With ASP.Net 4, is there any way that we can bind web-form controls to entity framework objects?
<asp:TextBox ID="UserName" runat="server" BoundTo="UserName" BindingSource="..."></asp:TextBox>
so just like in MVC I can
form.UpdateModel(userObj),
form.DisplayModel(userObj)
with asp.net 4, is there any way that we can automatically bind web controls (textbox, listbox, check, etc), to EF4 Objects?
View 2 Replieshave some Objects, lets say Employee and Role defined as below and I have defined relationships in my database that gives me a list of objects say employees and thanks to my framework each employee object also has a Role object linked via the RoleIDID, UserName, Password, Email, RoleIDRoleID, RoleNameSo in code I can do something like this
Employee emp = dataService_GetEmployeeByID(1);
string RoleName = emp.Role.RoleName;
Now here is my problemI can bind any object in a repeater and it works fine for the first level in my relationship
For instance <%# Eval("UserName") %>
But I need to be able to show the details for my child objects as well (Role) so something like this (which does not work)
<%# Eval("Role.RoleName") %>
I know how to bind a simple objects to a dropdown list. However I am having problems binding my objects which contains sub objects to the control.i.e. with simple object i just do ddl.DataValueField = "myproperty"
with my objects they contains sub objects which i want to bind. I have tried ddl.DataValueField = "sub-object.myproperty" which doesnt work.
I have been reading alot about this and for some reason I am just not able to grasp the concept. Hopefully someone here can enlighten me.As an example situation I have a collection of strongly typed User objects that represent a database table, and some properties that represent its columns: UserID(PK), Username,FirstName,LastName, etc..Here are some of my requirements/goals:1. Users/Objects needs to be bound to the gridview programatically.2. I do not want to update the database right away, I only want the underlying collection to be updated. I would like to call the database update method myself when I am ready.
3. I do not want the primary key stored on the client side.Summary:So I bind a List<Users> to a gridview with the appropriate bound fields set up, I exlude bound fields such as primary key because I don't want it being changed/hacked by the client side. When I edit and update a row it is saved back to the collection of objects. I will iterate through the objects manually at a later time and commit them to database.
Questions:1. Can I cast a gridview row directly back to my object, in the RowUpdating or RowUpdated events? I am assuming I can't... So....2. How can I reference back my original collection if the gridview does not contain a primary key?3. Where do I store my collection, should it be in Session or should I recreate it on each postback?Sorry if any of this is confusing, let me know if you need clarification.
I have a form which I use to create an issue. WHen you post the form, the form elements are that of a custom DTO. The DTO is then used on my POST method to create the new entity. That all works fine.
However, I want to add the functionality to add multiple issues at the same time from the same view. In effect, the user would click something like 'Report Additional Problem', and an extra set of form fields would appear (I will like use jquery for this, which I don't have an issue with). However, even with just leaving one set of form fields, the user should still be able to create just one issue. But if I habve my post method take a list or array of my DTO, it doesn't work.
Here is the post method before editing:
[Code]....
What I want to do is for this to take an array or list of NewIssueDto. I would then loop through each one in the list and create a new issue from it.
How can I bind an object to a dropdown list or gridview ? I am writing an application where my code behind calls an instance and bind the list to either dropdown or gridview.For example:
.aspx page: default.aspx
<asp:dropdownlist id="dd1" runat="server" />
Code Behind: default.VB
[code]...
I have a class that returns a list of "Category" Objects. I'd like to display them along the left-hand side of the page in a listview (if that's the best way to do it, even).
The category objects have normal attributes. Title, User, NumberOfProjects. I'd like to display both the title and the number of projects in this list.
Not worried about editability right now as we might make that separate (i.e. not in-line in a list view edit mode).
I have a List of complex objects containing other objects within that I give as the data source to a gridview.(currently I'm using BoundFields for the columns). I need to bind data to the columns from the objects within at run time. How can this be done?
View 1 RepliesI got a problem when getting some data out of my EntityFramework using Linq
Heres my code
[Code]....
Heres the ClientViewModel :
[Code]....
As you can se in the ClientViewModel the Users property is a List
But when trying to compile I get a error saying
Cannot implicitly convert type 'AdminMVC.Models.Clients_Username' to 'System.Collections.Generic.List<AdminMVC.Models.Clients_Username>'
I am having some issues with my base class inheritance. I am currently employing Table per Type Inheritance for the following tables:
Database:
Members Table
- Member ID (PK)
- First Name
- Last Name
- Email
- ...
Students Table
- Member ID (FK)
- Credits
- Notes
- ...
Instructors Table
- Member ID (FK)
- Biography
- Office Hours
- ...
