I created a table with relation with ApplicationUser and when I want to get with eager-loading, I could not get all columns from that table my search base on user authentication.
var UserSites = await _SqldbContext.Users
.Where(x => x.UserName == User.Identity.Name)
.Include(x => x.sites)
.ToListAsync() ;
return Json(UserSites);
But in return I only get one row of that table with two columns
[{"sites":[{"id":1,"userId":"c0e8be95-535c-449c-9aa1-06702cd4c983"
but I have more rows with this userId and also here I get only two columns but I have more than two columns, I am not sure what is wrong here please help me.
I think ToListAsync() works properly and If you make break point you may see all data from your site but here I think Json does not show it properly, instead of start from User table in your example I started with your proposed table name sites (to get all data of this table)
var UserSites = await _SqldbContext.sites.Include(x => x.[Name Of User in relation table]).Where(y=>y.[Name Of User in relation table].UserName== User.Identity.Name)
.ToListAsync();
List<sites> siteObject=new List<sites>();
UserSites.ForEach(x =>
{
sites site = new sites() {
// fill property of your class
};
siteObject.Add(site);
});
return Json(siteObject);
I hope this code works for you.
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I recently upgraded my project to .NET Core 6 and now removing records from my look up tables is not working. I have a Risk object that has a collection of Users. Removing users from the risk object no longer works. Any ideas what I'm doing wrong?
My lookup table is called RiskItemUser, and it has two columns, RiskItemId and UserId.
Code:
var postSavedRisk = _riskService.Queryable().Include(c => c.AssignedTo).Where(w => w.Id == riskitem.Id).FirstOrDefault();
List<User> usersToRemove = postSavedRisk.AssignedTo.Where(c => userNamesToRemove.Contains(c.UserName)).ToList();
using (var db = new ApplicationDbContext())
{
var postSavedAssginedTo = db.RiskItemUser
.Where(w => w.RiskItemId == riskitem.Id)
.ToList();
foreach (var userToRemove in usersToRemove)
{
foreach (var riskAssignedTo in postSavedAssginedTo)
{
if(userToRemove.Id == riskAssignedTo.UserId)
db.RiskItemUser.Remove(riskAssignedTo);
await db.SaveChangesAsync().ConfigureAwait(false);
}
}
}
The code, as you show it, looks like it should work, although some parts are hidden. Therefore, it's hard to tell how to make it work. But there's room for simplification, which should result in working code.
You want to remove users whose names are specified by userNamesToRemove from a risk that's specified by riskitem.Id. Assuming that there's a navigation property RiskItemUser.User, removing these data could be done by essentially one line of code:
db.RiskItemUser.RemoveRange(
db.RiskItemUser.Where(ru => ru.RiskItemId == riskitem.Id
&& userNamesToRemove.Contains(ru.User.Name)));
await db.SaveChangesAsync().ConfigureAwait(false);
You tagged EFC 6, but as of EFC 7.0, there's support for bulk delete (and update) functions, allowing for single-statement deletion of multiple database records:
db.RiskItemUser
.Where(db.RiskItemUser.Where(ru => ru.RiskItemId == riskitem.Id
&& userNamesToRemove.Contains(ru.User.Name)))
.ExecuteDelete();
This will execute one delete statement, whereas the previous method will execute one statement per row.
Note that this bulk method is like executing raw SQL. There's no communication with EF's change tracker and EF can't coordinate the correct order of statements. I think the general advice should be to not mix these bulk methods with regular SaveChanges calls.
Is there a simple way to modify this code to return only records where LocationID matches the id I'm trying to pass as a parameter? Needless to say, this doesn't compile. I thought Entity Framework was meant to make things easier, but I've searched online and can't find an understandable example of how to assign a simple query where a field in a single table/entity matches a number.
public async Task<List<PC>> GetPCsAsync(int id)
{
// Get our data. Don't yet know how to feed the variable to EF/Linq
PCList = await (from p in db.PC
select new PC {p.LocationID = id}).ToListAsync();
return PCList;
}
Thanks.
And also if you want to do it using Query Syntax it would be something like this:
PCList = await (from p in db.PC
where p.LocationID == id
select p).ToListAsync();
Here's a link to understand the differences between Query and Method syntax.
var list = db.PC.Where(x=>x.LocationID == id).ToList();
for async
var listAsync = await db.PC.Where(x=>x.LocationID == id).ToListAsync();
I hope it's help you!
I have this select which I expected to be executed by sending one command to SQL Server but I can see 10s requests instead. How can I fix it?
