How to filter/select member of JsonArray?

[gfox72]

Hi,

Using the assistant for deserializing a JSON string that contains 3 members with identical keys, I get the following output :
const char* balance = elem["balance"]; // "0.00000000", "0.00000001", "0.00000000"

How would I get only the 2nd parameter ? I looked at using a filter for getting only asset BNB (see below) but I can't figure it out using the documentation, doesn't seem to have that feature to only extract only balance value for asset==BNB ?

This is the complete JSON string to deserialize : [{"accountAlias":"mYfREZSgFzAu","asset":"USDT","balance":"0.00000000","crossWalletBalance":"0.00000000","crossUnPnl":"0.00000000","availableBalance":"0.00000000","maxWithdrawAmount":"0.00000000"},{"accountAlias":"mYfREZSgFzAu","asset":"BNB","balance":"0.00000001","crossWalletBalance":"0.00000000","crossUnPnl":"0.00000000","availableBalance":"0.00000000","maxWithdrawAmount":"0.00000001"},{"accountAlias":"mYfREZSgFzAu","asset":"BUSD","balance":"0.00000000","crossWalletBalance":"0.00000000","crossUnPnl":"0.00000000","availableBalance":"0.00000000","maxWithdrawAmount":"0.00000000"}]

And this is the code I'm using (based on assistant):

StaticJsonDocument<768> doc;
deserializeJson(doc, input);
for (JsonObject elem : doc.as()) {
const char* balance = elem["balance"]; // "0.00000000", "0.00000001", "0.00000000"
}
Serial.println(balance);

this gives me:
0.00000000
0.00000001
0.00000000

I need only the balance for asset BNB being 0.00000001

How to ? thanks !

[bblanchon]

Hi @gfox72,

It's currently not possible to filter elements of arrays because I couldn't find a satisfying API.
See this older answer for details.
I'm still opened to suggestions.

Best regards,
Benoit