When writing a for / if statement with the jinja2 template, the way line breaks are made depends on the presence or absence of hyphens and their positions. I always get lost when writing a for statement, so I will summarize it. How do I write to get the following output?

output

start

apple0
orange0

apple1
orange1

end

Pattern 1: Put hyphens in everything

The following template will be the standard for this time. Put hyphens before and after the start position and end position of the for statement.

jinja_test1.j2

start
{%- for i in range(2) -%}
apple{{ i }}
orange{{ i }}
{%- endfor -%}
end

Pattern 1: Execution result

There is a line break only between apple and orange. It seems that the content written in the for statement will break the line without permission.

output

startapple0
orange0apple1
orange1end

Pattern 2: Erase the hyphen before the start position of the for statement

jinja_test2.j2

start
{% for i in range(2) -%}
apple{{ i }}
orange{{ i }}
{%- endfor -%}
end

Pattern 2: Execution result

There was a line break between start and apple0. Before the start position of the for statement, a line break occurs only once at the start of the for statement.

output

start
apple0
orange0apple1
orange1end

Pattern 3: Erase the hyphen after the start position of the for statement

jinja_test3.j2

start
{%- for i in range(2) %}
apple{{ i }}
orange{{ i }}
{%- endfor -%}
end

Pattern 3: Execution result

There is a line break before apple0 and apple1. After the start position of the for statement, a line break occurs every time at the start position in the for statement.

output

start
apple0
orange0
apple1
orange1end

Pattern 4: Erase the hyphen before the end position of the for statement

jinja_test4.j2

start
{%- for i in range(2) -%}
apple{{ i }}
orange{{ i }}
{% endfor -%}
end

Pattern 4: Execution result

Line breaks are now added after orange0 and orange1. Before the end position of the for statement, a line break occurs every time on the last line in the for statement.

output

startapple0
orange0
apple1
orange1
end

Pattern 5: Erase the hyphen after the end position of the for statement

jinja_test5.j2

start
{%- for i in range(2) -%}
apple{{ i }}
orange{{ i }}
{%- endfor %}
end

Pattern 5: Execution result

A line break is now added after orange1. After the end position of the for statement, it seems that a line break occurs only once when leaving the for statement.

output

startapple0
orange0apple1
orange1
end

Summary

Based on the contents so far, it is as follows.

That is, to get the first output ・ Two line breaks between start and apple0 → No need for hyphens before and after the for statement start position -It is necessary to break twice between orange1 and end → No need for hyphens before and after the end position of the for statement So, "Erase all hyphens" is the correct answer, and it is as follows.

jinja_test6.j2

start
{% for i in range(2) %}
apple{{ i }}
orange{{ i }}
{% endfor %}
end

output

start

apple0
orange0

apple1
orange1

end