I'm new to db4o and i'm trying to figure out if it's possible to do the following:
public class Page
{
public Guid ID {get;set;}
public Page Parent {get;set;}
public IList<Page> Children {get;set;}
public String Name {get;set;}
public String Depth {get;set;}
}
When I save the page i have it's parent only.
IE
Page p1 = new Page() {
ID = Guid.NewGuid(),
Name = "p1",
Parent = null
};
Page p2 = new Page() {
ID = Guid.NewGuid(),
Name = "p2",
Parent = p1
};
Page p3 = new Page() {
ID = Guid.NewGuid(),
Name = "p3",
Parent = p1
};
When i load up p1 is there anyway to populate the two children??
Db4O will load also the collection of children as soon as you load p1 from the datastore, so yes it's possible...
Well the easiest way to do this is actually to just use the property-call to wire things up. Like this:
public class Page
{
private Page _parent;
public Page Parent {
get{return _parent;}
set{
value.Children.Add(this);
this._parent = value;
}
}
public IList<Page> Children {get;set;}
// omitted the the other properties
}
As soon as you assign a Page-instance to Page.Parent, the Page is in the Page.Children-property.
Is this a solution?
Not sure about DB4O but you should consider using the IComposite pattern for this.
Related
I have ASP.NET MVC 5 web project with E.F. 6.1.3.
I use IDbSet and its method Add to insert new data in my database. I also use context to save changes.
protected IDbSet<T> DbSet { get; set; }
public DbContext Context { get; set; }
private void Insert(T item)
{
this.DbSet.Add(item);
Context.SaveChanges();
}
When i insert new item in database
Is there any equivalent way in this interface to Sql Command.ExecuteScalar ?
In other words i need to get the Id of newly inserted item (my Id is first column and first row in current table).
You dont need ExecuteScalar (but you have to create your POCOs thru context.Set<T>().Create() method no, you dont have to, it works without proxy)
class MyPoco
{
[Key]
public int Id {get;set;}
}
...
var myPoco = context.Set<MyPoco>().Add(context.Set<MyPoco>().Create());
context.SaveChanges();
int newId = myPoco.Id;
However, if you have to have some direct store query, you can use context.ExecuteStoreQuery (its not on IDbSet, but on Context class)
var departments = context.ExecuteStoreQuery<string>
("select Name from Department where DepartmentID < #p0", 5);
EDIT (after you added code :) ):
You can add custom interface (or even base class) to your POCO with Id property:
public interface IId
{
int Id {get;}
}
class MyPoco
: IId
{
[Key]
public int Id {get;set;}
}
and update your Insert code like this:
private int Insert(T item)
where T : IId
{
this.DbSet.Add(item);
Context.SaveChanges();
return item.Id;
}
Note this doesnt work when you create your POCO simply by poco = new Poco() - this way, you give up lot of EF functionality (proxies), you have to use IDbSet<T>.Create() method) It work.
Or keep your item and take Id value after you send it to your Insert(item):
var myPoco = context.Set<MyPoco>().Add(context.Set<MyPoco>().Create());
context.Insert(myPoco);
int newId = myPoco.Id;
I am fairly new to MVC, and I've been reading a bit about ViewModels, but how do I go about sending two models to my View, where the queries are like so
public ActionResult Index(int Id)
{
var People = from a in db.Person
select a;
var Data = from a in db.Member
where a.Person.PersonId.Equals(Id)
select new
{
a.Project.ProjectId,
a.Project.Name,
a.Project.Customer,
a.Project.TechProfile.Select(x => new
{
x.TechId,
x.Name,
x.Elements
}),
a.MemberId,
a.Role,
a.Start,
a.End
};
return View(People);
}
I was using #model IQueryable<GeoCV.Models.Person> before so I could use a #foreach in my View but I don't know how to get my other query to the View so I can get data from it too.
Update
And I'm making a custom class for my Data query, but I don't know how to set the property of TechProfile
Right now I have
public IEnumerable<TechProfile> ProjectTechProfile { get; set; }
In my custom class, but it doesn't work, so I guess I have to specify TechId, Name and Elements?
But how?
A ViewModel wraps around the 2 models you are getting with your 2 queries, so you can return it as a single object to your view. In your case we need to adress another issue first. You are returning an anonymous object in your data query.
This means, your data query needs to return a strongly typed object instead of an anonymous object.
Create a class for your data query:
public class MyCustomDataObject
{
public int ProjectId { get; set; }
//... map all properties as needed
}
then edit your data query to return this object:
var Data = from a in db.Member
where a.Person.PersonId.Equals(Id)
select new MyCustomDataObject
{
ProjectId = a.Project.ProjectId,
//assign all properties
};
Now you need to create the actual ViewModel class:
public class MyViewModel
{
public IEnumerable<Person> Persons { get; set; }
public IEnumerable<MyCustomDataObject> Data { get; set; }
}
And after this you just need to assign the values to it in your Actionmethod:
public ActionResult Index(int Id)
{
var People = from a in db.Person
select a;
var Data = from a in db.Member
where a.Person.PersonId.Equals(Id)
select new MyCustomDataObject
{
ProjectId = a.Project.ProjectId,
//...
