Flutter：如何处理图像/文件空路径的异常？

问题描述 投票：-1回答：2

[enter image description here]当所有字段都不为空时，我的API调用有效。但是，我只想更新文本字段而不更新图像。而当我触发更新按钮时。它显示：未处理的异常：NoSuchMethodError：在null上调用了getter'path'。接收者：null尝试调用：路径

这是我在API_CODE_FOLDER中的POST

void updateData(
BuildContext context,
int id,
int userID,
String name,
String nric,
String dob,
File img,
String mobileNo,
int gender,
String nationality,
int race,
int religion,
String occupation,
String maritalStatus,
String deleteAt,
String createAt,
String updateAt,)async {
final SharedPreferences prefs = await SharedPreferences.getInstance();
final mimeTypeData =
    lookupMimeType(img.path, headerBytes: [0xFF, 0xD8]).split('/');
final file = await http.MultipartFile.fromPath('nric_front_copy', img.path,
    contentType: MediaType(mimeTypeData[0], mimeTypeData[1]));
refreshTokenApi(context);
print('UPDATE MOU');
accessToken = prefs.getString('access_token');
String myUrl = "$_url/personal_info";
var url = Uri.parse(myUrl);
var request = new http.MultipartRequest("POST", url);
request.headers['Accept'] = 'application/json';
request.headers['Authorization'] = 'Bearer $accessToken';
request.fields['id'] = id.toString();
request.fields['user_id'] = id.toString();
request.fields['name'] = name.trim();
request.fields['nric'] = nric.trim();
request.fields['date_of_birth'] = dob.trim();
request.files..add(file);
request.fields['mobile_no'] = mobileNo.trim();
request.fields['gender'] = gender.toString();
request.fields['nationality'] = nationality.trim();
request.fields['race_id'] = race.toString();
request.fields['religion_id'] = religion.toString();
request.fields['occupation'] = occupation.toString();
request.fields['marital_status'] = maritalStatus.toString();
request.fields['deleted_at'] = '';
request.fields['created_at'] = '';
request.fields['updated_at'] = '';
request.fields['_method'] = 'PATCH';
request.send().then((response){
  print(response.statusCode);
  print(response);
     if (response.statusCode == 200) {
    Navigator.pushReplacementNamed(context, '/Dashboard');
    print("updated!");
  } else if (response.statusCode != 201) {
    print(response.statusCode);
  }
});

}

这是我的更新

void updateButton() async {
print('TAPPED Update Button');
final SharedPreferences prefs = await SharedPreferences.getInstance();
// IF id & user_id is not empty then UPDATE.
if (prefs.getInt('id') != null || prefs.getInt('user_id') != null) {
    setState((){
    _gender = genderCon.text.isEmpty ? 1 : int.parse(genderCon.text);
    race = raceCon.text.isEmpty ? 2 : int.parse(raceCon.text);
    religion = religionCon.text.isEmpty ? 3 : int.parse(religionCon.text);
    _nric = icCon.text;
    _dob = dobCon.text;
    _name = nameCon.text;
    print(nameCon.text);
    print(nameCon.text.trim());
    callApi.updateData(
        context,
        id,
        userID,
        _name,
        _nric,
        _dob,
        _image,
        phoneCon.text,
        _gender,
        nationality,
        race,
        religion,
        occupation,
        maritalStatus,
        deleteAt,
        createAt,
        updateAt);
    print('UPDATE');
  });
}

}

这是我的获取图像功能

 void getImage() async {
var image = await ImagePicker.pickImage(
    source: ImageSource.gallery, imageQuality: 100);
setState(() {
  _image = image;
  Navigator.of(context);
});

