I'm using WCF OData service as my application Data Provider.OData service expose a entity that I don't want to get whole entity,I create LINQ query to get projection from this Entity.
But i have error in OData Service.This is my code:
from n in NewsInfos
select new NewsInfos
{
n.NewsId,
n.NewsTitle,
n.NewsLead,
n.NewsDate
};
This is entire code:
[System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)]
public class NewsDataService : DataService<NewsODataModel>
{
public static void InitializeService(DataServiceConfiguration config)
{
config.SetEntitySetAccessRule("*", EntitySetRights.AllRead);
config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;
config.DataServiceBehavior.AcceptProjectionRequests = true;
}
}
Yes, WCF Data Services and OData support projection. Projection is codified in the URL with the $select system query option, e.g.: http://services.odata.org/Experimental/OData/OData.svc/Products?$select=Name&$format=json. The LINQ Provider in the client bits enable this similarly to what you've shown in your example. Here is one such example:
using System;
using System.Data.Services.Client;
using System.Linq;
namespace Scratch
{
public class Program
{
public static void Main()
{
var context = new DataServiceContext(new Uri("http://services.odata.org/OData/OData.svc/"));
var categories = context.CreateQuery<Category>("Categories").Select(c => new { c.Name });
Console.WriteLine("context.Categories.Where(...): {0}", categories);
foreach (var category in categories)
{
Console.WriteLine(category.Name);
}
}
}
public class Category
{
public int ID { get; set; }
public string Name { get; set; }
}
}
One thing to consider with projection is that the magic in our client-side bits frequently requires you to use anonymous objects (hence the new { c.Name }).
Your error may be unrelated; if you're still getting the error after reading this can you update your service to return verbose errors as per http://blogs.msdn.com/b/phaniraj/archive/2008/06/18/debugging-ado-net-data-services.aspx? My guess is that you may be missing the [DataServiceKey] attribute on NewsInfos.
Just return an anonymous object from your select and it should work.
from n in NewsInfos
select new
{
n.NewsId,
n.NewsTitle,
n.NewsLead,
n.NewsDate
};
Related
I have a custom DbContext SnowflakeDbContext that I need to initialize with a SnowflakeDbConnection for it to work:
public class SnowflakeDbContext : DbContext
{
private readonly string connectionString = "";
public SnowflakeDbContext(DbContextOptions<SnowflakeDbContext> options) : base(options)
{
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
base.OnConfiguring(optionsBuilder);
var dbConnection = new SnowflakeDbConnection()
{
ConnectionString = this.connectionString
};
optionsBuilder.UseSqlServer(dbConnection);
optionsBuilder.AddInterceptors(new SnowflakeCommandInterceptor());
}
public DbSet<Opportunity> Opportunities { get; set; } = default!;
public DbSet<Account> Accounts { get; set; } = default!;
}
This works well with EF Core 5, were in Startup.cs (I am using an ASP.NET Core 5 web application) I use
.AddDbContext<SnowflakeDbContext>(ServiceLifetime.Singleton)
I want to use the SnowflakeDbContext with HotChocolate where it is recommended that I use AddPooledDbContextFactory<> in order to support pooling of connections and allowing the system to make simultaneous calls (described here).
I have modified Startup.cs:
public void ConfigureServices(IServiceCollection services)
{
services
.AddPooledDbContextFactory<SnowflakeDbContext>(options =>
{
var dbConnection = new SnowflakeDbConnection()
{
ConnectionString = this.connectionString
};
options.UseSqlServer(dbConnection);
options.AddInterceptors(new SnowflakeCommandInterceptor());
})
.AddGraphQLServer()
.AddQueryType<Query>();
}
Using the following GraphQL query (which uses parallel queries):
query GetAccountsInParallel {
a: accounts {
id, name
}
b: accounts {
id, name
}
c: accounts {
id, name
}
}
I get the following error:
"No service for type 'SnowflakeGraphQL.Snowflake.SnowflakeDbContext' has been registered.",
I can add
.AddDbContext<SnowflakeDbContext>()
in Startup.cs after the call to .AddPooledDbContextFactory<>. Now I get a different error:
"A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext."
