我有一个Web API，它返回一个数据表

public async Task<IHttpActionResult> SelectExtension(DateTime start, DateTime end, string institution)
{
    var identity = (ClaimsIdentity)User.Identity;
    var facility= claimIdentity.GetIdentityValue("Institution", identity).First();
    DataTable table = new DataTable("Result");
    var cmd = new SqlCommand();
    using (SqlConnection con = connection.DB())
    {
        try
        {
            con.Open();
            var query = generalData.SelectExtension(start, end, facility, institution);
            cmd = command.CreateQuery(query.Query, query.ProcdureParameters, con);
            SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(cmd);
            sqlDataAdapter.Fill(table);

        }
        catch (Exception e)
        {
            var error = $"Code: {e.HResult}\n Message: {e.Message}\n InnerException: {e.InnerException}\n Stack: {e.StackTrace}";
            await stream.WriteAsync(error);
            return InternalServerError();
        }
    }
    return Ok(table);
}

其中有一个数据类型为DateTime的列

table.Rows[6]["ApprovedExtendedEndDate"]
{11/25/2021 12:00:00 AM}
    Date: {11/25/2021 12:00:00 AM}
    Day: 25
    DayOfWeek: Thursday
    DayOfYear: 329
    Hour: 0
    Kind: Unspecified
    Millisecond: 0
    Minute: 0
    Month: 11
    Second: 0
    Ticks: 637733952000000000
    TimeOfDay: {00:00:00}
    Year: 2021

当返回到客户端时，列的数据类型将更改为string

• Http客户端代码 *

public async Task<DataTable> SelectExtension(DateTime start, DateTime end, string institution)
{
    try
    {
        var response = await ClientHttp.HttpClient.Client.GetAsync($"{controller}/SelectExtension/{start:yyyy-MM-dd}/{end:yyyy-MM-dd}/{institution}");
        if (response.IsSuccessStatusCode)
        {
            var result = await response.Content.ReadAsAsync<DataTable>();
            return result;
        }
        else if (response.StatusCode == HttpStatusCode.Unauthorized)
        {
            FormAction.Alert("You do not have permission to access this resource", FormAction.enmType.Error);
            return null;
        }
        return null;
    }

列中的值现在变为字符串

result.Rows[6]["ApprovedExtendedEndDate"]
"11/25/2021 00:00:00"

任何人都可以请帮助我确定为什么它是无法转换为一个日期时间。

它不是数据表中唯一的日期时间列，但此特定列返回字符串。