In my application, I have a Web API controller which should be adding an entity of type "Source" to my DB, then returning the created Source. Source contains a list/collection of "SourceFields", which are themselves made up of a number of fields. Source also inherits from a base entity which I use for change tracking, and which contains fields like date created, date modified, etc.
Using Postman, I've tested my API and verified that it properly returns when I post a Source, and it includes all of objects that are created. However, when I use Angular 2 HTTP with RxJS Observables to post, the value which is returned has dropped all of the base entity fields, as well as the sourcefields. I use a Source class in Angular 2 to do operations, but I don't use it anywhere in the calls, so I don't think it's being typecasted or coerced? The only way I've gotten the source response to return properly (i.e. including the base entity properties) is if I set sourcefields to null in the API POST method.
This dataservice does work perfectly with simple entities. For example, I have a client entity that doesn't contain a collection like sourcefields, and it returns the base entity fields just fine.
Any ideas?
My API POST method:
// POST api/Sources
[HttpPost]
public IActionResult Post([FromBody]Source source)
{
if (source == null)
{
return BadRequest();
}
dbContext.Sources.Add(source);
dbContext.SaveChanges();
//Hack to get source to return properly
//source.SourceFields = null;
return CreatedAtRoute("GetSource", new { id = source.SourceId }, source);
}
Angular 2 Dataservice method:
public Add (action: string, itemToAdd: any): Observable<any> {
var toAdd = JSON.stringify(itemToAdd);
return this._http.post(this.actionUrl + action, toAdd, { headers: this.headers })
.map(res => res.json())
.catch((error: any) => Observable.throw(error.json().error || 'Server Error'));
}
The place I'm subscribing to the dataservice:
this.addEditSource.sourceFields = this.sourceFields;
this._dataService.Add('Sources', this.addEditSource).subscribe(source => {
this.sources.push(source)
},
error => console.log(error));
If anyone wants to see my entity models or anything I can add them.
Related
I have a problem with EF Core 5 that is really getting me down.
FYI, LazyLoadingProxies are used (something else that just gives me a headache, but well, different topic).
Information for the code below:
Service: A service per entity, contains all CRUD operations into the database and other methods if needed.
Workflow: Uses multiple services at once to perform certain operations (e.g. create product -> create product folder -> save product).
Problem:
I have an entity "Product" which contains the following update method which is used to update the properties of the entity with those of another object:
public override void Update(Product source)
{
// Properties
AnnualPrice = source.AnnualPrice;
...
// Relations
var sourceRelatedProductIds = source.RelatedWithProductIds.Where(x => x != Id);
if (sourceRelatedProductIds.Count() != 0)
{
RelatedWithProducts.Clear();
foreach (var relatedWithProduct in ctx.Set<Product>().Where(x => source.RelatedWithProductIds.Contains(x.Id)).AsNoTracking())
{
RelatedWithProducts.Add(relatedWithProduct);
}
}
var oldShortDescriptions = ShortDescriptions.ToList(); <--- EXCEPTION
ShortDescriptions.Clear();
foreach (var shortDescription in source.ShortDescriptions)
{
shortDescription.Id = oldShortDescriptions.FirstOrDefault(x => x.Culture == shortDescription.Culture)?.Id ?? 0;
ShortDescriptions.Add(shortDescription);
}
...
}
In the line with the arrow and "Exception", I get the following exception:
System.InvalidOperationException: 'The instance of entity type 'Product' cannot be tracked because another instance with the key value '{Id: 1}' is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached.'
In itself, I understand what the exception is trying to tell me. My problem is that I can't find the reason for it anywhere. Because as far as I can tell, the product with ID 1 can't be tracked yet.
Of course, the problem is not in the update method, but before it, so here is the rest of the code.
ProductController.Update:
[HttpPut("update")]
public IActionResult Update(C.Product[] products)
{
if (!ModelState.IsValid)
{
return UnprocessableEntity(ModelState.Values.SelectMany(x => x.Errors));
}
var dbProducts = products.Select(ToDatabase).ToArray(); <--- Just converts the given client model into a Database model
var result = productWorkflow.Update(dbProducts); <--- Calls a workflow class, NOT the update method of the entity
return CoreToActionResultConverter.ToActionResult<Db.Product>(result);
}
ProductWorkflow.Update:
public ResultBase Update(params Product[] products)
{
var result = productService.AddOrUpdate(products); <--- This calls the Service CRUD AddOrUpdate method
if (result is not ServiceResult<Product>)
{
return result;
}
return new ServiceResult<Product>(ResultType.AddedOrUpdated);
}
ProductService.AddOrUpdate:
public virtual ResultBase AddOrUpdate(IEnumerable<TEntity> entities)
{
var currentEntities = new List<TEntity>();
foreach (var entity in entities)
{
var currentEntity = Get(entity.Id); <--- This line is the only one where I could imagine that it is already tracked here. The problem is only that it does not work ONLY with the workflow. If I call my AddOrUpdate method from the controller, which directly calls THIS method, it works (although this line is just executed the same way).