My Entity Data Model defines "Member" as the base class for both Students and Instructors, since members can be both students as well as instructors simultaneously. The problem, however, occurs when I attempt to get a list of Members objects. Because the database contains members who are indeed students AND instructors, the following exception is thrown:
All objects in the EntitySet 'CountyCollegeEntities.BaseMembers' must have unique primary keys. However, an instance of type 'CountyCollege.NET.Administrator' and an instance of type 'CountyCollege.NET.Student' both have the same primary key value, 'EntitySet=BaseMembers;ID=10016'.
I am beginning to think that I made a mistake by building these classes to inherit from Member although it has been ideal up until this point. But before I start ripping up all my existing code to remove this inheritance, I thought I would see if anyone has any tricks that would make this work. Any advice as to either how I can get around this error or a more appropriate way to structure my classes would be very much appreciated.
Cannot seem to find a good fit for my question so I will ask here.
Does Asp.Net 4.0 solve the problems with using Views with EntityFramework is not able to recognize primary keys.
I am using a server control on a single web.forms page. I have to use this control on a web.forms page since its a server control, although this is actually a MVC project. So I created a web.forms folder and put my new page in it. I then copy the example code from the signature control. I get the following error:
The base class includes the field 'ctrlSign', but its type (WebSignatureCapture.SignatureControl) is not compatible with the type of control (ASP.signaturecapture_signaturecontrol_ctlsignature_ascx).
I know the code works because if I removed the ID attribute from the server control, it no longer gives me this error and my control renders. But I need the attribute for the ID so I can perform is post event
I am using this signature control. Here's the web.forms code...
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Index.aspx.cs" Inherits="KahunaCentralTIDRevamp.SignatureCapture.Index" %> [code]....
I have Create and Edit forms for Categories. Columns are Id, CategoryName, Order, CreatedOn. On Create form I save the values for all but on Edit form I need to change only CategoryName. Below is the code. Problem is that on Edit form only CategoryName field exists which on submit button is passed to Edit Action. Whenever I update Order and CreatedOn becomes null because the values are not returned from form. Someone tell me any good approach how to Updated selected values in EF. Below is code.
Making multiple Get calls. Form is saving fine but I don't like the approach. Need clean approach. Anyone got better solution to thiis?
[Code]....
I am working on my first project with the Entity Framework and am having some difficulty displaying advanced information with the EntityDataSource and a ListView.
For example, given the two entities:
Item
Name
Price
Order
Number
Items <---- Navigation Property to Items contained in the Order
I want to display a list of all orders with a column with the total number of items in the order and a column with the sum of the prices of all items in the order.
I am using an EntityDataSource configured as follows:
<asp:EntityDataSource ID="eds" runat="server" ConnectionString="name=NDSEntities"
DefaultContainerName="NDSEntities" EnableFlattening="False" Include="Items"
EntitySetName="Orders"></asp:EntityDataSource>
In the ItemTemplate of the ListView, I can write the order number as follows:
<%# Eval("Number") %>
I had trouble figuring out how to display a count of items in the order. I tried using Items.Count() function in select statement in the EntityDataSource but that didn't work. Eventually I figured out I could do the following in my ItemTemplate:
<%# Eval("Items").Count() %>
Now I am stuck trying to get the sum of the items. I am stuck here. I have tried using
<%# Eval("Items").Sum(Function(i) i.Price)%>
but I get the following error:
Public member 'Sum' on type 'EntityCollection(Of Item)' not found.
This confuses me because I know that Sum is a method of EntityCollection(Of ).
My two questions are as follows:
Am I getting the item count correctly?
How should I go about getting the sum of the prices of the items?
Im tring to implement some generic logging in the entityframework 4.0 using the SavingChanges event in the entity context.
I want to record details about any create/ update and deleted records including the id of the record being changed (which is always an int identity field). During the update and delete processes I can get the id for the record using
Dim AddedItems = Statemanager.GetObjectStateEntries(EntityState.Added)
For Each entry As ObjectStateEntry In DirectCast(sender, ObjectContext).ObjectStateManager.GetObjectStateEntries(EntityState.Added)
NewLogItem.RecordId = CInt(entry.EntityKey.EntityKeyValues(0).Value.ToString())
Next
But I obviously cannot get the id of the about to be inserted record during an insert becuase it hasn't been written to the database yet, is there a simple way around this?
firstly a static class only ever exists once and is not an instance. Any static members (ie static int NoOfPeople;) is stored in one place and is shared between all sessions (like the old global variables).
Now static methods is where i'm not 100% sure. If I have a static method that doesn't use any other static members could this cause inconstant results, example (this is a fairly pointless method but just a quick example of the top of my head)
[Code]....
