Manually support gate.io minimum cost

[miracle2k]

gate.io returns a minimum amount via the API, and ccxt uses that + a minim-based derived from the decimal places to set the minimum cost. However, the gate.io API says:

ccxt.base.errors.ExchangeError: gateio {"result":"false","message":"Your order size is too small. The minimum is 1 USDT","code":20}

It does so when I want to sell 2 XLM on XLM/USDT. 2 XLM is much more than the minimum amount given via the API (0.0001), but clearly not enough. It seems there is a hidden "cost"-based limit from the API that we do not yet know.

I used trial an error here to figure those out.

[frosty00]

load these into the .markets attribute, not the code

[miracle2k]

Do you mean add them to the structure returned by describe()? (https://github.com/miracle2k/ccxt/blob/eeadbe46f8761be39555461bf8bd66b99bab47c4/js/gateio.js#L11)

Do you have an example of how to define per-currency limits in that structure?

[kroitor]

Do you have an example of how to define per-currency limits in that structure?

https://github.com/ccxt/ccxt/wiki/Manual#precision-and-limits
That info is stored in each market of .markets and in each currency of .currencies, under the limits key, where available )

[miracle2k]

Sorry for being thick. Can you link to an example, or to the line in the code where I am supposed to add these changes? It seems to me that we fetch the markets from the server, thus we construct .markets dynamically, and so at that point we are adding in the limits, no?

[frosty00]

Yeah load them in the .limits param - https://github.com/ccxt/ccxt/blob/master/js/base/Exchange.js#L523

[miracle2k]

I still don't get it. The code that you linked to:

• Loops through all the markets we collected from the server response.
• For each market, provides as a default market.limits and market.precision, by copying the exchange-wide default into the market - if the market has no value of it's own.

In this case, some limits are different for each market. The limit is based on the quote currency of the market. For the markets XRP/USDT and REP/USDT we have to use a cost-limit of 1, but for the market XRP/ETH, we have to use a cost limit of 0.001.

Can I ask you to have a second look at the patch to confirm that I really need to change something? Maybe I was not clear about the kind of change this is.