i am trying to update a user table with a single value update, but i can't figure out what i'm doing wrong. this is what i have:
public static void ApplyROB(string ROBread, string userName)
{
using (SERTEntities ctx = CommonSERT.GetSERTContext())
{
// +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=
// Audit of the transfer
datUser trUser = new datUserRole();
trUser.ROB = ROBread;
trUser.AccountName = userName;
// Persist update to DB
ctx.SaveChanges();
}
}
am i way off? nothing happens when i click on the update.
how do i say, where username = username? did i do it right?
basically in need a simple:
update datUser set ROB = "Y" where AccountName= "myusername"
it's turning out to be a bit more complicated in LINQ using Context
please help.
You're not adding your new entity to the context, thus when you save, the context is unaware of any changes. You need something like...
ctx.datUserRoles.Add(datUserRole)
To do an update, you need to retreive an entity from the context, make changes to it, then save... so:
var entity=ctx.datUserRoles.SingleOrDefault(dur=>dur.AccountName==someUserName);
if(entity!=null)
{
entity.someProp=someVal;
ctx.SaveChanges();
}
else
{
throw new UnexpectedOperationException(); //or however you want to fail
}
If you need an update. Maybe something like this:
public static void ApplyROB(string ROBread, string userName)
{
using (SERTEntities ctx = CommonSERT.GetSERTContext())
{
var trUser= ctx.datUserRole.Where(a=>a.AccountName==userName)
.FirstOrDefault();
if(trUser!=null)
{
trUser.ROB = ROBread;
ctx.SaveChanges();
}
}
}
If you are sure that you will always have something to update you can use First(). Then you do not need to check if the trUser is null
spender is correct in a sense, incorrect in another: you want to update an existing record.
For that you'll need to select the record first, for instance:
var user =
(from u in ctx.datUserRoles
where u.AccountName == "accountname"
select u).FirstOrDefault();
Where accountname is a valid thing of the same type - that doesn't matter, since you can select it how you want, you can touch that up to meet your criteria. Then once you have the item do the stuff:
if (user != null) {
user.ROB = ROBread;
ctx.SaveChanges();
}
Related
I am trying to add an entry into a table and use the primary key of that added entry to create an additional entry into another table.
The error I am getting is
The transaction manager has disabled its support for remote/network
transactions. (Exception from HRESULT: 0x8004D024)
I believe this is caused by creating multiple connections within a single TransactionScope, but I am doing everything within one context / using statement, so I do not believe that I should be receiving this error.
Service
[OperationBehavior(TransactionScopeRequired = true)]
public void CreateGroup(NewGroupData data)
{
var groupRepo = _GroupRepo ?? new InvestigatorGroupRepository();
groupRepo.CreateGroup(data.UserId, data.InvestigatorGroupName, data.HasGameAssignment, data.InstitutionId);
}
Repository
public void CreateGroup(string userId, string investigatorGroupName, bool hasGameAssignment, int institutionId)
{
using (var context = new GameDbContext())
{
var newGroup = new InvestigatorGroup()
{
InvestigatorGroupName = investigatorGroupName,
HasGameAssignment = hasGameAssignment,
InstitutionId = institutionId,
IsTrashed = false
};
int institutionUserId =
context.InstitutionUsers.Where(
iu => !iu.IsTrashed && iu.APUser.UserId == userId && iu.InstitutionId == institutionId).Select(iu => iu.InstitutionUserId).Single();
var newGroupUser = new InvestigatorGroupUser()
{
InstitutionUserId = institutionUserId,
InvestigatorGroup = newGroup,
CreationDate = DateTime.Now
};
context.InvestigatorGroupUsers.Add(newGroupUser);
context.SaveChanges();
}
}
You start with a wrong assumption.
The line...
int newGroupId = context.InvestigatorGroups.Add(newGroup).InvestigatorGroupId;
...will always assign 0 to newGroupId. The Add method only marks the entity for insert, but doesn't actually insert it. Only SaveChanges writes data to the database, not any other method in Entity Framework.
So the assignment...
InvestigatorGroupId = newGroupId,
...is faulty as well. You have to assign the new InvestigatorGroup to a navigation property in InvestigatorGroupUser:
InvestigatorGroup = newGroup,
Add this navigation property to InvestigatorGroupUser if you haven't got it yet.
If you have that, it's enough to execute these lines:
context.InvestigatorGroupUsers.Add(newGroupUser);
context.SaveChanges();
No need to Add the newGroup object too, It will be added by adding newGroupUser.
So if you do that, the only transaction you need is the one that SaveChanges uses internally by default. For the code you show, you don't need a TransactionScope. If this is part of a greater WCF transaction the story may be different, but I think at least you needed some misconceptions to be straightened out.
