I have a linq to sql and have been researching how to use linq to sql to group your results. I only see samples with count and sum in them. My model is that each customer order has a variety of notes and could have multiple notes. Right now it's listing all the customer orders and multiple times if it has multiple notes.
How do I use group by in Linq to Sql without the sums/counts aggregate
I have tried:
public IQueryable<object> getAllamcase()
{
try
{
var q = (from c in _context.Customer
join am in _context.table2 on c.id equals am.id
join ampn in _context.table3 on am.id equals ampn.id
join ay in _context.tabl4 on am.id equals ay.id
join oim in _context.table5 on am.id equals oim.id
group c.FileNum by new
{
FileNum = c.order,
assignmentdt = am.Assignment_DT,
oimname = oim.FullName,
notes = ampn.ProgressNotes,
years = ay.AMYear
}).AsQueryable();
return q;
}
catch (Exception ex)
{
_logger.LogError("Could not get......", ex);
return null;
}
}
My results are look as multiple jsons
Customer notes
1 notes 1
1 notes 2
1 notes 3
2 notes 1
2 notes 2
I just want it to return in one json like
Customer notes
1 notes 1
notes 2
notes 3
2 notes 1
notes 2
Your question is unclear, but as I #GertArnold stated, if you want to load notes of customers you should use Navigation properties. Also, please look at naming conventions. Your code will be much cleaner if you name variables, etc. correctly. But according to your question header, I can suggest you following. Imagine that you have Note class:
public class Note
{
public int CustomerId { get; set; }
public string NoteName { get; set; }
}
And you have list of Notes as following:
List<Note> notes = new List<Note>
{
new Note { CustomerId = 1, NoteName = "note 1" },
new Note { CustomerId = 1, NoteName = "note 2" },
new Note { CustomerId = 1, NoteName = "note 3" },
new Note { CustomerId = 1, NoteName = "note 4" },
new Note { CustomerId = 2, NoteName = "note 1" },
new Note { CustomerId = 2, NoteName = "note 2" },
new Note { CustomerId = 3, NoteName = "note 1" },
};
If you want to get CustomerId-s and related notes from this list you can easyli achieve it by grouping them:
var result = notes
.GroupBy(m => m.CustomerId)
.Select(g => new
{
CustomerId = g.Key,
Notes = g.Select(m => m.NoteName).ToList()
});
The result will be:
CustomerId || NoteName
1 note 1
note 2
note 3
note 4
2 note 1
note 2
3 note 1
I hope, it will help you.
Related
Is it possible to convert a string value to a decimal value within a LINQ expression that performs an aggregate function like SUM or AVERAGE?
Assume the example below where I have a collection of Bank Accounts where my goal is to obtain an average of each customers bank account if they have a balance. The data comes from an XML API where all the data is read in a strings.
public class BankAccount
{
string Id{ get; set; }
string CustomerId { get; set; }
string Balance { get; set; }
}
Sample data ...
{ Id = "1", CustomerId = "Bob", Balance = "1" }
{ Id = "2", CustomerId = "Bob", Balance = "2" }
{ Id = "3", CustomerId = "Sam", Balance = "4" }
{ Id = "4", CustomerId = "Sam", Balance = "" }
{ Id = "5", CustomerId = "Alice", Balance = "" }
LINQ grouping expression. Is there a way to convert the value of Balance to a decimal so an average can be taken within the LINQ statement? I tried x => Decimal.Parse(x.Balance) but got an Input string was not in a correct format error. I only need to convert the Balance property to decimal for the Average calculation as the results would be rendered as a string in the XML.
