I've created a OData V4 Service described in the articles on the ASP.NET Homepage.
I basically have a table Events where I assign Guests to. I need additional information to this many to many relationship, so I have created a EventGuest table.
Inserting Events and inserting Guests via OData just works fine. It just doesn't want to work, as soon as I want to insert related entities.
This is my Controller-Code:
public async Task<IHttpActionResult> Post(EventGuest eventGuest)
{
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
_db.EventGuest.AddOrUpdate(eventGuest);
await _db.SaveChangesAsync();
return Created(eventGuest);
}
And this is how I want to insert the relationship. For the Client Code I use the official T4 template.
var ev = container.Event.FirstOrDefault();
var guest = container.Guest.FirstOrDefault();
var evGuest = new EventGuest();
evGuest.Guid = Guid.NewGuid();
container.AddObject("EventGuest", evGuest);
container.SetLink(evGuest, "Event", ev);
container.SetLink(evGuest, "Guest", guest);
container.SaveChanges();
The request sent to the Server doesn't look too bad for me:
{"#odata.type":"#Entities.EventGuest","CreationTimestamp":"0001-01-01T00:00:00Z","Guid":"adf500e3-e3a1-4841-883e-2322ed863321","ID":0,"Event#odata.bind":"http://localhost/odata/Event(1)","Guest#odata.bind":"http://localhost/odata/Guest(1)"}
So the Server tries to use #odata.bind, but unfortunately in the POST-Method of the Controller the referenced entities "Guest" and "Event" are null.
Have you tried following the example at the MSDN Documentation? I noticed it always uses AddLink rather than SetLink, even in the SetLink documentation.
MSN Article is here: DataServiceContext.SetLink Method
Related
I'm very new to developing mobile applications with telerik appbuilder. There are some things I have a hard time to understand with fetching data from Everlive.
Lets consider a simple example. Lets say I have Blog Posts and Comments that belong to those Posts. And both Posts and Comments are made by Users.
In one view I want to present the Post with corresponding Comments and I also need the Username of the User who posted the Comment (Comment table only contains userId).
Both the Post and the Comments are easy to fetch since I have the id of the Post. But how do I fetch the corresponding user for each Comment?
The FriendsApp example does something very similar but it uses this line to get the user:
var user = $.grep(app.Users.users(), function (e) {
return e.Id === userId;
})[0];
This fetches all users and filters them client side? I guess this is okay if you have like 10 users. But what if you have a million users?
I am guessing that the FriendsApp uses this way of resolving the relations just for keeping the simplicity of the sample. Everlive offers a far more meaningful toolset for resolving relation fields called Expand. You can explore the REST API here:
http://docs.telerik.com/platform/backend-services/development/rest-api/relations/simple-expanding
or the JS SDK function here:
http://docs.telerik.com/platform/backend-services/development/javascript-sdk/relations/simple-expanding.
As the Friends app uses the Kendo UI data source component you can send an Expand header with the request. The following configuration of the data source will return the DisplayName of the user in each Activity/Comments entity:
var expandObject = {
"CreatedBy": {
"ReturnAs": "User",
"SingleField": "DisplayName"
}
};
var dataSource = new kendo.data.DataSource({
type: "everlive",
transport: {
typeName: 'Activities', // replace this with Comments
read: {
beforeSend: function (xhr) {
xhr.setRequestHeader("X-Everlive-Expand", JSON.stringify(expandObject))
},
}
},
schema: {
model: {
id: Everlive.idField
}
}
});
dataSource.fetch(function (data) {
console.log(data.items);
});
Same could be applied for resolving the comments for each Blog post. Given the Friends data schema you will need to use the External Relation resolver of the Everlive API. Note that it is available only in a GetById scenario, e.g. when retrieving an Activity by Id, you can resolve the Comments that point to this activity, which is generally very handy in master-detail views.
Following code converts the ViewModel query to model and then converts the returned result back to ViewModel as PageResult. All this works fine but when I try to use include as part of my default query(or even with the latest version as part of querycontext) then OData formatter plays funny and doesn't include child elements. I have debugged and confirmed that it actually contains child elements. This only happens for controllers that I extended from ODataController(so basically for the ones that are extended from ApiController all works fine but i need results in OData format).
Please note that I have also tried with the latest nightly build(Microsoft.Data.OData 5.5.0.0) and still it doesn't work for me.
