Can anyone tell where I make a mistake ? :( I want to insert a row using this. It's just not working. I also tried to use "context.SaveChanges();" but nothing changed. No insert at all, and no exception.
public List<string> Add_Address(string address, int selected_item)
{
List<string> list = new List<string>();
using(var context = new RSS_Reader_Database())
{
Address Address = new Address();
Category_Address Category_Address = new Category_Address();
Address.URL = address.ToString();
int max_id = Convert.ToInt32(context.Addresses.OrderByDescending(t => t.ID_Address).FirstOrDefault());
Category_Address.ID_Address = max_id;
Category_Address.ID_Category = selected_item+1;
var select_query = from t in context.Addresses select t.URL;
foreach (var element in select_query)
{
list.Add(element);
}
}
return list;
}
Edit: Following all Your advices, I made something that works. Looking at this code above, I have no idea what I was trying to do yesterday. Thanks a lot.
public List<string> Add_Address(string address, int selected_item)
{
List<string> list = new List<string>();
using(var context = new RSS_Reader_Database())
{
Address Address = new Address() { URL = address };
context.Addresses.Add(Address);
context.SaveChanges();
int max_id = context.Addresses.Max(u => u.ID_Address);
Category_Address Category_Address = new Category_Address() { ID_Address = max_id, ID_Category = selected_item + 1 };
context.Categories_Addresses.Add(Category_Address);
context.SaveChanges();
var query = from t in context.Addresses
select t.URL;
var data = query.ToList();
foreach (var element in data)
{
list.Add(element);
}
}
return list;
}
Saving with Entity Framework generally works like this. Using your above code as a starting point.
using(var context = new RSS_Reader_Database())
{
Address address = new Address();
// Set address properties
context.Addresses.Add(address);
context.SaveChanges();
}
You need to add the object to the DbSet<T> where T is the type of the entity that is defined on the DbContext. You then need to call SaveChanges() on the context.
I would suggest reading this. It is an easy to follow introduction to Entity Framework.
Not sure exactly what you are trying to do.
But if you are expecting to insert the data by the list.Add(element); command it won't work.
If you are planning to insert data into the same DB, you need to use one property from the context to represent the List collection add a new element on this property.
Something like:
context.Lists.Add(element);
if you want retrieve data, you should not call SaveChanges() !,
try get all values from one query like this:
List<string> select_query = (from t in context.Addresses select t.URL).ToList();
Related
The best way to get object list has just been inserted into the
database?
I have the code to add a new object list to the database, I want to retrieve the list of objects without having to select again from the database.
I expect something like insert in the SQL Server trigger.
Here is my code snippet.
List<string> productNames = new List<string>();
foreach (var name in productNames)
{
var product = new Product {Name = name, Color = "something", Body="something body" };
DbContext.Products.Add(product);
}
DbContext.SaveChanges();
var result = ListProductsInserted; // I want to get list product
I do not want to rewrite the query to retrieve data from the database
again.
Is there a better way?
If I understaood your question properly, Use code below
List<string> productNames = new List<string>();
List<Product> holdProducts = new List<Product>();
foreach (var name in productNames)
{
var product = new Product {Name = name, Color = "something", Body="something body" };
DbContext.Products.Add(product);
holdProducts.Add(product);
}
DbContext.SaveChanges();
var result = holdProducts;
The easiest way for you would be DbEntityEntry.Reload()
you can use it like this:
yourContext.Entry(yourEntity).Reload();
I am trying to access a stored procedure that retrieves a page using an id.
But I am getting an error:
Error 1 Cannot implicitly convert type
'System.Data.Entity.Core.Objects.ObjectResult<StorePageCMS.Models.mn_StorePage_Select_One_Result>' to 'StorePageCMS.Models.StorePage'
I am not sure how to fix this. The stored precedure that comes from dbEntities from SQL Server, does take an int parameter.
Any help is much appreciated.
public StorePage Get(int StorePageID)
{
using (dbEntities db = new dbEntities())
{
StorePage storepage = db.mn_StorePage_Select_One(StorePageID);
if (storepage == null)
{
throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotFound));
}
return storepage;
}
}
UPDATE
I rewrote the method this way:
public List<StorePage> Get(int StorePageID)
{
List<StorePage> storepagelist = new List<StorePage>();
using (dbEntities db = new dbEntities())
{
var results = db.mn_StorePage_Select_One(StorePageID).ToList();
foreach (var result in results)
{
var storepage = new StorePage()
{
StorePageID = result.StorePageID,
SPPreambleID = result.SPPreambleID,
Title = result.Title,
SEOTitle = result.SEOTitle,
ParentStorePageID = result.ParentStorePageID ?? -1,
Meta = result.Meta,
Image = result.Image,
ImageLink = result.ImageLink,
Blurb = result.Blurb,
RegionID = result.RegionID,
Footer = result.Footer
};
storepagelist.Add(storepage);
}
return storepagelist;
}
}
Does this looks more correct?
2 UPDATE
Does this looks correct?
If you're not using the Code First model of Entity Framework
Since StorePageCMS.Models.mn_StorePage_Select_One_Result has no conversion to StorePage, I'm assuming it's a stored procedure result. If that's a stored procedure result (of mn_StorePage_Select_One), you need to map it's result to the StorePage model instead in the EDMX designer.
