具有包含问题的实体框架Linq

Question

I have the following schema:

DMS_DocMaster {
    docmaster_id int,
    createddate datetime,
}

DMS_Master_Index {
    doctype_id int
    keyword_id int
    docmaster_id int
}

DMS_DocTypes {
    doctype_id int
    group_id int
    description varchar(50)
}

DMS_Keywords {
    keyword_id int
    label varchar(50)
    datatype varchar(50)
}

DMS_Doc_Keyword_XRef {
    doctype_id int
    keyword_id int
    seqorder int
}

With this schema, there are a series of document groups and document types (think "buckets") a user can submit documents to. With each document type, there can be a series of keywords (via bridge XRef table). When a document is submitted, the master ID is stored in the DocMaster table and the keyword values are stored in the Master_Index table (along with the master_id and doctype_id ).

My issue is, I'm working on a "search" query - when a user navigates to a page and presses search, they are presented with a dynamically generated list of inputs containing "From Date" and "Thru Date" as well as all the keywords for that specific document type. When the user hits the search button, the system is supposed to query based on all available values the user filled in (blank values are allowed). However, I'm having trouble building my Linq-to-Entities query.

What I have so far:

public IList<DMS_DocMaster> SearchDocuments(int groupId = -1, int typeId = -1, DateTime? fromDate = null, DateTime? thruDate = null, Dictionary<int, string> searchCriteria = null)
{
    List<DMS_DocMaster> results;

    using (var ctx = new DMSEntities())
    {
        //make sure Lazy Loading is off because we are including reference tables in the results
        //and the context will be closed at time of accessing reference tables --> exception thrown
        ctx.Configuration.LazyLoadingEnabled = false;

        //initial query regardless of type or not
        //it's an anonymous type to make sure all fields are included
        var res = from docMaster in ctx.DMS_DocMaster.Include(x => x.DMS_Notes)
                  join masterIndex in ctx.DMS_Master_Index on docMaster.docmaster_id equals masterIndex.docmaster_id
                  join docTypes in ctx.DMS_DocTypes on masterIndex.doctype_id equals docTypes.doctype_id
                  //join xref in ctx.DMS_Doc_Keyword_XRef on masterIndex.doctype_id equals xref.doctype_id
                  //join keys in ctx.DMS_Keywords on xref.keyword_id equals keys.keyword_id
                  where docTypes.group_id == groupId
                  //select new { docMaster, masterIndex, docTypes, xref, keys };
                  select new { docMaster, masterIndex, docTypes };

        //if type is provided, search against the type
        if (typeId > 0)
        {
            res = res.Where(i => i.docTypes.doctype_id == typeId);
        }

        //if there is a from date
        if (fromDate.HasValue)
        {
            res = res.Where(i => i.docMaster.createdate >= fromDate.Value);
        }

        //if there is a thru date
        if (thruDate.HasValue)
        {
            res = res.Where(i => i.docMaster.createdate <= thruDate.Value);
        }

        //if we have search criteria
        if (searchCriteria != null)
        {
            //loop over it, appending where clauses
            foreach (var criterion in searchCriteria)
            {
                 res = res.Where(i => i.masterIndex.keyword_id == criterion.Key && i.masterIndex.keyword_value.Equals(criterion.Value));
            }
        }

        //select just the Doc Master records from the anonymous type
        //include the Master Index reference table, and the links to the Keywords table
        //to get the keyword label
        var res1 = res.Select(i => i.docMaster);
        res1 = res1.Include(x => x.DMS_Notes);
        res1 = res1.Include(x => x.DMS_Master_Index);
        //res1 = res1.Include(x => x.DMS_Master_Index
        //  .Select(y => y.DMS_Doc_Keyword_XRef.DMS_Keywords));
        res1 = res1.Include(x => x.DMS_Master_Index.Where(y => y.doctype_id == typeId));  //this throws an error

        res1 = res1.OrderByDescending(i => i.createdate);

        results = res1.ToList();
    }

    return results;
}

The problem I am having is it's returning all instances of the keywords regardless of the document type - I need to filter the .Include of the Master_Index table, but it throws an ArgumentException error

The Include path expression must refer to a navigation property defined on the type. Use dotted paths for reference navigation properties and the Select operation for collection navigation properties

How can I modify my Linq query to search for all my provided criteria, and fill the navigation properties? I'm hoping to avoid multiple queries to the database if I can.

Update

Thanks to feedback from Lajos' comment, I went back to the drawing board (litterally a went to a white board) and re-wrote the function. I have broken the query down into two queries. The first one to return the list of docmaster_id 's that match the search criteria and the second one to fill in the associated keywords reguardless of values existing or not (I need at least the labels of the keywords to print on the screen)

Answer 1

Thanks to feedback from Lajos' comment, I went back to the drawing board (litterally a went to a white board) and re-wrote the function. I have broken the query down into two queries. The first one to return the list of docmaster_id's that match the search criteria and the second one to fill in the associated keywords reguardless of values existing or not (I need at least the labels of the keywords to print on the screen)