Cannot add an entity that already exists. (LINQ to SQL) - vb.net

in my database there are 3 tables
CustomerType
CusID
EventType
EventTypeID
CustomerEventType
CusID
EventTypeID
alt text http://img706.imageshack.us/img706/8806/inserevent.jpg
Dim db = new CustomerEventDataContext
Dim newEvent = new EventType
newEvent.EventTypeID = txtEventID.text
db.EventType.InsertOnSubmit(newEvent)
db.SubmitChanges()
'To select the last ID of event'
Dim lastEventID = (from e in db.EventType Select e.EventTypeID Order By EventTypeID Descending).first()
Dim chkbx As CheckBoxList = CType(form1.FindControl("CheckBoxList1"), CheckBoxList)
Dim newCustomerEventType = New CustomerEventType
Dim i As Integer
For i = 0 To chkbx.Items.Count - 1 Step i + 1
If (chkbx.Items(i).Selected) Then
newCustomerEventType.INTEVENTTYPEID = lastEventID
newCustomerEventType.INTSTUDENTTYPEID = chkbxStudentType.Items(i).Value
db.CustomerEventType.InsertOnSubmit(newCustomerEventType)
db.SubmitChanges()
End If
Next
It works fine when I checked only 1 Single ID of CustomerEventType from CheckBoxList1. It inserts data into EventType with ID 1 and CustomerEventType ID 1. However, when I checked both of them, the error message said
Cannot add an entity that already exists.
Any suggestions please? Thx in advance.

Did you change the EventID before you pressed the button again. To me it looks as you did not. This would result that the code tries to insert the event with the ID 1 into the database, although, it is already there.
Maybe try increasing the event ID automatically or check whether the event is alreay present before trying to insert it.
Edit:
OK, here is what I think you want to do ... if I understood it correctly (it's in C# as I am more fluent in that language - however you should be able to easily convert the algorithm to VB - so just take it as pseudo code):
var db = new CustomerEventDataContext();
var newEvent = db.EventTypeSingleOrDefault(x => x.EventTypeId == txtEventID.Text);
if (newEvent != null) {
newEvent = new EventType();
newEvent.EventTypeId = txtEventID.Text;
db.EventType.InsertOnSubmit();
}
var chkbx = (CheckBoxList) form1.FindControl("CheckBoxList1");
for (int i = 0; i < chkbx.Items.Count; i++) {
var value = chkbxStudentType.Items(i).Value;
if (db.CustomerEventTypes.SingleOrDefault(x => x.EventTypeId == newEvent.EventTypeId) != null) {
// item already exists
} else {
var newCustomerEventType = new CustomerEventType();
newCustomerEventType.INTEVENTTYPEID = newEvent.EventTypeId;
newCustomerEventType.INTSTUDENTTYPEID = value;
db.CustomerEventType.InsertOnSubmit(newCustomerEventType);
}
}
db.SubmitChanges();
Two things I noticed:
You were adding the new EventType and then selecting the last event type based upon the id. This may not result in the item you just added.
You do not have to call SubmitChanges after each InsertOnSubmit. The DataBaseContext implementaton holds the inserted objects for you and you can reference them. Then you do a single submit to commit all changes. Note, however, in some complex circumstances a separate SubmitChanges is necessary, but this is rarely the case.