Please, help me to handle this situation:
I meaningly switched off AutoDetectChangesEnabled and I load my
entities AsNoTracked() meaningly either.
And I can't update many-to-many relationship in this case:
Here is the code of Update method:
public void Update(User user)
{
var userRoleIds = user.Roles.Select(x => x.Id);
var updated = _users.Find(user.Id);
if (updated == null)
{
throw new InvalidOperationException("Can't update user that doesn't exists in database");
}
updated.Name = user.Name;
updated.LastName = user.LastName;
updated.Login = user.Login;
updated.Password = user.Password;
updated.State = user.State;
var newRoles = _roles.Where(r => userRoleIds.Contains(r.Id)).ToList();
updated.Roles.Clear();
foreach (var newRole in newRoles)
{
updated.Roles.Add(newRole);
}
_context.Entry(updated).State = EntityState.Modified;
}
All simple fields, like Name, LastName updated. But the set
of Roles for User doesn't get updated - it stays the same.
I tried loading Roles using
_context.Entry(updated).Collection("Roles").Load();
But I can't update this loaded set in any way.
I searched for similar items but failed to find the answer, thought it definitely already exists.
I'm really sorry for possible dublicate.
PS. I want to add that I don't want to delete or update child entities at all.
A lot of existing answers suggest manually delete / add child entities to database in whole, but it is not suitable for me.
Roles are independent entities, any other user can use them.
I just want to update User_Role table in database, but I can't.
How I can do just this ( a.myFavorits.Add()) without pulling the all object to var a , because a has a lot of data, and I don't want to pull all a object, but I can't find a way do do it.
I want to do the lambada and the linq without return something but linq is always return something
public static void addFavorits(long f,long idUser)
{
using (var db = dataBase())
{
// here i pull object user from users table
var a = db.users.Where(c => c.id == idUser).SingleOrDefault();
// here i adding to the object field myFavorits new value
//myFavorits is also a table of entitys that connected to user object
a.myFavorits.Add(new BE.FavoritsUsersLong { myLong = f });
db.SaveChanges();
}
}
I thought to do something like this but i dont know how to set the field users_TableId that is the key that connect the 2 tables
public static void addFavorits(long favoritId,long idUser)
{
using (var db = dataBase())
{
db.favoritsUsersLong.Add(new BE.FavoritsUsersLong {myLong = favoritId}
/*,users_TableId =idUser*/);
db.SaveChanges();
}
}
Here's a concrete example that does what you want. In this example, only the Name of a Company is modified and saved. Or an item is added to one of its collections.
var cmp = new Company{ CmpId = 1, Name = "Cmp1" }; // CmpId is the primary key
db.Companies.Attach(cmp);
db.Entry(cmp).Property(c => c.Name).IsModified = true;
// Or add an entity to a collection:
cmp.Users = new[] {new User { Name = "a1", PassWord = "a1" } };
try
{
db.Configuration.ValidateOnSaveEnabled = false;
db.SaveChanges();
}
finally
{
db.Configuration.ValidateOnSaveEnabled = true;
}
Result in SQL:
DECLARE #0 VarChar(30) = 'Cmp1'
DECLARE #1 Int = 1
UPDATE [dbo].[Company]
SET [Name] = #0
WHERE ([CmpId] = #1)
There are a few things to note here:
Obviously you need to know the Id of the entity you want to modify.
The object you create is called a stub entity, which is an incomplete entity. When you try to save such an entity, EF is very likely to complain about null values in required properties. That's why almost certain you'd have to disable validation (temporarily, or, better, dispose the context immediately).
If you want to add an item to a collection, you should leave validation enabled, because you'd want to know for sure that the new entity is valid. So you shouldn't mix these two ways to use a stub entity.
If you often need roughly the same small part of your entity you may consider table splitting.
I'm guessing this is what you want? I don't see you 'editting' I only see you adding.
using (var db = dataBase())
{
var a = new user();
....
//set properties etc..
...
a.myFavorits.Add(new BE.FavoritsUsersLong { myLong = f });
db.users.Add(a);
db.SaveChanges();
}
I have users table with generated LINQ-class with followed structure:
class User {
int Id;
string Login;
string Password;
string Mail;
...
Now I need to update specified columns (for ex. only Login and Password) and because I don't want to overwrite other fields, my code looks like this:
public User UpdateUser(int userId, User newUser)
{
User user = (from u in _context.Users
where u.Id == userId
select u).FirstOrDefault();
if (newUser.Login != default(string)) user.Login = newUser.Login;
if (newUser.Mail != default(string)) user.Mail = newUser.Mail;
if (newUser.Password != default(string)) user.Password = newUser.Password;
...
