Sort List of Dictionary using IComparer instead of OrderBy

Question

Following is my collection, along with data:

var data = new List>();
       data.Add(new Dictionary(         


        

Answer 1

Here is a class that you can use to chain comparers. It will accept a sequence of comparers and then to compare each item it uses each of the comparers, in order, returning the value of the first non-zero comparison, or zero if they're all zero.

You can use this to take all of the comparers that you have and create a single comparer that you can pass to a single call to Sort or whatever you need the single comparer for.

public class ComparerChain<T> : IComparer<T>
{
    private IEnumerable<IComparer<T>> comparers;
    public ComparerChain(IEnumerable<IComparer<T>> comparers)
    {
        this.comparers = comparers;
    }

    public int Compare(T x, T y)
    {
        return comparers.Select(comparer => comparer.Compare(x, y))
            .FirstOrDefault(result => result != 0);
    }
}

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On a side note, your OrderBy based method can be re-written to both only iterate the source sequence once, instead of three times, and also avoid much of the duplication:

public static IEnumerable<Dictionary<object, object>> Sort(
    this IEnumerable<Dictionary<object, object>> data,
    IEnumerable<OrderClause> orderClauseList)
{
    var ordered = data.OrderBy(_ => 1);
    return orderClauseList.Aggregate(ordered, (current, orderClause) =>
        (orderClause.IsAscending)
        ? current.ThenBy(d => d[orderClause.ColumnName])
        : current.ThenByDescending(d => d[orderClause.ColumnName]));
}