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[英][Flutter ]Unhandled Exception: NoSuchMethodError: The method '[]' was called on null
[英]Unhandled Exception NoSuchMethodError: The method '[]' was called on null in flutter
Code代表根據控制台指出的那行有錯誤的代碼行
錯誤顯示在三個部分。 第一:
新的 FlickrPhotoList.fromJson (package:flutter_app_new_flutter/flickerPhotoList.dart:22:26)
import 'package:flutter_app_new_flutter/model.dart';
class FlickrPhotoList {
int page;
int pages;
int perpage;
int total;
List<FlickrPhoto> photo;
FlickrPhotoList({
this.page,
this.pages,
this.perpage,
this.total,
this.photo
});
factory FlickrPhotoList.fromJson(Map<String, dynamic> parsedJson) {
var list = parsedJson['photo'] as List;
List<FlickrPhoto> photoList = list.map((i) => FlickrPhoto.fromJson(i)).toList();
return FlickrPhotoList(
page: parsedJson['page'],
pages: parsedJson['pages'],
perpage: parsedJson['perpage'],
total: parsedJson['total'],
photo: photoList);
}
}
第二個錯誤顯示在下面:
新的 FlickrResult.fromJson(包:flutter_app_new_flutter/flickerResult.dart:15:37)
import 'package:flutter_app_new_flutter/flickerPhotoList.dart';
class FlickrResult {
FlickrPhotoList photos;
String stat;
FlickrResult({
this.photos,
this.stat
});
factory FlickrResult.fromJson(Map<dynamic, dynamic> parsedJson) {
var photoList = FlickrPhotoList.fromJson(parsedJson['photos']);
return FlickrResult(
photos: photoList,
stat: parsedJson['stat']
);
}
}
這是第三個錯誤:
_SearchState.getSearchWallpapers。 (包:flutter_app_new_flutter/search.dart:47:33)
getSearchWallpapers(String query) async{
String requestUrl = "https://api.flickr.com/services/rest/?method=flickr.photos.search&api_key=b099758ce0d1e1bf8697f8491f7fb5fc&format=json&nojsoncallback=1&safe_search=1&text=$query";
var file = await DefaultCacheManager().getSingleFile(requestUrl);
http.Response response = await http.get(requestUrl);
String lines = await file.readAsString();
setState(() {
Map userMap = jsonDecode(lines);
flickrData = FlickrResult.fromJson(userMap);
resultsCount = flickrData.photos.photo.length;
});
}
昨天發生在我身上,而不是某個網站,我通過返回帶有標題的響應來修復它。 No such Method 錯誤是當您的模型與來自網站的 API 響應不匹配或服務器未提供您的請求示例時,這是錯誤
return FlickrPhotoList(
page: parsedJson['page'],
檢查 parsedJson 是否提供“頁面”; 所以首先向郵遞員或任何人發出請求並閱讀您的 API 響應。
當我們改進時,第二個將起作用,第三個也請發布 search.dart
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