转换Web API控制器以使用模型而不是直接数据库

Question

我们创建了用于查询Oracle DB的Web API，并以JSON格式返回结果。 Web API接受两个输入参数的数组，一个是需要选择的列名数组，另一个是WHERE子句中使用的ID数组。在我们的例子中，SQL语句使用各种表和各种连接非常复杂，因此我只是简单地选择此处而不是庞大的复杂SQL语句。

控制器如下所示

namespace PSData.Controllers
{
public class PDController : ApiController
{
public HttpResponseMessage Getdetails([FromUri] string[] id, [FromUri] string[] Column)
{           
   List<OracleParameter> prms = new List<OracleParameter>();
   List<string> selectionStrings = new List<string>();
    string connStr = ConfigurationManager.ConnectionStrings["PDConnection"].ConnectionString;
    using (OracleConnection dbconn = new OracleConnection(connStr))
    {
        var inconditions = id.Distinct().ToArray();
        var srtcon = string.Join(",", inconditions);
        DataSet userDataset = new DataSet();
        var colDict = new Dictionary<string, string>()
        {
        {"CATEGORY", "STPR_STD_ANML.DESCR"},
        {"SESSION_NUMBER", "STPR_STD_ANML.SESSION_NUM"},
        {"SESSION_START_DATE","Trunc(STPR_STD_ANML.START_DATE)"}
        };
        foreach (string col in Column)
        {
            string selector = colDict[col];
            selectionStrings.Add(string.Format("{0} AS {1}", selector, col));
        }
        string selectString = string.Join(",", selectionStrings);

        var strQuery =   string.Format(@"SELECT DISTINCT {0}
                         FROM 
                         STPR_STD_ANML WHERE
                         STPR_STUDY.STPR_STD_ANML(", selectString);
            StringBuilder sb = new StringBuilder(strQuery);
            for (int x = 0; x < inconditions.Length; x++)
            {
                sb.Append(":p" + x + ",");
                OracleParameter p = new OracleParameter(":p" + x, OracleDbType.NVarchar2);
                p.Value = inconditions[x];
                prms.Add(p);
            }
            if (sb.Length > 0) sb.Length--;
            strQuery = sb.ToString() + ")";
            using (OracleCommand selectCommand = new OracleCommand(strQuery, dbconn))
            {
                selectCommand.Parameters.AddRange(prms.ToArray());
                using (OracleDataAdapter adapter = new OracleDataAdapter(selectCommand))
                {
                    DataTable selectResults = new DataTable();
                    adapter.Fill(selectResults);
                    var returnObject = new { data = selectResults };
                    var response = Request.CreateResponse(HttpStatusCode.OK, returnObject, MediaTypeHeaderValue.Parse("application/json"));
                    ContentDispositionHeaderValue contentDisposition = null;
                    if (ContentDispositionHeaderValue.TryParse("inline; filename=PSData.json", out contentDisposition))
                    {
                        response.Content.Headers.ContentDisposition = contentDisposition;
                    }
                    return response;
                }
}}}}

因为我们遇到问题序列化响应正文并得到错误 "The 'ObjectContent1' type failed to serialize the response body for content type 'application/json; charset=utf-8'." 所以我试图将模型和数据库上下文嵌入到应用程序中。我试过都喜欢

namespace PSData.Models
{
public class StudyDataModel
{

    [Key]
    public string CATEGORY { get; set; }
    public int SESSION_NUMBER { get; set; }
    public DateTime SESSION_START_DATE { get; set; }
   }}

数据库上下文

 namespace PSData.Models
{
 public class StudyDataContext:DbContext

{
    public DbSet<StudyDataModel> details { get; set; }
}}

我不确定如何在Controller中使用此模型和DBContext，而不是直接处理数据库。这是我的第一个.NET应用程序，有点卡住了。非常感谢任何帮助。