Hi,
I am new to Linq and entity framework. I am doing something like this
I have 3 viewmodel:
1.
public class FlowViewModel
{
..........................
public List<FlowLevelViewModel> Levels { get; set; }
}
public class FlowLevelViewModel
{
.........................
public List<BlockDetailsViewmodel> Blocks { get; set; }
}
public class BlockDetailsViewmodel
{
.......................
}
and from my controller I am calling the datalayer.
var model = new FlowViewModel();
model = dataOb.GetFlowForTheDocument(company, docType);
model = dataOb.GetFlowStageForTheDocument(model);
return model;
and in my datalayer
public FlowViewModel GetFlowStageForTheDocument(FlowViewModel model)
{
var flowlevelviewModel = (from p in dbContext.FlowStages
where p.FlowID == model.FlowId
select new FlowLevelViewModel()
{
.................
Blocks = GetBlockDetailsForTheDocument(p.StageID, .StageType)
}).ToList();
model.Levels = flowlevelviewModel;
return model;
}
public List<BlockDetailsViewmodel> GetBlockDetailsForTheDocument(int StageID, string stageType)
{
var blockDetails = new List<BlockDetailsViewmodel>();
......................................
return blockDetails;
}
While I am running the program I am getting this error:
**NotSupportedException Was unhandled by user Code**
LINQ to Entities does not recognize the method 'System.Collections.Generic.List`1[SEADViewModel.BlockDetailsViewmodel] GetBlockDetailsForTheDocument(Int32, System.String)' method, and this method cannot be translated into a store expression.
My project is in production stage so I have no time at all. Does anyone know what I am doing wrong?
This should solve your problem:
var data = (from p in dbContext.FlowStages
where p.FlowID == model.FlowId
select p).ToList();
var flowlevelviewModel = (from p in data
select new FlowLevelViewModel()
{
.................
Blocks = GetBlockDetailsForTheDocument(p.StageID, .StageType)
}).ToList();
Note that this will evaluate the query at the first ToList(). If you need to run the entire query at once, you need to build a simple LINQ expression, you can't use your method GetBlockDetailsForTheDocument inside the query. See #Tilak's answer for a link to supported build in methods.
You are using Linq to Entities.
It does not support all the functions. List of supported and non supported functions
You need to write custom model defined function GetBlockDetailsForTheDocument to use it in LINQ query.
Related
I have the following ActionFilter class, to implement my custom authorization system:-
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
public class CheckUserPermissionsAttribute : ActionFilterAttribute
{
Repository repository = new Repository();
public string Model { get; set; }
public string Action { get; set; }
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
string ADusername = filterContext.HttpContext.User.Identity.Name.Substring(filterContext.HttpContext.User.Identity.Name.IndexOf("\\") + 1);
if (!repository.can(ADusername,Model,Action))
{
filterContext.Result = new HttpUnauthorizedResult("You cannot access this page");
}
base.OnActionExecuting(filterContext);
}
}
The above class will call the following repository method:-
public bool can(string user, string Model, string Action)
{
bool result;
bool result2;
int size =tms.PermisionLevels.Where(a5 => a5.Name == Action).SingleOrDefault().PermisionSize;
var securityrole = tms.SecurityroleTypePermisions.Where(a => a.PermisionLevel.PermisionSize >= size && a.TechnologyType.Name == Model).Select(a => a.SecurityRole).Include(w=>w.Groups).Include(w2=>w2.SecurityRoleUsers).ToList();
foreach (var item in securityrole)
{
result = item.SecurityRoleUsers.Any(a => a.UserName.ToLower() == user.ToLower());
var no = item.Groups.Select(a=>a.TMSUserGroups.Where(a2=>a2.UserName.ToLower() == user.ToLower()));
result2 = no.Count() == 1;
if (result || result2) {
return true;
}}
return false;
}
But inside my repository method , I am doing the following:-
Query the database and include all the Groups & SecurityRoleUsers when executing the .tolist()
Then filter the returned records insdie the server, based on the foreach loop.
But this will cause the following drawbacks:-
If I have many Groups and SecurityRoleUsers, then I will be getting them all from the DB, and then filter the result on the server.
And since this code will be executed whenever an action method is called, as it Is a security attribute at the begging of the controller class. So this might not be very efficient.
So my question is whether I can join all the queries inside the repository method to be single query , and do all the work on the Database and just return true or false to the server ?
The associated tables looks as follow:-
Ideally remove this foreach.
Try riding with Linq to Sql.