}

flutter dart nosuchmethoderror
2个回答
0
投票
    void updateData(
    BuildContext context,
    int id,
    int userID,
    String name,
    String nric,
    String dob,
    File img,
    String mobileNo,
    int gender,
    String nationality,
    int race,
    int religion,
    String occupation,
    String maritalStatus,
    String deleteAt,
    String createAt,
    String updateAt,)async {
    final SharedPreferences prefs = await SharedPreferences.getInstance();
    refreshTokenApi(context);
    print('UPDATE MOU');
    accessToken = prefs.getString('access_token');
    String myUrl = "$_url/personal_info";
    var url = Uri.parse(myUrl);
    var request = new http.MultipartRequest("POST", url);

    if(img != null){
       final mimeTypeData =
            lookupMimeType(img.path, headerBytes: [0xFF, 0xD8]).split('/');
    final file = await http.MultipartFile.fromPath('nric_front_copy', img.path,

           contentType: MediaType(mimeTypeData[0], mimeTypeData[1]));
           request.files..add(file);

        }

    request.headers['Accept'] = 'application/json';
    request.headers['Authorization'] = 'Bearer $accessToken';
    request.fields['id'] = id.toString();
    request.fields['user_id'] = id.toString();
    request.fields['name'] = name.trim();
    request.fields['nric'] = nric.trim();
    request.fields['date_of_birth'] = dob.trim();
    request.fields['mobile_no'] = mobileNo.trim();
    request.fields['gender'] = gender.toString();
    request.fields['nationality'] = nationality.trim();
    request.fields['race_id'] = race.toString();
    request.fields['religion_id'] = religion.toString();
    request.fields['occupation'] = occupation.toString();
    request.fields['marital_status'] = maritalStatus.toString();
    request.fields['deleted_at'] = '';
    request.fields['created_at'] = '';
    request.fields['updated_at'] = '';
    request.fields['_method'] = 'PATCH';
    request.send().then((response){
      print(response.statusCode);
      print(response);
         if (response.statusCode == 200) {
        Navigator.pushReplacementNamed(context, '/Dashboard');
        print("updated!");
      } else if (response.statusCode != 201) {
        print(response.statusCode);
      }
    });
0
投票

因此，从本质上讲，它说img为空，并且您试图在空对象上访问方法.path（）。

因此，要停止此操作，您需要使用null检查来包装您的内容。有很多更好的方法可以在dart中执行此操作，例如img?.path()，如果img不为null，它将仅执行path()。

然而，使代码正常工作的最简单方法是将它包装在图像部分的if中。

尝试一下：

void updateData(
BuildContext context,
int id,
int userID,
String name,
String nric,
String dob,
File img,
String mobileNo,
int gender,
String nationality,
int race,
int religion,
String occupation,
String maritalStatus,
String deleteAt,
String createAt,
String updateAt,)async {
final SharedPreferences prefs = await SharedPreferences.getInstance();
refreshTokenApi(context);
print('UPDATE MOU');
accessToken = prefs.getString('access_token');
String myUrl = "$_url/personal_info";
var url = Uri.parse(myUrl);
var request = new http.MultipartRequest("POST", url);
request.headers['Accept'] = 'application/json';
request.headers['Authorization'] = 'Bearer $accessToken';
request.fields['id'] = id.toString();
request.fields['user_id'] = id.toString();
request.fields['name'] = name.trim();
request.fields['nric'] = nric.trim();
request.fields['date_of_birth'] = dob.trim();
if(img != null)
{
    var mimeTypeData =
    lookupMimeType(img.path, headerBytes: [0xFF, 0xD8]).split('/');
    var file = await http.MultipartFile.fromPath('nric_front_copy', img.path,
    contentType: MediaType(mimeTypeData[0], mimeTypeData[1]));
    request.files..add(file);
}
request.fields['mobile_no'] = mobileNo.trim();
request.fields['gender'] = gender.toString();
request.fields['nationality'] = nationality.trim();
request.fields['race_id'] = race.toString();
request.fields['religion_id'] = religion.toString();
request.fields['occupation'] = occupation.toString();
request.fields['marital_status'] = maritalStatus.toString();
request.fields['deleted_at'] = '';
request.fields['created_at'] = '';
request.fields['updated_at'] = '';
request.fields['_method'] = 'PATCH';
request.send().then((response){
  print(response.statusCode);
  print(response);
     if (response.statusCode == 200) {
    Navigator.pushReplacementNamed(context, '/Dashboard');
    print("updated!");
  } else if (response.statusCode != 201) {
    print(response.statusCode);
  }
});
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