All of the examples I have seen on the web use .UseSqlServer(connectionString) where as I need to use the .UseSqlServer(dbConnection) version in order to be able to access our Snowflake database.
How do I configure my application in Startup.cs to use .AddPooledDbContextFactory()?
Update: Starting with the graphql-workshop code and replacing Sqlite with first SqlServer and then SqlServer using my SnowflakeDbContext I get it to work, so there must be a subtle difference somewhere in my code as described above that results in a failure in my case.
When retrieving the accounts records, we need to use the [ScopedService] rather than the [Service] like this:
[UseApplicationDbContext]
public async Task<List<Account>> GetAccounts([ScopedService] SnowflakeDbContext context) => await context.Accounts.ToListAsync();
I'm trying to implement authorization in my ASP.NET Core 2.0 Web app.
This app has like 20 models, each with a controller implementing at least a CRUD. I found these two pages and I liked the idea of using a handler to authorize requisitions. I would like initially to implement authorization by user, i.e., a user has only permission to see/edit his own entities. All my database entities have an OwnerId field.
These examples I found seem to only work for one specific controller.
So, my question is: is it possible to create one authorization handler for all controllers?
Have you found a solution or workaround yet that works with the authorization handler or authorization attributes? I have the exact same setup as you do.
I was trying to create a generic attribute to serve all may Entity CRUD owner checks, but generic attributes are not allowed by design.
The only two (unsatisfying) solutions that I came up with are:
Within the controller action, get the ownerId from the User, forward it all the way to your CRUD and include there a check for the ownerId. However, the code must be duplicated for every action in every controller.
[HttpGet("{id}"]
public async Task<IActionResult> GetById(int id)
{
var stringGuid = User.Claims.FirstOrDefault(c => c.Type == "sub")?.Value;
if (String.IsNullOrWhiteSpace(stringGuid)) return Unauthorized();
var ownerGuid = new Guid(stringGuid);
var entity = _yourCrudInstance.GetById(id, ownerGuid);
return Ok(entity);
}
Add a method to your CRUD repository like bool IsOwner(Guid ownerId) and use this method when creating the custom authorization handler (by creating a custom requirement together with a custom handler). This eliminates code duplication in the controller, because you can create a new policy with this custom authorization handler and consequently you can simply decorate every action with a [Authorize(Policy = "yourOwnershipPolicy")]. But still, there must be a service created for each and every controller. Moreover, the IsOwner(...) method adds an additional database call compared to solution 1 - one db call for checking the ownership (during authorization check) and one db call for actually getting the entity (by working through the controller action).
[Authorize(Policy = "yourOwnershipPolicy")]
public async Task<IActionResult> GetById(int id)
{
var entity = _yourCrudInstance.GetById(id);
return Ok(entity);
}
I am going with the first solution until I found a way to create a generic authorization handling for my generic CRUD repository, because one may forget creating the required authorization policy for a new entity, but one cannot forget to supply the parameter ownerId to .GetById(id, ownerGuid), provided there is no overload method, or the code doesn't compile.
Update:
I found a third solution in which was able to create a kind of generic authorization attribute. The trick was to use the type of concrete repository as input parameter in the authorization attribute. Yet, there is still a limitation: The authorization attribute must be copied for every type of Id, for example int Id, Guid id, etc. But still, this reduces repeated code to the types of ids. In most cases, people only have one type of id, probably int or Guid.