You should be more comfortable because it resembles SQL.
This link has several examples.
http://code.msdn.microsoft.com/101-LINQ-Samples-3fb9811b
Att
Julio Spader
wessolucoes.com.br
Use linq.
Ideally you should only have one line of code after you got the size value. e.g.
int size =tms.PermisionLevels.Where(a5 => a5.Name == Action).SingleOrDefault().PermisionSize;
var result = //One line of code to determine user authenticity
return result;
I think you should design you database in the way that join queries are easy to do. So you don't have to perform more than one select.
Try code-first EF, which links tables very easily.
You need to take care with Lazy Loading. If not used correctly, it will make a query to the database each object segmentation, especially in your foreach. With that already has a good improvement.
Take a look at this article. I think it will help you too.
http://www.sql-server-performance.com/2012/entity-framework-performance-optimization/
Att
Julio Spader
wessolucoes.com.br
I have a large object graph that I want to return to the client (an overview of the entire model) so I decided to send it back as one big object (I'm returning it as the object in question.)
In Breeze however I'm only getting the first object in each dependent object. So for example I have a 'policy' object with two 'vehicle' objects. I only see one vehicle (even when I put a breakpoint at var p = data.results[0]. The json coming back from the call shows two vehicles but breeze is catching only one.
What can I do to get the other ones? Here's the call I'm making:
var getPolicyByPolicyNumber = function (lob, policynumber, policyObservable) {
var params = {};
params['lOBCd'] = lob;
params['policyNumber'] = policynumber;
var query = EntityQuery.from('PolicyInquiry')
.withParameters(params);
return manager.executeQuery(query)
.then(querySucceeded)
.fail(queryFailed);
function querySucceeded(data) {
var p = data.results[0];
p.completeTree(true);
return policyObservable(p);
}
};
And in my breeze controller I have the following:
[System.Web.Http.HttpGet]
public Policy PolicyInquiry(string lOBCd, string policyNumber)
{
UserProfile userProfile = _contextProvider.Context.UserProfiles.SingleOrDefault(u => u.UserName == WebSecurity.CurrentUserName);
var policy = Uow.PolicyServices.GetPolicy(userProfile.BrokerId, userProfile.AgencyId, "csio:" + lOBCd, policyNumber);
return policy;
}
And here's an abbreviated model showing policy and vehicle:
public class Policy
{
public int Id { get; set; }
public string PolicyNumber { get; set; }
[InverseProperty("Policy")]
public ICollection<Vehicle> Vehicles { get; set; }
// other fields removed
}
public class Vehicle
{
public int Id {get; set}
public string ItemId { get; set; }
// other fields removed
//Foreign Keys
public int PolicyId { get; set; }
[IgnoreDataMember]
[ForeignKey("PolicyId")]
[Required]
public virtual Policy Policy { get; set; }
}
Now that I see your model I think I see the issue.
Breeze does not automatically resolve the entity graph on a query. i.e. if you retrieve a Policy, Breeze only returns the Policy instance itself without any navigation properties resolved. This is by design, so that a single query doesn't bring down the entire entity graph.
If you want the values of any navigation properties you have three options, the third of which is probably your best bet. I've taken some liberties in simplifying your model for the purposes of explanation. These all assume that the "Policy" type is actually defined as a Breeze entity type, i.e. has a metadata definition in the Breeze metadataStore.
1) Use an client side EntityQuery.expand clause
var query = EntityQuery.from('Policy')
.expand("Vehicles")
.withParameters(params);
2) Use a server side Include clause
[System.Web.Http.HttpGet]
public IEnumberable<Policy>(string lOBCd, string policyNumber) {
return _contextProvider.Context.Policies.Where(....).Include("Vehicles");
}
3) Use a anonymous result, that contains two known entity types.
[System.Web.Http.HttpGet]
public Object PolicyInquiry(string lOBCd, string policyNumber) {
UserProfile userProfile = _contextProvider.Context.UserProfiles.SingleOrDefault(u => u.UserName == WebSecurity.CurrentUserName);
var policy = Uow.PolicyServices.GetPolicy(userProfile.BrokerId, userProfile.AgencyId, "csio:" + lOBCd, policyNumber);
return new {
Policy = policy,
Vehicles = policy.GetVehicles() // insure that they are actually resolved on the server)
}
return policy;
}
More info here: Navigation Properties
I hope this is clear enough.
Sorry, but without seeing the underlying implementation of "policy" and its metadata, it's hard to tell what's going on. But I can make a general suggestion.
