[C#] Generic Linq where clause ORing together many

2009-11-12T11:43:12-08:00

Suddenly found myself having written this piece of ugly Extension method, and I'm wondering if there is a more clear way of doing this.

The idea is that given a list of objects, I want to generate the where expression/func that will give me all rows in the database (TDbTable), and I have a comparison that will match TEntity to TDbTable. In reality it generates this kind of SQL: "WHERE id = 1 or id = 2 or id = 3 ... "

        public static Func<TDbTable, bool> GetWhereClauseForAll<TDbTable, TEntity>(
            this List<TEntity> objects,
            Func<TEntity, Func<TDbTable, bool>> comparison)
        {
            Func<Func<TDbTable, bool>, Func<TDbTable, bool>, Func<TDbTable, bool>> concatWhereClauses
                = (existingWhereClause, toBeAddedWhereClause)
                    => row
                    => existingWhereClause(row) || toBeAddedWhereClause(row);

            Func<TDbTable, bool> whereClause = comparison(objects.First());

            for (int i = 1; i < objects.Count; i++)
                whereClause = concatWhereClauses(whereClause, comparison(objects[i]));

            return whereClause;
        }

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[C#] Generic Linq where clause ORing together many