_context.SubmitChanges();
return user;
}
And call it like this:
var user = new User { Password = "123" };
UpdateUser(123, user);
For each field I need to write IF statement and I thinking that I doing something wrong. Also because I am using comparsion with default(string) I cannot set empty values to rows.
Please, tell me, what is right way to do this?
P.S.: Please, sorry for my bad English.
You are misusing LINQ 2 SQL. You shouldn't even have a generic UpdateUser method because you don't need it. If you want to write a certain field of an entity, just do it:
var user = GetUser(userId);
user.Password = "123";
And you're done. When you have made all changes to the object model, call SubmitChanges at the end. It is not necessary to call it after each mutation.
You are using LINQ 2 SQL as a CRUD repository but it is not meant to be one. It is meant to give you a live object model that you can treat like normal C# objects. In the end you synchronize with the database by calling SubmitChanges.
This is possible just with SubmitChanges:
This gets the user:
var user=context.User.Where(m=>m.id == "xyz").FirstOrDefault();
This updates the above user:
user.Password = "xyz";
context.User.SubmitChanges();
I think you are looking into the wrong way for optimization. An update command on single column isn't much different than on every other column than PK. Your validation logics might take more time to process than your optimized update command.
However if it is always the password that needs to be updated, you can do it this way :
public User ChangePassword(int userId, string password)
{
var user = new User() { Id = userId };
_context.Users.Attach(user);
user.Password = password;
_context.SaveChanges();
return user;
}
Im want to delete rows from a table that in my data base.
i have the member
private static WeightScaleEntities Weight = new Weight();
this member contains my database. in the data base i have table: User_Activity.
I want to delete rows from user activity by given i_UserActivityId, as follow:
//Get the rows for delete
var deleteUserActivities = from details in Weight.User_Activity
where details.Id == i_UserActivityId
select details;
Now i want to delete this rows, so i tried to do:
foreach (var item in deleteUserActivities)
{
m_WeightScaleEntities.User_Activity.*
}
and i dont get the method DeleteOnSubmit!
Why?
there is another option???
User_Activity.*: is that a typo?
What I think you want is:
foreach (var item in deleteUserActivities)
{
Weight.DeleteObject(item);
}
And then SaveChanges() on the object context.
BTW, a static object context is not a good idea. You should carefully control the life cycle of object contexts.
There is more than one way to execute deletion in Entity Framework,
You must take into account what are the values that you want to delete? one Row or more.
when you need to delete on Row from table we can use these ways:
// first way
using (WeightScaleEntities db = new WeightScaleEntities())
{
var deleteUserActivities = from details in db.User_Activity
where details.Id == i_UserActivityId
select details;
if (deleteUserActivities.Count() > 0)
{
db.deleteUserActivities.Remove(deleteUserActivities.First());
db.SaveChanges();
}
}
this line deleteUserActivities.Count()>0 to check if you have result in the Query or not.
and this deleteUserActivities.First() if the query return set of rows delete the first. "to make the process more secure if you don't know about the data in the table"
// second way
using (WeightScaleEntities db = new WeightScaleEntities())
{
var deleteUserActivities = (from details in db.User_Activity
where details.Id == i_UserActivityId
select details).SingleOrDefault();
if (deleteUserActivities != null)
{
db.User_Activity.Remove(deleteUserActivities);
// or use this line
//db.Entry(deleteUserActivities).State = System.Data.Entity.EntityState.Deleted;
db.SaveChanges();
}
}
You can also use Single or SingleOrDefault to get a single object. Single or SingleOrDefault will throw an exception, if the result contains more than one element. Use Single or SingleOrDefault where you are sure that the result would contain only one element. If the result has multiple elements then there must be some problem.
Also, if you need to remove one or multi rows use this way:
using (WeightScaleEntities db = new WeightScaleEntities())
{
var deleteUserActivities = (from details in db.User_Activity
where details.Id == i_UserActivityId
select details).ToList<User_Activity>(); //<User_Activity> her name of your DbSet
foreach(deleteObject in deleteUserActivities)
{
db.Entry(deleteObject).State = System.Data.Entity.EntityState.Deleted;
}
db.SaveChanges();
}
Best Regards
and sorry about English language.
using(WeightScaleEntities db=new WeightScaleEntities())
{
var deleteUserActivities = from details in db.User_Activity
where details.Id == i_UserActivityId
select details;
if (deleteUserActivities.Count()>0)
{
db.deleteUserActivities.Remove(deleteUserActivities.First());
db.SaveChanges();
}
}