Here some code that demonstrates my architecture. It is heavily summarized and redacted, but should compile successfully. My original code is working and in production:
using System;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
[Route("api/yourcontroller")]
public class YourApiController : Controller
{
private readonly YourEntityXYZRepository _repo;
public YourApiController(YourDbContext yourDbContext)
{
_repo = new YourEntityXYZRepository(yourDbContext);
}
[HttpGet("{id}")]
[AuthorizeOwnerIntId(typeof(YourEntityXYZRepository), Policy = "YourCustomPolicy")]
public async Task<IActionResult> GetById(int id)
{
var entity = _repo.GetById(id);
return Ok(entity);
}
}
// The "generic" authorization attribute for type int id
// Similar authorization attributes for every type of id must be created additionally, for example Guid
[AttributeUsage(AttributeTargets.Method, AllowMultiple = true, Inherited = true)]
public class AuthorizeOwnerIntIdAttribute : AuthorizeAttribute, IAuthorizationFilter
{
private object _entityRepositoryObject;
private IAsyncOwnerIntId _entityRepository;
private readonly Type _TCrudRepository;
public AuthorizeOwnerIntIdAttribute(Type TCrudRepository)
{
_TCrudRepository = TCrudRepository;
}
public void OnAuthorization(AuthorizationFilterContext context)
{
var yourDbContext = context.HttpContext.RequestServices.GetService<YourDbContext>();
_entityRepositoryObject = Activator.CreateInstance(_TCrudRepository, yourDbContext);
_entityRepository = _entityRepositoryObject as IAsyncOwnerIntId;
var user = context.HttpContext.User;
if (!user.Identity.IsAuthenticated)
{
// it isn't needed to set unauthorized result
// as the base class already requires the user to be authenticated
// this also makes redirect to a login page work properly
// context.Result = new UnauthorizedResult();
return;
}
// get entityId from uri
var idString = context.RouteData.Values["id"].ToString();
if (!int.TryParse(idString, out var entityId))
{
context.Result = new UnauthorizedResult();
return;
}
// get subjectId from user claims
var ownerIdString = context.HttpContext.User.Claims.FirstOrDefault(c => c.Type == "sub")?.Value;
if (!Guid.TryParse(ownerIdString, out var ownerGuid))
{
context.Result = new UnauthorizedResult();
return;
}
if (!_entityRepository.IsEntityOwner(entityId, ownerGuid))
{
context.Result = new UnauthorizedResult();
}
}
}
// Your concrete repository
public class YourEntityXYZRepository : AsyncCrud<YourEntityXYZ, int>,
IAsyncOwnerIntId // Note that type concrete IAsyncOwnerIntId is only implemented in concrete repository
{
public YourEntityXYZRepository(YourDbContext yourDbContext) : base(yourDbContext)
{
}
}
// Your generic Crud repository
public abstract class AsyncCrud<TEntity, TId> : IAsyncCrud<TEntity, TId>
where TEntity : class, IEntityUniqueIdentifier<TId>, IEntityOwner
where TId : struct
{
protected YourDbContext YourDbContext;
public AsyncCrud(YourDbContext yourDbContext)
{
YourDbContext = yourDbContext;
}
// Note that the following single concrete implementation satisfies both interface members
// bool IsEntityOwner(TId id, Guid ownerGuid); from IAsyncCrud<TEntity, TId> and
// bool IsEntityOwner(int id, Guid ownerGuid); from IAsyncOwnerIntId
public bool IsEntityOwner(TId id, Guid ownerGuid)
{
var entity = YourDbContext.Set<TEntity>().Find(id);
if (entity != null && entity.OwnerGuid == ownerGuid)
{
return true;
}
return false;
}
// Further implementations (redacted)
public Task<bool> SaveContext() { throw new NotImplementedException(); }
public Task<TEntity> Update(TEntity entity){ throw new NotImplementedException(); }
public Task<TEntity> Create(TEntity entity, Guid ownerGuid) { throw new NotImplementedException(); }
public Task<bool> Delete(TId id) { throw new NotImplementedException(); }
public Task<bool> DoesEntityExist(TId id) { throw new NotImplementedException(); }
public virtual Task<TEntity> GetById(TId id) { throw new NotImplementedException(); }
}
// The interface for the Crud operations
public interface IAsyncCrud<TEntity, TId>
