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LINQ: select specific value in a datatable column

In table I have 4 Columns GroupName, Display, Value and ID
How can I just show a specific data in display. I only want to show some of the groupNames Data
for example I only want to show Groupname = company and display = Forbes
Here's my linq
sample = (from c in smsDashboardDBContext.CodeDefinitions
orderby c.Display ascending
select new CodeDefinitionDTO
{
GroupName = c.GroupName,
Display = c.Display,
Value = c.Value,
Id = c.Id
}).ToList();

You can add a where statement in the query.
where c.GroupName == "company" && c.Display == "Forbes"

I only want to show some of the groupNames Data for example I only want to show Groupname = company and display = Forbes
Before the ToList, use a Where to keep only those items that you want to show:
var company = ...
var forbes = ...
var result = smsDashboardDBContext.CodeDefinitions
.OrderBy(codeDefinition => codeDefintion.Display)
.Select(codeDefinition => new CodeDefinitionDTO
{
Id = codeDefinition.Id,
GroupName = codeDefinition.GroupName,
Display = codeDefinition.Display,
Value = codeDefinition.Value,
})
.Where(codeDefinition => codeDefition.GroupName == company
&& codeDefintion.Display == forbes);
In words:
Order all codeDefinitions that are in the table of CodeDefintions by ascending value of property codeDefintion.Display.
From every codeDefinition in this ordered sequence make one new CodeDefinitionDTO with the following properties filled: Id, GroupName, Display, Value
Frome every codeDefintion in this sequence of CodeDefinitionDTOs, keep only those codeDefinitions that have a value for property GroupName that equals company and a value for property Display that equals forbes.
There is room for improvement!
Suppose your table has one million elements, and after the Where, only five elements are left. Then you will have sorted almost one million elements for nothing. Consider to first do the Where, then the Order and finally a Select.
In LINQ, try to do aWhere as soon as possible: all following statements will have to work on less items
In LINQ, try to do a Select as late as possible, preferrably just before the ToList / FirstOrDefault / ... This way the Select has to be done for as few elements as possible
So first the Where, then the OrderBy, then the Select, and finally the ToList / FirstOrDefault, etc:
var result = smsDashboardDBContext.CodeDefinitions
.Where(codeDefinition => ...);
.OrderBy(codeDefinition => codeDefintion.Display)
.Select(codeDefinition => new CodeDefinitionDTO
{
...
});

C# Linq or querying IEnumerable

I have an Employee table which also has Department Manager information. I need to populate two dropdowns - one with Employees and other with Managers. Instead of using two queries to pull employees and another query to pull managers, I am querying table once and storing all info in cache in an IEnumerable EmployeeList.
I need some query to pull managers from that query - either using LINQ or loop within C# code. I have written loop but it is very inefficient.
Here is the SQL query to populate HCache:
SELECT [Dept_Mgr_ID] As MgrId,
EmployeeId,
EmpLastName,
EmpFirstName
FROM Employee_tbl
Here I am trying to loop through the cache and join EmployeeId and MgrId
List<DTO.Employee> Mgrs = new List<DTO.Employee>(0);
for (int i = 0; i < HCache.EmployeeList.Count(); i++)
{
foreach(var e in HCache.EmployeeList)
{
if (HCache.EmployeeList.ElementAt(i).EmployeeId == e.MgrId)
{
Mgrs.Add(new DTO.Employee() { MgrID = e.MgrId,
ManagerLastName = e.EmpLastName,
ManagerFirstName = e.EmpFirstName
});
}
}
}
I am not using this query, however, this is how I can get the results using 2nd query to get managers:
WITH CTE_Manager_ID
AS
(
SELECT DISTINCT [Dept_Mgr_ID]
FROM Employee_tbl
)
SELECT EmployeeId,
EmpLastName,
EmpFirstName
FROM Employee_tbl Emp
INNER JOIN CTE_Manager_ID cteMgr
ON cteMgr.Dept_Mgr_ID = Emp.EmployeeId

