How to add dynamic List to flutter nested map-CodePudding

Need a help!

This is my data from firebase

{
  "Engineering" : ["EEE", "CSE", "EE"],
  "Marketing" : [ "SEO", "Online Marketing", "Digital Marketing"],
}

I am using a nested dropdown to show these data to users, receiving data is something like this

Map<String, List<String>>

after selecting the dropdown, individual selection is something like this-

String _selectedCategory = "Engineering" ;
String _selectedSkill = "EEE" ;

at a time a user can select a category with a skill,

I want to create a dynamic map like this

{
  "Selected Category 1" : ["Selected Skill 1 from Category 1", "Selected Skill 2 from Category 1", "Selected Skill 3 from Category 1"],
  "Selected Category 2" : [ "Selected Skill 1 from Category 2", "Selected Skill 2 from Category 2", "Selected Skill 3 from Category 2"],
}

I tried to achieve this-

  List<String> addedSkills = [];
  Map<String, List<String>> addedData = {};

inside dropdown

setState((){
   addedSkills.add(_selectedSkill);
   addedData.addAll({_selectedCategory: _addedSkills})
});

data is showing like this

{
  "Selected Category 1" : ["Selected Skill 1 from Category 1", "Selected Skill 2 from 
   Category 2", "Selected Skill 3 from Category 2"],

}

but I want data something like this

{
  "Selected Category 1" : ["Selected Skill 1 from Category 1", "Selected Skill 2 from Category 1", "Selected Skill 3 from Category 1"],
  "Selected Category 2" : [ "Selected Skill 1 from Category 2", "Selected Skill 2 from Category 2", "Selected Skill 3 from Category 2"],
}

CodePudding user response：

Your output indicates that your _selectedCategory variable is not being upated before this line runs

addedData.addAll({_selectedCategory: _addedSkills})

addAll on a map will add any new key/value pairs and overwrite the value of any existing key. In your case, the value stored under the _selectedCategory key is being overwritten.

You could test this by hard coding a new key

addedData.addAll({'test_category': _addedSkills})

Assuming your addedData map already has at least one key value pair your data will look something like this

{
  "Selected Category 1" : ["Selected Skill 1 from Category 1", "Selected Skill 2 from Category 1", "Selected Skill 3 from Category 1"],
  "test_category" : ['selected skill'],
}

So your issue probably lies in the logic of updating the value of _selectedCategory from what is selected in the dropdown menu. If you need help with that then I suggest sharing that code.

CodePudding user response：

There was some logical error on my code so finally i did this way

     setState(() {
                        _selectedSkill = newValue.toString();
                        if (addedData.isNotEmpty) {
                          if (addedData
                              .containsKey(_selectedSkillCategory)) {
                            List<String> _tmpValue =
                                addedData[_selectedSkillCategory];
                            if (_tmpValue
                                .contains(_selectedSkill.toString())) {
                            } else {
                              _tmpValue.add(_selectedSkill.toString());
                            }
                          } else {
                            addedData[_selectedSkillCategory.toString()] = [
                              _selectedSkill.toString()
                            ];
                          }
                        } else {
                          //start a brand new map
                          addedData[_selectedSkillCategory.toString()] = [
                            _selectedSkill.toString()
                          ];
                        }