The following code doesn't seem to get the correct count.....
var materials = consRepository.FindAllMaterials().AsQueryable();
int count = materials.Count();
Is it the way to do it.... Here is my repository which fetches records...
public IQueryable<MaterialsObj> FindAllMaterials()
{
var materials = from m in db.Materials
join Mt in db.MeasurementTypes on m.MeasurementTypeId equals Mt.Id
where m.Is_Deleted == 0
select new MaterialsObj()
{
Id = Convert.ToInt64(m.Mat_id),
Mat_Name = m.Mat_Name,
Mes_Name = Mt.Name,
};
return materials;
}
Edit:
when i use this,
var materials = consRepository.FindAllMaterials().AsQueryable();
return View("Materials", materials);
I get 18 rows in my table... So y cant i get the count as 18 instead it gives 12
Ans:
Breakpoint doesn't seem produce me the result but response.Write(count) did...
This should get the correct count:
int count = consRepository.FindAllMaterials().Count();
How are you iterating through the model in your view?
Is it possible that you are displaying duplicate entries?
Is it possible that you're not joining on the correct columns? The only reason I ask is that your id columns aren't consistently named in each class. For Materials you are using Mat_id, but in MeasurementTypes you are using simply, Id. It makes me wonder if you're trying to join a natural key value against an artificial primary key instead of the corresponding natural foreign key.
Related
I have an already sorted list of objects, and need to perform a "group by" and assign a sequence number to each object in the group.
[Essentially, I am trying to mimic the effect of a sql window function such as "seq = row_number() over (partition by cust_id)"]
Right now, I am achieving this using the below code, but would like to learn if there is a different way to do it using Java 8 features like stream() or forEach(). Thanks for the help.
int count = 0;
String prev_cust_id = "";
// OrdersList is already sorted by cust_id
for (Order o : orderList) {
// reset index for each new group
if (!o.cust_id.equals(prev_cust_id))
count = 0;
o.seq = ++count;
prev_cust_id = o.cust_id;
}
Update: I was also able to achieve the same with below code, but it is less readable and seems more inefficient. Is there is a better way.
orderList.get(0).seq = 1;
IntStream.range(1, orderList.size())
.forEach(i -> orderList.get(i).seq = orderList.get(i).cust_id.equals(orderList.get(i-1).cust_id) ? OrdersList.get(i-1).seq + 1 : 1);
Based on user design I have to union together four queries and put them in a repeater.
var qryIssuer = from l in dbRRSP.LOA
join lrb in dbRRSP.LOAOrReferredBy on l.LOAOrReferredById equals lrb.LoaOrReferredById
join lat in dbRRSP.LOAAccessType on l.LOAAccessTypeId equals lat.LOAAccessTypeId
join iss in dbRRSP.Issuer on l.IssuerId equals iss.IssuerId
where
l.PersonId == personId
select new
{
LOAOrReferredByDescription = lrb.LoaOrReferredByDescription,
lat.LOAAccessTypeDescription,
PersonType = "Issuer",
LOAName = iss.CompanyName,
l.DateAdded
};
var qryEMD = from l in dbRRSP.LOA
join lrb in dbRRSP.LOAOrReferredBy on l.LOAOrReferredById equals lrb.LoaOrReferredById
join lat in dbRRSP.LOAAccessType on l.LOAAccessTypeId equals lat.LOAAccessTypeId
join emd in dbRRSP.Agent on l.AgentId equals emd.AgentId
where
l.PersonId == personId
select new
{
LOAOrReferredByDescription = lrb.LoaOrReferredByDescription,
lat.LOAAccessTypeDescription,
PersonType = "EMD",
LOAName = emd.CompanyName,
l.DateAdded
};
var qryEmdRep = from l in dbRRSP.LOA
join lrb in dbRRSP.LOAOrReferredBy on l.LOAOrReferredById equals lrb.LoaOrReferredById
join lat in dbRRSP.LOAAccessType on l.LOAAccessTypeId equals lat.LOAAccessTypeId
join ar in dbRRSP.AgentRepresentative on l.EMDRepresentativeId equals ar.AgentRepresentativeId
join arp in dbRRSP.Person on ar.PersonId equals arp.PersonId
where
l.PersonId == personId
select new
{
LOAOrReferredByDescription = lrb.LoaOrReferredByDescription,
lat.LOAAccessTypeDescription,
PersonType = "EMD Rep",
LOAName = arp.FirstName + ' ' + arp.LastName, l.DateAdded
};
var qryLOAPerson = from l in dbRRSP.LOA
join lrb in dbRRSP.LOAOrReferredBy on l.LOAOrReferredById equals lrb.LoaOrReferredById
join lat in dbRRSP.LOAAccessType on l.LOAAccessTypeId equals lat.LOAAccessTypeId
join lp in dbRRSP.LOAPerson on l.LOAPersonId equals lp.LOAPersonId
where
l.PersonId == personId
select new
{
LOAOrReferredByDescription = lrb.LoaOrReferredByDescription, lat.LOAAccessTypeDescription,
PersonType = "Person",
LOAName = lp.LOAPersonName,
l.DateAdded
};
This is the four queries. And the trickiest part is that the last field is a datetime, which is causing me some issues. I know how to union two of them together like this:
var qryMultipleLOA = qryIssuer.Union(qryEMD).ToList().Select(loa => new ExtendedLOA
{
LOAOrReferredByDescription = loa.LOAOrReferredByDescription,
LOAAccessTypeDescription = loa.LOAAccessTypeDescription,
PersonType = loa.PersonType,
LOAName = loa.LOAName,
DateAdded = DateTime.Parse(loa.DateAdded.ToString()).ToString("MM/dd/yyyy")
});
But I'm at a loss on how to add the last two queries - first I tried wrapping it in brackets and adding a .Union which didn't work, and then when I tried to nest them with appropriate .ToLists, that didn't work either.
