I have this fragment of code:
SmsDataClassesDataContext dc = new SmsDataClassesDataContext();
// Get the customer
Customer currentCustomer = dc.Customers.Single( c => c.Hash1 == forThisHash );
// Get from Name (LINQ to XML)
var q = from c in thisSmsPack.Descendants("from")
select c;
string from = q.First().Value;
foreach ( XElement element in thisSmsPack.Descendants("to") )
{
// Create the queue
SmsQueue sq = new SmsQueue();
sq.CustomerId = currentCustomer.CustomerId;
sq.MsgFrom = from;
sq.MsgTo = element.Attribute("name").Value;
sq.MsgPhone = element.Attribute("phone").Value;
sq.MsgBody = element.Attribute("msg").Value;
sq.Priority = currentCustomer.SendsSmsAtPriority;
sq.DontSendUntil = GetNextSendDate();
// sq.TimeCreated = System.DateTime.Now;
currentCustomer.SmsQueues.Add(sq);
}
dc.SubmitChanges();
I am creating new instances of "SmsQueues", populating the values and when the foreach loop is finished I submit the changes. Given the new lambda/linq/anonymous types that .NET 3.5 has, is there a more "modern" way to accomplish the above?
As a side question, maybe related, can I return an existing type composed of different columns in the select part of the linq expression?
Suppose you have three tables:
T1 == T1.Id, T1.Name
T2 == T2.Id, T2.Phone
T3 == T3.Name, T3.Phone, T3.SomethingElse
Can I perform a LINQ query that returns:
T1.Name, T2.Phone, SomethingElseNew
And let .NET know that that is of Type T3 (and it's a new instance of it)?
That way when I SubmitChanges, new T3 instances are inserted in the DB?
I don't know if I make myself clear :S
I don't have a system available to test this, but I think this (or something very close) should work.
CustomerId = currentCustomer.CustomerId;
var sqrange = from element in thisSmsPack.Descendants("to") )
select new SmsQueue
{
// Create the queue
MsgFrom = from,
MsgTo = element.Attribute("name").Value,
MsgPhone = element.Attribute("phone").Value,
MsgBody = element.Attribute("msg").Value,
Priority = currentCustomer.SendsSmsAtPriority,
DontSendUntil = GetNextSendDate()
// TimeCreated = System.DateTime.Now
};
currentCustomer.SmsQueues.AddRange(sqrange);
EDIT: Fixed the numerous syntax errors (as delineated in the comments)
You could do something like this (syntax may be off slightly, no intellisense here):
var q = T1.Join(T2, t => t.Id, t2 => t2.Id)
select new T3{Name=t.Name,Phone=t2.Phone,SomethingElseNew="Chickens"};
Related
I'm trying to build a linq query coming from a table grid from the client side, so im expecting page offset, page start, order and the traditional paging parameters. I have the following code:
[Route("api/settings/logs")]
public Rest.DatatablesResponse GetLogs(int draw, int start, int length) {
var query_string = Request.GetQueryNameValuePairs().ToDictionary(x => x.Key, x => x.Value);
var search = query_string["search.value"];
int order_column = int.Parse(query_string["order[0].column"]);
var order_direction = query_string["order[0].dir"];
var count = db.Logs.Count(q => q.Mode == 2);
var logs = (from l in db.Logs
where l.Mode == 2
select new {
id = l.ID,
mode = l.Mode,
phase_id = l.Phase.ID,
created = l.Created,
user = l.User.Name,
blender_name = l.Blender.Name,
oil_name = l.Oil,
oil_quantity = l.OilQuantity,
production_cycle_name = l.ProductionCycle.Name
});
if (order_direction == "asc") {
if (order_column == 0) logs.OrderBy(q => q.created);
else if (order_column == 2) logs.OrderBy(q => q.production_cycle_name);
} else {
if (order_column == 0) logs.OrderByDescending(q => q.created);
else if (order_column == 2) logs.OrderByDescending(q => q.production_cycle_name);
};
if (!string.IsNullOrEmpty(search)) {
logs.Where(q => q.blender_name.Contains(search) ||
q.oil_name.Contains(search) ||
SqlFunctions.StringConvert((decimal)q.id).Contains(search));
}
logs.Skip(start).Take(length);
DateTime dtDateTime = new DateTime(1970,1,1,0,0,0,0,System.DateTimeKind.Utc);
var steps = from l in logs.ToList()
select new {
id = l.id,
message = StringHelpers.FormatWith(_tpl_message[l.phase_id.ToString() + l.mode.ToString() ], l) ,
created = dtDateTime.AddSeconds(l.created).ToString("h:mmtt - MMMM d, yyyy"),
production_cycle_name = l.production_cycle_name
};
return new Rest.DatatablesResponse {
draw = draw,
recordsTotal = count,
recordsFiltered = count,
data = steps.ToArray()
};
}
My problem is the skip and take and orderby expressions are getting ignored for some reason, and this is the SQL code generated just before converting my linq expressions to a list. From my understanding, the query should not be executed or evaluated until my logs.ToList() call, so the ordering and take/skip should be taken into account, but it's not:
{SELECT
[Extent1].[ID] AS [ID],
[Extent1].[Mode] AS [Mode],
[Extent1].[Phase_ID] AS [Phase_ID],
[Extent1].[Created] AS [Created],
[Extent2].[Name] AS [Name],
[Extent3].[Name] AS [Name1],
[Extent1].[Oil] AS [Oil],
[Extent1].[OilQuantity] AS [OilQuantity],
[Extent4].[Name] AS [Name2]
FROM [dbo].[Steps] AS [Extent1]
LEFT OUTER JOIN [dbo].[Users] AS [Extent2] ON [Extent1].[User_Id] = [Extent2].[Id]
LEFT OUTER JOIN [dbo].[Blenders] AS [Extent3] ON [Extent1].[Blender_ID] = [Extent3].[ID]
LEFT OUTER JOIN [dbo].[ProductionCycles] AS [Extent4] ON [Extent1].[ProductionCycle_ID] = [Extent4].[ID]
WHERE 2 = [Extent1].[Mode]}
Irrelevant P.S. I'm using the not so clever ifs for building the order expression instead of using DynamicLINQ since i have only two sortable columns.