if (currentEntity == null)
{
currentEntity = Ctx.CreateProxy<TEntity>();
Ctx.Attach(currentEntity);
}
if (currentEntity != entity)
{
currentEntity.Update(entity);
}
currentEntities.Add(currentEntity);
}
Ctx.AddRange(currentEntities.Where(x => x.Id == 0));
Ctx.UpdateRange(currentEntities.Where(x => x.Id != 0));
try
{
Ctx.SaveChanges();
}
catch (DbUpdateException ex)
{
// Commented out the error handling to remove unnecessary things for the post
}
return new ServiceResult<TEntity>(ServiceResult.ResultType.AddedOrUpdated, currentEntities);
}
I found the problem and it was not on the line where the exception was thrown, but before.
In my Product.Update() method (the first code snippet), I get the Related Products by ID and add them to the list (Simply a Many to Many relationship, from Product <--> Product). When calling Update, I specified ID 1 in the RelatedProductIds, however the entity itself also has ID 1, so it references itself. I have now just fixed that by omitting the ID, if the same as the object itself.
This still doesn't explain why it works with a breakpoint, because it's still tracked in that case (or not tracked, since I'm using AsNoTracking(), but good).
I will state up front I am still very new to asp.net core and entity framework but I am familiar with ADO and recordset which it seems entity framework is built from. I am struggling to use entity framework because I am able to run the query but I am not sure how to use the results and most help docs I see online only discuss the procedures and methods and not how to use the results. I am building login functionality on my site and have developed the following code to query DB in my UserAccount table. FOr this login I really only want the Username, Password, and the ID however I have multiple fields in this table that I dont need for this aspect. I come from using ADO and recordsets so really I just prefer to use raw sql and determine what i want to do with those results and not bind them to some objects which it seems entity framework does for the most part. I do liek the ease of use of the entity framework and using parameters though so I prefer to just go this route (not sure if this is bad practice or not). Everything works great except when I add ToList it starts to say error "InvalidOperationException: The required column 'AccessLevel' was not present in the results of a 'FromSql' operation." I am not even tryign to use that field in the query so not sure why that is even coming up and I am using a rawsql query method so why is it trying to see what I have in the model for that table? Lastly, this shoudl return a single record in which case I want to pull the password value from that record field similar to how i use to do in ADO as you will see in my passwordhash verification but I cannot figure out how to even pull that from the query result. Thanks for any help on this as I am getting a headache trying to learn this stuff!!
var UserResults = _context.UserAccounts.FromSqlInterpolated($"SELECT USERACCOUNT.USERNAME, USERACCOUNT.PASSWORD, USERACCOUNT.ID,USERACCOUNT.ACCESS_LEVEL FROM DBO.USERACCOUNT WHERE USERACCOUNT.USERNAME={UserName}");
if (UserResults.Count() == 1) //if we have more than 1 result we have security issue so do not allow login
{
var passwordHasher = new PasswordHasher<string>();
var hashedPassword = passwordHasher.HashPassword(null, Password);
var testResults = UserResults.ToList();
if (passwordHasher.VerifyHashedPassword(null, hashedPassword, THIS SHOULD BE VALUE FROM DB RIGHT HERE!!!) == PasswordVerificationResult.Success)
{
var claims = new List<Claim>
{
new Claim(ClaimTypes.Name, UserName)
};
My DBContext is as follows:
public partial class LoginDBContext : DbContext
{
public DbSet<UserAccount> UserAccounts { get; set; }
public LoginDBContext(DbContextOptions<LoginDBContext> options) : base(options)
{
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<UserAccount>(entity =>
{
//entity.ToTable("UserAccount");
entity.HasNoKey();
//entity.Property(e => e.Id)
// .HasMaxLength(50)
// .IsUnicode(false);
//entity.Property(e => e.Username)
// .HasMaxLength(50)
// .IsUnicode(false);
//entity.Property(e => e.Password)
// .HasMaxLength(50)
// .IsUnicode(false);
});
}
}
If you don't want to load all columns of the user table you can return anonymous object with properties you need or create a class for the columns you need and return it.
var users = _context.UserAccounts
.Where(a => a.UserName == UserName)
.Select(a => new { a.Id, a.UserName, a.Password })
.ToArray();
if (users.Length == 1)
{
var user = users.First();
if (passwordHasher.VerifyHashedPassword(null, hashedPassword, user.Password) == PasswordVerificationResult.Success)
{
// ... your magic
}
}
I have a very simple question.
