I have two lists of deserialized json data, and I want to cross join the tables. The example data is item1:name, item2:date for both lists. I have the return type as List but my return type is not valid. Not sure what I am doing wrong here.
What I have so far:
List<JsonData> jdOne = GetDeserializedData(jsonUrlOne);
List<JsonData> jdTwo = GetDeserializedData(jsonUrlTwo);
var query = from urlOne in jdOne
from urlTwo in jdTwo
select new { urlOne, urlTwo };
return query;
You probably want to use a Tuple to do this....
public List<Tuple<JsonData,JsonData>> myFunc() {
List<JsonData> jdOne = GetDeserializedData(jsonUrlOne);
List<JsonData> jdTwo = GetDeserializedData(jsonUrlTwo);
var query = from urlOne in jdOne
from urlTwo in jdTwo
select Tuple.Create(urlOne, urlTwo);
return query.ToList();
}
Then with your results you can access the two items like so.
var results=myFunc();
var x1=results[0].Item1;
var x2=results[0].Item2;
x1 contains the first pair from the first list result, x2 contains the second pair.
Is this what you want by using Linq: Zip
var result = jdOne.Zip(jdTwo, (urlOne, urlTwo) => new {urlOne, urlTwo});
Looks like you trying to return anonymous type from function. Declare type to hold both values, and return it
select new YourType(){Field1 = urlOne, Field2 = urlTwo}
Related
I am using the following method:
public PagedResult<PaymentPlanItems> GetPagedRequest(SearchRequest searchRequest, List<int> idsToExclude)
{
var list = _dbSetList.AsQueryable();
if (idsToExclude != null)
{
list = list.Where(item => !idsToExclude.Contains(item.ItemId));
}
var query = SearchHelper.GetFilteredSearch<PaymentPlanItems>(list, searchRequest);
var pagedResultMessage = SearchHelper.GetPagedResult(query, searchRequest);
return pagedResultMessage;
}
where idsToExclude I originally got using this (found from another SO thread):
if (!string.IsNullOrEmpty(searchViewModel.ItemsToExclude))
{
List<int> idsToExclude = new List<int>(Array.ConvertAll(searchViewModel.ItemsToExclude.Split(','), int.Parse));
searchViewModel.Result = _paymentPlanItemsAdapter.GetPagedRequest(searchViewModel.SearchRequest, idsToExclude);
}
I then look at the generated query using profile and I see that I get the following as part of my query:
WHERE ( NOT ([Extent1].[ItemId] IN (440, 1017)))
I don't know if I should be really concerned as my numbers get inserted into the query directly and not as parameters and if I should be, what modifications to this method / approach I should take to make this query use parameters?
In a table, Leads, there is a column Data that contains a JSON string. In a LINQ statement, I need to extract a field from that JSON:
var results = from l in leads
select new MyLeadObject
{
LeadID = l.LeadID,
...
RequestType = (string)l.Data["RequestTypeID"]
};
Here's a shortened version of the JSON:
{
"RequestTypeID":1
}
RequestTypeID is a string.
I've been reading other threads and trying to cobble this together. Not having much luck.
EDIT:
With help from Nkosi, I got this far:
RequestType = (string)JSONNetSerialization.DeserializeJsonNet<LeadData>(l.Data).RequestTypeID
The only problem is that LeadData.RequestTypeID is an enum, so it won't convert the enum to a string. I'm not sure how to get the value of the enum instead of the entire enum itself. Outside of LINQ I could do this: RequestTypeID.GetDisplayName(); but .GetDisplayName() is not recognized by LINQ.
You can use Json.Net to parse the JSON in Data field to get the property.
var results = leads.Select(l =>
new MyLeadObject {
LeadID = l.LeadID,
//...
RequestType = (string)JsonConvert.DeserializeObject(l.Data)["RequestTypeID"]
});
As the question suggests I want to remove the columns from a select query where in that column are empty.
var query = from a in ...
select new
{
A =(decimal?)null,
B =(decimal?)null,
C = a.Amount1
};
var query2 = from b in ...
select new
{
A = b.Amount2,
B = b.Amount3,
C = (decimal?)null
};
var query3 = query.Concat(query2);
Output:
query3=[0]{A=null, B=null, C=100.00}
[1]{A=100.00, B=50.25, C=null}
Expected Result:
query3=[0]{C=100.00}
[1]{A=100.00, B=50.25}
You can't do this. The result set has to contain items of the same type and even if fields are null they still have to be there.
