Return multiple props using Find

Question

User-1129879462 posted

var project = Context.Single<Project>(p => p.ProjectCode == projectCode, 
                                      p => p.WorkItems, p => p.Notes, p => p.Resources);

How can I do the same using Find?

Context.All<Project>().ToList().Find(p=>p.ProjectCode==projectCode)

returns WorkItems, Notes and Resources as null.

Thanks.

Answer 1

User-832373396 posted

Hi <g class="gr_ gr_42 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling" id="42" data-gr-id="42">krisrajz</g>,

 Context.Single<

Context.All<

It seems that it's not Entity Framework, May I know what's this?

and I guess that could be Context.Find(p=>p.ProjectCode==projectCode) if you want to return a row record ;

With regards, Angelina Jolie

Answer 2

User-1129879462 posted

As Find is faster than Single/First (these products TOP(x) clause which slows down) I could not use those two and would like to return only first match.

Answer 3

User-832373396 posted

Hi Krisrajz,

krisrajz

As Find is faster than Single/First (these products TOP(x) clause which slows down) I could not use those two and would like to return only first match.

Yeah, I understand you right now.

But, we still can not <g class="gr_ gr_452 gr-alert gr_gramm gr_inline_cards gr_run_anim Style multiReplace" id="452" data-gr-id="452">use </g><g class="gr_ gr_452 gr-alert gr_gramm gr_inline_cards gr_disable_anim_appear Style multiReplace" id="452" data-gr-id="452">.</g>Find(p=>p.ProjectCode==projectCode) directly; From link

For improving query performance, we could add AsNoTracking() likes the code shown below:

		 string city =  "New York";
		 List<School> schools = db.Schools
		     .AsNoTracking()
		     .Where(s => s.City == city)
		     .Take(1)
		     .ToList();

From https://www.red-gate.com/simple-talk/dotnet/net-tools/entity-framework-performance-and-what-you-can-do-about-it/

Reference:

• No Tracking LINQ to Entities queries

When the context derives ObjectContext: 

context.Products.MergeOption = MergeOption.NoTracking;
var q = context.Products.Where(p => p.Category.CategoryName == "Beverages");

 When the context derives DbContext:

var q = context.Products.AsNoTracking()
                        .Where(p => p.Category.CategoryName == "Beverages");

Pros

• Improved performance over regular LINQ queries.
• Fully materialized objects.
• Simplest to write with syntax built into the programming language.

Cons

• Not suitable for CUD operations.
• Certain technical restrictions, such as:
  • Patterns using DefaultIfEmpty for OUTER JOIN queries result in more complex queries than simple OUTER JOIN statements in Entity SQL.
  • You still can’t use LIKE with general pattern matching.

Note that queries that project scalar properties are not tracked even if the NoTracking is not specified. For example:

var q = context.Products.Where(p => p.Category.CategoryName == "Beverages").Select(p => new { p.ProductName });
 

This particular query doesn’t explicitly specify being NoTracking, but since it’s not materializing a type that’s known to the object state manager then the materialized result is not tracked.  From official document  link( there are many other way to improve performance in it)

•  Entity Framework and AsNoTracking

http://www.c-sharpcorner.com/UploadFile/ff2f08/entity-framework-and-asnotracking/ 

With regards, Angelina Jolie

Answer 4

User-1129879462 posted

Angie is great! Needless to say, everybody knows!!