c# - 为什么 JsonConvert.DeserializeObject 返回错误：异常：值不能为空。（参数“来源”）

问题描述

我有一个public async Task GetCompaniesAsync()这样编码的：

public async Task GetCompaniesAsync()
{
    _getCompaniesSuccessful = false;

    var result = await _http.GetAsync($"https://somesite.com/api/companies");

    if (result.IsSuccessStatusCode)
    {
        // I split the code after the suggestion of @mjwills (thanks)
        var content = await result.Content.ReadAsStringAsync();
        var obj = JsonConvert.DeserializeObject<StockMarket>(content).Companies;

        // at this point, content.Length has a value (e.g. 24429)
        // but, obj is null (after JsonConvert)

        if (obj != null)
        {
            _companies = obj.ToList();
            _getCompaniesSuccessful = true;
        }
}

在其他一些课程中，我使用以下代码：

await MyService.GetCompaniesAsync();
                
if (MyService.GetCompaniesSuccessful)
{
    foreach (var record in MyService.Companies)
    {
        await Context.Channel.SendMessageAsync($"{record.TickerSymbol,-10}\t{record.CompanyName,-10}");
    }
}

但是当我收到以下错误时：异常：值不能为空。（参数'source'） 会不会是数据还没有完成呢？请帮忙...

顺便说一句，webapi url 返回 JSON 数据，它看起来像这样：

{
    "companies": [
        {
            "ticker": "HEY",
            "name": "Hey Corporation",
            "status": "open"
        },
        {
            "ticker": "PER",
            "name": "Pears Corporation",
            "status": "close"
        },
        {
            "ticker": "BRGR",
            "name": "Burger Inc.",
            "status": "open"
        },
    ]
}

这些是 StockMarket 和 Company 类：

public class StockMarket
{
    public StockMarket()
    {
    }

    public ICollection<Company> Companies { get; set; }
}

public class Company
{
    public Company()
    {
        TickerSymbol = "";
        CompanyName = "";
        Status = "";
    }

    public string TickerSymbol { get; set; }
    public string CompanyName { get; set; }
    public string Status { get; set; }
}

标签： c#.net-corejson.netdiscord.net

c# - 为什么 JsonConvert.DeserializeObject 返回错误：异常：值不能为空。（参数“来源”）

问题描述

解决方案

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