At the same time, if an account does not have a balance listed (i.e. it's blank like Sams's first account and Alice's only account above) then I don't want the Average to take that entry included in the average, though I still want the account grouped in for display.
var groupedResults = allAccounts
.GroupBy(x => new {x.CustomerId, x.Balance})
.Select(g => new BankAccount {
CustomerId = g.Customer.Key.CustomerId,
Balance = g.Average(x => x.Balance)
}).ToList();
These are the results I am looking for:
{ CustomerId = "Bob", Balance = "1.5" }
{ CustomerId = "Sam", Balance = "4" }
{ CustomerId = "Alice", Balance = "" }
I think to achieve the result you are looking for you should try this:
var groupedResults = allAccounts
.GroupBy(x =>x.CustomerId)
.Select(g => new BankAccount {
CustomerId = g.Key,
Balance = g.Where(x =>!string.IsNullOrEmpty(x.Balance))
.Select(x =>(decimal?)decimal.Parse(x.Balance))
.DefaultIfEmpty(null)
.Average().ToString()
}).ToList();
First just group by CustomerId, is not necessary to include the Balance there. Then, to get the average and avoid the error parsing include the condition to make sure the Balance is not empty.
Another way to do it using query syntax:
from e in allAccounts
group e by e.CustomerId into g
let temp=g.Where(x =>!string.IsNullOrEmpty(x.Balance))
select new BankAccount(){CustomerId = g.Key,
Balance =temp.Any()?
temp.Average(x =>Decimal.Parse(x.Balance)).ToString():""
};
decimal d;
var groupedResults = allAccounts.GroupBy(a => a.CustomerId)
.Select(g => new BankAccount { CustomerId = g.Key, Balance = g.Average(b =>
decimal.TryParse(b.Balance, out d) ? (decimal?)d : null).ToString() }).ToList();
The .TryParse part results in (decimal?)null for strings that can't be parsed, which are then ignored by .Average. Also, the last average for Alice results in (decimal?)null and then in "".
I need to make a query to filter records, when get distinct records, get these records information by difference conditions. Also I need these to be dynamic(quantity filter in first select)
Let me show you an example:
I have 2 tables:
tblCustomers:
id customerName
1 John
2 Philip
3 Steve
tblOrders
id customerId ordId payment
1 1 100 True
2 1 101 True
3 1 102 False
4 2 101 True
5 2 102 True
6 2 103 False
7 3 101 True
My condition is:
where (orderId = 101 and orderId = 102)
but get all records of this customer that payment = true I mean my condition is different from what I need to see.
I want to receive all records with payment=True without care of orderId
I must get:
john 100
john 101
Philip 101
Philip 102
Clearing: I need two step - first filter customer who has orderId=101&102, in second step i want to show these selected customers' orderId which payment is true. so for example in first step i get john(who has order id =101&102) then show john 100 - john 101 (which payment istrue). consider tblorder.id=1 isn't in first query but I must show in final result.
#Raphael direct me to better expression:I want to see all payment true order for the customers that have orders (101 & 102). but orderids may be more than 2 (thanks #Raphael).
2nd problem is: it must be dynamic. Sometimes I have more than 10 orderId that must be checked - sometimes less. I mean my query must be flexible.
In SQL Server select command, I can prepare a string variable and use but in linq I can't do it.
From what I understood from your post and the comments, you need all customers, where the orderId is 101 or 102 and the payment is true.
You need the where clause with the orderIds to be dynamic so you can change the Ids to be checked against outside of the query.
List<int> IDList = new List<int>();
IDList.Add(101);
IDList.Add(102);
IDList.Add(110);
//...
var result = from cust in tblCustomers
join order in tblOrders on cust.id equals order.customerId
where IDList.Contains(order.ordId) && order.payment == true
select new {
Name = cust.customerName
OrderId = order.ordId
payment = order.payment
//...
}
With this you can store all orderIds which need to be checked against in a list, which in turn you can edit from your code.
EDIT
I really haven't found a clean solution to your problem, so I took a detour, which isn't very clean but should work. In my example I created 2 classes, Customer & Order and filled it with your data from above. Then I took my first query and attached a groupBy to it and a where-clause comparing the length of the grouping with the length of the list
var result = (from cust in Customers
join order in Orders on cust.Id equals order.customerId
where IDList.Contains(order.orderId) &&
order.payment == true
select new {
Name = cust.Name,
OrderId = order.orderId,
Payment = order.payment
//...