Below is the code to bind it to the repeater.
rptLOA.DataSource = qryMultipleLOA;
rptLOA.DataBind();
Suggestions would be greatly appreciated.
Did you try something like?
var qryMultipleLOA = qryIssuer.Union(qryEMD).Union(qryEmdRep).Union(qryLOAPerson).ToList();
Provided your queries' footprints are the same, this shouldn't be an issue to chain them upon each other.
Edit:
I would also recommend the following:
Create a class to hold an instance of the resultant data.
Instead of creating lists of dynamic variables generated from Linq and hoping they all match, funnel the linq results into a List. That way you can tell immediately if you have a type mismatch.
Once you have four lists of the same List, Unions as per my syntax above will be a snap.
Dynamic Linq lists can be a pain, unwieldy and a single property type change can throw of your code at runtime rather than design time. If you follow the steps above, your code will be much more maintainable and clear to you and others.
I hope this helps in some way.
In my Person table is a RequestedLocation column which stores location IDs. The IDs match the LocationId column in the Locations table, the Locations table also has the text location names, in the LocatioName column.
In my view, I need to display the string LocationName in the view which has the Person model passed to it. The view will be displaying a List of people in a telerik grid. CUrrently it works great, except the RequestedLocation column is all integers.
I am populating all my grids with methods containing LINQ queries. Here is the method that currently works:
public List<Person> GetPeople()
{
var query = from p in _DB.Person.ToList()
select p;
return query.ToList();
}
Here is the regular SQL query that works, and I need to convert into LINQ:
SELECT ApplicantID
,FirstName
,LastName
,MiddleName
,DateofBirth
,Gender
,RequestedVolunteerRole
,RequestedVolunteerLocation
,l.LocationName
FROM Form.Person p
JOIN dbo.Location l ON p.RequestedVolunteerLocation = l.LocationID
Order BY ApplicantID
Here is my attempt to convert to LINQ:
public List<NewApplicantViewModel> GetPeople()
{
var query = from pl in _DB.Person.ToList()
join l in _Elig_DB.Locations.ToList() on pl.RequestedVolunteerLocation equals l.LocationID
select new
{
pl.RequestedVolunteerLocation = l.LocationName
};
return query.ToList();
The number of errors I get from this are numerous, but most are along the lines of:
Cannot convert from type Annonymous to Type List<NewAPplicantModel>
and
Invalid annonymous type declarator.
Please help, and thank you for reading my post.
Oh, and I have only been programming for a couple months, so if I am going about this all wrong, please let me know. Only thing I have to stick with is the table structure because it is an existing app that I am updating, and changing the location or person tables would have large consequences.
public List<NewApplicantViewModel> GetPeople()
{
var query = from pl in _DB.Person
join l in _Elig_DB.Locations on pl.RequestedVolunteerLocation
equals l.LocationID
select new NewApplicantViewModel
{
LocationName = l.LocationName,
otherPropery = p.Property
};
return query.ToList();
}
Beware of calling _DB.Person.ToList() it will load all persons from DB because ToList() immediately executes the query and the join would be performed in memory (not in DB).
The reason you are getting an error is you are projecting an anonymous type
select new
{
pl.RequestedVolunteerLocation = l.LocationName
};
Instead, you need to project a NewApplicantViewModel
select new NewApplicantViewModel
{
RequestedVolunteerLocation = l.LocationName
};
I have created a set of search results, and I wish to create a filter of available cats, with the number of results within that filter. however I get the most strangest error when trying to do this.
Unable to create a constant value of type 'NAMESPACE.Models.Products'. Only primitive types ('such as Int32, String, and Guid') are supported in this context.
this is the code i have tried:
var cats = (from p in ctx1.SubCategories
where myCats.Contains(p.subCategoryId) && p.enabled
select new
AvailableSubCats
{
CategoryName = p.subCategoryName,
Id = p.subCategoryId,
TotalItems = model.Count(x => x.subCategoryId == p.subCategoryId)
}).Distinct();
Products is the object that is called model on the line of totalItems.
