authentication - Google script: cannot refer to users using Session.getActiveUser() -

i have google script executes me. in script, want know user's email. refer email of user accessing application session.getactiveuser().getemail()

that's not working out @ all. google script giving error, saying session.getactiveuser().getemail() null.

when manually enter dummy email instead of session.getactiveuser().getemail(), code works perfectly

heeeeelp

ps: app must execute me, because needs access contacts.

you cannot have session.getactiveuser().getemail() return user's email id while app running you. there workarounds can try

ask user's email id explicitly.
write 2 scripts - 1 front end ui etc. run user accessing app (this allows session.getactiveuser().getemail() return user's email address). have second script tasks contacts accessed. call second script first using dopost , doget methods in second script. example,

script 1:

function whatever(){   urlfetchapp.fetch('service_url_of_script_2');  }

script 2:

function doget(e){   // code access contact, parameters in e.parameters  }

Three