In Java code, I used to use Data Transfer Objects for Requests / Responses.
For example, in my Spring webapp I was creating some request dto, like
public class SaveOfficeRequest {
private String officeName;
private String officePhone;
private String officeAddress;
/* getters / setters */
}
After that i had controller with "mapped" method like
#ResponseBody
public SaveOfficeResponse saveOffice(#RequestBody SaveOfficeRequest) { ... }
.
Every request is json request. When some controller method was called i converted request dto to domain dto entities and do some business logic.
So!
Should I save the practice in my new scala project based on Play Framework?
Case classes can be used to represent the request and response objects. This helps make the API explicit, documented and type-safe, and isolate concerns, by avoiding to use domain objects directly in external interface.
For example, for a JSON endpoint, the controller action could use a pattern like this:
request.body.asJson.map { body =>
body.asOpt[CustomerInsertRequest] match {
case Some(req) => {
try {
val toInsert = req.toCustomer() // Convert request DTO to domain object
val inserted = CustomersService.insert(toInsert)
val dto = CustomerDTO.fromCustomer(inserted)) // Convert domain object to response DTO
val response = ... // Convert DTO to a JSON response
Ok(response)
} catch {
// Handle exception and return failure response
}
}
case None => BadRequest("A CustomerInsertRequest entity was expected in the body.")
}
}.getOrElse {
UnsupportedMediaType("Expecting application/json request body.")
}
I have written a REST service using Web API and after reading sections of this Web API Design from Brian Mulloy, was trying to figure out how I could implement associations with Web API.
Web API Design Extract:
Associations
Resources almost always have relationships to other
resources. What's a simple way to express these relationships in
aWebAPI?
Let's look again at the API we modeled in nouns are good,
verbs are bad -theAPI that interacts with our dogs resource.
Remember, we had two base URLs: /dogs and dogs/1234.
We're using HTTP
verbs to operate on the resources and collections. Our dogs belong to
owners. To get all the dogs belonging to a specific owner, or to
create a new dog for that owner, do a GET or a POST:
GET /owners/5678/dogs
POST /owners/5678/dogs
Now, the relationships can be
complex. Owners have relationships with veterinarians, who have
relationships with dogs, who have relationships with food, and so on.
It's not uncommon to see people string these together making a URL 5
or 6 levels deep. Remember that once you have the primary key for one
level, you usually don't need to include the levels above because
you've already got your specific object. In other words, you shouldn't
need too many cases where a URL is deeper than what we have above
/resource/identifier/resource.
So I tried to add a controller method for the association like follows:
public class EventsController : ApiController
{
// GET api/events
public IEnumerable<Event> Get()
{
// get list code
}
// GET api/events/5
public Event Get(int id)
{
// get code
}
// POST api/events
public void Post([FromBody]Event evnt)
{
// add code
}
// POST api/events/5
public void Post(int id, [FromBody]Event evnt)
{
// update code
}
// DELETE api/events/5
public void Delete(int id)
{
// delete code
}
// GET api/events/5/guests
public IEnumerable<Guest> Guests(int id)
{
// association code
}
}
I also modified my route templates to the following:
config.Routes.MapHttpRoute("ApiWithAssociations",
"api/{controller}/{id}/{action}");
config.Routes.MapHttpRoute("DefaultApi",
"api/{controller}/{id}",
new { id = RouteParameter.Optional });
Unfortunately, when I do an update/post of the event resource I now get a HTTP 500 Internal Server Error with a response body stating
Multiple actions were found that match the request
I've tried modifying the route templates in conjunction with adding System.Web.Http.HttpPostAttribute (and other HTTP verbs) as well but to no avail.
Has anyone tried this and got it working? Any help would be appreciated. If it is absolutely not possible to have multiples for an http verb then I guess I'll have to abandon associations with my REST service.