You could not show them in your UI, but exactly how you do that will depend on the UI.
You can't. A class has a predefined set of fields (not to speak about ExpandoObject which has some compiler tricks going on). This is the same for anonymous type, which you use.
You can't just hide or remove fields which are not filled. What if you iterate over the instances and try to retrieve item.C, which was null and thus removed? That would normally give you a compiler error. How would .NET resolve that?
The only other thing you can do is put in two different types in your list (a list of objects, so untyped), a very bad idea in my opinion. Keep it like this. You could add an indicator which type the row is, to be able to test it easily.
So:
select new
{
Type = "A", // or "B"
A =(decimal?)null,
B =(decimal?)null,
C = a.Amount1
};
A LINQ query typically outputs objects of a common type, so each object has to have the same base type (and the columns associated. The only way to concatenate objects of different types is to cast them to object:
var query = from a in ...
select new
{
C = a.Amount1
};
var query2 = from b in ...
select new
{
A = b.Amount2,
B = b.Amount3,
};
var query3 = query.Cast<object>().Concat(query2.Cast<object>());
but since they're anonymous you'll have to use dynamic to access them since you won;t be able to cast back to the original type, so you'll end up with something like this:
Console.WriteLine(((dynamic)(query3[0])).C);
Console.WriteLine(((dynamic)(query3[1])).A);
or at best:
dynamic list = query3.ToList();
Console.WriteLine(list[0].C);
Console.WriteLine(list[1].A);
but in any case you'll lose compile-time type safety.
I am trying to return a list of an object that contains another object list as a databmember using linq. I've tried the examples shown but I keep getting ad different error with each attempt. One of which is as follows: LINQ to Entities does not recognize the method 'System.Collections.Generic.List1[SunGard.Tools.Notifications.LinkVariable] ToList[LinkVariable](System.Collections.Generic.IEnumerable1[SunGard.Tools.Notifications.LinkVariable])' method, and this method cannot be translated into a store expression.
I have an object (AlertMessageReturn) that contains some string datamembers as well as a list aof another object (List). I have a class that defines the LinkVarible and a table that contains the values. My query looks like this:
AlertMessagesQuery = from alertMessage in this.context.AlertMessages
where alertMessage.UserId=UserId
select new AlertMessageReturn()
{ PAM_ShortMessage = alertMessage.PAM_ShortMessage,
PAM_LongMessage = alertMessage.PAM_LongMessage,
PAM_LongMessageRemote = alertMessage.PAM_LongMessageRemote,
LinkVariables = (from linkVariable in this.context.AlertMessageLinks
from user in this.context.AlertMessageUsers
where user.PAMU_PAM_ID == linkVariable.PAML_PAM_ID && user.PAMU_UserId == UserId
select new LinkVariable()
{
Name = linkVariable.PAML_SessionVariableName,
Value = linkVariable.PAML_SessionVariableValue
})
};
The error is related to the type returned for linkvariables.
Please help.
I changed the code as follows:
LinkDataQuery = from linkData in this.context.AlertMessageLinks
from user1 in this.context.AlertMessageUsers
where user1.PAMU_PAM_ID == linkData.PAML_PAM_ID && user1.PAMU_UserId == UserId
select new LinkData
{
Name = linkData.PAML_SessionVariableName,
Value = linkData.PAML_SessionVariableValue
};
var links = LinkDataQuery.ToList();
AlertMessagesQuery = from alertMessage in this.context.AlertMessages
where alertMessage.UserId=UserId
select new AlertMessageReturn()
{ PAM_ShortMessage = alertMessage.PAM_ShortMessage,
PAM_LongMessage = alertMessage.PAM_LongMessage,
PAM_LongMessageRemote = alertMessage.PAM_LongMessageRemote,
LinkVariables = links
};
var AlertMessages = AlertMessagesQuery.ToList(); // this is where the error point to
if (AlertMessages.Any())
{
return AlertMessages;
}
The error I now get is:System.NotSupportedException: Unable to create a constant value of type 'SunGard.Tools.Notifications.LinkData'. Only primitive types ('such as Int32, String, and Guid') are supported in this context.
