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VB.NET - LINQ - dbContext - Where - Letter is not declared error. Trying to update single record


VB.NET - LINQ - dbContext - Where - Letter is not declared error. Trying to update single record

By : user2949031
Date : November 15 2020, 06:54 AM
may help you . I'm in the process of writing an update code to update user information on an asset used for a project I have. The code is below... , >= is a comparison operator.
To create a lambda in VB, write
code :
Function(c) c....


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LINQ .OrderBy single letter then by another letter

LINQ .OrderBy single letter then by another letter


By : user2129705
Date : March 29 2020, 07:55 AM
I wish this help you If you only have those distinct values in the field, then you can just use a dictionary to translate the strings into suitable numbers, like this:
code :
var order = new Dictionary<string, int>();
order.Add("S", 0);
order.Add("P", 1);
order.Add("NB", 2);
order.Add("V", 3);
order.Add("Nc", 4);
repeater.DataSource = query.OrderBy(p => order[p.Title]);
repeater.DataSource = query.ToList().OrderBy(p => order[p.Title]);
How to update LINQ-to-SQL Single XML Record?

How to update LINQ-to-SQL Single XML Record?


By : user3753970
Date : March 29 2020, 07:55 AM
Does that help This won't work because you aren't changing the instance that you retrieve from the database. You are creating a new object using the values from the original - twice - and then changing it. The LINQ-to-SQL context has no knowledge that you're changing database rows, just some unrelated XML that you've constructed.
Firstly, the value you retrieve from the database is being put into an XElement
code :
XmlData = XElement.Parse(i.XML)
select new FormItem 
{         
    FormId = i.Id,         
    DateTimeCompleted = i.XmlData.Element("DateTimeCompleted").Value     
} 
// just get the item
var userForm = (
    from i in dataContext.RequestFormItems
    join c in dataContext.RequestFormInstances on i.TypeGuid equals c.TypeGuid
    where i.Id == FormID
    select i).FirstOrDefault();

// parse the XML
var xml = XElement.Parse(userForm.XML);

RFDateTimeCompleted = xml.Element("DateTimeCompleted").Value;
xml.Element("DateTimeCompleted").Value = "New Data";

// and finally, because you're again just changing XML 
// unrelated to the context, update the original object
userForm.XML = xml.ToString();
context.SubmitChanges();
Why can I not update a record with dbContext?

Why can I not update a record with dbContext?


By : Calvin
Date : March 29 2020, 07:55 AM
this will help Because Entity Framework uses change tracking (by default...but you can switch it off using different MergeOptions), you cannot attach two entities with the same key (in the same context).
So, you either have to detach the old object first, or simple do not attach the new one (since the change tracker is already doing this job for you).
Why are type variables for generics commonly declared as a single letter (e.g.: <T>)?

Why are type variables for generics commonly declared as a single letter (e.g.: <T>)?


By : Quen Không
Date : March 29 2020, 07:55 AM
help you fix your problem The Java docs for Generics Types has a really good paragraph about this - and it applies to all languages that supports type variables:
Type Parameter Naming Conventions
With linq, do you create a single dbContext per request like nHibernate requires?

With linq, do you create a single dbContext per request like nHibernate requires?


By : vivek
Date : March 29 2020, 07:55 AM
Does that help DataContexts are intended to be used for a single set of actions interacting with your database. I know, that's vague. Their usage is situational. If you are doing related, or specifically sequential activities, then one DataContext is probably good for you. If you are doing unrelated or parallel activities, consider using a DataContext for each activity.
Consider a few guidelines:
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