Eiffel: multilines string formatting - eiffel

Question

Didn't find a better way to format a multiline string than this way... seems complicated. What would be the best way to format this type of code?
l_qry := "SELECT%
% * %
%FROM %
% enumerate %
%WHERE %
% " + {like item_prototype}.Primary_key_db_column_name + " = " + l_category_id + " %
%UNION %
% SELECT %
% e.* %
% FROM %
% enumerate e %
%INNER JOIN %
% enumerates_leaves s ON s." + {like item_prototype}.Primary_key_db_column_name + " = e." + {like item_prototype}.Category_db_column_name + " %
%) SELECT * FROM enumerates_leaves WHERE enumerates_leaves." + {like item_prototype}.Category_db_column_name + " IS NOT NULL;"

Answer 1

You can use Verbatin Strings for that purpose.
sql_select_country : STRING = "[
SELECT *
from COUNTRY
]"
-- Select all country
For building SQL queries dynamically, you can define a template
with placeholders and then replace them with the expected values.
template_query : STRING = "[
SELECT
*
FROM
enumerate
WHERE
$Primary_key_db_column_name = :id
UNION
SELECT
e.*
FROM
enumerate e
INNER JOIN
enumerates_leaves s ON s.$Primary_key_db_column_name = e.$Category_db_column_name
) SELECT * FROM enumerates_leaves WHERE enumerates_leaves.$Category_db_column_name IS NOT NULL;"
]"
-- Template query `query_name` ....
Using the template
l_query: STRING
create l_query.make_from_string (template_query)
l_query.replace_substring_all ("$Primary_key_db_column_name", {like item_prototype}.Primary_key_db_column_name)
...
In fact, one can generalize this idea an build something like
sql_query_builder (query_template: READABLE_STRING_GENERAL; arguments: ITERABLE [READABLE_STRING_GENERAL]) :STRING