Flutter中筛选API返回的docStatus为Open的文档列表用于下拉选择

问题背景 #

在Flutter开发中，我需要将API返回的同类数据存入变量，用于后续下拉选择功能。API返回的JSON数据如下：

[{
    "docId": 1053,
    "tokenNo": 23477779999999,
    "docTitle": "Karishma resort ,baner",
    "address": "baner",
    "city": "pune",
    "partyName": "Rajesh patil",
    "pinCode": "452899",
    "docType": "Commercial",
    "duration": "24",
    "startDate": "2023-01-11",
    "endDate": "2025-01-10",
    "docStatus": "Open",
    "rentDesc": "17000",
    "createdBy": "Vaishnavi",
    "updatedBy": "null"
}, {
    "docId": 1052,
    "tokenNo": 22010799911122,
    "docTitle": "swapnapurti heights",
    "address": "Pirangut",
    "city": "Pune",
    "partyName": "Pranjali Sul",
    "pinCode": "411033",
    "docType": "Residential",
    "duration": "12",
    "startDate": "2023-01-07",
    "endDate": "2024-01-06",
    "docStatus": "Open",
    "rentDesc": "",
    "createdBy": "",
    "updatedBy": ""
}, {
    "docId": 1050,
    "tokenNo": 72389572857572,
    "docTitle": "Krishna Murti Nivas",
    "address": "Bavdhan",
    "city": "pune",
    "partyName": "Suhas kale",
    "pinCode": "736476",
    "docType": "Residential",
    "duration": "24",
    "startDate": "2023-01-14",
    "endDate": "2025-01-13",
    "docStatus": "Open",
    "rentDesc": "87033",
    "createdBy": "null",
    "updatedBy": "null"
}, {
    "docId": 932,
    "tokenNo": 2212010909755,
    "docTitle": "6/10 B Digital Apartment",
    "address": "Kothrud",
    "city": "Pune",
    "partyName": "Suresh",
    "pinCode": "411112",
    "docType": "Residential",
    "duration": "11",
    "startDate": "2022-12-01",
    "endDate": "2023-12-01",
    "docStatus": "Open",
    "rentDesc": "5000",
    "createdBy": "Swati",
    "updatedBy": null
}]

我尝试用以下代码获取docStatus为"Open"的文档，但逻辑存在问题：

List<Document> docs = [];
openedDocs() async {
    final docs = await DocumentController.getdocs(value);
    List<Document> opened;
    for (int i = 0; i <= docs.length; i++) {
      docs[i].docStatus == "Open" ? this.docs = docs : this.docs = List.empty();
    }
}

API调用的getdocs方法实现如下：

static Future<List<Document>> getdocs(String query) async {
    await SharedPrefService.init();
    var AuthToken = SharedPrefService.pref.getString('authToken');
    final url = Uri.parse('http://192.168.0.131:8080/AtdochubJ-3/document/');
    final response = await http.get(url, headers: {
      HttpHeaders.authorizationHeader: '${AuthToken}',
      'Content-Type': 'application/json; charset=UTF-8',
    });

    if (response.statusCode == 200) {
      final List docs = json.decode(response.body);
      return docs.map((json) => Document.fromJson(json)).where((doc) {
        final titleLower = doc.docTitle.toLowerCase();
        final tokenLower = doc.tokenNo.toString();
        final searchLower = query.toLowerCase();

        return titleLower.contains(searchLower) ||
            tokenLower.contains(searchLower);
      }).toList();
    } else {
      throw Exception();
    }
}

需要解决如何正确获取所有docStatus为"Open"的文档列表。

解决方案 #

当前openedDocs方法存在两个核心问题：

1. 循环条件错误：i <= docs.length会触发数组越界异常，正确的条件应该是i < docs.length
2. 筛选逻辑错误：每次循环直接替换整个this.docs变量，无法累积符合条件的文档

可以通过以下两种方式实现正确筛选：

方式一：在openedDocs中直接筛选 #

利用Dart内置的where方法过滤列表，代码简洁高效：

List<Document> docs = [];
openedDocs() async {
    final fetchedDocs = await DocumentController.getdocs(value);
    // 筛选出所有docStatus为"Open"的文档
    this.docs = fetchedDocs.where((doc) => doc.docStatus == "Open").toList();
}

方式二：在API请求方法中同时处理搜索和状态筛选 #

如果希望API返回的结果直接满足搜索条件且状态为"Open"，可以修改getdocs的过滤逻辑：

static Future<List<Document>> getdocs(String query) async {
    await SharedPrefService.init();
    var AuthToken = SharedPrefService.pref.getString('authToken');
    final url = Uri.parse('http://192.168.0.131:8080/AtdochubJ-3/document/');
    final response = await http.get(url, headers: {
      HttpHeaders.authorizationHeader: '${AuthToken}',
      'Content-Type': 'application/json; charset=UTF-8',
    });

    if (response.statusCode == 200) {
      final List docs = json.decode(response.body);
      return docs.map((json) => Document.fromJson(json)).where((doc) {
        final titleLower = doc.docTitle.toLowerCase();
        final tokenLower = doc.tokenNo.toString();
        final searchLower = query.toLowerCase();
        // 同时满足搜索条件和状态为Open
        return (titleLower.contains(searchLower) || tokenLower.contains(searchLower)) && doc.docStatus == "Open";
      }).toList();
    } else {
      throw Exception('Failed to fetch documents');
    }
}

修改后，openedDocs可以简化为：

List<Document> docs = [];
openedDocs() async {
    this.docs = await DocumentController.getdocs(value);
}

额外注意事项 #

• 确保字符串匹配一致：API返回的docStatus是"Open"，判断时要完全匹配大小写；如果存在大小写不一致的可能，可以用doc.docStatus?.toLowerCase() == "open"兼容
• 处理空值情况：如果docStatus字段可能为null，需要添加空值判断避免异常

内容的提问来源于stack exchange，提问作者Minal Suryawanshi