I'd say you should use your second SQL query to get the managers, but I'll try to speed up your code.
Problems:
Assuming EmployeeList is an IEnumerable, EmployeeList.ElementAt(i) is an O(n) operation, i.e. slow. It's a nested loop behind the scenes.
EmployeeList.Count() is an O(n) operation, i.e. slow.
The resulting complexity of your code is O(n^3), i.e. very slow.
How to improve:
Do one pass to build a map from EmployeeId to Employee (or whatever you store in HCache.EmployeeList). This will enable you to find them quickly by id (in O(1)).
Do another pass through EmployeeList to collect the managers.
The overall complexity is O(n), i.e. proportional to the size of the EmployeeList collection.
Here is some code to illustrate the idea:
class Emp {
public int EmployeeId {get;set;}
public int MgrId {get;set;}
public string EmpLastName {get;set;}
}
IEnumerable<Emp> EmployeeList = new List<Emp> {
new Emp { EmployeeId = 1, MgrId = 0, EmpLastName = "boss" },
new Emp { EmployeeId = 2, MgrId = 1, EmpLastName = "dude" } };
IDictionary<int, Emp> dict = EmployeeList.ToDictionary(e => e.EmployeeId);
var managers = EmployeeList
.Select(e => dict.TryGetValue(e.MgrId, out Emp mgr) ? mgr : null)
.OfType<Emp>()
.ToList()
// List<Emp>(1) { Emp { EmpLastName="boss", EmployeeId=1, MgrId=0 } }
Note that this code potentially produces duplicates in the managers list, which may or may not be what you want, but your code behaves this way so I preserved the behavior.

Dynamics CRM products and bundles in a order

I am experimenting with the example CalculatePrice on the Dynamics CRM example page.
And im having a hard time understanding how to get products and bundles in a good manner.
What i wanna try and do is get products from an order with a productstructure attribute and a producttypecode. But it seems whatever i try i get a error The given key was not present in the dictionary.
The query below should look for productID from salesorder based on productID
QueryExpression query = new QueryExpression("salesorderdetail");
query.ColumnSet.AddColumns("quantity", "salesorderispricelocked", "priceperunit", "producttypecode", "_productid_value");
query.Criteria.AddCondition("salesorderid", ConditionOperator.Equal, entity.Id);
QueryExpression query2 = new QueryExpression("product");
query2.ColumnSet.AddColumns("productstructure", "productnumber" , "productid");
query.Criteria.AddCondition("productid", ConditionOperator.Equal, ec.Entities["_productid_value"]);
Then i try to iterate the list of objects to see if they have productstructure and their producttypecode
for (int i = 0; i < ec.Entities.Count; i++)
{
if (ec.Entities[i].GetAttributeValue<int>("producttypecode") == 6)
{ you are a product
if (ec.Entities[i].GetAttributeValue<int>("productstructure") == 3){ you are a bundle
This is the link to the sample code i use:
https://learn.microsoft.com/en-us/dynamics365/customer-engagement/developer/sample-calculate-price-plugin

For starters, the _productid_value notation is the WebAPI's way to access a lookup field. To access the productid using the SDK's late-bound paradigm, use:
myEntity["productid"] or
myEntity.GetAttributeValue<Guid>("productid") or
myEntity.GetAttributeValue<EntityReference>("productid").
Beyond that, since Product is a lookup on the OrderDetail, using a couple LinkEntity objects you could get away with a single query.
I would probably use LINQ and do something like this:
private void getProducts(Guid salesOrderId)
{
using (var context = new Microsoft.Xrm.Sdk.Client.OrganizationServiceContext(svc))
{
var query = from od in context.CreateQuery("salesorderdetail")
join so in context.CreateQuery("salesorder")
on od.GetAttributeValue<Guid>("salesorderid") equals so.GetAttributeValue<Guid>("salesorderid")
join p in context.CreateQuery("product")
on od.GetAttributeValue<Guid>("productid") equals p.GetAttributeValue<Guid>("productid")
where od.GetAttributeValue<Guid>("salesorderid").Equals(salesOrderId)
select new
{
OrderDetailId = od.GetAttributeValue<Guid>("salesorderdetailid"),
ProductId = od.GetAttributeValue<EntityReference>("productid"),
Quantity = od.GetAttributeValue<decimal?>("quantity"),
IsPriceLocked = so.GetAttributeValue<bool?>("ispricelocked"),
PricePerUnit = od.GetAttributeValue<Money>("priceperunit"),
ProductTypeCode = od.GetAttributeValue<OptionSetValue>("producttypecode"),
ProductStructure = p.GetAttributeValue<OptionSetValue>("productstructure"),
ProductNumber = p.GetAttributeValue<string>("productnumber")
};
var results = query.ToList();
var products = results.Where(e => e.ProductStructure.Value == 6).ToList();
var bundles = results.Where(e => e.ProductStructure.Value == 3).ToList();
}
}
Please note that local variables results, products, and bundles are an anonymous type. You can loop through and access the properties of each object, but there's also a strong chance you'd want to cast them into instances of a real class.

