Telegram get chat messages /posts - python Telethon

The accepted answer is good, but recent versions of Telethon let you achieve the same more easily. This will iterate over all messages in chat (for this example we use telethon.sync to avoid typing out async):

from telethon.sync import TelegramClient

with TelegramClient(name, api_id, api_hash) as client:
    for message in client.iter_messages(chat):
        print(message.sender_id, ':', message.text)

Where the variables should be obvious, for example (note these API values won't work, you need your own):

name = 'anon'
api_id = 123
api_hash = 'abcdefgh'
chat = 'me'

More examples using async are available in client.iter_messages documentation.

update :

in the new version of Telethon, @Lonami answer is best and use it.

############################################################

you can use this code for get messages :

client = TelegramClient('session_name',
                    api_id,
                    api_hash,
                    update_workers=1,
                    spawn_read_thread=False)
assert client.connect()
if not client.is_user_authorized():
    client.send_code_request(phone_number)
    me = client.sign_in(phone_number, input('Enter code: '))

channel_username='tehrandb' # your channel
channel_entity=client.get_entity(channel_username)
posts = client(GetHistoryRequest(
    peer=channel_entity,
    limit=100,
    offset_date=None,
    offset_id=0,
    max_id=0,
    min_id=0,
    add_offset=0,
    hash=0))
# messages stored in `posts.messages`

that work for me!

api_hash from https://my.telegram.org, under API Development.

from telethon import TelegramClient, events, sync

api_id = 'your api_id'
api_hash = 'your api_hash'

client = TelegramClient('session_name', api_id, api_hash)
client.start()
channel_username = 'username'# your channel
for message in client.get_messages(channel_username, limit=10):
    print(message.message)