How to pass a map into an action

Question

I'm trying to pass a map into action, but there is serialization error:

Error: expected object containing data: undefined

There is a function signature:

void init(uint64_t id, const map<uint8_t, asset>& balances);

There is tx data I pass:

data: {
    id: id,
    balances: {0: "1.0000 EOS", 1: "1.0000 TOKEN"}
}

I also tried this tx data:

data: {
    id: id,
    balances: [{0: "1.0000 EOS"}, {1: "1.0000 TOKEN"}]
}

Answer 1

balances field should look like [{'key': 1, 'value': '1.0000 EOS'}]

Answer 2

They changed the map property names (since v4.0.0 I believe).

The balances field should now look like this: [{"first": 1, "second": "1.0000 EOS"}]