};
//store data of both queries in your ViewModel class here:
var vm = new MyCustomDataObject();
vm.Persons = People;
vm.Data = Data
//return ViewModel to View.
return View(vm);
}
And then declare it in your view: #model Namespace.Subfolder.MyCustomDataObject
You can use #Html.Action("actionName","controllerName") method in view. You can divide your original view into multiple partial view and then you can render that partial view with dynamic model binding using #Html.Action("actionName","controllerName") method.
For more details with sample code http://devproconnections.com/development/how-use-aspnet-mvc-render-action-helpers
You can have methods like below to get multiple model in single view
private IList<People> GetPeople()
{
return from a in db.Person
select a;
}
private IList<Data> GetData()
{
return from a in db.Member
where a.Person.PersonId.Equals(Id)
select new
{
a.Project.ProjectId,
a.Project.Name,
a.Project.Customer,
a.Project.TechProfile.Select(x => new
{
x.TechId,
x.Name,
x.Elements
}),
a.MemberId,
a.Role,
a.Start,
a.End
};
}
public ActionResult Index(int Id)
{
var MultipleModel = new Tuple<IList<People>,IList<Data>>(GetPeople(),GetData()) { };
return View(MultipleModel);
}
Here's a codeproject tutorial on the subject.
Perhaps there is an easy solution for my problem but I simply cannot seem to find it. I have read lots of tutorials about Knockout so I get the basics but I ask this question because my entity-structure is a bit more complicated than a person with a name and a list of friends which may or may not be on Twitter (Video on Channel9: Helping you build dynamic JavaScript UIs with MVVM and ASP.NET). Here's my situation:
I have a class PersonnelClass with this basic structure:
[Serializable]
//The interface is for the implementation of 'Name' and 'Description'
public class PersonnelClass : IPersonnelClassOrPerson
{
public PersonnelClass() : this(Guid.NewGuid(), "", "") { }
public PersonnelClass(Guid id, String name, String description = null)
{
if (id == Guid.Empty) { throw new ArgumentNullException("id"); }
Id = id;
Name = name;
Description = description;
Properties = new PropertyCollection();
}
public Guid Id { get; private set; }
public String Name { get; set; }
public String Description { get; set; }
public PropertyCollection Properties { get; private set; }
}
The PropertyCollection class and associated AbstractProperty class look like this:
[Serializable]
public class PropertyCollection: List<AbstractProperty> { }
[Serializable]
public abstract class AbstractProperty: IEntity, IProperty
{
public AbstractProperty(String name, String description = null) : this(Guid.NewGuid(), name, description) { }
public AbstractProperty(Guid id, String name, String description = null)
{
if (id == Guid.Empty) { throw new ArgumentNullException("id"); }
if (String.IsNullOrEmpty(name)) { throw new ArgumentNullException("name"); }
Id = id;
Name = name;
Description = description;
}
public Guid Id { get; private set; }
public String Name { get; private set; }
public String Description { get; private set; }
}
In my Controller, I create an instance of a PersonnelClassViewModel that has this structure:
public class PersonnelClassViewModel
{
public PersonnelClass PersonnelClass { get; set; }
public List<AbstractProperty> Properties { get; set; }
}
I fill this viewmodel with a new PersonnelClass and two test-properties to pass to my View like this:
var properties = new List<AbstractProperty>
{
new TextProperty("prop1", "descr1"),
new TextProperty("prop2", "descr2")
//TextProperty is derived from AbstractProperty
};
var vm = new PersonnelClassViewModel { Properties = properties };
return View(vm);
I get everything in my View as I wanted. From the View I want to create a new PersonnelClass with a set of selected properties. I have the fields for Name and Description and to add the properties I have a ListBox with the properties that already exist (for demo-purpose they came from the controller now). Through a bit of Knockout JavaScript code I can select items from this list and populate an HTML select-control () with the selected properties to add to the PersonnelClass. This all works fine, until I want to build up an object to pass back to the Controller and create the PersonnelClass.
My question is: what Knockout JS code is needed to build up this object and pass it to the Controller by submitting the form and in my Controller how should I receive this object, meaning: what type of object should this be (PersonnelClass, PersonnelClassViewModel, ...) ?
If any more info/code is needed, please do ask. Thanks in advance!
Update after answer of 'B Z':
I followed a few more of Steven Sanderson's tutorials about this to be sure I understand this, especially the one you provided in your answer. Now I have following code in my View to start with:
var initialData = #Html.Raw(new JavaScriptSerializer().Serialize(Model));
var viewModel = {
personnelClassViewModel : ko.mapping.fromJS(initialData),
properties : personnelClassViewModel.Properties,
selectedProperties : ko.observableArray([]),
addedProperties : ko.observableArray([])
};
ko.applyBindings(viewModel);
The variable 'initialData' contains the values I expect it to have but then I get the following error:
Microsoft JScript runtime error: 'personnelClassViewModel' is undefined
I have no clue anymore. Can anyone help me fix this?