So in this example if two sessions (or threads) were to call this at the same time - would they both get back the expected results, because the method only uses private data (a, b and totalToReturn).Im sure this sounds a little simple but I will be using static methods to build user objects and various other objects that there will have to be a 100% garentee that the objects will not get mixed up between sessions and the wrong things return to the user.
SaveChanges can generate an UpdateException when an object added to the ObjectContext cannot be successfully created in the data source. This can happen if a row with the foreign key specified by the relationship already exists. When this occurs, you cannot use Refresh to update the added object in the object context. Instead, reload the object with a value of OverwriteChanges for MergeOption.
In a table, a foreign key column can have a single value multiple times. e.g. DepartmentID foreign key in Users Table: More than one User can have same DepartmentID foreign key.
So how can this cause an UpdateException ?
I would like to call a method in the ObjectContext which returns EntityCollection and have it sorted the way I want by default. For example, Imagine I have the following Category table/class:
CategoryID (PK)
Name
ParentID (FK_Category) foreign key
pointing to CategoryID itself.
(This table is the base for a tree structure of Categories and SubCategories)
Now, in my data model, the public partial class Category : EntityObject has a property which returns all Categories that have ParentID==CategoryID, in other words, EntityCollection<Category> SubCategories.
Alright, now i want to show in my page all the Categories and SubCategories by using Repeater:
<asp:Repeater ID="rptSubCategories" runat="server">
<ItemTemplate>
<%# Eval("CategoryID") %> - <%# Eval("Name") %>
<asp:Repeater ID="rptSubCategoryCategories" runat="server" DataSource='<%#Eval("SubCategories")) %>'>
<ItemTemplate>
<%# Eval("CategoryID") %> - <%# Eval("Name") %>
</ItemTemplate>
</asp:Repeater>
</ItemTemplate>
</asp:Repeater>
Then in code behind, I set the DataSource:
IList<Category> categoryList = new CategoryProvider().GetAll();
rptSubCategories.DataSource = categoryList;
rptSubCategories.DataBind();
Simply and everything works! Except that, rptSubCategoryCategories doesn't gives sorted Categories by Name. The only way I found to do it, is to change its DataSource from:
DataSource='<%# Eval("SubCategories")) %>'
to:
DataSource='<%# ((EntityCollection<Category>)Eval("SubCategories")).OrderBy(p => p.Name) %>'
but I wish I could do something else to have a default sorting so i don't need to call the OrderBy. Something like Attributes like we do in DynamicData, following the tutorial at [URL] Setting the default sort column of an Entity with DisplayColumnAttribute. Unless somebody tells me it's impossible what I want to do.
Using .NET 4.0 BETA 2
I'm working on a project which is using EntityFramework 4 and I am using the entity objects as my business objects. I ran into an issue recently where I had a context declared in a using statement in a user control. The method the statement was in returned an entity object which got used in another control. So I had to detach the entity then attach it to the new context in the other control. I would like to avoid this if possible. What I'm thinking is I would like to declare a context in the master page and then pass that to any page/usercontrol that needs it so they are all using the same context and I don't have to write all these using statements.
My questions are these:
1) is it a bad practice to declare a context on Pre_Init/Page_Load and then dispose of it on Page_Unload?
2) if it is what is the best practice for handling them?
3) if I do go the route of declaring the context in the master page what is the best way to pass that to the pages/usercontrols?
I have not found any way to intercept or override calls to createquery in my datacontext. What I am trying to do is to allow for global filters, i.e. if a user has access to only a subset of entities I would like to filter away these on the lowest level possible. Is there a way to do this? I have tried several apporaches but no one worked out. Perhaps I lack patience or is just plain stupid, but I think it should be possible! So if anyone has any pointers to where
View 2 Repliesin webform 1, i have search button when i click its open webform2 and there the gridview.
I want when i click the link in gridview in webform 2 then it close webform 2 and change the datasource parameter in webform 1 without open the new window (still same window)
What is right way to send visitors from one webform to other. What are their limitations and their plus points.
View 2 RepliesI'm working on a project in which we have a database, data layer (entity framework), business layer and web/UI layer.I want to use ASP.NET Dynamic Data for the web layer, but don't want it to access the data layer or database, as I want it to be purely running off business logic, and not directly accessing the data.However, it appears that Dynamic Data only allows Linq-to-SQL or entity framework data sources to be used.Has anyone used it with business-layer objects instead?
View 1 RepliesLets say I am doing a shoping cart. I authenticate the user with a session variable.For example:
If(Request.IsAuthenticated)
// Here I want to add to the shoping cart.
// Can I do the following
Session["Cart"] = "Washing Machine";
Now will this Session["Cart"] value which is washing machine here be unique to diff customers?