where TEntity : class, IEntityUniqueIdentifier<TId>
where TId : struct
{
bool IsEntityOwner(TId id, Guid ownerGuid);
Task<bool> DoesEntityExist(TId id);
Task<TEntity> GetById(TId id);
Task<TEntity> Create(TEntity entity, Guid ownerGuid);
Task<TEntity> Update(TEntity entity);
Task<bool> Delete(TId id);
Task<bool> SaveContext();
}
// The interface for the concrete type method for int id
// Similar interfaces for every type of id must be created additionally, for example Guid
public interface IAsyncOwnerIntId
{
bool IsEntityOwner(int id, Guid ownerGuid);
}
// Typical db context
public class YourDbContext : DbContext
{
public YourDbContext(DbContextOptions<YourDbContext> options) : base(options)
{
}
public DbSet<YourEntityXYZ> YourEntityXYZ { get; set; }
}
public class YourEntityXYZ : IEntityUniqueIdentifier<int>, IEntityOwner
{
public int Id { get; set; }
public Guid? OwnerGuid { get; set; }
// ... Additonal custom properties
}
public interface IEntityUniqueIdentifier<TId>
where TId : struct
{
TId Id { get; set; }
}
public interface IEntityOwner
{
Guid? OwnerGuid { get; set; }
}
Using Entity Framework 6, I was able to use execute a Raw SQL Query and use a custom model which was not defined in the DBContext in order to store the output of the query. A simple example is the following:
List<MyModel> data = context.Database.SqlQuery<MyModel>("SELECT Orders.OrderID, Customers.CustomerName FROM Orders INNER JOIN Customers ON Orders.CustomerID=Customers.CustomerID;").ToList();
I execute one SQL command and I expect a list of custom models.
I try to do something similar with Entity Framework Core and the closest example that I found will force me to define a property from DBContext. This will not allow me to use a custom model to fill the data that SQL server will return.
var books = context.Books.FromSql("SELECT * FROM Books").ToList();
This query informs Entity Framework Core that the query will return a list of books. Is there a way to implement something like this in Entity Framework Core?
From .NET Core 2.1:
Add modelBuilder.Query<YourModel>() to OnModelCreating(ModelBuilder modelBuilder)
Use context.Query<YourModel>().FromSql(rawSql) to get data
Here's how I was able to get this working (for completeness):
MyModel.cs:
public class MyModel
{
// The columns your SQL will return
public double? A { get; set; }
public double? B { get; set; }
}
Add class that just inherits from your original EF context class (i called mine DbContextBase):
public class DbContext : DbContextBase
{
public virtual DbSet<MyModel> MyModels { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
// Necessary, since our model isnt a EF model
modelBuilder.Entity<MyModel>(entity =>
{
entity.HasNoKey();
});
}
}
Use that class (instead of your original EF context class):
// Use your new db subclass
using (var db = new DbContext())
{
var models = await db.MyModels.FromSqlRaw(...).ToListAsync(); // E.g.: "SELECT * FROM apple A JOIN banana B ON A.col = B.col"
}
Notes:
If you need to, just use FromSqlInterpolated instead of
FromSqlRaw
The "db context" subclass allows you to update EF models without affecting your "polyfill" code
Works with SQL Server stored procs that return only 1 result set
The question was about .NET Core 2. Now I have a solution and I am going to write it here so that someone else could use it in case he/she needs it.
First of all we add the following method in dbContext class
public List<T> ExecSQL<T>(string query)
{
using (var command = Database.GetDbConnection().CreateCommand())
{
command.CommandText = query;
command.CommandType = CommandType.Text;
Database.OpenConnection();
List<T> list = new List<T>();
using (var result = command.ExecuteReader())
{
T obj = default(T);
while (result.Read())
{
obj = Activator.CreateInstance<T>();
foreach (PropertyInfo prop in obj.GetType().GetProperties())
{
if (!object.Equals(result[prop.Name], DBNull.Value))
{
prop.SetValue(obj, result[prop.Name], null);
}
}
list.Add(obj);
}
}
Database.CloseConnection();
return list;
}
}
Now we can have the following code.
