ADO.NET :: EF: Creating Database And Model?
Mar 25, 2011
This is a simplified example of what I need. Imagine a person table with several different club tables. Every person can belong to any number of clubs, but must belong to at least one club. The association would be a 1 to zero or one between the person table and each of the club tables.I've created the databases, then the entity model. The associations are all 1 to many, which isn't what I want.
Is there a way to modify the database so that the model is created correctly? I'm still building the project, making lots of changes, and I've had problems with updating the model, so I keep recreating it. Setting up the database correctly would be preferable.I'm trying to follow the quickstart here: [URL]but I'm using the SQL Management Studio designer, and I can't find how to fix the associations I add.
I've been reading about using or not using foreign keys in the model, but it's only confused me more. Can someone help me understand this? I'm starting to write code with what I have, and I'm running into problems. I'm about to start using joins, which means I'm trying to use a hammer instead of a saw because I don't know how to use my saw. I'd rather understand my tools and use them the right way!
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May 31, 2010
I am trying to create a relation between 2 of my model classes. I have separated my Model classes to be in their own project "Domain Model" and the application exists in the "WebUI" project.
I have 2 models.... SupportIssues and Users....
SupportIssues has a column UserID which is also a primary key in the Users table.
I want to create a relationship where one user can have many support issues.
I just can figure out how to do this?
Here is a snippet of my supportIssue.cs class:
[Code]....
How can i link UserID to my User.cs class?
Is it anything to do with the [Associate] tag?
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Sep 3, 2010
Trying to create a strongly typed view but the model "that is a class" is not listed in the "View data class" dropdown?
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Sep 13, 2010
I'm trying to build a link to an external website using some properties of my model class in my view page, e.g. I want it to render as something like -[URL]where post-id would be pulled from the model (I'm using a strongly typed view model here - I can't use ViewData as there's a list of items being pulled back all of which need seperate links).I tried doing < a href="<% model.PermaLink(); %>">, where PermaLink is just some string, however the value doesn't get picked up.If I try < a href="<%= model.PermaLink %>">, I get an error - CS1502: The best overloaded method match for 'System.IO.TextWriter.Write(char)' has some invalid argumentsIs there any way to do this? I tried adding the runat="server" attribute, however this just linked to my local site and controller/model actions.
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Mar 13, 2011
EDIT: This question is vague and will likely be of little use to anyone. I am awarding internet monies to the gentleman below whom "helped" me.Sorry that the title is a little vague. I am still new to asp mvc & EF. Here is my issue. I have a DB somewhat like this.
Employee
- ID
- Name
- Address
EmployeeJob
- EmployeeID
- JobID
- StartDate
JobTypes
- ID
- JobName
I want a create form that will show all the Employee fields as well as a list of JobTypes for the users to be able to select. Then I will post the results back to the controller and update the DB. I have started looking into custom viewmodels, but am still unsure of exactly how to put that together and get it to work.
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Nov 1, 2010
I'm trying to customize correct displaying of dropdownlists so information shown in comboboxes is relevant to the kind of user logged on (maintaining referential integrity at data level)
e.g.: I have a user already logged on and depending on his profile I'd like to display to this user only the portion of the database that he would be allowed to see. That would mean that he might have acces to an specific subset of data, e.g.: businesstype = "3", loging level = "2", etc.
Is there a way of creating an Ado.Net Entity Data Model filtered on a Session variables as to maintain proper referential integrity at data level?
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Mar 17, 2011
I can't believe I'm having so much trouble finding this information. I'm endeavouring to learn about creating model classes with Linq to SQL. By default VS2010 wants to use SQL Express, but our organisation has several database servers for development so I'd rather use one of those. PLEASE can somebody tell me how I can configure VS2010 to do that, as all I get is 'A network-related or instance-specific error occurred while establishing a connection to SQL Server ... Verify that the instance name is correct'. Yeah, thanks Microsoft. Actually telling me how to verify the instance name would be a really good move here.
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Jan 4, 2010
I have created a class UserDetailsModel.cs in my folder model. I have populated a selectedList in the model class.
I have create a view which is both strongly-typed and partial and the view data class is the abc.cs
I have the following code in the view
[Code]....
However, i`m getting the error of
[Code]....
[Code]....
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Sep 16, 2010
I created an Entity Frameworks model (.edmx).
Now, I want to change the database that my model is using.
How do I do that? Just change the connection string in the .edmx Properties, or is there more that is required?
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Sep 13, 2010
Im just wondering how you go about creating dynamic properties on entities that generated from a database generated model.For example I have a UserInformation table. In that table it has basic information on the user (well derr) like user name, address details etc etc. I want to add a readonly property that concatenates the user's Name, Address details and Phone Number into one string that I can output to a view. Any ideas on how i would go about creating this dynamic property. This is just a simple example, i am wanting to do some more complex calculating and concatenating.
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Jan 19, 2011
I have an application that uses multiple identical databases. When the user logs in they select the database that will be working with for that session. I am EF 4.0 for to access the database. What I can't figure out is how to dymaically pass the database name of the database from a session variable to the code in the EDMX file.
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Feb 22, 2011
I am trying to get the FailedPasswordAttemptCount from the ASP.NET built in objects and I am not able to find one, is there any way I can get this value without creating a new storedProc?
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Aug 3, 2010
I have a group of radiobuttons. The field they are 'bound' to is of datatype tinyint (sql server), byte .NET. It is set to NOT accept nulls in the database column (col1) and no default value has been set for the column, or indeed, anywhere else.
View code as follows:
<ul> <li><%= Html.RadioButton("col1", "1")%></li> <li><%= Html.RadioButton("col1", "2")%></li> <li><%= Html.RadioButton("col1", "3")%></li></ul><%= Html.ValidationMessage("col1", "*") %>
If the user doesn't select any of them, I would expect null to be that the model would attempt to insert into the database. I would therefore get a validation error that I can display to the user, prompting them to choose one of the options.
However, instead of null, the model inserts a 0 into the database. As this does not fail, no error is raised.
I am not setting the default value to 0 anywhere, not in the mvc app or the database
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Oct 11, 2010
I've been using entity data models for quite a few sections of my website and find it really good for saving things to the database.
After searching for a while, I can't seem to find a good way to populate a new instance with data from a database other than using a data reader. E.G:
MyClass.myID = reader("myID")
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Jun 7, 2010
I've described my model using an Ado Entity Data Model file (*.edmx), and i wish now to generate my db schema and tables from it. Is it possible?
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Jan 31, 2011
I'm having trouble connecting to my model to my existing database using Entity Framework . Here is the code I'm working with:
[Code]....
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Mar 20, 2011
How can i make this work like i have 5 fields in my database table . 2) i created a model for validation with datannotation and created the compare password field as well with comparepassword attribute. (now my model has 6 fields including one external field compare password and 5 database fields)3) i created a view with that model.(User)4) now i created a controller as well but the problem arise here that when calling that actionmethod the compiler complains about the external field and tells it cannot find any extension method . how can i create the extension method or solve this error?
[Code]....
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May 4, 2010
I ask this because i'm using Partial classing to extend my db model, and in doing so some snags i've run into using inheritance and also snags i've run into declaring my db model in another class as a property and just using it like that ie: Public Property DBModelClass as DBModelClassType - however, doign direct partial classing has worked out the best, with no snags... except for an issue i seem to be running into now.
that is, i create new properties with half-page code in the 'Get' part of the property decleration, these are like virtual/new properties that the db or db model isn't supposed to know anything about, the sort of stuff you generate/use but without saving it in your db, as i'm sure all of you have these. every time i submit my DBModel through an action, somehow, one of these properties 'Get' section is running (being called) even though i'venever asked for it to. of course, because it aint ready to run (it shouldn't) errors like null errors get returned (however, they wouldn't error if it were to run only when i asked for it to).
edit:
so this second part of my question, are all properties in a model generated from a db (linq to sql) ran or called by the model state automatically? without being asked to do so?
an aside:
(i do do a modelstate.isvalid - however, this running occurs before isvalid is called as it errors out before i even see validation information). that being, is the auto calling of all properties on a db model object even when not used normal? i tried using bind(false) and scaffold off on the problemed properties. and the first part of my question, just as a reminder, is if i should or should not be using partial classing as a substitute to inheritance when extending db model's?
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Feb 6, 2011
I been working on a simple site today and when I found myself surprised about this. I got a object model that gone have like a lot of emails to it so I thought Ill do a string array to keep them, then I paused and tried to figure how do I save that to a database and how do I work with this? I always found myself working with collections of objects instead. So I'm kinda embaries to say this but how do I work with this? can I save a array to database
[Code]....
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Mar 10, 2011
I'm currently facing a performance problem with creating POCO objects from my database. I'm using Entity Framework 4 as OR-Mapper. The whole application is a prototype for now. Let's assume I want to have some business objects like classes 'Printer' or 'Scanner'. Both classes inherit from a BaseClass called Product.
The business classes exist.
I try to use a more generic database approach. I don't want to create tables for "Printer" nor "Scanner". I want to have 3 tables: One called Product, and the other Property and PropertyValue (which stores all assigned values to a specific Product). In my business layer I do create a specific object like this:
public Printer GetPrinter(int IDProduct)
{
Printer item = new Printer();
// get the product object with EF
// get all PropertyValues
// (with Reflection) foreach property in item.GetType().GetProperties
// {
// property.SetValue("specific value")
// }
return item;
}
This is how the EF model looks like: Works fine so far. For now I'm doing performance tests for retrieving multiple sets. I've created a prototype and improved it several times to increase the performance. It is still far away from being usable. I takes 919ms to create 300 objects who only contain 3 properties. The reason for choosing such DB design is to have a generic database design. Adding new properties should only be done in the business model.
Am I just being too stupid to create a performant way of retrieving xx objects or is my approach totally wrong? As far as I understand OR-Mapper, they are basically doing the same?
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Jan 22, 2011
I need to pull the data from DB and fill the view model, is there any better way to do this? Currently I'm doing something like this.
ViewModel vm = new ViewModel();
var recentBill = context.Money.Take(10);
foreach (var r in recnetBill)
{
vm.lst.Add(r);
}
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Nov 8, 2010
Is it possible to get the sql script for creating the database, when using Entity Framework 4.0 code first, without using the designer? When i use the designer it creates an .....edmx.sql file with the script. But i don't want to use the designer.
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Jul 7, 2010
Really new to C# & Web developing - but have used the DAL & BLL model from a number of the turorials. Have a situation that I not sure the best way to accomplish. I have an application dealing with courses, books, etc. utilizing an Access Database. All was going well in creating an on-line catalog using Formview and tables to display the db values stored in the Course Table (Course ID the key). User is able to use dropdown list to locate the course - dropdown list showed the Course Nbr & Name, but used the Course ID to get the detail. This issue appeared when they introduced a Prerequisite field in the Course Table. This contains the Course ID of the prerequisite course, but they want to display the Course Nbr and Name in the table field. So today it show 18 (Course ID) and they want B101 Intro to Biology. Hope I have provided enough information of what the code looks like below
Here is the FORMVIEW & TABLEROW
<asp:FormView ID="FVGeeralidades" runat="server" DataKeyNames="ClaveAsignaturas"
DataSourceID="ObjectDataSource1">
<ItemTemplate>
<asp:TableRow ID="TableRow5" runat="server">
<asp:TableCell ID="TableCell11" runat="server" HorizontalAlign="Left" Text="<STRONG>1.6</STRONG> Prerrequisito"
Width="150px"></asp:TableCell>
<asp:TableCell ID="TableCell12" runat="server"></asp:TableCell>
<asp:TableCell ID="PrerrequisitoValue" runat="server" HorizontalAlign="Left">
<%# Eval("AsignaturaPrerrequisito")%>
</asp:TableCell>
Here is also the OBJECT DATA SOURCE
<asp:ObjectDataSource ID="ObjectDataSource1" runat="server" OldValuesParameterFormatString="original_{0}"
SelectMethod="GetCourseByCourseID" TypeName="CoursesBLL">
<SelectParameters>
<asp:ControlParameter ControlID="DDLCourse" Name="CourseID" PropertyName="SelectedValue"
Type="String" />
</SelectParameters>
</asp:ObjectDataSource>
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Aug 19, 2010
When adding a stored procedure into the Entity Data Model I can select whether the procedure returns a scalar, a (new) complex type or one of the entity types I already defined.I mean assuming I have a view like this
CREATE VIEW FilteredFoos as SELECT Foo.* FROM Foo join ... WHERE ...(that is a view that implements some involved filtering, but returns all columns from one table) how do I add it to the project so that I can use the entity set, but get the Foo objects, not some new FilteredFoo objects.
var foos = myDB.FilteredFoos.Include("Bar").ToList();
foreach (Foo foo in foos) { ...
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Oct 14, 2010
I have been reading the below article and I have got it to work.
[URL]
The problem is when I use my database script file it throws an error 1001 saying error next to keyword 'GO'. But if i take the exact same script and run it in SQL Management Studio it works fine.
Try this small script, this is what I am using and its giving me an error, An above is a lovely article to creating a database from microsoft.
[Code]....
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