The LINQ to SQL engine cannot turn your sub-query to generate the LinkVariables into SQL. More importantly, SQL cannot return nested data sets like that.
Any time you get a message of type 'cannot be translated into a store expression' it is an indicator that you are doing something with your linq that is attempting to be translated into other statements (usually SQL). For example, if you say
....select new MyObject
{
Id = Guid.Parse( passedIdentity ),
....
}
while this is a totally valid C# statement you will get an error that Guid.Parse cannot be handled by linq. If it is possible to move the variables into external variables that are used inside the query then it would work. So you would do...
string name = linkVariable.PAML_SessionVariableName;
string nValue = ....
....
select New LinkVariable
{
Name=name,
Value=nValue
};
Also ... you do not need the closing parens on the Select New statement.
While LINQ to SQL can bring back object heirarchies, it can't project into types that aren't part of the model. Instead of projecting into the AlertMessageReturn type, try projecting into an anonymous type in the IQueryable portion of the code. Once you're done structuring your database query, force the results to come back (using AsEnumerable) and then project that into your AlertMessageReturn type. It's more overhead, but does work. Alternatively, you can use something like AutoMapper to translate your anonymous type into the result types.
AlertMessagesQuery =
from alertMessage in this.context.AlertMessages
where alertMessage.UserId=UserId
select new
{
alertMessage.PAM_ShortMessage,
alertMessage.PAM_LongMessage,
alertMessage.PAM_LongMessageRemote,
LinkVariables = from linkVariable in this.context.AlertMessageLinks
from user in this.context.AlertMessageUsers
where user.PAMU_PAM_ID == linkVariable.PAML_PAM_ID && user.PAMU_UserId == UserId
select new
{
Name = linkVariable.PAML_SessionVariableName,
Value = linkVariable.PAML_SessionVariableValue
})
};
var alertMessageResults =
from message in AlertMessagesQuery.AsEnumerable()
select new AlertMessageResult
{
PAM_ShortMessage = mesage.PAM_ShortMessage,
PAM_LongMessage = message.PAM_LongMessage,
PAM_LongMessageRemote = message.PAM_LongMessageRemote,
LinkVariables = (from variable in message.LinkVariables
select new LinkVariable { Name=variable.Name, Value = variable.Value})
.ToList()
};
return alertMessageResults.ToList();
ASP.NET 3.5 C#
I am joining two tables using Linq.
Table names are MapAssets and ExitPoint.
In Database they are related with 'has a relationship'
I am writing a function in my BLL to return the joined table
public List<ExitPoints> GetExitPointDetailsByProjectID(int iProjectID)
{
ctx = new CoreDBDataContext();
var exitPointDetails = from ma in ctx.MapAssets
join ep in ctx.ExitPoints
on ma.MapAssetID equals ep.MapAssetID
where ma.ProjectID == iProjectID
select new
{
//would like to have data from both tables here
ctx.MapAssets,
ctx.ExitPoints
};
return exitPointDetails.ToList();
}
This obviuosly doesn't work. And I dont know what to return at all.
All constraint I have for the return is to be able to be bound to a gridview.
is this the correct way? Or else whats the correct way?
You can't, or better, the only way is to return them boxed in a List of object, but this hugely complicates things, because you can't cast them to any type (of course it's anonymous) and you can only access their properties through reflection....
In cases like that, I'd highly suggest you to create a custom class.
EDIT:
On a side note...
If you were using .net 4, things would be easier because you could returns dynamic Type instead of object (look at this link to see dynamic's simplifications), but I'd prefer to create a custom class anyway.
Have a look at how to return anonymous types from Method.
http://forums.asp.net/t/1387455.aspx.