Here, you'd need to say it returns a collection of StorePageCMS.Models.StorePage Entities.
I try to get all data from collection into MongoDB server using C# driver.
The idea is connect to the server and get all collection than insert into list of class.
List<WatchTblCls> wts;
List<UserCls> users;
List<SymboleCls> syms;
public WatchTbl()
{
InitializeComponent();
wts = new List<WatchTblCls>();
users = new List<UserCls>();
syms = new List<SymboleCls>();
}
public async void getAllData()
{
client = new MongoClient("mongodb://servername:27017");
database = client.GetDatabase("WatchTblDB");
collectionWatchtbl = database.GetCollection<WatchTbl>("Watchtbl");
collectionUser = database.GetCollection<UserCls>("Users");
collectionSymbole = database.GetCollection<SymboleCls>("Users");
var filter = new BsonDocument();
using (var cursor = await collectionWatchtbl.FindAsync(filter))
{
while (await cursor.MoveNextAsync())
{
var batch = cursor.Current;
foreach (var document in batch)
{
wts.Add(new WatchTblCls(document["_id"], document["userId"], document["wid"], document["name"], document["Symboles"]));
}
}
}
}
I get this error under
wts.Add(new WatchTblCls(document["_id"], document["userId"], document["wid"], document["name"], document["Symboles"]));
Cannot apply indexing with [] to an expression of type 'WatchTbl'
I don't understand the reason behind using WatchTbl and WatchTblCls both together. Is WatchTblCls a model for the entity WatchTbl here? Im not sure.
In any case. If you go for aggregation and want to convert WatchTbl collection to WatchTblCls list, your desired solution might look like the following. I don't know the defiitions of the classes so I'm assuming:
var client = new MongoClient("mongodb://servername:27017");
var database = client.GetDatabase("WatchTblDB");
var collectionWatchtbl = database.GetCollection<WatchTbl>("Watchtbl");
var collectionUser = database.GetCollection<UserCls>("Users");
var collectionSymbole = database.GetCollection<SymboleCls>("Users");
var list = collectionWatchtbl.AsQueryable().Select(x => new WatchTblCls() {
id = x.id,
userId = x.userId,
.....
});
If you can use the same WatchTbl class and still want to load the full collection to a local List (which is definitely not a good idea):
List<WatchTbl> list = await collectionWatchtbl.Find(x => true).ToListAsync();
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 method that looks like this:
private static IEnumerable<OrganizationViewModel> GetOrganizations()
{
var db = new GroveDbContext();
var results = db.Organizations.Select(org => new OrganizationViewModel
{
Id = org.OrgID,
Name = org.OrgName,
SiteCount = org.Sites.Count(),
DbSecureFileCount = 0,
DbFileCount = 0
});
return results;
}
This is returns results pretty promptly.
However, you'll notice the OrganizationViewModel has to properties which are getting set with "0". There are properties in the Organization model which I added via a partial class and decorated with [NotMapped]: UnsecureFileCount and SecureFileCount.
If I change those 0s to something useful...
DbSecureFileCount = org.SecureFileCount,
DbFileCount = org.UnsecureFileCount
... I get the "Only initializers, entity members, and entity navigation properties are supported" exception. I find this a little confusing because I don't feel I'm asking the database about them, I'm only setting properties of the view model.
However, since EF isn't listening to my argument I tried a different approach:
private static IEnumerable<OrganizationViewModel> GetOrganizations()
{
var db = new GroveDbContext();
var results = new List<OrganizationViewModel>();
foreach (var org in db.Organizations)
{
results.Add(new OrganizationViewModel
{
Id = org.OrgID,
Name = org.OrgName,
DbSecureFileCount = org.SecureFileCount,
DbFileCount = org.UnsecureFileCount,
SiteCount = org.Sites.Count()
});
}
return results;
}
Technically this gives me the correct results without an exception but it takes forever. (By "forever" I mean more than 60 seconds whereas the first version delivers results in under a second.)
Is there a way to optimize the second approach? Or is there a way to get the first approach to work?
Another option would be to load the values back as an anonymous type and the loop through those to load your viewmodel (n+1 is most likely the reason for the slowness).
For example:
var results = db.Organizations.Select(org => new
{
Id = org.OrgID,
Name = org.OrgName,
DbSecureFileCount = org.SecureFileCount,
DbFileCount = org.UnsecureFileCount,
SiteCount = org.Sites.Count()
}).ToList();
var viewmodels = results.Select( x=> new OrganizationViewModel
{
Id = x.Id,
Name = x.Name,
DbSecureFileCount = x.DbSecureFileCount,
DbFileCount = x.DbFileCount,
SiteCount = x.SiteCount
});
Sorry about the formatting; I'm typing on a phone.
You are basically lazy loading each object at each iteration of the loop, causing n+1 queries.
What you should do is bring in the entire collection into memory, and use it from there.
Sample code:
var organizationList = db.Organizations.Load();
foreach (var org in organizationList.Local)
{
//Here you are free to do whatever you want
}