how to update data of an array inside a map in flutter

Question

I want to Update a array inside a map

Map<int, List<String>> testtable = {
    1: ['a', 'b', 'c', 'e'],
    2: ['f', 'g', 'h', 'j'],
  };

I want to Update e => d in array which has key = 1 ,

I Have Tried this testtable.update(1, (list[3]) => d); but doesn't work

Vayth · Accepted Answer · 2021-01-28 13:03:06Z

1

update expect the new value as the parameter, so you have to return the whole list.

testtable.update(1, (list) {
    list[3] = 'd';
    return list;
});

answered Jan 28, 2021 at 13:03

Vayth

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Ali Alizadeh · Accepted Answer · 2021-01-28 13:01:39Z

1

You can do it this way:

testtable.update(
  1,
  (value) {
    value[3] = 'd';
    return value;
  },
);

answered Jan 28, 2021 at 13:01

Ali Alizadeh

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Comments

Andrija · Accepted Answer · 2021-01-28 13:09:54Z

1

Another option:

void main() {
  Map<int, List<String>> testtable = {
    1: ['a', 'b', 'c', 'e'],
    2: ['f', 'g', 'h', 'j'],
  };
  
  print (testtable);
  
  testtable[1][3]='d';
  print (testtable);
}

answered Jan 28, 2021 at 13:09

Andrija

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3 Comments

Sanket Kankariya Over a year ago

this doesn't work,, it only works with List<List<String>> ,not map

Ali Alizadeh Over a year ago

Why shouldn't it work? It is valid and works. One way to read values from a Map is uisng the [] operator. In this example your Map's keys are integers so testtable[1] is totally correct and returns the value of key 1.

Andrija Over a year ago

I tested it in dartpad before posting, and it worked just fine.

Aathi · Accepted Answer · 2021-05-10 14:47:12Z

1

Update nested Map

 Map<String, Map> selectedTimes = {
    "monday": {"open": "7:30 AM", "close": "10:30 AM"},
    "tuesday": {"open": "7:30 AM", "close": "10:30 AM"},
    "wednesday": {"open": "7:30 AM", "close": "10:30 AM"},
    "thursday": {"open": "7:30 AM", "close": "10:30 AM"},
    "friday": {"open": "7:30 AM", "close": "10:30 AM"},
    "saturday": {"open": "7:30 AM", "close": "10:30 AM"},
    "sunday": {"open": "7:30 AM", "close": "10:30 AM"}
  };


selectedTimes.update(day, (list) {
  list.update(
      time, (value) => selectedTimeRTL!.format(context).toString());
  return list;
})

answered May 10, 2021 at 14:47

Aathi

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