Related

Unable to set date values in SAP B1 matrix combobox

I am trying to set values in a matrix combobox but I cannot be able to set the first value of date to that combobox. It shows blank and when I select a date, it does not fill the field anyway.
The values I get from the DB are as follows:
Here is my code below including binding the combobox field to a userdatasource:
_expDate = _form.DataSources.UserDataSources.Add("iV_15", SAPbouiCOM.BoDataType.dt_DATE, 100);
oIColumns = oIMatrix.Columns;
_colExpDate = oIColumns.Item("iV_15");
_colExpDate.DataBind.SetBound(true, "", "iV_15");
The below code runs when there is a lost focus change event to the item selection field:
#region Item Change Event Expiry dates
_cmbExpDate = (SAPbouiCOM.ComboBox)oIMatrix.Columns.Item("iV_15").Cells.Item(pVal.Row).Specific;
int count = _cmbExpDate.ValidValues.Count;
if (count > 0)
{
_expDate.ValueEx = "";
for (int j = 0; j <= count - 1; j++)
_cmbExpDate.ValidValues.Remove(0, SAPbouiCOM.BoSearchKey.psk_Index);
}
var expDates = (from oi in _db.OITMs
join ob in _db.OBTNs
on oi.ItemCode equals ob.ItemCode
where ob.ItemCode == _itemNo.ValueEx && oi.OnHand > 0
orderby ob.ExpDate
select new
{
ExpDate = ob.ExpDate
}).Distinct().ToList();
if (expDates.Count > 0)
{
foreach (var item in expDates)
_cmbExpDate.ValidValues.Add(item.ExpDate?.ToString(), item.ExpDate?.ToString());
_cmbExpDate.Select(0, SAPbouiCOM.BoSearchKey.psk_Index);
_expDate.ValueEx = _cmbExpDate.Value;
}
#endregion
What could be wrong. Is there a better way to achieve what I need in SAP B1?
as a test try a different data type for your:
_expDate = _form.DataSources.UserDataSources.Add("iV_15", SAPbouiCOM.BoDataType.dt_DATE, 100);
test it with: SAPbouiCOM.BoDataType.dt_LONG_TEXT
you can also try just selecting the value on the combo, instead of setting uds as well.

Getting original object from Entity Framework SaveChanges function?

For auditing reasons I am overriding the SaveChanges function. However, I want to capture to original and current values as the original object (i.e person) so that I can serialize both the before and after.
Public Overrides Function SaveChanges() As Integer
ChangeTracker.DetectChanges()
Dim ctx As ObjectContext = DirectCast(Me, IObjectContextAdapter).ObjectContext
Dim objectStateEntryList As List(Of ObjectStateEntry) = ctx.ObjectStateManager.
GetObjectStateEntries(EntityState.Added Or EntityState.Modified Or EntityState.Deleted).ToList()
For Each ent As ObjectStateEntry In objectStateEntryList
If Not ent.IsRelationship Then
Dim objectType As Type = ObjectContext.GetObjectType(ent.Entity.GetType)
Dim audit As New Audit With {
.ObjectId = ent.EntityKey.EntityKeyValues.First.Value,
.ObjectType = ObjectContext.GetObjectType(ent.Entity.GetType).Name,
.User = (From u In Users Where u.Username = My.User.Name).First
}
With audit
Select Case ent.State
Case EntityState.Added
.Action = "Created"
.Detail = "Record created"
Case EntityState.Deleted
.Action = "Deleted"
.Detail = "Record deleted"
Case EntityState.Modified
Dim newObj As String = SerializeToString(
Convert.ChangeType(ent.Entity, objectType)
)
.Action = "Modified"
.Detail = newObj.ToString
End Select
End With
End If
Next
Return MyBase.SaveChanges()
End Function
That's how far I got, but when I try and ChangeType it throws "Object must implement IConvertible".
The last time I worked on a project that absolutely needed to track every change, we used a history table and an ON UPDATE trigger. Changing data would fire the trigger, which would then copy the original row into the history table.
This is 100% EF compatible, but you need to set it up separately for each table.
This doesn't exactly answer your main question but may help you to improve your auditing.
Disclaimer: I'm the owner of the project Entity Framework Plus
I recommend you to look at our EF+ Audit Feature, all auditing information can be easily retrieved using this library.
// using Z.EntityFramework.Plus; // Don't forget to include this.
var ctx = new EntityContext();
// ... ctx changes ...
var audit = new Audit();
audit.CreatedBy = "ZZZ Projects"; // Optional
ctx.SaveChanges(audit);
// Access to all auditing information
var entries = audit.Entries;
foreach(var entry in entries)
{
foreach(var property in entry.Properties)
{
}
}
// CALL your serializer here
SerializeToString(entries, ...);
The code is Open Source.