Copying the code from the link.
object ReturnAnonymous()
{
return new { Name="Faisal", City="Chakwal" };
}
// Application entry-point
void Main()
{
object o = ReturnAnonymous();
// This call to 'Cast' method converts first parameter (object) to the
// same type as the type of second parameter - which is in this case
// anonymous type with 'Name' and 'City' properties
var typed = Cast(o, new { Name="", City="" });
Console.WriteLine("Name={0}, City={1}", typed.Name, typed.City);
}
// Cast method - thanks to type inference when calling methods it
// is possible to cast object to type without knowing the type name
T Cast<T>(object obj, T type)
{
return (T)obj;
}
You can use the method mentioned below to return List and
List<object> lstAnonymousTypes = GetExitPointDetailsByProjectID(1);
foreach(object o in lstAnonymousTypes)
{
//Change it accordingly
var typed = Cast(o, new { new MapAssets() , new ExitPoints() });
}
Hope this helps not tried.
You can't return an anonymous type, you can only use an anonymous type in the scope of the method it's in. You could need to create a new class with MapAssets/ExitPoints properties and select a new instance of that class.
You are trying to return List ExitPoints and List of MapAssets which is not possible because you are getting the output from both tables ie ExitPoints and MapAssets. And it is also not possible to return an anonymous type. So in order to retrun the query create a class name ExMapClass with properties that you need as output of the queries. Now after executing the linq query which you have written iterate it ie
create list of newly created class
list newclass = new list ();
foreach( var result in ctx )
{
instantiate the created class
obj.Property1 = var.MapAssets;
obj.Property2 = var.ExitPoints;
newclass.add(obj);
}
now retrun the list of newlycreated class.
hope you got it.
Do you have to bind to this object after you've created it? If not then you can create an "persistent AnonymousType" class that stores the values in a dictionary and returns the property values with a method like:
string lastName AnonType.GetValue<string>("LastName");
int age AnonType.GetValue<int>("Age");
Here is a link to an excellent example. The author also has an example where he creates the "AnonymousType" from a datatable.
I have worked on a variation of this where I provide the ability to query a list of "AnonymousType" with the following syntax:
// Here's the query
var dept13 = anonAgents.AsQueryable()
.Where(x => x.Has("Department", Compare.Equal, 13);
// Here is how the List is constructed
private static AnonymousType ProvisionAgent(string name, int department)
{
return AnonymousType.Create(new
{
Name = name,
Department = department
});
}
private List<AnonymousType> CreateAnonAgentList()
{
var anonAgents = new List<AnonymousType>();
// Dave and Cal are in Department 13
anonAgents.Add(AnonymousType.Create(CreateAgentAnonType("Dan Jacobs", 13, 44)));
anonAgents.Add(AnonymousType.Create(CreateAgentAnonType("Calvin Jones", 13, 60)));
// Leasing = Dept 45
anonAgents.Add(AnonymousType.Create(CreateAgentAnonType("Stanley Schmidt", 45, 36)));
anonAgents.Add(AnonymousType.Create(CreateAgentAnonType("Jeff Piper", 45, 32)));
anonAgents.Add(AnonymousType.Create(CreateAgentAnonType("Stewart Blum", 45, 41)));
anonAgents.Add(AnonymousType.Create(CreateAgentAnonType("Stuart Green", 45, 38)));
// HR = Dept 21
anonAgents.Add(AnonymousType.Create(CreateAgentAnonType("Brian Perth", 21, 25)));
anonAgents.Add(AnonymousType.Create(CreateAgentAnonType("Katherine McDonnel", 21, 23)));
return anonAgents;
}
Just use and ArrayList
public static ArrayList GetMembersItems(string ProjectGuid)
{
ArrayList items = new ArrayList();
items.AddRange(yourVariable
.Where(p => p.yourProperty == something)
.ToList());
return items;
}
wont this work ?
ctx = new CoreDBDataContext();
var exitPointDetails = from ma in ctx.MapAssets
join ep in ctx.ExitPoints
on ma.MapAssetID equals ep.MapAssetID
where ma.ProjectID == iProjectID
select Tuple.Create(ma, ep);
return exitPointDetails.ToList();