Any help would highly be appreciated.
public class ProductsController : ODataController
{
APPContext context = new APPContext();
public PageResult<ProductViewModel> Get(ODataQueryOptions QueryOptions)
{
EdmModel model = new EdmModel();
ODataQueryContext queryContext = new ODataQueryContext(model.GetEdmModel(), typeof(Product));
var mappedQuery = new ODataQueryOptions(queryContext, QueryOptions.Request);
var results = new List<ProductViewModel>();
foreach (var result in mappedQuery.ApplyTo(this.context.Serials.Include("Status").Include("Category")))
{
AutoMapper.Mapper.CreateMap(result.GetType(), typeof(ProductViewModel));
results.Add(AutoMapper.Mapper.Map<ProductViewModel>(result));
}
PageResult<ProductViewModel> pr = new PageResult<ProductViewModel>(results.AsEnumerable<ProductViewModel>(), mappedQuery.Request.GetNextPageLink(), mappedQuery.Request.GetInlineCount());
return pr;
}
}
In OData related entities are represented as navigation links. So, if you have a customers feed, the related orders for each customer will not be part of the customers feed. Instead, they would be represented as navigation links. You can explicitly tell the OData service to expand the related entities using the $expand query option. So, if you want the related orders for each customer to be expanded, you should ask for the url ~/Customers?$expand=Orders.
I've managed to create number of readonly Web Api OData services following the tutorials here: http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api. I'm therefore employing the ODataConventionModel builder to create the model from a set of entities (incidentally coming from a Telerik ORM). This all seems to work fine and I can happily issue queries, view the metadata and so forth on the service.
I've now tried to turn my attention to the other CRUD operations - firstly Create and have stumbled into a problem! Namely, the Post method fires correctly (CreateEntity) but the entity parameter is null - by doing a check against the ModelState.IsValid, it shows that the problem is a null ID (key) value. This is unsurprising because the database uses a Database Generated Identity for the ID column and therefore the ID would be created when the entity is saved into the database context.
I've therefore tried all sorts of ways of marking the ID column as database generated, but haven't managed to find anything. Strangely, I can't seem to find even one post of someone asking for this - surely I can't be the only one?!
I noted that when looking at the EF modelbuilder (for example here: http://forums.asp.net/t/1848984.aspx/1) there appears to be a means of affecting the model builder with a .HasDatabaseGeneratedOption property, but no similar option exists in the System.Web.Http.OData equivalent.
So the questions therefore are:
Is there a means of altering the model builder (or something else) so that the controller will accept the object and deserialize the entity even with a null key value?
If so, how can I do this?
If not, any suggestions as to other options?
I realise that I could potentially just populate the object with an (in this case) integer value from the client request, but this seems a) semantically wrong and b) won't necessarilly always be possible as a result of the client toolkit that might be used.
All help gratefully received!
Many thanks,
J.
You need to create a viewmodel for insert which does not contain the ID parameter. Use Automapper to map the properties of the incoming insert-model to your data entities.
The problem that you're having is that ID is a required attribute in your data model because it is your PK, except during insert, where it shouldn't be specified.
In my case, my database-generated key is a Guid.
As a work-around, in my TypeScript client code, I submit (via http POST) the object with an empty Guid like this: Note: ErrorId is the key column.
let elmahEntry: ELMAH_Error = {
Application: 'PTUnconvCost',
Host: this.serviceConfig.url,
Message: message,
User: that.userService.currentUserEmail,
AllXml: `<info><![CDATA[\r\n\r\n${JSON.stringify(info || {})}\r\n\r\n]]></info>`,
Sequence: 1,
Source: source,
StatusCode: 0,
TimeUtc: new Date(Date.now()),
Type: '',
ErrorId: '00000000-0000-0000-0000-000000000000'
};
Then, in my WebApi OData controller, I check to see if the key is the empty guid, and if so, I replace it with a new Guid, like this:
// POST: odata/ELMAH_Error
public IHttpActionResult Post(ELMAH_Error eLMAH_Error)
{
if (eLMAH_Error.ErrorId == Guid.Empty)
{
eLMAH_Error.ErrorId = Guid.NewGuid();
}
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
db.ELMAH_Error.Add(eLMAH_Error);
try
{
db.SaveChanges();
}
catch (DbUpdateException)
{
if (ELMAH_ErrorExists(eLMAH_Error.ErrorId))
{
return Conflict();
}
else
{
throw;
}
}
return Created(eLMAH_Error);
}
I am new to MVC and EF and I have a question.
I have built a site with models views controllers etc.