}).GroupBy (r => r.Name)
.Where (r => r.Count() == IDList.Count());
Output:
Name OrderId Payment
Philip 101 True
Philip 102 True
If you want/need it, I can provide you with the whole Linqpad query, so you can see my whole code and what I have done. Speaking of Linqpad: ignore the result.Dump() line. It won't work on visual Studio.
void Main()
{
List<Customer> customers = new List<Customer>
{
new Customer { Id = 1, Name = "John" },
new Customer { Id = 2, Name = "Philip" },
new Customer { Id = 3, Name = "Steve" }
};
List<Order> orders = new List<Order>
{
new Order { Id = 1, CustomerId = 1, OrderId = 100, Payment = true },
new Order { Id = 2, CustomerId = 1, OrderId = 101, Payment = true },
new Order { Id = 3, CustomerId = 1, OrderId = 102, Payment = false },
new Order { Id = 4, CustomerId = 2, OrderId = 101, Payment = true },
new Order { Id = 5, CustomerId = 2, OrderId = 102, Payment = true },
new Order { Id = 6, CustomerId = 2, OrderId = 103, Payment = false },
new Order { Id = 7, CustomerId = 3, OrderId = 101, Payment = true }
};
List<int> orderIds = new List<int> { 101, 102 };
var customersWithRelevantOrders =
from ord in orders
group ord by ord.CustomerId into customerOrders
where orderIds.All (
i => customerOrders.Select (co => co.OrderId).Contains(i))
select customerOrders.Key;
var paymentTrueOrdersForTheseCustomers =
from ord in orders
join cust in customers on ord.CustomerId equals cust.Id
where ord.Payment
where customersWithRelevantOrders.Contains(cust.Id)
select new
{
Name = cust.Name,
OrderId = ord.OrderId
};
}
public class Customer
{
public int Id { get; set; }
public string Name { get; set; }
}
public class Order
{
public int Id { get; set; }
public int CustomerId { get; set; }
public int OrderId { get; set; }
public bool Payment { get; set; }
}
I am looking for a way to identify duplicate records...only I want / expect to see them.
So the records aren't duplicated completely but the unique fields I am unconcerned with at this point. I just want to see if they have made X# payments of the exact same amount, via the exact same card, to the exact same person. (Bogus example just to illustrate)
The collection is a List<> further whatever X# is the List<>.Count will be X#. In other words all the records in the list match (again just the fields I am concerned with) or I will reject it.
The best I can come up with is to take the first record get value of say PayAmount and LINQ the other two to see if they have the same PayAmount value. Repeat for all fields to be matched. This seems horribly inefficient but I am not smart enough to think of a better way.
So any thoughts, ideas, pointers would be greatly appreciated.
JB
Something like this should do it.
var duplicates = list.GroupBy(x => new { x.Amount, x.CardNumber, x.PersonName })
.Where(x => x.Count() > 1);
Working example:
class Program
{
static void Main(string[] args)
{
List<Entry> table = new List<Entry>();
var dup1 = new Entry
{
Name = "David",
CardNumber = 123456789,
PaymentAmount = 70.00M
};
var dup2 = new Entry
{
Name = "Daniel",
CardNumber = 987654321,
PaymentAmount = 45.00M
};
//3 duplicates
table.Add(dup1);
table.Add(dup1);
table.Add(dup1);
//2 duplicates
table.Add(dup2);
table.Add(dup2);
//Find duplicates query
var query = from p in table
group p by new { p.Name, p.CardNumber, p.PaymentAmount } into g
where g.Count() > 1
select new
{
name = g.Key.Name,
cardNumber = g.Key.CardNumber,
amount = g.Key.PaymentAmount,
count = g.Count()
};
foreach (var item in query)
{
Console.WriteLine("{0}, {1}, {2}, {3}", item.name, item.cardNumber, item.amount, item.count);
}
Console.ReadKey();
}
}
public class Entry
{
public string Name { get; set; }
public int CardNumber { get; set; }
public decimal PaymentAmount { get; set; }
}
The meat of which is this:
var query = from p in table
group p by new { p.Name, p.CardNumber, p.PaymentAmount } into g
where g.Count() > 1
select new
{
name = g.Key.Name,
cardNumber = g.Key.CardNumber,
amount = g.Key.PaymentAmount,
count = g.Count()
};
You're unique entries are based off of the 3 criteria of Name, Card Number, and Payment Amount so you group by them and then use .Count() to count how many of those unique values exist. where g.Count() > 1 filters the group to duplicates only.