I have also tried this:
var cats = from c in ctx1.SubCategories
join p in model on c.subCategoryId equals p.subCategorySubId
group p by c.subCategoryName
into g
select new
AvailableSubCats
{
CategoryName = g.Key,
Id = 0,
TotalItems = g.Count()
};
with the same error, and dont like this because i dont know how to get the name of the category and its ID.
help much appreciated.
thanks
p.s I am using Entity framework 4.1, .net 4 and MVC 3, mysql
in short i am trying to run this in linq, but were the the products side is already a result
select c.*, (select count(productId) from Products where Products.subCategoryId = c.subCategoryId) as counter from SubCategories c
You could try turning your list of products into a list of subCategoryId's so EF can understand it. Something like:
var subCategoryIds = model.Select(m => m.subCategoryId);
var cats = (from p in ctx1.SubCategories
ctx1.SubCategories
where myCats.Contains(p.subCategoryId) && p.enabled
select new
AvailableSubCats
{
CategoryName = p.subCategoryName,
Id = p.subCategoryId,
TotalItems = subCategoryIds.Count(x => x == p.subCategoryId)
}).Distinct();
I'm quite new to linq, so please bear with me.
I'm working on a asp.net webpage and I want to add a "search function" (textbox where user inputs name or surname or both or just parts of it and gets back all related information). I have two tables ("Person" and "Application") and I want to display some columns from Person (name and surname) and some from Application (score, position,...). I know how I could do it using sql, but I want to learn more about linq and thus I want to do it using linq.
For now I got two main ideas:
1.)
var person = dataContext.GetTable<Person>();
var application = dataContext.GetTable<Application>();
var p1 = from p in Person
where(p.Name.Contains(tokens[0]) || p.Surname.Contains(tokens[1]))
select new {Id = p.Id, Name = p.Name, Surname = p.Surname}; //or maybe without this line
//I don't know how to do the following properly
var result = from a in Application
where a.FK_Application.Equals(index) //just to get the "right" type of application
//this is not right, but I don't know how to do it better
join p1
on p1.Id == a.FK_Person
2.) The other idea is just to go through "Application" and instead of "join p1 ..." to use
var result = from a in Application
where a.FK_Application.Equals(index) //just to get the "right" type of application
join p from Person
on p.Id == a.FK_Person
where p.Name.Contains(tokens[0]) || p.Surname.Contains(tokens[1])
I think that first idea is better for queries without the first "where" condition, which I also intended to use. Regardless of what is better (faster), I still don't know how to do it using linq. Also in the end I wanted to display / select just some parts (columns) of the result (joined tables + filtering conditions).
I really want to know how to do such things using linq as I'll be dealing also with some similar problems with local data, where I can use only linq.
Could somebody please explain me how to do it, I spent days trying to figure it out and searching on the Internet for answers.
var result = from a in dataContext.Applications
join p in dataContext.Persons
on p.Id equals a.FK_Person
where (p.Name.Contains("blah") || p.Surname.Contains("foo")) && a.FK_Application == index
select new { Id = p.Id, Name = p.Name, Surname = p.Surname, a.Score, a.Position };
Well as Odrahn pointed out, this will give you flat results, with possibly many rows for a single person, since a person could join on multiple applications that all have the same FK. Here's a way to search all the right people, and then add on the relevant application to the results:
var p1 = from p in dataContext.Persons
where(p.Name.Contains(tokens[0]) || p.Surname.Contains(tokens[1]))
select new {
Id = p.Id, Name = p.Name, Surname = p.Surname,
BestApplication = dataContext.Applications.FirstOrDefault(a => a.FK_Application == index /* && ???? */);
};
Sorry - it looks like this second query will result in a roundtrip per person, so it clearly won't be scalable. I assumed L2S would handle it better.
In order to answer this properly, I need to know if Application and Person are directly related (i.e. does Person have many Applications)? From reading your post, I'm assuming that they are because Application seems to have a foreign key to person.
If so, then you could create a custom PersonModel which will be populated by the fields you need from the different entities like this:
class PersonModel
{
string Name { get; set; }
string Surname { get; set; }
List<int> Scores { get; set; }
List<int> Positions { get; set; }
}
Then to populate it, you'd do the following:
// Select the correct person based on Name and Surname inputs
var person = dataContext.Persons.Where(p => p.Name.Contains("firstname") || p.Name.Contains("surname")).FirstOrDefault();
// Get the first person we find (note, there may be many - do you need to account for this?)
if (person != null)
{
var scores = new List<int>();
var positions = new List<int>();
scores.AddRange(person.Applications.Select(i => i.Score);
positions.AddRange(person.Applications.Select(i => i.Position);
var personModel = new PersonModel
{
Name = person.Name,
Surname = person.Surname,
Scores = scores,
Positions = positions
};
}
Because of your relationship between Person and Application, where a person can have many applications, I've had to account for the possibility of there being many scores and positions (hence the List).
Also note that I've used lambda expressions instead of plain linqToSql for simple selecting so that you can visualise easily what's going on.