How to pass String type parameter in function to IconData in Flutter

Question

I've been working with this flutter project for 2 weeks, and I've a problem in how to pass String type parameter in function to IconData type. Before that, I've JSON response like this:

{
  "status": "success",
  "data": {
    "general": [
      {
        "id": 1,
        "name": "Sumbangan Pembinaan Pendidikan",
        "icon": "credit_card",
        "type": "monthly",
        "amount": 125000
      },
      {
        "id": 2,
        "name": "Uang Bangunan",
        "icon": "credit_card",
        "type": "yearly",
        "amount": 1250000
      }
    ],

I want to pass 'icon' key, and my button function look like this:

Widget studentFeeButtonMenu(BuildContext context, String text, IconData iconFee){
    return Container(
      width: double.infinity,
      height: screenHeight(context)*(1/12),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(10),
      ),
      child: Center(
        child: Container(
          width: screenWidth(context)*(1/1.3),
          height: double.infinity,
          color: Colors.red,
          child: Row(
            children: [
              Icon(
                iconFee,
                color: Color(0xff84923f),
              ),
              SizedBox(
                width: screenWidth(context)*(1/10),
              ),
              Text(
                text,
                style: TextStyle(
                  color: Colors.black,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

I want to create ListView.builder and the itemBuilder is using that function, like this:

child: ListView.builder(
            itemCount: generalStudentFees == null ? 0 : generalStudentFees.length,
            itemBuilder: (context, index){
              return studentFeeButtonMenu(context, generalStudentFees[index]['name'], Icons.generalStudentFees[index]['icon']);
            },
          ),

The 'name' key is working perfectly and can fetch with the data, but I don't know how to pass the icon, the error message says:

The getter 'generalStudentFees' isn't defined for the type 'Icons'.

Pat9RB Pat9RB · Accepted Answer · 2020-11-16T08:14:55

Flutter's Icons class gets its icons from MaterialFonts like this:

IconData icon = IconData(0xea00, fontFamily: 'MaterialIcons')

That hex number is the Unicode codepoint for the glyph in the font.

You could use a Map<String,Int> to map your json icon String value to the codepoint int you want it to represent. For example:

Map<String, Int> iconCodepoint = {
  'credit_card': 0xe06c,
  'gift_card'  : 0xe020,
  //etc.
}

//String iconName holds your icon String value ('credit_card')
studentFeeButtonMenu(context, 'Hello World', IconData(iconCodepoint[iconName], fontFamily: 'MaterialIcons');

The .codepoint files here contain the glyph codepoint numbers: Material-Design-icons on Github

How to pass String type parameter in function to IconData in Flutter

2 Answers