Entity Framework – AutoDetectChangesEnabled

From MSDN

When using most POCO entities the determination of how an entity has changed (and therefore which updates need to be sent to the database) is handled by the Detect Changes algorithm. Detect Changes works by detecting the differences between the current property values of the entity and the original property values that are stored in a snapshot when the entity was queried or attached. The techniques shown in this topic apply equally to models created with Code First and the EF Designer.

But some times we need to turn off this feature. for example, I need to upload a excel file it contains a bulk data. At this time AutoDetectChangesEnabled is true then it take a lot time for insert all rows. I can do the data validations at db side.

Just check the difference of AutoDetectChangesEnabled ON and OFF while inserting a bulk data.

Normal way:

namespace TestAutoDetectChangesEnabled
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Title = "Time Test - AutoDetectChangesEnabled";
            string[] names = { "Arun", "Raj", "Musthaan", "Majeed", "Muzafir",
                                 "Hari", "Dharma", "Kannan", "Imran", "Santo",
                                 "Rahmath", "Jayesh" };
            Stopwatch sw = new Stopwatch();
            sw.Start();
            var db = new AppContext();
            foreach (var i in Enumerable.Range(1, 20000))
            {
                var student = new Student()
                {
                    Name = names[(new Random().Next(0, 10))],
                    ContactNo = "9870002735",
                    RegNo = i.ToString().PadLeft(7, '0')
                };
                db.Students.Add(student);
                Console.Clear();
                Console.WriteLine("{0} records added", i);
            }
            db.SaveChanges();
            sw.Stop();
            Console.WriteLine("Taked time - {0}", sw.ElapsedMilliseconds);
            Console.ReadKey();
        }
    }

    public class AppContext : DbContext
    {
        public AppContext()
            : base("AppConnection")
        {

        }
        public DbSet<Student> Students { get; set; }
    }
    public class Student
    {
        public long Id { get; set; }
        public string Name { get; set; }
        public string RegNo { get; set; }
        public string ContactNo { get; set; }

    }
}

AutoDetectChangesEnabled-before

After disable AutoDetectChanges

 class Program
    {
        static void Main(string[] args)
        {
            Console.Title = "Time Test - AutoDetectChangesEnabled";
            string[] names = { "Arun", "Raj", "Musthaan", "Majeed", "Muzafir",
                                 "Hari", "Dharma", "Kannan", "Imran", "Santo",
                                 "Rahmath", "Jayesh" };
            Stopwatch sw = new Stopwatch();
            sw.Start();
            var db = new AppContext();
            try
            {
                db.Configuration.AutoDetectChangesEnabled = false;

                foreach (var i in Enumerable.Range(1, 20000))
                {
                    var student = new Student()
                    {
                        Name = names[(new Random().Next(0, 10))],
                        ContactNo = "9870002735",
                        RegNo = i.ToString().PadLeft(7, '0')
                    };
                    db.Students.Add(student);
                    Console.Clear();
                    Console.WriteLine("{0} records added", i);
                }
                db.SaveChanges();
            }
            finally
            {
                db.Configuration.AutoDetectChangesEnabled = true;
            }
            sw.Stop();
            Console.WriteLine("Taked time - {0}", sw.ElapsedMilliseconds);
            Console.ReadKey();
        }
    }

AutoDetectChangesEnabled-after

See the difference, it almost 10x faster. But use it with care. Don’t forget to re-enable detection of changes after the loop — used a try/finally to ensure it is always re-enabled even if code in the loop throws an exception.

See System.Data.Entity.Validation.DbEntityValidationException Details

Today i got an error on saving data to db using EF.

An exception of type ‘System.Data.Entity.Validation.DbEntityValidationException’ occurred in EntityFramework.dll but was not handled in user code

Additional information: Validation failed for one or more entities. See ‘EntityValidationErrors’ property for more details.

System.Data.Entity.Validation.DbEntityValidationException

but I can’t find out what are the failed validations.

System.Data.Entity.Validation.DbEntityValidationException2

No more details in quick watch. I stucked a little. At this time i find out the use of $exception.That is a special debugger variable. You cannot access it via code.

https://msdn.microsoft.com/en-us/library/ms164891.aspx

https://blogs.msdn.microsoft.com/shaykatc/2004/02/20/vs-2003-tip-3-view-exception-information-with-exception/

look  $exception in quickwatch.

System.Data.Entity.Validation.DbEntityValidationException3

 

The JSON request was too large to be deserialized.

I am working on a list and it has a bulk update through api. I am tested with upto 30 records and its working fine on my dev system. whilie update to QA they added a lot of records to update at that time I got an error The JSON request was too large to be deserialized

JSON request was too large
Problem is I am sending data as JSON as MVC’s default maximum Json deserializer members count is 1000. So I changed it in web.config.

