DateTime column not automaticaly updated

Darfer

10y2.6k.NET

I work on an Entity Framework 6.1.3, ASP.NET MVC 5, Code First with an existing databse project. My database (SQL Server 2016) includes a table with a “ModifiedDate” (datetime, DEFAULT (getdate)) column. When trying to create a new record in browser the server applies the value automatically as it should be done.

Unfortunately, when I update an existing record the old ModifiedDate value as it is shown in the textbox is applied (not the current date). Moreover, the ModifiedDate textbox should always be inactive to the user, both when creating or editing a record (i.e. the user shouldn’t be allowed to enter a value himself).

This is the model class for the “Title” table:

public partial class Title
{
public int TitleID { get; set; }
[Column("Title")]
[Required]
[StringLength(50)]
public string Title1 { get; set; }
[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public DateTime? ModifiedDate { get; set; }
}

Any suggestions would be appreciated.

Darfer

16 Replies

Know the answer? Post it — somebody with the same question will find it here.

Omid Naghizadeh5y ago
You can overwrite the SaveChanges method and use the below code:

Create a BaseEntity class and add
public class BaseEntity{
public DateTime CreatedDate { get; set; }
public DateTime UpdatedDate { get; set; }
}
All antities need to be inherited from BaseEntity and then you can overwrite the SaveChanges on the dbContext class
public override int SaveChanges() {
var entries = ChangeTracker
.Entries()
.Where(e => e.Entity is BaseEntity &&
( e.State == EntityState.Added || e.State == EntityState.Modified));
foreach (var entityEntry in entries)
{ ((BaseEntity)entityEntry.Entity).UpdatedDate = DateTime.Now;
if (entityEntry.State == EntityState.Added)
{
((BaseEntity)entityEntry.Entity).CreatedDate = DateTime.Now;
}
}
return base.SaveChanges();
}
0
Darfer10y ago
Hi Nitin. I'll check your instructions a bit later. At the moment I have to solve a rather tricky problem concerning creating cascading dropdownlists out of a single table of categories.
+1
Nitin Sontakke10y ago
Okay.
When you did that, did you remove the DatabaseGenerated attribute of the property.
I suspect that it is to do with this attribute that any value for this property is not being sent to db at all by EF.
You will need to do both.
1/ Initialize property value in constructor.
2/ Remove the attribute DatabaseGenerated
+1
Darfer10y ago
Hi Nitin.
What I meant by "not working" is that still, it was fine for creating a new record, but in edit mode asking for user input for the date or apply the date that the record was created. I've hidden the textbox for ModifiedDate in Create and Edit views so that ModifiedDate only shows up in List view.
+1
Nitin Sontakke10y ago
Good to hear that!
However, when you said, "It didn't work", may be more details should have been shared. For example, (as i understand now) did you remove the DatabaseGenerated attribute. Because it was essential otherwise value generated by c# code will not be sent to db.
Personally, I am not sure if trigger good solution in this scenario. Typically, we should avoid triggers as much as possible. Anyway.
You will need following piece of code in trigger, otherwise it will be called recursively. Because there is an UPDATE statement in the trigger!
IF(UPDATE([ModifiedDate]))
RETURN;
0
D Donthu10y ago
we can use conversation
when you use the data.now it come in default date time format please use the conversion class

DateTime date = DateTime.Parse(Time, System.Globalization.CultureInfo.CurrentCulture);
0
Darfer10y ago
I finally came to a solution:

1. I've set the ModifiedDate property as:

[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public DateTime ModifiedDate { get; set; }

2. I created a trigger in database to update ModifiedDate:

CREATE TRIGGER [dbo].[trg_UpdateModifiedDate]
ON [dbo].[Title]
AFTER UPDATE
AS
UPDATE dbo.Title
SET ModifiedDate = GETDATE()
WHERE TitleID IN (SELECT DISTINCT TitleID FROM Inserted)

Thanks everybody for assisting me.
+1
Darfer10y ago
Hi Nitin. Unfortunately this doesn't work.
+1
Nitin Sontakke10y ago
If possible, please accept one of the replies being an answer.
+1
Darfer10y ago
Thanks Nitin. I appreciate your input.
Darfer
+1
Nitin Sontakke10y ago
Please do let me know if you need help implementing suggested solution.
+1
Darfer10y ago
Thanks both Nitin and Midhun. I'll check your suggestions.
Darfer.
+1
Nitin Sontakke10y ago
Unfortunately, I am also new to all of this. However, my logic says you can do a very simple thing.
Create a constructor (if it is allowed) and initialize that property in constructor itself.
I just came to know new syntax introduced in C# 6.0 as follows:
public DateTime ModifiedDate { get; set; } = DateTime.Now;
+1
Midhun Tp10y ago
Hi,
I don't have much knowledge about the code first approach. So I don't know the code you are using to update the table. Anyways you can give value for modifieddate column as DateTime.Nowduring the updation.
0
Darfer10y ago
Midhun, thanks for you response. Isn't there some code that could pick up the current datetime and apply it when edits are saved?
0
Midhun Tp10y ago
Hi,
As per my knowledge, the default value for a column works only during insert. Not on update. So you may need to manually pass current date to that table during update.
0