Attributes of tables in VS by coding with C#

I have this table:
Please, don't mind because it's on my native language and it doesn't matter..
Those are all attributes in table but when I go to Visual StudioS and try to use some of this I get this one:
I see all "normal" attributes in VS but where is those FK attributes?
I need them to compare few ones and get values?
I can't use it from name of other tables [dot] attribute etc...
like for example:
I need this: table1.ID == table2.ID
and not this: table1.ID == table1.table2.ID
Where or what is FK attribute in VS that is shown in SQL table ??
public void setParametri(int desID)
{
foreach (desavanje d in DM_Class.dc.desavanje)
if (d.desavanjeID == desID)
{
//THIS FIRST 4 LINES WORKS PERFECTLY
this.naziv_des = d.naziv_des;
this.datum_po = d.datum_pocetka.ToString();
this.datum_zav = d.datum_kraja.ToString();
this.cijena = d.cijena_des;
//foreach (klijenti k in DM_Class.dc.klijenti)
//{
// if(k.klijentID == //WHAT TO PUT HERE TO COMPARE VALUE klijentID from tables klijenti with FK value in table desavanje)
// this.klijent = k.Ime + ' ' + k.Prezime;
//}
//ON THIS LINE I'M GETTING ERROR - Object reference not set to an instance of an object. but why?
//I have data on that field in DB ?
//this.grad = d.mjesto_desavanja.gradovi.naziv_grada.ToString();
//this.mjesto = d.mjesto_desavanja.naziv_objekta;
//this.organizator = d.organizator.Ime + ' ' + d.organizator.Prezime;
//this.tip = d.tip_desavanja.vrsta_des;
this.klijent = d.klijenti.Ime + ' ' + d.klijenti.Prezime;
//this.status = d.status_desavanja.naziv_statusa;
//this.br_gost = d.specifikacija_desavanja.br_osoba;
}
}
If is there other solution to get values for attributes I'm willing to try it without using another foreach loop?
Ok, I managed this.. I've used a linq query to generate data that I need and in that queries I've compared needed ID's and finally get some working stuff.

