使用许多嵌套的 forEach 处理对象的更好方法？

Question

I would like to know if there is a better way to deal with nested forEach when it comes to dealing with objects with properties that are nested arrays themselves.

My object (summarized):

{
 ...,
 "tx_responses": [
   {
     ...
     "logs" : [
       {
         ...,
         "events": [
             {
                 "type": "coin_received",
                 "attributes": [
                     {
                         "key": "receiver",
                         "value": "somesome"
                     },
                     {
                         "key": "amount",
                         "value": "somesome"
                     }
                 ]
             },
             ...
             {
                 "type": "transfer",
                 "attributes": [
                     {
                         "key": "recipient",
                         "value": "somesome"
                     },
                     {
                         "key": "sender",
                         "value": "somesome"
                     },
                     {
                         "key": "amount",
                         "value": "somesome"
                     }
                 ]
             },
             {
                 "type": "withdraw_rewards",
                 "attributes": [
                     {
                         "key": "amount",
                         "value": "somesomesomehere"
                     },
                     {
                         "key": "validator",
                         "value": "somesome"
                     }
                 ]
             },
             ...
         ]
     }
 ],
...

I am essentially trying to extract all { key: 'amount', value: 'somesomesomehere' } objects in the "attributes" array of the "type": "withdraw_rewards" object in the "events" array.

Currently this is the code I wrote to carry out my task:

getWithdrawnAmounts: async(del_addr_) => {
    let withdrawnAmounts = [];
    const res = await axios.get("some_url_that_uses_del_addr_");
    res.data.tx_responses.forEach(txr => {
        txr.logs.forEach(log => {
            log.events.forEach(evnt => {
                if (evnt.type == "withdraw_rewards") {
                    evnt.attributes.forEach(attr => {
                        if (attr.key == "amount") {
                            withdrawnAmounts.push(attr);
                        }
                    })
                }
            })
        })
    });
    return withdrawnAmounts;
}

The code helps me to get what I need, but I was wondering if there is a better way to write my code so that I dont have to use so many nested .forEach methods. I was wondering if I should use .flat() or .flatMap() but I'm curious to know how would people approach this?

Thank you!

Answer 1

You are going to have to call some kind of iteration for each level you're going deeper.

Now, there is a more functional way to get the desired data, using flatMap and filter :

 const data = { "tx_responses": [{ "logs": [{ "events": [{ "type": "coin_received", "attributes": [{ "key": "receiver", "value": "somesome" }, { "key": "amount", "value": "somesome" }]}, { "type": "transfer", "attributes": [{ "key": "recipient", "value": "somesome" }, { "key": "sender", "value": "somesome" }, { "key": "amount", "value": "somesome" }]}, { "type": "withdraw_rewards", "attributes": [{ "key": "amount", "value": "somesomesomehere" }, { "key": "validator", "value": "somesome" }]}]}]}]}; const result = data.tx_responses.flatMap(r => r.logs.flatMap(l => l.events.filter(e => e.type === 'withdraw_rewards').flatMap(e => e.attributes.filter(a => a.key === 'amount')) ) ); console.log(result);