title: How to set initial default value in drop down flutter
body: <p>I've one drop down and there some value inside the drop-down button and I need to by default selected value. you can seel below piece of snippet where you can find the drop-down value. I need it always there is by default selected value Normal. hope you understand the question.</p>
  
  <pre><code>FormBuilder(
        autovalidate: autovalidate,
        child: FormBuilderCustomField(
            attribute: "Select Address",
            validators: [
              FormBuilderValidators.required(),
            ],
            formField: FormField(
              builder: (FormFieldState&lt;dynamic&gt; field) {
                return InputDecorator(
                  decoration: InputDecoration(
                    errorText: field.errorText,
                    filled: false,
                    isDense: true,
                    border: InputBorder.none,
                    icon: Container(
                      width: 50.0,
                      height: 50.0,
                      decoration: BoxDecoration(
                        borderRadius: BorderRadius.circular(20.0),
                        color: colorStyles['primary_light'],
                      ),
                      child: Icon(
                        Icons.business_center,
                        color: colorStyles['primary'],
                      ),
                    ),
                  ),
                  isEmpty: _typeValue == [],
                  child: new DropdownButtonHideUnderline(
                    child: DropdownButton(
                      hint: Text("Service Type"),
                      isExpanded: true,
                      items: [
                        "normal",
                        "urgent",
                        "emergency",
                      ].map((option) {
                        return DropdownMenuItem(
                          child: Text("$option"),
                          value: option,
                        );
                      }).toList(),
                      value: field.value,
                      onChanged: (value) {
                        field.didChange(value);
                        _serviceType = value;
                      },
                    ),
                  ),
                );
              },
            )),
      );
  </code></pre>