CODEWITHSUNDEEP
c#linqlinq-to-sql
yeomandev
yeomandev

Reputation: 11806

How to convert this linqTOsql query to lambda

This is more of a brain teaser for me as the linqTOsql query is fulfilling the need. I am just curious as to how a query like this could be converted to lambda's or if that's even possible.

I had originally tried to accomplish this with lambdas, but the only way I could figure out how to accomplish the joins so I could order results correctly was to use the query syntax:

        var entries = from e2c in entry2CatsTable
                      join sEntries in streamEntryTable
                      on e2c.streamEntryID equals sEntries.seID
                      orderby sEntries.seDateCreated descending
                      orderby e2c.e2cOrder
                      where e2c.catID == catID
                      select sEntries;

I had played around with this using lambdas and this is how far i got:

        IQueryable<Entry2Cats> e2c = entry2CatsTable
                                        .Where(x => x.catID == catID)
                                        .OrderBy(x => x.e2cOrder);
        IQueryable<StreamEntry> entries = e2c.SelectMany(x => x.StreamEntry);

These lambdas return the correct results but I couldn't order them correctly because I needed to order based on fields in the Entry2Cats table and the StreamEntry table. Because that was a many to many a statement like this doesn't work:

// doesn't work because it doesn't know which x.Entry2Cats.e2cOrder to use
entries.OrderByDescending(x => x.seDateCreated).OrderBy(x => x.Entry2Cats.e2cOrder);

Any thoughts?

Note:

Also, results need to be returned as IQueryable because the controller adds pagination functionality.

Upvotes: 2

Views: 104

Answers (1)

Anthony Pegram
Anthony Pegram

Reputation: 126952

var entries = entry2CatsTable
                .Join(streamEntryTable, e2c => e2c.streamEntryID, sEntries => sEntries.seID, (e2c, sEntries) => new { e2c, sEntries })
                .Where(item => item.e2c.catID == catID)
                .OrderByDescending(item => item.sEntries.seDateCreated)
                .ThenBy(item => item.e2c.e2cOrder)
                .Select(item => item.sEntries);

Upvotes: 2

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