<appSettings>
    <add key="aspnet:MaxJsonDeserializerMembers" value="150000" />
</appSettings>

List of all default Excel NumberFormatId’s

If you’d like to format your date another way, here is a list of all default Excel NumberFormatId’s

 

ID FORMAT CODE
0 General
1 0
2 0.00
3 #,##0
4 #,##0.00
9 0%
10 0.00%
11 0.00E+00
12 # ?/?
13 # ??/??
14 d/m/yyyy
15 d-mmm-yy
16 d-mmm
17 mmm-yy
18 h:mm tt
19 h:mm:ss tt
20 H:mm
21 H:mm:ss
22 m/d/yyyy H:mm
37 #,##0 ;(#,##0)
38 #,##0 ;[Red](#,##0)
39 #,##0.00;(#,##0.00)
40 #,##0.00;[Red](#,##0.00)
45 mm:ss
46 [h]:mm:ss
47 mmss.0
48 ##0.0E+0
49 @

Kendo Grid – add custom class to a column

logo kendoui

In many situation I was required a class for some specific columns. This is a simple solution for that.

$("#grid").kendoGrid({
 dataSource: GridSource,
 columns: [{
                title: "",
                template: actionTemplate,
                filterable: false,
                width: 105
            },
            {
                field: "Title",
                title: "Title",
                width: 350,
                attributes: {
                    "class": "table-cell"
                    }
             }]
   });

We can add in-line styles in the same way.

$("#grid").kendoGrid({
 dataSource: GridSource,
 columns: [{
                title: "",
                template: actionTemplate,
                filterable: false,
                width: 105
            },
            {
                field: "Title",
                title: "Title",
                width: 350,
                attributes: {
                    style: "text-align: right"
                    }
             }]
   });

kendoGrid cancel edit event

logo kendoui

My kendo grid need edit functionality for some specific rows. That is requirement. We can set editable column level
or grid level. I did’t find out an option for disable editable for rows.

I found two options for revert back to normal mode from edit mode.

$("#grid").data("kendoGrid").cancelChanges();
$("#grid").data("kendoGrid").closeCell();

I add a field in model for check is this row editable and check it on edit event.

$("#grid").kendoGrid({

			
			dataSource: GridSource,
			height: 450,
			sortable: true,
			resizable: true,			
			editable: true,
			pageable: true,
			dataBound: ongridDataBound,
			edit: function (e) {
				if (e.model.IsEditable == false) {
					e.sender.closeCell();
				}
			},
			columns: [...]

		});

Now disabled edit functionality for some rows is working fine.

Kendo Grid Date Format

 $("#grid").kendoGrid({            
	dataSource: GridSource,
        height: 540,
        editable: true,
        pageable: true,
        columns: [ 
        	{
			field: "Title",
                        title: "Title", 
                        width: 350
                 }, {
                        field: "RepositoryFilename",
                        title: "Repository Filename", 
                        width: 250,
                    }, {
                        field: "CreatedDate",
                        title: "Create Date", 
                        format:"{0:dd MMM, yyyy}" ,
                        filterable: false, width: 100
                    },   {
                        field: "ModifiedDate",
                        title: "Last Modified", 
                        format: "{0:dd MMM, yyyy}",
                        filterable: false, width: 100
                    }
            ]
        });

User.Identity.Name is null

At this time I am set claims like following line.

identity.AddClaim(new Claim("UserName", context.UserName));

I changed this to


using (AuthRepository _repo = new AuthRepository())
{
  IdentityUser user = await _repo.FindUser(context.UserName, context.Password);

  if (user == null)
  {
     context.SetError("invalid_grant", "The user name or password is incorrect.");
     return;
  }
  ClaimsIdentity identity = new ClaimsIdentity(OAuthDefaults.AuthenticationType);
  identity.AddClaim(new Claim(ClaimTypes.Name, user.UserName));
  identity.AddClaim(new Claim(ClaimTypes.NameIdentifier, user.Id));
  context.Validated(identity);

}

IAppBuilder does not contain definition for UseWebApi

When I try to implement WebApi with owin, i got an error

IAppBuilder’ does not contain a definition for ‘UseWebApi’ and no extension method ‘UseWebApi’ accepting a first argument of type ‘IAppBuilder’ could be found (are you missing a using directive or an assembly reference?)

Solution is you need to install Microsoft ASP.NET Web API2 OWIN Self Host which will resolve the issue.

You can use the NuGet command Install-Package Microsoft.AspNet.WebApi.OwinSelfHost.
nuget_webapi_selfhost

The types of all properties in the Dependent Role of a referential constraint must be the same as the corresponding property types in the Principal Role

web_services[1]Some days before I got an error while try to update migration like :

UploadedData_GrpCategory_Target_UploadedData_GrpCategory_Source: : The types of all properties in the Dependent Role of a referential constraint must be the same as the corresponding property types in the Principal Role. The type of property ‘Category’ on entity ‘UploadedData’ does not match the type of property ‘Id’ on entity ‘GrpCategory’ in the referential constraint ‘UploadedData_GrpCategory’.

 

 

I didn’t understand what it is in first look.  Then I understood , I created Primary key and foreign key in different datatypes in Entities.