No implicit conversion of string into integer on ruby on rails

Question

I am trying to identify this problem: "no implicit conversion of String into Integer"

The problem is in this line <% if coin == x["symbol"] %>

The code:

<% for x in @coins %>
    <% for coin in @my_coins %>
        <% if coin == x["symbol"]%>
            <%= x["name"]%>
        <%end%>
    <%end%>
<%end%>

The variables

class HomeController < ApplicationController
  def index
    require 'net/http'
    require 'json'
    @url = 'https://pro-api.coinmarketcap.com/v1/cryptocurrency/listings/latest?start=1&limit=100&CMC_PRO_API_KEY=MyKey'
    @uri = URI(@url)
    @response = Net::HTTP.get(@uri)
    @coins = JSON.parse(@response)
    @my_coins = ["BTC", "XRP", "ADA", "ETH", "USDT"]
  end
  def about
  end 
  def lookup
  end
end

The first lines of API and the first example:

"data":
[
{
"id":1,"name":"Bitcoin",
"symbol":"BTC",
"slug":"bitcoin",
"num_market_pairs":9676,
"date_added":"2013-04-28T00:00:00.000Z",
"tags":["mineable","pow","sha-256","store-of-value","state-channels","coinbase-ventures-portfolio","three-arrows-capital-portfolio","polychain-capital-portfolio"],
"max_supply":21000000,
"circulating_supply":18629531,
"total_supply":18629531,"platform":null,"cmc_rank":1,"last_updated":"2021-02-15T15:54:02.000Z",
"quote":{"USD":{"price":47907.843633498785,
"volume_24h":79376349219.00912,
"percent_change_1h":-0.13222586,
"percent_change_24h":-1.5128616,
"percent_change_7d":10.59948497,
"percent_change_30d":28.8994407,
"market_cap":892500658113.4182,
"last_updated":"2021-02-15T15:54:02.000Z"}}},

Answer 1

The root of the problem is that x isn't a hash. I expect it's an array.

For example this will give you the same error:

[]["symbol"]

Basically, when x is an array, the input of the [] method expects an integer, and therefore tries to convert what is passed in, into an integer. The error occurs when the conversion fails.