Steven Sanderson has an example of how to to work with variable length lists and knockoutjs
http://blog.stevensanderson.com/2010/07/12/editing-a-variable-length-list-knockout-style/
Having said that, I think your problem isn't so much on the knockout side and more on the how to databind the data correctly on the server side. In the link above, Steven uses a FromJson attribute to model bind which you may find useful...
HTH
How can I write code in View so as to access the groupby fields in linq. Here the data is rendered through a web service.
public class HomeController : Controller
{
public ActionResult Index()
{
ViewBag.Message = "Find Member";
var obj = new SearchMemberServiceClient();
List<MemberProxy> members = obj.FindMember("Mason", "Birkes", "", "", "", "").Members;
var sorted = from a in members
orderby a.FirstName ascending
group a by new { a.FormattedFullName, a.PersonId, a.Associations, a.MembershipsProxy[0].MembershipId } into k
select new { formattedname = k.Key.FormattedFullName, id = k.Key.PersonId, assoc = k.Key.Associations, memprox = k.Key.MembershipId };
return View(sorted.ToList());
}
}
You are passing an anonymous object to your view. Anonymous objects are emitted as internal by the compiler. Internal classes can only be used within the same assembly. ASP.NET MVC views are dynamically compiled by the ASP.NET runtime in separate assemblies. This basically means that you cannot access the anonymous types created in your controller actions inside your views. As a consequence this means that you should absolutely never pass anonymous objects to your views. So if you cannot pass anonymous objects, well, pass a named object by creating one. In this case they will be called a view model. A view model is class that you specifically define to meet the requirements of your view.
So what are the requirements of your view is the first question you should ask yourself when designing an ASP.NET MVC application? Well, in this case you seem to need a couple of properties (formattedname, id, assoc and memprox). Great, let's write a view model:
// you probably want to find a more suitable name
public class MyViewModel
{
public int Id { get; set; }
public int MemProx { get; set; }
public string FormattedName { get; set; }
public IEnumerable<Association> Associations { get; set; }
}
and then have your action pass this view model to the view:
public ActionResult Index()
{
var obj = new SearchMemberServiceClient();
var members = obj.FindMember("Mason", "Birkes", "", "", "", "").Members;
IEnumerable<MyViewModel> sorted =
from a in members
orderby a.FirstName ascending
group a by new
{
a.FormattedFullName,
a.PersonId,
a.Associations,
a.MembershipsProxy[0].MembershipId
} into k
select new MyViewModel
{
FormattedName = k.Key.FormattedFullName,
Id = k.Key.PersonId,
Associations = k.Key.Associations,
MemProx = k.Key.MembershipId
};
return View(sorted.ToList());
}
OK, now you can strongly type your view to this view model and present the information that it contains however you want:
#model IEnumerable<MyViewModel>
#foreach (var item in Model)
{
<div>#item.FormattedName</div>
...
}
I would like to use Linq and strongly typed views in the right way. at the moment I do the following:
Make a Model to verify agianst:
public class Menu
{
public int Id { get; private set; }
public string Text { get; private set; }
public string Action { get; private set; }
public string Controller { get; private set; }
public string Parameter { get; private set; }
public string Langue { get; private set; }
public Menu(int id, string controller, string action, string parameter, string text)
{
Id = id;
Controller = controller;
Action = action;
Text = text;
Parameter = parameter;
}
Use Linq to get the data from the database into the model:
public static List<Menu> GetTabListForMenu(string langue)
{
Page_dbEntities entity = new Page_dbEntities();
var tabList = (from ml in entity.wpmenulangue
where ml.Langue == langue
from m in entity.wpmenu
where ml.Menu == m.Id
from l in entity.wplangue
where ml.Langue == l.Langue
from p in entity.wppage
where p.Id == m.Page
select new { m.Id, p.Controller, p.Action, p.Parameter, ml.Text}).ToList();
List<Menu> menu = new List<Menu>();
foreach (var item in tabList)
{
menu.Add(new Menu(item.Id, item.Controller, item.Action, item.Parameter, item.Text));
}
return menu;
}
I am pretty convinced that this is not the optimal way to do this and have 2 questions:
When I get the data from the database I first use a var and then have to move it to the object with a foreach. this seems like a waste of both my time and less effeicent then getting it with sql.
I have been told that I can just verify up agianst the entitymodel. Even if i use multiple entities in a view. is this true? (the one telling me this wes not able to get it to work and I have not been able to find anything about it online).
I will try to look back on this post in the next couple of hours, but might have to wait 24 hours.
public static List<Menu> GetTabListForMenu(string langue)
{
Page_dbEntities entity = new Page_dbEntities();
return (from ml in entity.wpmenulangue
where ml.Langue == langue
from m in entity.wpmenu
where ml.Menu == m.Id
from l in entity.wplangue
where ml.Langue == l.Langue
from p in entity.wppage
where p.Id == m.Page
select new Menu(m.Id, p.Controller, p.Action, p.Parameter, ml.Text)
).ToList();
}
As for the validation is concerned you shouldn't use multiple entities in the view. You should use a single entity which is called ViewModel. This ViewModel is a class that represents the data on the view. If you are using DataAnnotations for validation you could decorate this view model properties with attributes that indicate how to be validated.