存储过程的实体框架上下文SqlQuery <t>返回SqlParameter已包含在另一个SqlParameterCollection

Question

我需要将复杂实体的过滤从Linq到SQL移到存储过程，因为我需要将数据加载到内存中，以便使用ToList（）应用某些过滤器。 Linq查询导致某些搜索超时。当我切换到存储过程时，将因此更改功能：

    private IQueryable<ProposalLogVM> ApplyProposalSearch(IndexSearchVM search)
    {
        SqlParameter YearCode;
        SqlParameter ProposalStatus;
        SqlParameter Company;
        SqlParameter SearchString;

        if (!String.IsNullOrWhiteSpace(search.SearchString) && search.Year == null)
        {
            search.Year = DateTime.Now.Year;
        }

        if (!String.IsNullOrWhiteSpace(search.Year.ToString()))
        {
            YearCode = new SqlParameter("@Year", search.Year.ToString());
        }
        else
        {
            YearCode = new SqlParameter("@Year", DBNull.Value);
        }

        if (!String.IsNullOrWhiteSpace(search.ProposalStatus))
        {
            ProposalStatus = new SqlParameter("@ProposalStatus", search.ProposalStatus);
        }
        else
        {
            ProposalStatus = new SqlParameter("@ProposalStatus", DBNull.Value);
        }

        if (!String.IsNullOrWhiteSpace(search.CompanyID.ToString()))
        {
            Company = new SqlParameter("@CompanyID", search.CompanyID.ToString());
        }
        else
        {
            Company = new SqlParameter("@CompanyID", DBNull.Value);
        }

        if (!String.IsNullOrWhiteSpace(search.SearchString))
        {
            SearchString = new SqlParameter("@SearchString", search.SearchString);
        }
        else
        {
            SearchString = new SqlParameter("@SearchString", DBNull.Value);
        }

        var proposals = _dbpm.Database.SqlQuery<ProposalLogVM>("EXEC spSearchProposals @Year, @ProposalStatus, @CompanyID, @SearchString", YearCode, ProposalStatus, Company, SearchString).AsQueryable();

        switch (search.SortOption)
        {
            case "ProposalNumber":
                proposals = proposals.OrderBy(p => p.ProposalNumber);
                break;
            case "ProjectName":
                proposals = proposals.OrderBy(p => p.ProjectName);
                break;
            case "ProjectNameD":
                proposals = proposals.OrderByDescending(p => p.ProjectName);
                break;
            case "BidDate":
                proposals = proposals.OrderBy(p => p.BidDate);
                break;
            case "BidDateD":
                proposals = proposals.OrderByDescending(p => p.BidDate);
                break;
            case "Owner":
                proposals = proposals.OrderBy(p => p.Owner);
                break;
            case "OwnerD":
                proposals = proposals.OrderByDescending(p => p.Owner);
                break;
            default:
                proposals = proposals.OrderByDescending(p => p.ProposalNumber);
                break;
        }

        return proposals;

    }

现在，我得到“另一个SQLParameterCollection已经包含了SqlParameter”。执行该行时

        // get the raw proposal list, but don't execute or copy to memory
        IQueryable<ProposalLogVM> rawProposals = ApplyProposalSearch(viewModel.Search);

        // Allow ToPagedList() to do the hard work
        viewModel.Proposals = rawProposals.ToPagedList((int)viewModel.Search.Page, (int)viewModel.Search.Lines);

如果我只执行该行：

        var proposals = _dbpm.Database.SqlQuery<ProposalLogVM>("spSearchProposals @Year, @ProposalStatus, @CompanyID, @SearchString", YearCode, ProposalStatus, Company, SearchString).AsQueryable().ToList();

它运行正常，并返回所有预期的390,000条记录。

在过去的几个小时中，我已经阅读了所有其他有关Stack Overflow的文章，并尝试了这些解决方案，但似乎都没有效果。