How to operate the get_actions endpoint to get transaction history

Question

Following what I think is the official EOS documentation for get_actions . I stumble upon the parameters pos and offset, but they are not documented anywhere.

Can somebody explain to me, what these parameters do, and how to use them? Thanks a lot in advance.

Answer 1

UPDATE:

After doing some fiddling, here is what I learned (though an official explanation is nowhere to be found :/ ) :

Let's say an account has 128 actions, then we make the following calls:

<server>/v1/history/get_actions(<account_name>, pos=100, offset=-100)

This gets us the earliest 100 actions.

<server>/v1/history/get_actions(<account_name>, pos=200, offset=-100)

This gets us the latest 28 actions.

So in other words, we can get all actions for an account (provided that we ask a full history node, which is a longer story). But we will get them in chronological order, and not latest first. And we do this by running a loop where we increment pos variable until we do not receive any more actions. Some pseudo code:

var pos = 100;
while(moreFetched)
{
    var actions = _urlHandler.Post(...);
    if(actions == null) break;

    pos += 100;
}

But it would still be very nice (and appropriate) to get a professional review of this approach.

And here is some info regarding blockchain history: https://medium.com/@cc32d9/history-and-notifications-in-eosio-blockchain-8255194af93