How do I return the column names of a LINQ entity

I am using LINQ to SQL queries to return data in my application. However I find it is now needful for me to return the column Names. Try as I might I have been completely unable to find out how to do this on the internet.
So if my LINQ entity table has the properties (Last_Name, First_name, Middle_Name) I need to return:
Last_name
First_Name
Middle_name
rather than the usual
Smith
John
Joe
You could certainly do it with some LINQ-To-Xml directly against the ".edmx" file or the embedded model resources in the compiled assembly.
The below query gets the field (not column) names. If you need the columns then just change the query to suit.
var edmxNS = XNamespace.Get(#"http://schemas.microsoft.com/ado/2007/06/edmx");
var schemaNS = XNamespace.Get(#"http://schemas.microsoft.com/ado/2006/04/edm");
var xd = XDocument.Load(#"{path}\Model.edmx");
var fields =
from e in xd
.Elements(edmxNS + "Edmx")
.Elements(edmxNS + "Runtime")
.Elements(edmxNS + "ConceptualModels")
.Elements(schemaNS + "Schema")
.Elements(schemaNS + "EntityType")
from p in e
.Elements(schemaNS + "Property")
select new
{
Entity = e.Attribute("Name").Value,
Member = p.Attribute("Name").Value,
Type = p.Attribute("Type").Value,
Nullable = bool.Parse(p.Attribute("Nullable").Value),
};
Lets assume you're talking about the Contact Table in the assembly named YourAssembly in a Context called MyDataContext
Using Reflection against a Table
You can use reflection to get the properties like you would any type
var properties = from property in
Type.GetType("YourAssembly.Contact").GetProperties()
select property.Name
;
foreach (var property in properties)
Console.WriteLine(property);
As shaunmartin notes this will return all properties not just Column Mapped ones. It should also be noted that this will return Public properties only. You'd need to include a BindingFlags value for the bindingAttr Parameter of GetProperties to get non-public properties
Using the Meta Model
You can use the Meta Model System.Data.Linq.Mapping to get the fields ( I added IsPersistant to only get the Column Mapped properties)
AttributeMappingSource mappping = new System.Data.Linq.Mapping.AttributeMappingSource();
var model = mappping.GetModel(typeof (MyDataContext));
var table = model.GetTable(typeof (Contact));
var qFields= from fields in table.RowType.DataMembers
where fields.IsPersistent == true
select fields;
foreach (var field in qFields)
Console.WriteLine(field.Name);
Using Reflection from a query result
If on the other hand you wanted it from a query result you can still use reflection.
MyDataContextdc = new MyDataContext();
Table<Contact> contacts = dc.GetTable<Contact>();
var q = from c in contacts
select new
{
c.FirstName,
c.LastName
};
var columns = q.First();
var properties = (from property in columns.GetType().GetProperties()
select property.Name).ToList();
I stumbled upon this answer to solve my own problem and used Conrad Frix 's answer. The question specified VB.NET though and that is what I program in. Here are Conrad's answers in VB.NET (they may not be a perfect translation, but they work):
Example 1
Dim PropertyNames1 = From Prprt In Type.GetType("LocalDB.tlbMeter").GetProperties()
Select Prprt.Name
Example 2
Dim LocalDB2 As New LocalDBDataContext
Dim bsmappping As New System.Data.Linq.Mapping.AttributeMappingSource()
Dim bsmodel = bsmappping.GetModel(LocalDB2.GetType())
Dim bstable = bsmodel.GetTable(LocalDB.tblMeters.GetType())
Dim PropertyNames2 As IQueryable(Of String) = From fields In bstable.RowType.DataMembers
Where fields.IsPersistent = True
Select fields.Member.Name 'IsPersistant to only get the Column Mapped properties
Example 3
Dim LocalDB3 As New LocalDBDataContext
Dim qMeters = From mtr In LocalDB3.tblMeters
Select mtr
Dim FirstResult As tblMeter = qMeters.First()
Dim PropertyNames3 As List(Of String) = From FN In FirstResult.GetType().GetProperties()
Select FN.Name.ToList()
To display the results:
For Each FieldName In PropertyNames1
Console.WriteLine(FieldName)
Next
For Each FieldName In PropertyNames2
Console.WriteLine(FieldName)
Next
For Each FieldName In PropertyNames3
Console.WriteLine(FieldName)
Next
Please also read Conrad's answer for notes on each method!

NHibernate query count

I am new to NHibernate and I want to have a count of rows from database. Below is my code,
SearchTemplate template = new SearchTemplate();
template.Criteria = DetachedCriteria.For(typeof(hotel));
template.Criteria.Add(Restrictions.Lt("CheckOutDate", SelDate) || Restrictions.Eq("CheckOutDate", SelDate));
template.Criteria.Add(Restrictions.Eq("Canceled", "False"));
int count = template.Criteria.SetProjection(Projections.Count("ID"));
It gives me an error when I try to compile app that says
"Cannot implicitly convert type 'NHibernate.Criterion.DetachedCriteria' to 'int'"
I want to have a count of rows of the table hotel..
You want to use GetExecutableCriteria:
SearchTemplate template = new SearchTemplate();
template.Criteria = DetachedCriteria.For(typeof(hotel));
template.Criteria.Add(Restrictions.Lt("CheckOutDate", SelDate) || Restrictions.Eq("CheckOutDate", SelDate));
template.Criteria.Add(Restrictions.Eq("Canceled", "False"));
var count = DoCount(template.Criteria, session /* your session */);
public long DoCount(DetachedCriteria criteria, ISession session)
{
return Convert.ToInt64(criteria.GetExecutableCriteria(session)
.SetProjection(Projections.RowCountInt64())
.UniqueResult());
}
On a side note, you should take a look at using NHibernate.Linq:
var result = (from h in Session.Linq<Hotel>()
where h.CheckOutDate <= SelDate
where h.Canceled != true
select h).Count();
More information here.