Dart - Read Keys and Values from a Map inside a Map

Question

I have a variable with the following structure:

final Map<String, Map<double, String>> ingredients;

I need to access, as string, the "inner" map keys and values after indexing the external map:

ingredients.keys.elementAt(index)

The above code returns a "regular string", but when accessing the "inner" map:

ingredients.values.elementAt(index).keys

The result prints with round brackets around it. I suppose it occurs because the first example returns a string and the second returns an Itarable. But how do I make it a string without the round brackets?

.toString() does not work.

I can't make it a single Map<String, String> because I need the double value separated from the second string (a unit specification).

I will put the result inside a Flutter Text() widget inside a ListView.builder(), that is the reason of the indexing.

Resuming: I am getting (200)(g) and I need 200g.

Thanks for the attention. Any help is appreciated.

"But how do I make it a string without the round brackets?" Can you provide an example of the exact output you're looking for? That is, given a Map<double, String> with values {1.0, 'some string'}, what string representation do you want? — jamesdlin
@jamesdlin Sure. I am getting (200)(g) and I need 200g as string output. — Rodrigo
Can the inner Map actually contain multiple key-value pairs? If not, it'd be simpler to define your own class (e.g. class Quantity { double amount; String units; Quantity(this.amount, this.units); String toString() => '$amount$units'; }). — jamesdlin
I see, the inner map just haver a pair. I'll try to implement your Idea. Thank you very much. — Rodrigo

Prabhanshu Tiwari Prabhanshu Tiwari · Accepted Answer · 2021-06-06T20:55:52

try this -

var _value = ingredients.values.elementAt(index).values;
print(_value.substring(1,_value.length-1));

Dart - Read Keys and Values from a Map inside a Map

1 Answers