We have Companies which have Customers and Orders. For some reasons Orders are under Company entity.
var q = _dbContext.Companies
.Include(x => x.Customers)
.Include(c => c.Orders)
.Where(a => a.CompanyId == 123);
var total = await q.CountAsync();
q = q.OrderByDescending(x => x.CompanyCode)
.Skip((pageIndex - 1) * pageSize).Take(pageSize);
var res = await q.Select(x => new ResultDto()
{
CompanyCode = x.CompanyCode,
Customers = x.Customers
.Where(c => c.IsActive)
.Select(c => new CustomerDto()
{
FirstName = c.FirstName,
Surname = c.Surname,
Orders = x.Orders
.Where(o => o.IsOpen)
.Select(o => new OrderDto()
{
DateCreated = o.DateCreated
}).ToList()
}).FirstOrDefault(),
}).ToListAsync();
This is EF.NetCore optimization.
You actually cant achieve one query when your navigation properties are collections.
I can't find any links right now, but this is by design.
Once you have a collection in your navigations inside select or inside includes it will produce a separate query for each root entity. The reason I believe is the redundant data amount produced by such a query.
I suggest leave it as is if you have not a lot of data < 1000 rows in a result. You will see a lot of queries but they will be really fast.
As I can see you have pagination here so it shouldn't be a problem.
Otherwise, select your collections separately and join them in memory carefully.
Unfortunately, there is no other way for EF Core
Also, I recommend to turn on EF core logs to what is going on early. I bet FirstOrDefault will produce some warning.
I want to assign Linq Query result to dropdownlist which contain a
Distinct function
My Code:-
var area = de.City_Area_View
.Select(m => new { m.Area_Id, m.Area_Name})
.Distinct()
.ToList();
drpfilter.DataTextField = "Area_Name";
drpfilter.DataValueField = "Area_Id";
drpfilter.DataSource = area;
drpfilter.DataBind();
Problem :- When I write this code then I get Below Error
Error:- The method 'Distinct' is not supported.
I get System.NotSupportedException.
I want to assign a Distinct name of area to the DropDownList
So please help me for this problem.
If your set is small enough (so you don't mind fetching all the values from the database), the simplest thing would be to force the distinct part to be performed locally:
var area = de.City_Area_View
.Select(m => new { m.Area_Id, m.Area_Name})
.AsEnumerable()
.Distinct()
.ToList();
AsEnumerable simply "changes" the expression type to IEnumerable<T> instead of IQueryable<T>, so that the compiler calls Enumerable.Distinct instead of Queryable.Distinct - and Enumerable.Distict will definitely work.
Normally I use stored procedures / work in SQL so apologies if I get the terminology slightly off here..
I have a database, with 3 seperate tables, and I need to search multiple fields in each of the 3 tables.
Im sure that I am not doing this the mose effective way, initially I am trying to do it in simple seteps to understand it.
I have the following;
var foo1 = entities.table1.Where(a => a.bodyText.Contains(searchString) || a.pageTitle.Contains(searchString));
var foo2 = entities.table2.Where(b => b.newsArticle.Contains(searchString) || b.newsArticle.Contains(searchString));
var foo3 = entities.table3.Where(c => c.ImageDescriptionContains(searchString));
I need to combine all these results into a single repeater for display.
At this point all 3 sets of data are in seperate, unique collections of anonymous data. So whats the best way of converting these into a single coherent bindable source?
I was thinking of itereating through each list in turn, pulling out the fields I need to display and putting them in a new class, then binding a lsit of these classes to the repeater.
But it all seems a bit clunky to me.
Is there a way of doing the search across all 3 tables in one go, and returning just the fields I need from each table, with a common name (i.e. in SQL I could write
select b.newsArticle as myText,
or
select newsArticle, ''
to return the news article and an empty string).
This would combine:
var foos = foo1.ToList();
foos.AddRange(foo2);
foos.AddRange(foo3);
To get just what you want:
var myExtractedValues = foos.Select(x => new {
Article = !string.IsNullOrEmpty(x.newsArticle))
? x.newsArticle
: string.Empty});
I have used an anonymous type here but you could swap the new {} with a type of your own.
I reverse the operator on the IsNullOrEmpty but that is just a personal preference (I prefer how is reads.)
To get all the results in one go you'll need to define a common class that will be used by all three queries to store the result. This class may be as well anonymous but I'll name it just for clarity.
class Data
{
public string Text{ get; set;}
}
Now, in your code you'll fetch instances of Data from database and you can use Union:
using( var entities = new YourDataContext)
{
var foo1 = entities.table1
.Where(a => a.bodyText.Contains(searchString) ||
a.pageTitle.Contains(searchString))
.Select(a => new Data{ Text = a.bodyText});
var foo2 = entities.table2
.Where(b => b.newsArticle.Contains(searchString) ||
b.newsArticle.Contains(searchString))
.Select(b => new Data{ Text = b.newsArticle});
var foo3 = entities.table3
.Where(c => c.ImageDescription.Contains(searchString))
.Select(c => new Data{ Text = c.ImageDescription});
return foo1.Union(foo2).Union(foo3);
}