logs.Skip(start).Take(length);
Creates a IQueryable<T> where T is the same anonymous type of which logs is an IQueryable<T> but with start items skipped. Then from that it creates a similarly typed IQueryable<T> where lenght items are the most that will be taken.
Then it throws that away and lets it be garbage collected. (Or ideally the compiler or jitter steps will realise it's thrown away and cut out the whole thing).
Then logs.ToList() goes back to the logs you still have and creates a list from it.
You should replace the Skip and Take line with:
logs = logs.Skip(start).Take(length);
So that you are actually making use of this skipping and taking.
I'm using the not so clever ifs for building the order expression instead of using DynamicLINQ since i have only two sortable columns.
There's nothing particularly not-clever about that, except that you make the same mistake; apply the OrderBy and then throwing away the result instead of using it. Likewise with the Where. You need logs = logs.OrderBy(...) etc.
I'd also question from l in logs.ToList() select new {…} here.
It might be the best approach, if obtaining that list in one step has some advantage. However otherwise:
from l in logs select new {…}
Do the select work on the database, retrieving just what you need.
from l in logs.AsEnumerable() select new {…}
Do the select work in the application, appropriate if part of it cannot be converted to database work, but do it as it comes rather than loading it all into memory first.
from l in await logs.ToListAsync() select new {…}
Has the downside of ToList() but in asynchronous uses, then (assuming your provider has a ToListAsync() method) allows for awaiting.
ToList() is rarely the best option here.
I have an array filled with long type values and for each value in the array I need to implement a query. I used foreach loop as you can see from the code below:
var result;
foreach(long id in PrdIdArr)
{
var mainQuery = (from o in db.OPERATIONs
join u in db.UNITs on o.OP_UNIT_ID equals u.UNIT_ID into smt
from s in smt
join x in db.XIDs on s.UNIT_ID equals x.UNIT_ID
where o.OP_OT_CODE == OtCode
where x.IDTYP_CD == "BSN"
where s.START_PRD_ID == id
where o.OP_UPD_DATE >= _StartDate
where o.OP_UPD_DATE <= _EndDate
select new
{
o.OP_ID,
o.OP_UPD_DATE,
x.EXTERNAL_ID,
o.OP_OS_CODE,
o.OP_START,
o.OP_ST_STATION,
s.START_PRD_ID
}).Take(_RowNumber);
//var result = mainQuery.ToList();
result.add(mainQuery.ToList());
}
data = this.Json(result);
data.JsonRequestBehavior = JsonRequestBehavior.AllowGet;
return data;
However, I have a problem in my code; I have to define a main list just before the foreach loop so that I could add results of each query to the that main list. my question is: How can I define this list as you can see at the beginning of my code? Thanks for the help...
How can I define this list as you can see at the beginning of my code?
Make
new {
o.OP_ID,
o.OP_UPD_DATE,
x.EXTERNAL_ID,
o.OP_OS_CODE,
o.OP_START,
o.OP_ST_STATION,
s.START_PRD_ID
}
into a concrete type (say QueryResult, although something a little more specific than that), and then just declare
var result = new List<QueryResult>();
Also, you should consider turning
foreach(long id in PrdIdArr)
and
where s.START_PRD_ID == id
into
where PrdIdArr.Contains(s.Start_PRD_ID)
var result = new List<object>();
foreach(long id in PrdIdArr)
{
....
result.Add(mainQuery.ToList());
}
You could do this:
var result = PrdIdArr.Select(id =>
from o in db.OPERATIONs
join u in db.UNITs on o.OP_UNIT_ID equals u.UNIT_ID into smt
from s in smt
join x in db.XIDs on s.UNIT_ID equals x.UNIT_ID
where o.OP_OT_CODE == OtCode
where x.IDTYP_CD == "BSN"
where s.START_PRD_ID == id
where o.OP_UPD_DATE >= _StartDate
where o.OP_UPD_DATE <= _EndDate
select new
{
o.OP_ID,
o.OP_UPD_DATE,
x.EXTERNAL_ID,
o.OP_OS_CODE,
o.OP_START,
o.OP_ST_STATION,
s.START_PRD_ID
}
.Take(_RowNumber)
.ToList()
).ToList();
I highly recommend performing some Extract Method refactorings, as the code is pretty complex and hard to understand/mange this way.
