字符串值为空时发生Web api错误

Question

这是我尝试传递其中一个值“in blank”/ null时得到的错误。奇怪的是，只有一个参数会导致这个问题...只是“nomePai” 在数据库上，storedprocedure就可以了......

如果我通过NomeEnvolvido = Teste，nomeMae = Teste，nomePai = Teste，Dtnasc = 01/01 / 2000 - ＆gt; OKKKKK

如果我通过NomeEnvolvido = Teste，nomeMae =，nomePai = Teste，Dtnasc = 01/01 / 2000 - ＆gt; OKKKKK

但是如果我通过NomeEnvolvido = Teste，nomeMae = Teste，nomePai =，Dtnasc = 01/01 / 2000，我收到错误：

  

{“Message”：“发生错误。”，“ExceptionMessage”：“'ObjectContent'1'类型无法序列化内容类型'application / json; charset = utf-8'的响应正文。” ，“ExceptionType”：“System.InvalidOperationException”，“StackTrace”：null，“InnerException”：{“消息”：“发生了错误。”，“ExceptionMessage”：“Objetonãodepode ser convertido de DBNull em outros tipos。 “，”ExceptionType“：”System.InvalidCastException“，”StackTrace“：”em System.DBNull.System.IConvertible.ToDateTime（IFormatProvider provider）\ r \ n em em System.Convert.ToDateTime（Object value）\ r \ n em WebApiApp.Controllers.NomesController。＆lt;＆gt; c.b__1_0（DataRow行）na C：\ Users \ 50216740 \ Documents \ Visual Studio 2015 \ Projects \ AppMobilePCRJ \ AppMobilePCRJ \ WebApiApp \ Controllers \ NomesController.cs：linha 69 \ r \ n em System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext（）\ r \ n em Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList（JsonWriter writer，IEnumerable values，JsonArrayContract contrac t，JsonProperty成员，JsonContainerContract collectionContract，JsonProperty containerProperty）\ r \ n em Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue（JsonWriter writer，Object value，JsonContract valueContract，JsonProperty member，JsonContainerContract containerContract，JsonProperty containerProperty）\ r \ n em Newtonsoft .Json.Serialization.JsonSerializerInternalWriter.Serialize（JsonWriter jsonWriter，Object value，Type objectType）\ r \ n em Newtonsoft.Json.JsonSerializer.SerializeInternal（JsonWriter jsonWriter，Object value，Type objectType）\ r \ n em System.Net.Http .Formatting.BaseJsonMediaTypeFormatter.WriteToStream（类型类型，对象值，流writeStream，编码effectiveEncoding）\ r \ n \ n系统System.Net.Http.Formatting.JsonMediaTypeFormatter.WriteToStream（类型类型，对象值，流writeStream，编码effectiveEncoding）\ r \ n \ n em System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStream（Type type，Object value，Stream writeStream，Ht tpContent content）\ r \ n em System.Net.Http.Formatting.BaseJsonMediaTypeFormatter.WriteToStreamAsync（Type type，Object value，Stream writeStream，HttpContent content，TransportContext transportContext，CancellationToken cancellationToken）\ r \ n --- Fim do rastreamento de pilha System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）\ r \ n em，System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）\ r \ n em System.Web.Http.WebHost.HttpControllerHandler.d__1b.MoveNext（）“}}

[控制器代码]

 [HttpGet]
        [Route("Envolvidos")]
        public IEnumerable<Envolvido> GetEnvolv(string nomePesquisa, string nomeMae, string nomePai,  Nullable<DateTime> dtnasc
            , string nRG, string nCPF)
        {

            DataSet lretorno = new DataSet();

            string connectionString = GetConnectionString();
            using (OracleConnection connection = new OracleConnection())
            {
                connection.ConnectionString = connectionString;

                OracleDataReader reader = null;
                OracleCommand cmd = new OracleCommand();
                cmd.Connection = connection;
                cmd = new OracleCommand("MOBILE.XAPIMANDADOMOBILE.BUSCAPOSSIVEISCANDIDATOSPF", connection);
                cmd.CommandType = CommandType.StoredProcedure;

                //variáveis entrada            
                cmd.Parameters.Add(new OracleParameter("ivnome",nomePesquisa));
                cmd.Parameters.Add(new OracleParameter("ivmae", nomeMae));
                cmd.Parameters.Add(new OracleParameter("ivpai", nomePai));
                cmd.Parameters.Add(new OracleParameter("ivdatanasc", dtnasc));
                cmd.Parameters.Add(new OracleParameter("ivrg", nRG));
                cmd.Parameters.Add(new OracleParameter("icpf", nCPF));
                //variáveis de saida          
                cmd.Parameters.Add(new OracleParameter("oretorno", OracleDbType.RefCursor)).Direction = ParameterDirection.Output;
                cmd.Parameters.Add(new OracleParameter("qretorno", OracleDbType.RefCursor)).Direction = ParameterDirection.Output;

                connection.Open();
                cmd.ExecuteNonQuery();

                reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);

                //CRIO A LISTA
                lretorno.Load(reader, LoadOption.OverwriteChanges, "BUSCAPOSSIVEISCANDIDATOSPF");
                connection.Close();
                connection.Dispose();

                //CARREGO O DATASET E TRANSFORMO PARA IENUMERABLE E RETORNO SEUS VALORES PRO JSON
                return lretorno.Tables[0].AsEnumerable().Select(row => new Envolvido
                {
                    ID = Convert.ToInt32(row["SUSPID"]),
                    IVNOME = Convert.ToString(row["SUSPNOME"]),
                    IVMAE = Convert.ToString(row["SUSPMAE"]),
                    IVPAI = Convert.ToString(row["SUSPPAI"]),
                    IVDATANASC = Convert.ToDateTime(row["SUSPDATANASC"]).ToString("dd/MM/yyyy"),
                    IVRG = Convert.ToString(row["RG"]),
                    ICPF = Convert.ToString(row["CPF"]),
                    MANDADO = Convert.ToInt16(row["TEMMANDADO"]),
                    OCORRENCIA = Convert.ToInt16(row["TEMOCORRENCIA"]),

                });

            }
        }

[Envolvido课程]

namespace WebApiApp.Models
{
    public class Envolvido
    {
        [Key]
        public Int32 ID { get; set; }
        public string IVNOME { get; set; }
        public string IVMAE { get; set; }
        public string IVPAI { get; set; }
        public string IVDATANASC { get; set; }
        public string IVRG { get; set; }
        public string ICPF { get; set; }
        public Int16 MANDADO { get; set; }
        public Int16 OCORRENCIA { get; set; }
    }
}

...问候