List<Customer> Customers = _context.ExecSQL<Customer>("SELECT ......");
follow these steps:
Create your model
Probably it could be better if you can reduce it to a model as generic as possible but it's not a must:
public class MyCustomModel
{
public string Text { get; set; }
public int Count { get; set; }
}
Add it to your own DbContext
Create DbSet for your custom model
public virtual DbSet<MyCustomModel> MyCustomModelName { get; set; }
Keep in mind to specify your custom model has no key
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
...
modelBuilder.Entity<MyCustomModel>().HasNoKey();
}
Use it from your dbContext instance
async public Task<List<MyCustomModel>> GetMyCustomData()
{
var rv = new List<MyCustomModel>();
using (var dataContext = new DbContext())
{
var sql = #"
select textField as 'Text', count(1) as 'Count'
from MyTable";
rv = await dataContext.Set<MyCustomModel>().FromSqlRaw(sql).ToListAsync();
}
return rv;
}
We have a problem concerning Entity Framework objects and sending them through WCF.
We have a database, and Entity Framework created classes from that database, a 'Wallet' class in this particular situation.
We try to transfer a Wallet using this code:
public Wallet getWallet()
{
Wallet w = new Wallet();
w.name = "myname";
w.walletID = 123;
return w;
}
We need to transfer that Wallet class, but it won't work, we always encounter the same exception:
"An error occurred while receiving the HTTP response to localhost:8860/ComplementaryCoins.svc. This could be due to the service endpoint binding not using the HTTP protocol. This could also be due to an HTTP request context being aborted by the server (possibly due to the service shutting down). See server logs for more details."
We searched on the internet, and there is a possibility that the error is due to the need of serialization of Entity Framework-objects.
We have absolutely no idea if this could be the case, and if this is the case, how to solve it.
Our DataContract looks like this (very simple):
[DataContract]
public partial class Wallet
{
[DataMember]
public int getwalletID { get { return walletID; } }
[DataMember]
public string getname { get { return name; } }
}
Does anyone ever encountered this problem?
EDIT: Our Entity Framework created class looks like this:
namespace ComplementaryCoins
{
using System;
using System.Collections.Generic;
public partial class Wallet
{
public Wallet()
{
this.Transaction = new HashSet<Transaction>();
this.Transaction1 = new HashSet<Transaction>();
this.User_Wallet = new HashSet<User_Wallet>();
this.Wallet_Item = new HashSet<Wallet_Item>();
}
public int walletID { get; set; }
public string name { get; set; }
public virtual ICollection<Transaction> Transaction { get; set; }
public virtual ICollection<Transaction> Transaction1 { get; set; }
public virtual ICollection<User_Wallet> User_Wallet { get; set; }
public virtual ICollection<Wallet_Item> Wallet_Item { get; set; }
}
}
Thanks for helping us.
I had the same problem some time ago and the solution for this was:
The entity framework was returning a serialized class instead of normal class.
eg. Wallet_asfawfklnaewfklawlfkawlfjlwfejlkef instead of Wallet
To solve that you can add this code:
base.Configuration.ProxyCreationEnabled = false;
in your Context file.
Since the context file is auto generated you can add it in the Context.tt
In the Context.tt file it can be added around lines 55-65:
<#=Accessibility.ForType(container)#> partial class <#=code.Escape(container)#> : DbContext
{
public <#=code.Escape(container)#>()
: base("name=<#=container.Name#>")
{
base.Configuration.ProxyCreationEnabled = false;
<#
if (!loader.IsLazyLoadingEnabled(container))
{
#>
this.Configuration.LazyLoadingEnabled = false;
<#
Try specifying a setter for the properties, something like this :
[DataContract]
public partial class Wallet
{
[DataMember]
public int getwalletID { get { return walletID; } set { } }
[DataMember]
public string getname { get { return name; } set { } }
}
If it still doesn't work, you may consider creating an intermediate POCO class for this purpose, and use mapper library like AutoMapper or ValueInjecter to transfer the data from the EF objects.