EDIT: SOLUTION
Using Radim Köhler's answer, I was able to get this working. Add the HttpGetAttribute to the Guests method like so:
// GET api/event/5/guests
[HttpGet]
public IEnumerable<Guest> Guests(int id)
{
// association code
}
And added an addition route to cater for the default GET action like follows:
config.Routes.MapHttpRoute("DefaultGet",
"api/{controller}/{id}",
new {action = "Get"},
new {httpMethod = new HttpMethodConstraint(HttpMethod.Get)});
config.Routes.MapHttpRoute("ApiWithAssociations",
"api/{controller}/{id}/{action}");
config.Routes.MapHttpRoute("DefaultApi",
"api/{controller}/{id}",
new {id = RouteParameter.Optional});
The solution, could be in an explicit POST mapping
Just add new definition, which will be used for events/5 POST
// explicit Post() mapping
config.Routes.MapHttpRoute(
name: "DefaultPost",
routeTemplate: "api/{controller}/{id}",
defaults: new { action = "Post" }
, constraints: new { httpMethod = new HttpMethodConstraint(HttpMethod.Post) }
);
// existing
config.Routes.MapHttpRoute("ApiWithAssociations",
"api/{controller}/{id}/{action}");
config.Routes.MapHttpRoute("DefaultApi",
"api/{controller}/{id}",
new { id = RouteParameter.Optional });
I have a Vehicle with an association to Model, Model has an association to Make.
Here is my Generic Repository as pertaining to associations as LazyLoadingEnabled = false in my project:
public IQueryable<T> IncludeMultiple<T1>(params Expression<Func<T, object>>[] associations) where T1 : class
{
var source = (IQueryable<T>)DbContext.Set<T>();
if (associations != null)
{
foreach (Expression<Func<T, object>> path in associations)
source = DbExtensions.Include<T, object>(source, path);
}
return source;
}
In my api controller, I am using Unit of work pattern. Here is my GetAll method:
public IEnumerable<Vehicle> GetAll()
{
var vehicles = Uow.VehicleRepository.IncludeMultiple<Vehicle>(c => c.VehicleModel).ToList();
return vehicles;
}
Everything works fine and Json retrieves the Vehicle class data as well as the related VehicleModel class data.
However, Vehicle has no direct association to VehicleMake, only VehicleModel does. Now, if my GetAll method has this:
public IEnumerable<Vehicle> GetAll()
{
var vehicles = Uow.VehicleRepository.IncludeMultiple<Vehicle>(c => c.VehicleModel, c => c.VehicleModel.VehicleMake).ToList();
return vehicles;
}
while I see in debug that vehicles does indeed have the vehicles and their relevant VehicleModel and VehicleMake data, it returns a Http 500 error in Fiddler.
Update:
Added another association in Vehicle called "Test", with the GetAll method being:
(c => c.VehicleModel, c => c.Test)
No error, all data was returned via fiddler. So, it appears that a "Non-direct association" (ie Vehicle -> VehicleMake) is the cause of the error.
Question:
What would be the correct way to retrieving the relevant Vehicle data and its associated classes' data and return it to Json while not getting a Http 500 error?
*SOLVED *
This works:
public HttpResponseMessage GetAll()
{
var vehicles = from data in Uow.VehicleRepository.IncludeMultiple<Vehicle>(c => c.VehicleModel,c => c.VehicleModel.VehicleMake)
select new
{
VehDesc = data.Description,
VehVIN = data.VIN,
VehTransmissionType = data.TransmissionType,
VehFuelType = data.FuelType,
VehYear = data.Year,
VehMileage = data.Mileage,
VehCylinderSize = data.CylinderSize,
VehEngineSize = data.EngineSize,
VehVehicleModel = data.VehicleModel.Name,
VehMakeName = data.VehicleModel.VehicleMake.Name
};
return Request.CreateResponse(HttpStatusCode.OK, vehicles);
}
Basically,
1. I used an HttpResponseMessage as my return type;
2. I used projection to create an anonymous type;
Why did I have to do this?
As near as I can tell, the issue centered on JSON receiving a "circular" return with VehicleModel and VehicleMake. That is, VehicleModel had a association to VehicleMake and VehicleMake has a collection of VehicleModels. When I looked in my debug code I could see a cascade of VehicleModel to VehicleMake to VehicleModel, etc, etc, etc, so to me that meant it was circular.
If anyone knows a better way w/o using anonymous type nor removing the virtual keyword from my navigation properties, I would certainly like to know it. But this does truly work.
FinalNote: Be sure NOT to use the model's property names in anonymous type, ie replace property "TransmissionType" with something like "VehTransmissionType".