CODEWITHSUNDEEP
c#linq.net-4.0lambda
O.O
O.O

Reputation: 11287

How to order by a date part?

I have a DataColumn of DateTime datatype and I want to order by the year in descending order followed by the month in descending order.

Here's what I tried:

table.AsEnumerable()
    .OrderByDescending(o => o.Field<DateTime>("MaxDateTaken").Year)
    .ThenByDescending(o => o.Field<DateTime>("MaxDateTaken").Month)

I get an invalid cast error because both Year and Month are int datatypes, but I'm specifying DateTime in the <>

Any ideas?

Upvotes: 1

Views: 245

Answers (3)

Bruno Silva
Bruno Silva

Reputation: 3097

Why are you ignoring the day part? It could get simpler:

table = table.AsEnumerable()
   .OrderByDescending(o => DateTime.Parse(o.Field<string>("MaxDateTaken")))

Upvotes: 1

O.O
O.O

Reputation: 11287

I fixed it like this:

table = table.AsEnumerable()
   .OrderByDescending(o => DateTime.Parse(o.Field<string>("MaxDateTaken")).Year)
   .OrderByDescending(o => DateTime.Parse(o.Field<string>("MaxDateTaken")).Month)

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1500275

You shouldn't get a cast error because of that - are you sure that field is really a DateTime?

It sounds like you really just want

table.AsEnumerable()
     .OrderByDescending(o => o.Field<DateTime>("MaxDateTaken"))

anyway, given that ordering by the year and the month descending is basically ordering by the date descending, except it doesn't do anything with the "day" part. Do you really not want to include the "day" part in your ordering?

Upvotes: 3

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