The POCO class should have same properties as your EF class :
[DataContract]
public class WalletDTO
{
[DataMember]
public int walletID { get; set; }
[DataMember]
public string name { get; set; }
}
And modify your method to return this class instead :
public WalletDTO getWallet()
{
Wallet w = new Wallet(); // or get it from db using EF
var dto = new WalletDTO();
//assuming we are using ValueInjecter, this code below will transfer all matched properties from w to dto
dto.InjectFrom(w);
return dto;
}
Are you trying to recieve a IEnumerable<Wallets>? If - yes, please modify your server class that returns the IEnumerable by adding .ToArray() method
I'm brand new to OData and WCF data services so this might be an easy problem. I'm using VS Web Developer Express 2010 where I have a very simple WCF Data Service hosted in a console app. It's returning an IQuerable collection of a simple 'Study' class from a repository (located in a separated dll project), which in turn retrieves 'Study' classes from a db project in another dll (so 3 projects in the solution).
I also have an 'Experiment' class in the db project and there can be multiple Experiments in a Study. When I exclude the Experiment class from the Study everything works and I get data coming back. The problem happens when I add a List collection to the Study class, then I get a runtime error when I try to run the service. In Firebug the error is '500 Internal Server Error', and the message in the browser is 'Request Error. The server encountered an error processing the request. See server logs for more details.'
I have IIS 7 and I also just installed IIS 7.5 but again it's brand new to me, so I can't figure out where the service is hosted or where to view the server / web logs. There are only IIS 7 logs visible in 'C:\inetpub\logs\LogFiles\W3SVC1'. The VS web server (Cassini) doesn't start when I run the app, so this suggests it's being hosted in IIS 7.5 (?).
So
- how do I return child classes / complex objects?
- how do I know where my service is hosted and where can I find the server logs?
Here's the host app:
using MyStudyRepository;
using MyStudyDB;
namespace MyStudyService
{
public class Program
{
public static void Main(string[] args)
{
string serviceAddress = "http://localhost:998";
Uri[] uriArray = { new Uri(serviceAddress) };
Type serviceType = typeof(StudyDataService);
using (var host = new DataServiceHost(serviceType,uriArray))
{
host.Open();
Console.WriteLine("Press any key to stop service");
Console.ReadKey();
}
}
}
public class StudyDataService : DataService<StudyRepository>
{
public static void InitializeService(IDataServiceConfiguration config)
{
config.SetEntitySetAccessRule("*", EntitySetRights.AllRead);
}
}
}
Here's the repository:
using MyStudyDB;
namespace MyStudyRepository
{
public class StudyRepository
{
List<Study> _List = new List<Study>();
//Add constructor to populate myStudies list on creation of class
public StudyRepository()
{
for (int i = 1; i < 5; i++)
{
Study myStudy = new Study() { ID = i, StudyOwnerId = i, StudyName = "Study" + i.ToString() /*, Experiments = null */ };
_List.Add(myStudy);
}
}
public IQueryable<Study> Studies
{
get
{
return _List.AsQueryable<Study>();
}
}
}
}
And here's the DB:
namespace MyStudyDB
{
public class Study
{
public int ID { get; set;}
public int StudyOwnerId { get; set; }
public string StudyName { get; set; }
//public List<Experiment> Experiments { get; set; }
}
public class Experiment
{
public int ID { get; set; }
public string Name { get; set; }
public int StudyId { get; set; }
}
}
To debug the WCF Data Service please refer to this blog post: http://blogs.msdn.com/b/phaniraj/archive/2008/06/18/debugging-ado-net-data-services.aspx
As to why the collection of Experiment doesn't work, there are two reasons:
The Experiment class is not recognized as an entity type because there's no entity set for it. (Entity set is the IQueryable property on your repository class, which you don't have). As a result the Experiment class is only recognized as a complex type.
The currently released version of WCF Data Services doesn't support MultiValues, MultiValue is effectively a collection of primitive or complex types.
So you have two way to "fix" this. Either make sure that Experiment is in fact an entity, by adding IQueryable property on your repository class.
Or use the latest CTP (http://blogs.msdn.com/b/astoriateam/archive/2011/06/30/announcing-wcf-data-services-june-2011-ctp-for-net4-amp-sl4.aspx) which does support MultiValues.
Thanks! And I guess it is missing the DataServiceKey attribute on the class as follows:
[DataServiceKey("ID")]
public class Study
{
.....
}