1) If you want to return an aggregate object and have Breeze recognize it's constituent parts, the recommended mechanism is to create a projection and return that. i.e. something like
public IQueryable<Object> CompanyInfoAndOrders() {
return ContextProvider.Context.Customers.Select(c => new { Customer = c, Orders = c.Orders });
}
In this example, providing that Breeze has metadata for the Customer and Order types,
Breeze will deconstruct the result and add the Customer and its orders to the EntityManager, and return a collection of json objects each with a "Customer" and Orders property. The Customer and individual Orders will each have been "adapted" to the current model library as well (i.e. knockout, backbone, or backingStore - for Angular).
I want to add a relationship between multiple existing entities and another existing entity. Here is my model:
public class Term
{
public int TermId { get; set; }
public virtual ICollection<SubForm> SubForms { get; set; }
}
public class SubForm
{
public int SubFormId { get; set; }
public virtual ICollection<Term> Terms { get; set; }
}
I have an update repository method as follows:
public IQueryable<Term> GetTerms()
{
IQueryable<Term> query = db.Terms.AsNoTracking();
return query;
}
public Term UpdateTerm(Term term, IEnumerable<Expression<Func<Term, object>>> properties)
{
if (term.TermId == 0)
{
throw new InvalidOperationException("Term does not exist");
}
db.Terms.Attach(term);
if (properties != null)
{
foreach (var selector in properties)
{
string propertyName = Helpers.PropertyToString(selector.Body);
db.Entry(term).Property(propertyName).IsModified = true;
}
}
db.SaveChanges();
return term;
}
Now I assume this would work when I make this call in my service layer:
public void AddFormToTerm(int termId, int formId)
{
var term = termsRepository.GetTerms().FirstOrDefault(t => t.TermId == termId);
var subForms = termsRepository.GetSubForms().Where(t => t.FormId == formId);
//I assume this would work by adding existing forms to an existing term.
foreach (var subForm in subForms)
{
term.SubForms.Add(subForm);
}
termsRepository.UpdateTerm(term, null);
}
Unfortunately, this doesn't get updated, there is nothing in the intermediate table when I checked the database. No exception was also thrown.
Using AsNoTracking in this case is the problem. Without AsNoTracking it will work. You must keep in mind that you can update a many-to-many relationship only with the change tracking mechanism. But in your code the EF context will know about term and the SubForms collection for the first time when you call Attach in your UpdateTerm method. EF does not notice that you did add the SubForms to the term because those entities were not attached to the context (since you used AsNoTracking = "EF, please do not attach to the context!"). But after Attach nothing happened anymore before you called SaveChanges = No change = No database commands.
So removing AsNoTracking (or creating another method or a parameter to load with tracking) is the best option. Everything else will involve ugly "tricks" like this:
public Term UpdateTerm(Term term, ...)
{
//...
// Restore the state before adding the subforms = current state in DB
var tempSubForms = term.SubForms;
term.SubForms = null;
// Inform EF about this state = term exists, subforms exist
// in DB but no relationships
db.Terms.Attach(term);
foreach (var subForm in tempSubForms)
db.SubForms.Attach(subForm);
// Change the state: EF change tracking recognizes this
term.SubForms = tempSubForms;
//...
// EF now will send INSERT statements for the join table
db.SaveChanges();
return term;
}
Hy Guys.
I have 2 entities: "Interactions" and "Orders", which has many "Interactions".
On View, I wanna a different class (like <tr class=#cssClass>) for the Orders which has interactions unread. So I created a ViewModel.
My ViewModel:
public class OrderViewModel
{
public Order Order{get;set;}
public bool isRead{get;set;}
}
My controller (I'm working with repositories):
var orders = orderRepo.All();
var viewModel = orders.Select(order=> new orderViewModel
{
Order = order, '<------------'
isRead = order.Interactions.Any(x => x.Read == true),
});
return View(viewModel);
If I take out the Order = order, It works fine. But with this code I'm getting this error:
QueryException was unhandled by user code. Could not instantiate: Models.OrderViewModel
InnerException: When casting from a number, the value must be a number less than infinity
InnerException: Make sure the source type is convertible to the destination type.
If, instead of use the objects I use their properties, it works fine:
ViewModel:
public int IdPedido { get; set; }
public string CategoryOrder { get; set; }
public string ModuleOrder { get; set; }
Controller:
var viewModel = orders.Select( order => new OrderViewModel{
CategoryOrder=Order.Category,
ModuleOrder=Order.Module,
...});
What am I missing? I'm not understanding what should be convertible. Or isn't possible to use Objects on ViewModel, only Properties?