Query Row count from Grouped EF query

I have this query to group the levels of a particular row in EF
var awards = from a in context.Awards
where a.TWID == employee.TWID
group a by a.AwardLevel;
This gives me the awards for each level (1-4) what I'm trying to figure out is how to extract the count from the awards for a specific level.
ie: level1.count,level2.count etc.
I know this should be some simple lambda expression or something but I just can't get it.
UPDATE What I'm looking for is a way NOT to write 4 different queries. For example:
var level1 = awards.Level[0]
var level2 = awards.Level[1]

Try:
var awards = from a in context.Awards
where a.TWID == employee.TWID
group a by a.AwardLevel into award
select new
{
AwardLevel = award.Key,
Count = award.Count()
};
Update based on updated question:
var awards = (from a in context.Awards
where a.TWID == employee.TWID
group a by a.AwardLevel into award
select new
{
AwardLevel = award.Key,
Count = award.Count()
}).ToDictionary( t => t.AwardLevel, t => t.Count );

LINQ query with SELECT and two GROUP-BY condition

What's the equivalent LINQ instruction for a Datatable of the following SQL query:
SELECT code_direction, count(TP) AS CN
FROM table1
WHERE cod_time = 'A011'
GROUP BY TP,code_direction;
and how to get the result into a new datatable?
I tried to convert it but I there're some errors. Someone could take a look on this:
var query = from t in table1.AsEnumerable()
group t by new { t.TP, t.code_direction }
into grp
select new
{
grp.Key.code_direction,
CN = grp.Count(t.TP)
};
foreach (var x in query)
{
Console.Write(x.code_direction);
Console.Write(x.CN);
}

As far as your first question goes. The LINQ equivalent of the SQL query is:
var query = from t in table1.AsEnumerable()
where t.cod_time == "A011"
group t by new { t.TP, t.code_direction }
into grp
select new
{
grp.Key.code_direction,
CN = grp.Count()
};
Note that you don't have to pass any argument to grp.Count(). (For the obvious reason that in SQL COUNT(TP) is the same as COUNT(*), i.e. just count the number of rows. The story would be different if you'd use COUNT(DISTINCT TP) or similar.)
As far as the second question goes, if your query just returned an IEnumerable<T> where T is DataRow (i.e. a query like table1.AsEnumerable().Where(r => r.cod_time == "A011")) then you could just the DataTableExtensions.CopyToDataTable extension method. As your query returns an anonymous type however, you will have to follow these instructions found on MSDN.

I Have been using LINQ to work on a JSON object returned from a remote sharepoint web service. I have posted this because most of the answers I found online were slightly different from what I needed.
a json list of daily activities is returned from a remote sharepoint list & is then summarised using LINQ
The simplified version of a custom object definition is shown below( & which is defined in the models area of an MVC application)
public class MyCustomObjectList
{
public string eventdate { get; set; }
public string userid { get; set; }
public string action { get; set; }
}
The JSON object is serialised into a MyCustomObjectList array.
var customobject = serializer.Deserialize<MyCustomObjectList>(jsonobject);
I wanted to work out how many actions of each type happened on a given day. NB eventdate is stored as a string in format yyyy-mm-dd hh:MM:ss. This was to simplify conversions between c#, JSON & Jquery ( where required I create DateTime objects elsewhere in the code using the
eventdate.
Some will argue this is inefficient, but I prefer to split processes into a sequential set of really simple operations, for the sake of easier debugging & to help other people follow my code. Thats why there are 2 Linq queries .
querya strips out the time component from the eventdate This ensures our later grouping happens by day, & not by second. To be doubly sure that there is no caching, I create it in a new field called actionday. I also rename action to activity, because intellisense was getting confused!! The other columns are copied as is.
var querya =
from c in customobject.rows
select new { actionday = c.eventdate.Substring(0, 10), activity = c.action, c.userid,
c.eventdate };
/* queryb produces a grouped count of querya, grouped on actionday & activity, creating new columns actionkey,ActionCount,Dte,action & DetailList ( which is a summary for debugging purposes)
*/
var queryb=
from p in querya group p by new { p.actionday, p.activity} into idGroup
actionkey = idGroup.Key,
ActionCount = idGroup.Count(),
Dte = idGroup.Key.actionday,
action = idGroup.Key.activity,
DetailList = idGroup
};
Here’s a version that sumarises by 3 columns
var queryc = from p in querya
group p by new { p.actionday, p.userid, p.activity} into idGroup
select new
{
actionday = idGroup.Key,
ActionCount = idGroup.Count(),
userid = idGroup.Key.userid,
Dte = idGroup.Key.actionday,
action = idGroup.Key.activity,
DetailList = idGroup
};