Looks like join cannot use sets defined inside query or am I doing something wrong?
from a in new[] {
new { Id = 1 },
new { Id = 2 } }
let bees = new[] {
new { Id = 2 },
new { Id = 3 } }
join b in bees on a.Id equals b.Id
select 1;
This one gives compile time error 'Element "bees" does not exist in the current context.' What's wrong with the query?
This is not legal either way you slice it - you cannot declare a range variable "in the middle" of a join - internally the let clause gets translated to a Select() statement with an anonymous type - but you cannot use Select() either in the middle of the join, you have to move it after the join.
Have a look at this question - I think it covers things:
Can i use join with let in linq - c#
Basically you can only use the let for the query, rather than for joins.
The following does seem to work, but its not as nice:
from a in new[] {
new { Id = 1 },
new { Id = 2 } }
join b in new[] {
new { Id = 2 },
new { Id = 3 } } on a.Id equals b.Id
select 1;
I can't get this bit of logic converted into a Linq statement and it is driving me nuts. I have a list of items that have a category and a createdondate field. I want to group by the category and only return items that have the max date for their category.
So for example, the list contains items with categories 1 and 2. The first day (1/1) I post two items to both categories 1 and 2. The second day (1/2) I post three items to category 1. The list should return the second day postings to category 1 and the first day postings to category 2.
Right now I have it grouping by the category then running through a foreach loop to compare each item in the group with the max date of the group, if the date is less than the max date it removes the item.
There's got to be a way to take the loop out, but I haven't figured it out!
You can do something like that :
from item in list
group item by item.Category into g
select g.OrderByDescending(it => it.CreationDate).First();
However, it's not very efficient, because it needs to sort the items of each group, which is more complex than necessary (you don't actually need to sort, you just need to scan the list once). So I created this extension method to find the item with the max value of a property (or function) :
public static T WithMax<T, TValue>(this IEnumerable<T> source, Func<T, TValue> selector)
{
var max = default(TValue);
var withMax = default(T);
var comparer = Comparer<TValue>.Default;
bool first = true;
foreach (var item in source)
{
var value = selector(item);
int compare = comparer.Compare(value, max);
if (compare > 0 || first)
{
max = value;
withMax = item;
}
first = false;
}
return withMax;
}
You can use it as follows :
from item in list
group item by item.Category into g
select g.WithMax(it => it.CreationDate);
UPDATE : As Anthony noted in his comment, this code doesn't exactly answer the question... if you want all items which date is the maximum of their category, you can do something like that :
from item in list
group item by item.Category into g
let maxDate = g.Max(it => it.CreationDate)
select new
{
Category = g.Key,
Items = g.Where(it => it.CreationDate == maxDate)
};
How about this:
private class Test
{
public string Category { get; set; }
public DateTime PostDate { get; set; }
public string Post { get; set; }
}
private void Form1_Load(object sender, EventArgs e)
{
List<Test> test = new List<Test>();
test.Add(new Test() { Category = "A", PostDate = new DateTime(2010, 5, 5, 12, 0, 0), Post = "A1" });
test.Add(new Test() { Category = "B", PostDate = new DateTime(2010, 5, 5, 13, 0, 0), Post = "B1" });
test.Add(new Test() { Category = "A", PostDate = new DateTime(2010, 5, 6, 12, 0, 0), Post = "A2" });
test.Add(new Test() { Category = "A", PostDate = new DateTime(2010, 5, 6, 13, 0, 0), Post = "A3" });
test.Add(new Test() { Category = "A", PostDate = new DateTime(2010, 5, 6, 14, 0, 0), Post = "A4" });
var q = test.GroupBy(t => t.Category).Select(g => new { grp = g, max = g.Max(t2 => t2.PostDate).Date }).SelectMany(x => x.grp.Where(t => t.PostDate >= x.max));
}
Reformatting luc's excellent answer to query comprehension form. I like this better for this kind of query because the scoping rules let me write more concisely.
from item in source
group item by item.Category into g
let max = g.Max(item2 => item2.PostDate).Date
from item3 in g
where item3.PostDate.Date == max
select item3;