On an edit view for a Case (pretty big model so I won't post it here) I have a FK to a Customer model using CustomerID. When a user selects a customer id from a drop down list, I would like to display CustomerName, CustomerPhone etc after the selection of the ID. I think I might need to do a post back for this to work?
Also, do I need to Include the related entities as part of the initial data "get"? I have read some detail on that but I dont fully understand how that needs to work.
Please let me know if I should post more info. Thanks!
Here is my ActionResult for Edit
public ActionResult Edit(int id)
{
Cases cases = db.Cases.Find(id);
//related data needs to loaded to show related data fields
//include related data entities
var v = db.Cases.Include("Customers");
ViewBag.TechnicianID = new SelectList(db.Technicians, "TechnicianID", "LastName", cases.TechnicianID);
ViewBag.BranchID = new SelectList(db.Branches, "BranchID", "BranchName", cases.BranchID);
ViewBag.EngineModelID = new SelectList(db.EngineModels, "EngineModelID", "EngineModelName", cases.EngineModelID);
ViewBag.CaseCategoryID = new SelectList(db.CaseCategories, "CaseCategoryID", "CategoryName",cases.CaseCategoryID);
ViewBag.Qualified = new SelectList(new[] { "YES", "NO", "PARTIALLY" });
ViewBag.CaseStatus = new SelectList(new[] { "OPEN/IN PROCESS", "CLOSED" });
return View(cases);
}
The line
var v = db.Cases.Include("Customers")
is what I am trying to use to load related customer data and then show in my edit view like this:
#Html.EditorFor(model => model.Customer.CustomerName)
Well it depends on what you are trying to do. You could include a model which holds all the required data and send it with every call on that page (initial empty ofcourse)
Once you selected the customer, do post-back and send the customerId to your application and return the same page with the desired model.
You could do that via AJAX too.
Also, do I need to Include the related entities as part of the initial data "get"?
Not sure if I understand what you are trying to say. You mean that you think you would have to send all customer's data down to the page and select the related data on client side?
I am trying to build an ADO.NET Data Service with lots of entities and a few service operations. On one side I created a ASP.NET Web Application, in which an ADO.NET Entity Data Model and an ADO.NET Data Service are located. On the other side I created a second ASP.NET Web Application that has a Service Reference to the Data Service.
Entities are coming through very well, I can use LINQ to retrieve the data I want:
TestEntities entities = new TestEntities(
new Uri("http://localhost/service/service.svc"));
var query = from customer in entities.Customers
where customer.ID == 1234
select customer;
query.ToList();
This works. However, retrieving information through Service Operations completely eludes me.
Data Service-side code:
public static void InitializeService(IDataServiceConfiguration config) {
config.SetEntitySetAccessRule("*", EntitySetRights.All);
config.SetServiceOperationAccessRule("*", ServiceOperationRights.All);
}
[WebInvoke]
public IQueryable<Customer> GetSomeCustomers() {
TestEntities entities = new TestEntities();
return from customer in entities.Customers
where customer.ID > 0 && customer.ID < 20
select customer;
}
When I added the Service reference to my client project, Visual Studio didn't pick up on any Service Operations. I know I can access them through constructed URIs and the BeginExecute method of either the DataServiceContext object or the TestEntities object (in this case), or something like that, but that is not how I want it.
What I want is to use LINQ to go through the returned data of the Service Operation.
Is this possible? It should be, right?
Simple stuff once you know.
Just a few things to know:
Currently DataServiceClientGenerator (which uses the EntityClassGenerator) doesnt create methods for the service operations.
Using CreateQuery method on the context is not supported for service operations, currently they work because there is no validation on the client side for that (you will notice that if you use CreateQuery the "()" is added to the end of the Query Method like this "http://localhost/service.svc/method()?parameter=2", you can use CreateQuery but it is not recommended.
Not all Service operations return values, but for this example i will only show an example for the ones that do.
public partial class NorthwindEntities
{
public IQueryable<Order> OrdersByRegion(int regionId)
{
return this.Execute<Orders>(new Uri(string.Format("{0}OrdersByCountry?regionId={1}", this.BaseUri, regionId), UriKind.RelativeOrAbsolute));
}
}
If you require more information please feel free to ask any questions.
PS.: On your example you dont need to create a new data context on your service operation (server side) the DataService has already a reference instantiated when the service is called.
You can actually override the create of the data context on the service side like this:
protected override NorthwindEntities CreateDataSource()
{
return new NorthwindEntities();
}