If it's a usable information, I'm using the Nhibernate ORM.
Tks guys!
EDIT
Based on #elspiko question, I realized that Order and Orders didn't have the same type. So I set orders: IEnumerable<Order> orders = pedido.Repo.All(); And now it's working.
I thought it would work before editing. Why was it considered different types?
Your code doesn't look right, it should be:
var viewModel = orders.Select(order=>new OrderViewModel
{
Order = order, '<------------'
But i'm assuming thats just a typo?
It might have something to do with lazy loading, if you put a debugger on the select statement, what type does order have? Is it some form of proxy object?
I have been scratching my head all morning behind this but still haven't been able to figure out what might be causing this.
I have a composite repository object that references two other repositories. I'm trying to instantiate a Model type in my LINQ query (see first code snippet).
public class SqlCommunityRepository : ICommunityRepository
{
private WebDataContext _ctx;
private IMarketRepository _marketRepository;
private IStateRepository _stateRepository;
public SqlCommunityRepository(WebDataContext ctx, IStateRepository stateRepository, IMarketRepository marketRepository)
{
_ctx = ctx;
_stateRepository = stateRepository;
_marketRepository = marketRepository;
}
public IQueryable<Model.Community> Communities
{
get
{
return (from comm in _ctx.Communities
select new Model.Community
{
CommunityId = comm.CommunityId,
CommunityName = comm.CommunityName,
City = comm.City,
PostalCode = comm.PostalCode,
Market = _marketRepository.GetMarket(comm.MarketId),
State = _stateRepository.GetState(comm.State)
}
);
}
}
}
The repository objects that I'm passing in look like this
public class SqlStateRepository : IStateRepository
{
private WebDataContext _ctx;
public SqlStateRepository(WebDataContext ctx)
{
_ctx = ctx;
}
public IQueryable<Model.State> States
{
get
{
return from state in _ctx.States
select new Model.State()
{
StateId = state.StateId,
StateName = state.StateName
};
}
}
public Model.State GetState(string stateName)
{
var s = (from state in States
where state.StateName.ToLower() == stateName
select state).FirstOrDefault();
return new Model.State()
{
StateId = s.StateId,
StateName = s.StateName
};
}
AND
public class SqlMarketRepository : IMarketRepository
{
private WebDataContext _ctx;
public SqlMarketRepository(WebDataContext ctx)
{
_ctx = ctx;
}
public IQueryable<Model.Market> Markets
{
get
{
return from market in _ctx.Markets
select new Model.Market()
{
MarketId = market.MarketId,
MarketName = market.MarketName,
StateId = market.StateId
};
}
}
public Model.Market GetMarket(int marketId)
{
return (from market in Markets
where market.MarketId == marketId
select market).FirstOrDefault();
}
}
This is how I'm wiring it all up:
WebDataContext ctx = new WebDataContext();
IMarketRepository mr = new SqlMarketRepository(ctx);
IStateRepository sr = new SqlStateRepository(ctx);
ICommunityRepository cr = new SqlCommunityRepository(ctx, sr, mr);
int commCount = cr.Communities.Count();
The last line in the above snippet is where it fails. When I debug through the instantiation (new Model.Community), it never goes into any of the other repository methods. I do not have a relationship between the underlying tables behind these three objects. Would this be the reason that LINQ to SQL is not able to build the expression tree right?
These are non-hydrated queries, not fully-hydrated collections.
The Communities query differs from the other two because it calls methods as objects are hydrated. These method calls are not translatable to SQL.
Normally this isn't a problem. For example: if you say Communities.ToList(), it will work and the methods will be called from the objects as they are hydrated.
If you modify the query such that the objects aren't hydrated, for example: when you say Communities.Count(), linq to sql attempts to send the method calls into the database and throws since it cannot. It does this even though those method calls ultimately would not affect the resulting count.
The simplest fix (if you truly expect fully hydrated collections) is to add ToList to the community query, hydrating it.
Try adding another repository method that looks like this:
public int CommunitiesCount()
{
get { return _ctx.Communities.Count(); }
}
This will allow you to return a count without exposing the entire object tree to the user, which is what I think you're trying to do anyway.
As you may have already guessed, I suspect that what you are calling the anonymous types are at fault (they're not really anonymous types; they are actual objects, which you are apparently partially populating in an effort to hide some of the fields from the end user).