Vim: How do I map vimgrep command to avoid typing the file pattern? -

i search in projects using vimgrep command in fahsion:

:vimgrep /{pattern}/gj app_name/**/*.py 

all significant source code lives inside app_name directory , search inside python files, create command avoid writing search path on , on (i'm using project specific vimrc custom mappings). this:

:proj_search {pattern} 

you can use command

command -nargs=1 projsearch vimgrep /<args>/gj app_name/**/*.py 

:h 40.2

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edit: mcubik pointed out

user-defined commands must start capital letter. cannot use ":x", ":next" , ":print". underscore cannot used! can use digits, discouraged.