Question

我无法反序列化包含多个Account类型对象的JSON文件。以下是我构建data.json文件的方法。我有一个帐户列表List<Account>，它像往常一样序列化。我通过添加一个新行来分隔json文件中的每个对象。

List<Account> listOfAccounts = new List<Account>();
if (listOfAccounts != null)
{
    foreach (var item in listOfAccounts)
    {
        JavaScriptSerializer ser = new JavaScriptSerializer();
        string outputJSON = ser.Serialize(item);
        // I added Environmetn.NewLine to separate each account in json file.
        File.AppendAllText("data.json", outputJSON + Environment.NewLine);
    }
}

现在，当我尝试将所有帐户从JSON文件检索到List<Account>时，我收到错误消息：System.ArgumentException: 'Invalid JSON primitive:
请帮助找到solutin，这样我就可以从JSON文件中获取所有对象。

private void JsonFileLoad()
{
    if(File.Exists("data.json"))
    {
        String JSONtxt = File.ReadAllText("data.json");
        JavaScriptSerializer ser = new JavaScriptSerializer();
        // Not sure how to deserialize all lines into List<account>
        List<Account> desirializedAccounts = ser.Deserialize<List<Account>>(JSONtxt);                      
    }
}

我非常感谢您提供的任何帮助。

Answer 1

首先，您应该使用标准的json格式进行序列化。你正在做的是序列化对象和写入文件。应该是，将列表完全序列化为json格式。但假设您可能有特定的原因，我在不同的场景中给出了许多可能的解决方案。

注意：我使用了Newtonsoft.Json，因为这很快，我觉得很容易。 http://www.newtonsoft.com/json

https://www.nuget.org/packages/newtonsoft.json/

解决方案：

//Class for testing object
public class Account
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }

解决方案1：推荐

/// <summary>
/// Serializing the list in single go
/// </summary>
public void Serialize()
{
    List<Account> listOfAccounts = new List<Account>();
    listOfAccounts.Add(new Account { Id = 1, Name = "First" });
    listOfAccounts.Add(new Account { Id = 2, Name = "Second" });
    listOfAccounts.Add(new Account { Id = 3, Name = "Third" });

    string outputJSON = Newtonsoft.Json.JsonConvert.SerializeObject(listOfAccounts, Newtonsoft.Json.Formatting.Indented);
    File.WriteAllText(@"c:\temp\data.json", outputJSON + Environment.NewLine);
}

/// <summary>
/// Serializing the list, one by one object
/// Comma is appended to every object in json format
/// Finally, enclosed it with [ and ] to make it array of objects
/// </summary>
public void Serialize2()
{
    List<Account> listOfAccounts = new List<Account>();
    listOfAccounts.Add(new Account { Id = 1, Name = "First" });
    listOfAccounts.Add(new Account { Id = 2, Name = "Second" });
    listOfAccounts.Add(new Account { Id = 3, Name = "Third" });
    string outputJSON = "";
    foreach(var item in listOfAccounts)
    {
        outputJSON += Newtonsoft.Json.JsonConvert.SerializeObject(item, Newtonsoft.Json.Formatting.Indented)+",";
    }

    File.WriteAllText(@"c:\temp\data.json", "["+outputJSON + "]");
}

/// <summary>
/// Read serialized data into list of objects
/// </summary>
public void DeSerialize()
{
    if (File.Exists(@"c:\temp\data.json"))
    {
        String JSONtxt = File.ReadAllText(@"c:\temp\data.json");
        var accounts = Newtonsoft.Json.JsonConvert.DeserializeObject<IEnumerable<Account>>(JSONtxt);
    }
}

解决方案2：根据您的要求

/// <summary>
/// Non standard json serialization (object one by one) Highly discouraged unless you have specific reason
/// Assuming the output will not have internal objects 
/// </summary>
public void SerializeNonStandard()
{
    List<Account> listOfAccounts = new List<Account>();
    listOfAccounts.Add(new Account { Id = 1, Name = "First" });
    listOfAccounts.Add(new Account { Id = 2, Name = "Second" });
    listOfAccounts.Add(new Account { Id = 3, Name = "Third" });

    foreach (var item in listOfAccounts)
    {
        string outputJSON = Newtonsoft.Json.JsonConvert.SerializeObject(item, Newtonsoft.Json.Formatting.Indented);
        File.AppendAllText(@"c:\temp\data-ns.json", outputJSON + Environment.NewLine);
    }
}
/// <summary>
/// Deserializes the list in one by one fashion and appends to list
/// </summary>
public void DeSerializeNonStandard()
{
    if (File.Exists(@"c:\temp\data-ns.json"))
    {
        List<Account> listOfAccounts = new List<Account>();
        String JSONtxt = File.ReadAllText(@"c:\temp\data-ns.json");

        //Capture JSON string for each object, including curly brackets 
        Regex regex = new Regex(@".*(?<=\{)[^}]*(?=\}).*", RegexOptions.IgnoreCase);
        MatchCollection matches = regex.Matches(JSONtxt);
        foreach(Match match in matches)
        {
            string objStr = match.ToString();
            Account account = Newtonsoft.Json.JsonConvert.DeserializeObject<Account>(objStr);
            listOfAccounts.Add(account);
        }
    }
}

/// <summary>
/// Deserializes the non standard json to list of accounts
/// Splits the object strings, merges with comma and encloses with [] to make it array of objects format and deserializes
/// </summary>
public void DeSerializeNonStandardList()
{
    if (File.Exists(@"c:\temp\data-ns.json"))
    {
        String JSONtxt = File.ReadAllText(@"c:\temp\data-ns.json");

        //Capture JSON string for each object, including curly brackets 
        Regex regex = new Regex(@".*(?<=\{)[^}]*(?=\}).*", RegexOptions.IgnoreCase);
        MatchCollection matches = regex.Matches(JSONtxt);

        string joinedJSON = string.Join(",", matches.Cast<Match>().Select(m => m.Value));
        joinedJSON = string.Format("[{0}]", joinedJSON);

        var listOfAccounts = Newtonsoft.Json.JsonConvert.DeserializeObject<IEnumerable<Account>>(joinedJSON);

    }
}

Answer 2

您正在序列化帐户而不是帐户列表，这就是为什么反序列化失败的原因。你需要在新的行中分开这些帐户吗？如果是这样你可以尝试添加char＆＃39; [＆＃39;在第一个和最后一个char＆＃39;]＆＃39;在data.json。

如何将JSON文件反序列化为List <t> c＃

2 个答案: