I have the following database schema:
Here's how I populate a DropDownList in my AreaController.cs:
public ActionResult Edit(int id)
{
Area area = areaRepository.GetArea(id);
JefeRepository jefe = new JefeRepository();
ViewData["Jefes"] = new SelectList(jefe.FindAllJefes().ToList(), "ID", "Nombre", area.Jefe.Nombre);
return View(area);
}
Then in my View I display it like so:
<%: Html.DropDownList("IDJefe", (SelectList)ViewData["Jefes"]) %>
The DropDownList loads correctly but only shows the Name of the Jefe. I want to display both name and last name. How can I achieve this?
I've tried doing something like this but it only display the first name.
ViewData["Jefes"] = new SelectList(jefe.FindAllJefes().ToList(), "ID", "Nombre", area.Jefe.Nombre + area.Jefe.Apellido);
This is how it shows:
In your class you can make an property which will combine it for you and also can be bind to your list, f.e. if I have Person class:
public class Person
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string FullName { get { return string.Format("{0} {1}", FirstName, LastName); } }
}
Then you can easily bind it like:
ViewData["Persons"] = new SelectList(persons, "Id", "FullName ", ...);
As far as it have just the getter it will not involved into your business logic processes - it will only helps ;)
PS. Sorry for another example, but I really do not understand spanish ;)
Related
I've been trying to grok EF many-to-many relationships for the past two days now and I'm still missing something even after scouring a dozen different questions here.
I've got a model named Text that can have an arbitrary number of Tag models associated with it, and obviously, at least in theory, each Tag can be associated with an arbitrary number of Texts. Entity Framework seems to understand this well enough to create a table named TextTags in the database without me asking it to do so, and I can access Text.Tags without trouble, but when I attempt to access Tag.Texts in my code, I get a null reference exception.
Now, I could just add every text to every tag manually (or could I? that seems to throw some kind of error), but that would seem to defeat the purpose... Besides which, it also seems error prone. What am I failing to understand?
Code as requested:
Text model:
public class Text
{
public int ID { get; set; }
public Author Author { get; set; }
public string Content { get; set; }
public virtual ICollection<Tag> Tags { get; set; }
}
Tag model:
public class Tag
{
public int ID { get; set; }
public string Name { get; set; }
public ICollection<Text> Texts { get; set; }
}
Data insert:
using (var db = new TextDbContext())
{
db.Authors.Add(new Author()
{
Name = "Poe"
});
db.Tags.Add(new Tag() { Name = "lame" });
db.Tags.Add(new Tag() { Name = "example" });
db.SaveChanges();
db.Texts.Add(new Text()
{
Author = db.Authors.First(),
Tags = db.Tags.ToList(),
Content = "This is the first text by Poe."
});
db.Texts.Add(new Text()
{
Author = db.Authors.First(),
Tags = db.Tags.ToList(),
Content = "This is the second text by Poe."
});
db.Texts.Add(new Text()
{
Author = db.Authors.First(),
Tags = db.Tags.ToList(),
Content = "This is the third text by Poe."
});
db.SaveChanges();
}
Error:
foreach (var tag in db.Tags)
{
foreach (var text in tag.Texts)
{
Console.WriteLine("Tag: {0}\tText: {1}", tag.Name, text.Content);
// Null reference on line above.
}
}
You get a NullReferenceException because your navigation property Tag.Texts is not marked as virtual. As a result lazy loading does not work to load the Tag.Texts collection when you access it and the collection is null. (Text.Tags is virtual, hence no exception here.)
I'm using Entity Framework 5 with Visual Studio with Entity Framework Power Tools Beta 2 to reverse engineer moderately sized databases (~100 tables).
Unfortunately, the navigation properties do not have meaningful names. For example, if there are two tables:
CREATE TABLE Contacts (
ContactID INT IDENTITY (1, 1) NOT NULL,
...
CONSTRAINT PK_Contacts PRIMARY KEY CLUSTERED (ContactID ASC)
}
CREATE TABLE Projects (
ProjectID INT IDENTITY (1, 1) NOT NULL,
TechnicalContactID INT NOT NULL,
SalesContactID INT NOT NULL,
...
CONSTRAINT PK_Projects PRIMARY KEY CLUSTERED (ProjectID ASC),
CONSTRAINT FK_Projects_TechnicalContact FOREIGN KEY (TechnicalContactID)
REFERENCES Contacts (ContactID),
CONSTRAINT FK_Projects_SalesContact FOREIGN KEY (SalesContactID)
REFERENCES Contacts (ContactID),
...
}
This will generate classes like this:
public class Contact
{
public Contact()
{
this.Projects = new List<Project>();
this.Projects1 = new List<Project>();
}
public int ContactID { get; set; }
// ...
public virtual ICollection<Project> Projects { get; set; }
public virtual ICollection<Project> Projects1 { get; set; }
}
public class Project
{
public Project()
{
}
public int ProjectID { get; set; }
public int TechnicalContactID { get; set; }
public int SalesContactID { get; set; }
// ...
public virtual Contact Contact { get; set; }
public virtual Contact Contact1 { get; set; }
}
I see several variants which would all be better than this:
Use the name of the foreign key: For example, everything after the last underscore (FK_Projects_TechnicalContact --> TechnicalContact). Though this probably would be the solution with the most control, this may be more difficult to integrate with the existing templates.
Use the property name corresponding to the foreign key column: Strip off the suffix ID (TechnicalContactID --> TechnicalContact)
Use the concatenation of property name and the existing solution: Example TechnicalContactIDProjects (collection) and TechnicalContactIDContact
Luckily, it is possible to modify the templates by including them in the project.
The modifications would have to be made to Entity.tt and Mapping.tt. I find it difficult due to the lack of intellisense and debug possibilities to make those changes.
Concatenating property names (third in above list) is probably the easiest solution to implement.
How to change the creation of navigational properties in Entity.tt and Mapping.tt to achieve the following result:
public class Contact
{
public Contact()
{
this.TechnicalContactIDProjects = new List<Project>();
this.SalesContactIDProjects = new List<Project>();
}
public int ContactID { get; set; }
// ...
public virtual ICollection<Project> TechnicalContactIDProjects { get; set; }
public virtual ICollection<Project> SalesContactIDProjects { get; set; }
}
public class Project
{
public Project()
{
}
public int ProjectID { get; set; }
public int TechnicalContactID { get; set; }
public int SalesContactID { get; set; }
// ...
public virtual Contact TechnicalContactIDContact { get; set; }
public virtual Contact SalesContactIDContact { get; set; }
}
There a few things you need to change inside the .tt file. I choose to use the third solution you suggested but this requires to be formatted like FK_CollectionName_RelationName. I split them up with '_' and use the last string in the array.
I use the RelationName with the ToEndMember property to create a property name. FK_Projects_TechnicalContact will result in
//Plularized because of EF.
public virtual Contacts TechnicalContactContacts { get; set; }
and your projects will be like this.
public virtual ICollection<Projects> SalesContactProjects { get; set; }
public virtual ICollection<Projects> TechnicalContactProjects { get; set; }
Now the code you may ask. Ive added 2 functions to the CodeStringGenerator class in the T4 file. One which builds the propertyName recieving a NavigationProperty. and the other one generating the code for the property recieving a NavigationProperty and the name for the property.
//CodeStringGenerator class
public string GetPropertyNameForNavigationProperty(NavigationProperty navigationProperty)
{
var ForeignKeyName = navigationProperty.RelationshipType.Name.Split('_');
var propertyName = ForeignKeyName[ForeignKeyName.Length-1] + navigationProperty.ToEndMember.Name;
return propertyName;
}
public string NavigationProperty(NavigationProperty navigationProperty, string name)
{
var endType = _typeMapper.GetTypeName(navigationProperty.ToEndMember.GetEntityType());
return string.Format(
CultureInfo.InvariantCulture,
"{0} {1} {2} {{ {3}get; {4}set; }}",
AccessibilityAndVirtual(Accessibility.ForProperty(navigationProperty)),
navigationProperty.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many ? ("ICollection<" + endType + ">") : endType,
name,
_code.SpaceAfter(Accessibility.ForGetter(navigationProperty)),
_code.SpaceAfter(Accessibility.ForSetter(navigationProperty)));
}
If you place the above code in the class you still need to change 2 parts. You need to find the place where the constructor part and the navigation property part are being build up of the entity. In the constructor part (around line 60) you need to replace the existing code by calling the method GetPropertyNameForNavigationProperty and passing this into the escape method.
var propName = codeStringGenerator.GetPropertyNameForNavigationProperty(navigationProperty);
#>
this.<#=code.Escape(propName)#> = new HashSet<<#=typeMapper.GetTypeName(navigationProperty.ToEndMember.GetEntityType())#>>();
<#
And in the NavigationProperties part (around line 100) you also need to replace the code with the following.
var propName = codeStringGenerator.GetPropertyNameForNavigationProperty(navigationProperty);
#>
<#=codeStringGenerator.NavigationProperty(navigationProperty, propName)#>
<#
I hope this helps and you can always debug the GetPropertyNameForNavigationProperty function and play a little with the naming of the property.
Building on BikeMrown's answer, we can add Intellisense to the properties using the RelationshipName that is set in MSSQL:
Edit model.tt in your VS Project, and change this:
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
<#
}
#>
<#=codeStringGenerator.NavigationProperty(navigationProperty)#>
<#
}
}
to this:
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
<#
}
#>
/// <summary>
/// RelationshipName: <#=code.Escape(navigationProperty.RelationshipType.Name)#>
/// </summary>
<#=codeStringGenerator.NavigationProperty(navigationProperty)#>
<#
}
}
Now when you start typing a property name, you get a tooltip like this:
It's probably worth noting that if you change your DB model, the properties may find themselves pointing at different DB fields because the EF generates navigation property names based on their respective DB field name's alphabetic precedence!
Found this question/answer very helpful. However, I didn't want to do as much as Rikko's answer. I just needed to find the column name involved in the NavigationProperty and wasn't seeing how to get that in any of the samples (at least not without an edmx to pull from).
<#
var association = (AssociationType)navProperty.RelationshipType;
#> // <#= association.ReferentialConstraints.Single().ToProperties.Single().Name #>
The selected answer is awesome and got me going in the right direction for sure. But my big problem with it is that it took all of my already working navigation properties and appended the base type name to them, so you'd end up with with things like the following.
public virtual Need UnitNeed { get; set;}
public virtual ShiftEntered UnitShiftEntered {get; set;}`
So I dug into the proposed additions to the .tt file and modified them a bit to remove duplicate type naming and clean things up a bit. I figure there's gotta be someone else out there that would want the same thing so I figured I'd post my resolution here.
Here's the code to update within the public class CodeStringGenerator
public string GetPropertyNameForNavigationProperty(NavigationProperty navigationProperty, string entityname = "")
{
var ForeignKeyName = navigationProperty.RelationshipType.Name.Split('_');
var propertyName = "";
if (ForeignKeyName[ForeignKeyName.Length-1] != entityname){
var prepender = (ForeignKeyName[ForeignKeyName.Length-1].EndsWith(entityname)) ? ReplaceLastOccurrence(ForeignKeyName[ForeignKeyName.Length-1], entityname, "") : ForeignKeyName[ForeignKeyName.Length-1];
propertyName = prepender + navigationProperty.ToEndMember.Name;
}
else {
propertyName = navigationProperty.ToEndMember.Name;
}
return propertyName;
}
public string NavigationProperty(NavigationProperty navigationProperty, string name)
{
var endType = _typeMapper.GetTypeName(navigationProperty.ToEndMember.GetEntityType());
var truname = name;
if(navigationProperty.ToEndMember.RelationshipMultiplicity != RelationshipMultiplicity.Many){
if(name.Split(endType.ToArray<char>()).Length > 1){
truname = ReplaceLastOccurrence(name, endType, "");
}
}
return string.Format(
CultureInfo.InvariantCulture,
"{0} {1} {2} {{ {3}get; {4}set; }}",
AccessibilityAndVirtual(Accessibility.ForProperty(navigationProperty)),
navigationProperty.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.Many ? ("ICollection<" + endType + ">") : endType,
truname,
_code.SpaceAfter(Accessibility.ForGetter(navigationProperty)),
_code.SpaceAfter(Accessibility.ForSetter(navigationProperty)));
}
public static string ReplaceLastOccurrence(string Source, string Find, string Replace)
{
int place = Source.LastIndexOf(Find);
if(place == -1)
return Source;
string result = Source.Remove(place, Find.Length).Insert(place, Replace);
return result;
}
and here's the code to update within the model generation,
update both occurrences of this:
var propName = codeStringGenerator.GetPropertyNameForNavigationProperty(navigationProperty)
to this
var propName = codeStringGenerator.GetPropertyNameForNavigationProperty(navigationProperty, entity.Name);
I have a model like this
public class Exam
{
public int NewsId { get; set; }
public string Title { get; set; }
public string Description{ get; set; }
public string Program{ get; set; }
}
and a view model like this
public class ExamViewModel
{
public int NewsId { get; set; }
public string Title { get; set; }
}
and I do config Automapper like this
AutoMapper.Mapper.CreateMap<Exam, ExamViewModel>();
and in an ActionResult I used Automapper like this:
public ActionResult Exam()
{
var examsDb = db.Exams;
IEnumerable<ExamViewModel> examViewModel = AutoMapper.Mapper.Map<IEnumerable<Exam>, IEnumerable<ExamViewModel>>(examsDb);
return View(examViewModel);
}
and in view I loop through it
#model IEnumerable<AraParsESOL.ViewModels.ExamViewModel>
<ul>
#foreach (var e in Model)
{
<li>
#Html.ActionLink(e.Title, "Type", "Exam")
</li>
}
</ul>
My problem is that:
As you can see in the Model There are 4 properties but in viewModel there are only 2 properties.
How can i get only those 2 properties in viewModel and not the entire Model?
What happens here is that in view after each loop it goes and get the required column from the database but i want only those 2 properties and not going back to database.
i can get the database like this
db.Exam.ToList();
but it will cause the entire database gets back.
i want to use best practices here?
i know i can get the data from database by anonymouse type and select command but then what is the use of automapper?
what is the best solution here?
Don't use AutoMapper. It's not appropriate for IQueryable<T>. Instead, use LINQ projections:
public ActionResult Exam()
{
var examsDb = db.Exams;
IEnumerable<ExamViewModel> examViewModel =
from e in db.Exams
select new ExamViewModel
{
NewsId = e.NewsId,
Title = e.Title
};
return View(examViewModel);
}
If you look at the generated SQL, you will see that only the NewsId and Title columns are retured. It looks like the AutoMapper folks were interested in addressing this shortcoming, but I haven't heard anything about it since this.
Conclusion in Images, can be found in the bottom
I'm having some trouble to get how Forms work in MVC (as I'm a WebForms Developer and really wanna start using MVC in one big project)
I took the MVC2 Web Project and add a simple ViewModel to it
namespace TestForms.Models
{
public class myFormViewModel
{
public myFormViewModel() { this.Options = new List<myList>(); }
public string Name { get; set; }
public string Email { get; set; }
public List<myList> Options { get; set; }
}
public class myList
{
public myList() { this.Value = this.Name = ""; this.Required = false; }
public string Name { get; set; }
public string Value { get; set; }
public string Type { get; set; }
public bool Required { get; set; }
}
}
Created a Strongly Typed View, passed a new object to the view and run it.
When I press submit, it does not return what's in the Options part... how can I bind that as well?
my view
alt text http://www.balexandre.com/temp/2010-10-11_1357.png
filling up the generated form
alt text http://www.balexandre.com/temp/2010-10-11_1353.png
when I press Submit the Options part is not passed to the Model! What am I forgetting?
alt text http://www.balexandre.com/temp/2010-10-11_1352.png
Conclusion
Changing the View loop to allocate the sequential number, we now have
<%= Html.TextBox("model.Options[" + i + "].Value", option.Value)%>
model is the name of our Model variable that we pass to the View
Options is the property name that is of type List
and then we use the property name
Looking at your UI it seems that you did not put the data from the Options member on it.
<% foreach (myList obj in Model.Options) { %>
// Add the object to your UI. they will be serialized when the form is submitted
<% } %>
Also check that you enclose the data in a form element
EDIT:
Sorry! I did'nt realized that you was filling the object inside the controller. Can you please show the code you have in the view?
I have searched like a fool but does not get much smarter for it..
In my project I use Entity Framework 4 and own PoCo classes and I want to use DataAnnotations for validation. No problem there, is how much any time on the Internet about how I do it. However, I feel that it´s best to have my validation in ViewModels instead and not let my views use my POCO classes to display data.
How should I do this smoothly? Since my repositories returns obejekt from my POCO classes I tried to use AutoMapper to get everything to work but when I try to update or change anything in the ModelState.IsValid is false all the time..
My English is really bad, try to show how I am doing today instead:
My POCO
public partial User {
public int Id { get; set; }
public string UserName { get; set; }
public string Password { get; set; }
}
And my ViewModel
public class UserViewModel {
public int Id { get; set; }
[Required(ErrorMessage = "Required")]
public string UserName { get; set; }
[Required(ErrorMessage = "Required")]
public string Password { get; set; }
}
Controller:
public ActionResult Edit(int id) {
User user = _userRepository.GetUser(id);
UserViewModel mappedUser = Mapper.Map<User, UserViewModel>(user);
AstronomiGuidenModelItem<UserViewModel> result = new AstronomiGuidenModelItem<UserViewModel> {
Item = mappedUser
};
return View(result);
}
[HttpPost]
public ActionResult Edit(UserViewModel viewModel) {
User user = _userRepository.GetUser(viewModel.Id);
Mapper.Map<UserViewModel, User>(viewModel, user);
if (ModelState.IsValid) {
_userRepository.EditUser(user);
return Redirect("/");
}
AstronomiGuidenModelItem<UserViewModel> result = new AstronomiGuidenModelItem<UserViewModel> {
Item = viewModel
};
return View(result);
}
I've noticed now that my validation is working fine but my values are null when I try send and update the database. I have one main ViewModel that looks like this:
public class AstronomiGuidenModelItem<T> : AstronomiGuidenModel {
public T Item { get; set; }
}
Why r my "UserViewModel viewModel" null then i try to edit?
If the validation is working, then UserViewModel viewModel shouldn't be null... or is it that the client side validation is working but server side isn't?
If that's the case it could be because of the HTML generated.
For instance, if in your view you have:
<%: Html.TextBoxFor(x => x.Item.UserName) %>
The html that gets rendered could possibly be:
<input name="Item.UserName" id="Item_UserName" />
When this gets to binding on the server, it'll need your action parameter to be named the same as the input's prefix (Item). E.g.
public ActionResult Edit(UserViewModel item) {
To get around this, do as above and change your action parameter to item OR you could encapsulate the form into a separate PartialView which takes the UserViewModel as it's model - that way the Html.TextBoxFor won't be rendered with a prefix.
HTHs,
Charles
Ps. If I'm totally off track, could you please post some code for the view.