

print(
    t.render(
        var1="one",
        var2="two",
        var3="three",
        var4=["this", "is", "a", "test"],
        some_value="is",
    )
)

Which outputs:

<a href="/route?var1=one&var2=two&var3=three&var4=this,a,test">
thing
</a>