如何根据颤动中选定的下拉菜单项填充其他字段

Question

我在如何实现一些很酷的东西方面遇到了一些挑战。我有一个动态的下拉菜单项。 dropdown 的端点返回除 id 和 value 之外的其他属性，即将显示在 dropdownmenuItems 中的名称。所以我现在的挑战是：如何根据所选下拉项填充其他文本表单字段，例如数量和单价，因此这些属性的最后更新值位于下拉端点的响应 json 中。

这是返回下拉列表的函数：

  Future _scanQR(stockoid, context) async {
    try {

      // This take the barcode Id and parse it to the addItem function to populate the add dialog

      // String qrResult = await BarcodeScanner.scan();
      String qrResult = 'result'; - // this is just to bypass the barcode scan process
      // ignore: avoid_print
      print('$qrResult poi');

      // Make a call to the endpoints that will get the products with a response what contains 
     products attributes

      // print('Anchor ${widget.stockData.anchorOid}, Season  ${widget.stockData.seasonOid}, State ${widget.stockData.stateOid}',);
      _prefs = await SharedPreferences.getInstance();
      var _productService = ProductService();
      var result = await _productService.getAllProducts(
          widget.stockData.seasonOid,
          _prefs.getInt('providerOid'),
          widget.stockData.anchorOid);

      var products = await json.decode(result.body);
      print("Stock Item Products");
      print(products); - // this results contain more than name and oid other attributes can be seen in the json response below

      products.forEach((product) {
        setState(() {
          _productLists.add(DropdownMenuItem(
            child: Text(product['name']),
            value: product['oid'],
          ));
        });
      });
      setState(() {
        _isLoading = false;
      });


      addItem(qrResult, stockoid, context);
      setState(() {
        result = qrResult;
      });
  
    } on PlatformException catch (ex) {
      if (ex.code == BarcodeScanner.CameraAccessDenied) {
        setState(() {
          result = "Camera permission was denied";
        });
      } else {
        setState(() {
          result = "Unknown Error $ex";
        });
      }
    } on FormatException {
      setState(() {
        result = "You pressed the back button before scanning anything";
      });
    } catch (ex) {
      setState(() {
        result = "Unknown Error $ex";
      });
    }
  }

这是表单域：

SingleChildScrollView(
          child: Column(
            children: [
              Container(
                child: Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    Container(
                      child: Text(
                        "Add Stock Items",
                        style: style.PoppinsSemiBold(
                          color: Colors.black,
                          fontSize: size.convert(context, 20),
                        ),
                      ),
                    ),
                    BoxIcon(
                      CustomIcon: Icon(
                        Icons.cancel,
                        color: Colors.blueGrey,
                      ),
                      ontap: () {
                        Navigator.pop(context);
                      },
                    )
                  ],
                ),
              ),
              SpacebetweenTextField(
                spacing: 20,
              ),
             
              Container(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Container(
                      child: Text(
                        "Enter Date",
                        style: style.PoppinsSemiBold(
                          fontSize: size.convert(context, 14),
                          color: Colors.black,
                        ),
                      ),
                    ),
                    SpacebetweenTextField(
                      spacing: 5,
                    ),
                    DropdownButtonFormField(
                      value: _selectedProduct,
                      items: _productLists,
                      hint: const Text('Select Product'),
                      onChanged: (value) {
                        setState(() {
                          _selectedProduct = value;
                        });
                      },
                    ),
                    SpacebetweenTextField(
                      spacing: 5,
                    ),
                    TextFormField(
                      controller: quantity,
                      decoration: InputDecoration(
                        border: OutlineInputBorder(
                          borderSide: BorderSide(
                            color: Colors.red, //this has no effect
                          ),
                          borderRadius: BorderRadius.circular(10.0),
                        ),
                        hintText: "0.00",
                      ),
                    ),

                      TextFormField(
                      controller: price,
                      decoration: InputDecoration(
                        border: OutlineInputBorder(
                          borderSide: BorderSide(
                            color: Colors.red, //this has no effect
                          ),
                          borderRadius: BorderRadius.circular(10.0),
                        ),
                        hintText: "NGN 0.00",
                      ),
                    ),
                  ],
                ),
              ),
              
              SpacebetweenTextField(
                spacing: 40,
              ),
              Container(
                child: filledButton(
                  leftWidget: Icon(Icons.save, color: Colors.white),
                  txt: "Submit",
                  color1: Color(0xff1b7ec2),
                  onTap: () {
                    setState(() {
                      _isLoading = true;
                    });
                    _addStock(widget.anchorOid, selectedDate, widget.seasonOid,
                        widget.stateOid, context);

                    Navigator.pop(context);
                  },
                ),
              )
            ],
          ),
        ));

响应结果：

Response body
Download
[
  {
    "oid": 2,
    "name": "Certified Seed (Per Kg)",
    "unitPrice": 400,
    "quantity": 1,
    "total": 400,
    "isProduct": true,
    "boldHeader": false
  },
  {
    "oid": 3,
    "name": "Empty Bags",
    "unitPrice": 150,
    "quantity": 1,
    "total": 150,
    "isProduct": true,
    "boldHeader": false
  },
  {
    "oid": 4,
    "name": "Fertilizer UREA",
    "unitPrice": 8000,
    "quantity": 1,
    "total": 8000,
    "isProduct": true,
    "boldHeader": false
  },
  {
    "oid": 5,
    "name": "Fertilzer NPK 15-15-15",
    "unitPrice": 7500,
    "quantity": 1,
    "total": 7500,
    "isProduct": true,
    "boldHeader": false
  }
]