Just create the anonymous type outside with the same property names and the correct type
var result = Enumerable.Range(0, 0).Select(x => new
{
OP_ID = 1,
OP_UPD_DATE = DateTime.Now,
EXTERNAL_ID = 1,
OP_OS_CODE = 1,
OP_START = DateTIme.Now,
OP_ST_STATION = "",
START_PRD_ID = 1,
}).ToList();
And in your loop call AddRange
result.AddRange(mainQuery.ToList());
The following code works, but it's not a nice code. (low performance)
I have a dictionary with value and key.
First i go trough every webcodes who exist. Then i load all participants in a list (where webcode equals the actual webcode in the foreach). After that i add the data (parameter of the webcode and a count of participants to the dictionary).
Guid compID = Guid.Parse(wID);
ChartModel webcodes = new ChartModel();
webcodes.Title = "Webcodes Statistics";
webcodes.Data = new Dictionary<string, int>();
var webcodesData = db.t_Webcode;
foreach (var w in webcodesData)
{
var wData = db.t_Participant.Where(t => t.FK_Competition == compID && t.Webcode == w.Webcode);
if (wData.Count() != 0)
webcodes.Data.Add(w.Parameter, wData.Count());
}
ViewBag.Webcodes = webcodes;
TIA
You need something along these lines:
webcodes.Data = (from w in db.t_Webcode
join p in db.t_Participant on w.Webcode equals p.Webcode
where p.FK_Competition == compID
group w by w.Parameter into g
select new { g.Key, Count = g.Count() }).ToDictionary();
I can't test it but that is the type of query you need.
This will assume that you have relationships defined in your database and that your LINQ to SQL datacontext are aware of them. If not, you will need to join manually on t_Participants from tWebcode.
This should execute in 1 single SQL query, instead of 1 query per row in tWebcode.
var webcodesAndNoOfParticipants =
from webcode in db.tWebcode
// Define number of participants for this webcode
let numberOfParticipants = webcode.t_Participants.Count(participant => participant.FK_Competition == compID)
where numberOfParticipants > 0
select new {
WebcodeParameter = webcode.Parameter,
NoOfParticipants = numberOfParticipants
};
webcodes.Data = webcodesAndNoOfParticipants.ToDictionary(x => x.WebcodeParameter, x => x.NoOfParticipants);
I have 2 tables, and want to get records from 1 table and to "update" one of its fields from another table, and to pass final list of "Payment" objects somewhere. I cannot use anonymouse type, i need to get the list of proper typed objects.
There was a long way.
Got data:
var paymentsToShow = from p in paymentsRepository.Payments
join r in recordTypeRepository.RecordType
on p.RecordType equals r.Reference into p_r
where p.Customer == CustomerRef
from r in p_r.DefaultIfEmpty()
select new
{
Payment = p,
RecordType = r
};
var objList = paymentsToShow.ToList();
Change required field (basically, Payment.RecordTypeName is empty):
foreach (var obj in objList)
{
obj.Payment.RecordTypeName = obj.RecordType.Name;
}
Got list with correct type:
var paymentsList = from o in objList
select o.Payment;
Is there any way to get code shorter, to make required field update in the query or something else? I dont know where to look for.
I cannot change database.
You could do it like this:
var paymentsToShow = (from p in paymentsRepository.Payments
join r in recordTypeRepository.RecordType
on p.RecordType equals r.Reference into p_r
where p.Customer == CustomerRef
from r in p_r.DefaultIfEmpty()
select new
{
Payment = p,
RecordType = r
}).Select(x =>
{
x.Payment.RecordTypeName = x.RecordType.Name;
return x.Payment;
});
This will result in an IEnumerable<Payment>, so no anonymous type used.
What do I put in my order by?? I want to order by Name. I have moved the orderby after the distinct because I read that it needs to be done last.
var result = (from r in db.RecordDocs
where r.RecordID == recordID
select new
{
DocTypeID = r.Document.DocType.DocTypeID,
Name = r.Document.DocType.Name,
Number = r.Document.DocType.Number
}
).Distinct().OrderBy( );
Just do
.OrderBy(doc => doc.Name)
Another option, if you really prefer the query expression syntax would be to chain your query construction across multiple statements:
var query = from r in db.RecordDocs
where r.RecordID == recordID
select new
{
DocTypeID = r.Document.DocType.DocTypeID,
Name = r.Document.DocType.Name,
Number = r.Document.DocType.Number
};
query = query.Disctinct();
query = from doc in query orderby doc.Name select doc;
Since all of these methods are deferred, this will result in the exact same execution performance.