Perform search by Date using entity framework

Question

I try to make search query in Entity framework. I have table Project with 'Id', 'ProjectName', 'Description' and "modificationdate" etc. I want to perform search on 'ProjecName', 'Description' and "modificationdate". I successfully perform search on 'ProjectName' & 'Description' but i don't know how perform search by date

var found = from n in context.Project
                            where n.projectName.Contains(SearchKey) ||
                            n.description.Contains(SearchKey) 
                        select n;

Have a look At Entity Functions http://msdn.microsoft.com/en-us/library/system.data.objects.entityfunctions_methods%28v=vs.110%29.aspx — Lotok, Oct 28 '13 at 10:04
What's the problem with something like `|| n.Modification > DateTime.Now` ? — ta.speot.is, Oct 28 '13 at 10:05
@ta.speot.is The search would include the time. You need an Entity Function to truncate the time — Lotok, Oct 28 '13 at 10:06
@James So get rid of the time `|| n.Modification > DateTime.Now.Date` — ta.speot.is, Oct 28 '13 at 10:08
This would help also: http://stackoverflow.com/questions/14778758/use-linq-query-to-compare-date-only-with-datetime-field — Sadek Noureddine, Oct 28 '13 at 10:12

Henk Mollema · Answer 1 · 2013-10-28T10:52:48.440

2

You can use the greather-than >, less-than < and equals == operators for example (see this for a complete list) to search by date. Example to get projects modified a week ago or less:

DateTime.Now.AddDays(-7) > n.modificationdate

If you don't want to include the time, you can use the Date property to exclude it:

DateTime.Now.AddDays(-7).Date > n.modificationdate.Date

Edit: search by given date:

date == n.modificationdate

Where date is the given date. If the date is specified in the SearchKey variable (which I assume is a string), you have to parse it to a date first.

edited Oct 28 '13 at 10:52

answered Oct 28 '13 at 10:09

Henk Mollema

44,194
12
93
104

This would be inaccurate without truncating the time as is if you search at 2pm, the search will not pull back items from 7 days ago at 1pm. – Lotok Oct 28 '13 at 10:12
The point is you are still having partial days due to time. Just truncate the time and provide a more accurate search – Lotok Oct 28 '13 at 10:13
I've updated my question with a note to the `Date` property of `DateTime`. – Henk Mollema Oct 28 '13 at 10:13
*facepalm* you still have a time on the modificationdate! – Lotok Oct 28 '13 at 10:14
@James A minor typo on my behalf. If you want everything that changed from yesterday (i.e. one day ago) then subtract one day and use the date and compare with `>=`. So if something was modified `27/10/2013 1:00pm` then `28/10/2013 - 1 Day` is `27/10/2013 12:00am`. There's no need for entity functions. – ta.speot.is Oct 28 '13 at 10:16
Actually i try to perform search on given date – Vicky Oct 28 '13 at 10:43
@Vicky you could use `date == n.modificationdate` for that. Where `date` is the variable containing the given date. – Henk Mollema Oct 28 '13 at 10:50

score 2 · Answer 2 · answered Oct 28 '13 at 10:53

To take what you're saying from the comments:

Actually i try to perform search on given date

If you want to search for modifications on a given date, just search for values greater than or equal to the start of the date and then everything less than the day after.

var searchDate = new DateTime(2013, 2, 5); // or searchDateWithTime.Date
var searchDatePlusOne = searchDate.AddDays(1);

return from n in context.Project
       where n.ModificationDate >= searchDate
             && n.ModificationDate < searchDatePlusOne
       select n;

If n.ModificationDate contains a date and nothing more, then n.ModificationDate == searchDate is a sufficient predicate.

Perform search by Date using entity framework

2 Answers2