I have the following QueryOver:
var q = Session.QueryOver<CostCenter>().Where(c => c.PrimeCompany.Id == idPrimeCompany);
I need to clone the QueryOver but without the "where clausule". Is this possible?
use the root entity (class used in the call of session.QueryOver<>) and build a new query
var roottype = theQueryOver.UnderlyingCriteria.GetRootEntityTypeIfAvailable();
var totalCount = session.CreatCriteria(roottype).SetProjection(Projections.RowCount()).UniqueReasult<long>();
Related
I am currently updating a BackEnd project to .NET Core and having performance issues with my Linq queries.
Main Queries:
var queryTexts = from text in _repositoryContext.Text
where text.KeyName.StartsWith("ApplicationSettings.")
where text.Sprache.Equals("*")
select text;
var queryDescriptions = from text in queryTexts
where text.KeyName.EndsWith("$Descr")
select text;
var queryNames = from text in queryTexts
where !(text.KeyName.EndsWith("$Descr"))
select text;
var queryDefaults = from defaults in _repositoryContext.ApplicationSettingsDefaults
where defaults.Value != "*"
select defaults;
After getting these IQueryables I run a foreach loop in another context to build my DTO model:
foreach (ApplicationSettings appl in _repositoryContext.ApplicationSettings)
{
var applDefaults = queryDefaults.Where(c => c.KeyName.Equals(appl.KeyName)).ToArray();
description = queryDescriptions.Where(d => d.KeyName.Equals("ApplicationSettings." + appl.KeyName + ".$Descr"))
.FirstOrDefault()?
.Text1 ?? "";
var name = queryNames.Where(n => n.KeyName.Equals("ApplicationSettings." + appl.KeyName)).FirstOrDefault()?.Text1 ?? "";
// Do some stuff with data and return DTO Model
}
In my old Project, this part had an execution from about 0,45 sec, by now I have about 5-6 sec..
I thought about using compiled queries but I recognized these don't support returning IEnumerable yet. Also I tried to avoid Contains() method. But it didn't improve performance anyway.
Could you take short look on my queries and maybe refactor or give some hints how to make one of the queries faster?
It is to note that _repositoryContext.Text has compared to other contexts the most entries (about 50 000), because of translations.
queryNames, queryDefaults, and queryDescriptions are all queries not collections. And you are running them in a loop. Try loading them outside of the loop.
eg: load queryNames to a dictionary:
var queryNames = from text in queryTexts
where !(text.KeyName.EndsWith("$Descr"))
select text;
var queryNamesByName = queryName.ToDictionary(n => n.KeyName);
one can write queries like below
var Profile="developer";
var LstUserName = alreadyUsed.Where(x => x.Profile==Profile).ToList();
you can also use "foreach" like below
lstUserNames.ForEach(x=>
{
//do your stuff
});
I have the following query:
var list = repositoy.Query<MyClass>.Select(domain => new MyDto()
{
Id = domain.Id,
StringComma = string.Join(",", domain.MyList.Select(y => y.Name))
});
That works great:
list.ToList();
But if I try to get the Count I got an exception:
list.Count();
Exception
NHibernate.Hql.Ast.ANTLR.QuerySyntaxException
A recognition error occurred. [.Count[MyDto](.Select[MyClass,MyDto](NHibernate.Linq.NhQueryable`1[MyClass], Quote((domain, ) => (new MyDto()domain.Iddomain.Name.Join(p1, .Select[MyListClass,System.String](domain.MyList, (y, ) => (y.Name), ), ))), ), )]
Any idea how to fix that without using ToList ?
The point is, that we should NOT call Count() over projection. So this will work
var query = repositoy.Query<MyClass>;
var list = query.Select(domain => new MyDto()
{
Id = domain.Id,
StringComma = string.Join(",", domain.MyList.Select(y => y.Name))
});
var count = query.Count();
When we use ICriteria query, the proper syntax would be
var criteria = ... // criteria, with WHERE, SELECT, ORDER BY...
// HERE cleaned up, just to contain WHERE clause
var totalCountCriteria = CriteriaTransformer.TransformToRowCount(criteria);
So, for Count - use the most simple query, i.e. containing the same JOINs and WHERE part
If you really don't need the results, but only the count, then you shouldn't even bother writing the .Select() clause. Radim's answer as posted is a good way to both get the results and the count, but if your database supports it, use future queries to execute both in the same roundtrip to the database:
var query = repository.Query<MyClass>;
var list = query.Select(domain => new MyDto()
{
Id = domain.Id,
StringComma = string.Join(",", domain.MyList.Select(y => y.Name))
}).ToFuture();
var countFuture = query.Count().ToFutureValue();
int actualCount = countFuture.Value; //queries are actually executed here
Note that there in NH prior to 3.3.3, this would still execute two round-trips (see https://nhibernate.jira.com/browse/NH-3184), but it would work, and if you ever upgrade NH, you get a (minor) performance boost.
I have a linq object and I want to write the query using linq.
please help me.
INPUT:
var tags = (from row in tempChildData.AsEnumerable()
join tagOrder in tupleInfoDataset.Tables["TagHierarchy"].AsEnumerable() on row.Field<Int64>("TAGID") equals tagOrder.Field<Int64>("TAGID")
join tagName in tupleInfoDataset.Tables["SequenceChoiceList"].AsEnumerable() on tagOrder.Field<Int64>("PARENTTAGID") equals tagName.Field<Int64>("TAGID")
join facet in tupleInfoDataset.Tables["FacetType"].AsEnumerable() on tagName.Field<string>("Tag_Name") equals facet.Field<string>("Facetname")
join tagIdInfo in schDataTogetTagid.AsEnumerable() on row.Field<string>("refTagName").Contains(":") ? row.Field<string>("refTagName").Split(':').Last():row.Field<string>("refTagName") equals tagIdInfo.Field<string>("TAGNAME")
where ( childList.Contains(row.Field<Int64>("TAGID")) && facet.Field<string>("FacetType").ToLower().Equals("ctype"))
select new
{
Tagid = row.Field<Int64>("TAGID"),
TagIdToInsert=tagIdInfo.Field<Int64>("TAGID"),
MaxOccur = row.Field<string>("Maxoccurs"),
MinOccur =Convert.ToInt32(Convert.ToString(row.Field<string>("Minoccur"))),
ParentTagId=tagOrder.Field<Int64>("PARENTTAGID"),
Order=tagOrder.Field<Int64>("TAG_ORDER"),
ParentTagname = tagName.Field<string>("Tag_Name"),
FacetId=facet.Field<Int64>("FacetID")
}).ToList();
var parentTagID = (from tagIdInfo in tupleInfoDataset.Tables["Tuple"].AsEnumerable()
where tagIdInfo.Field<Int64>("TAGID").Equals(key.Key)
select tagIdInfo.Field<Int64>("ConceptID")).ToList();
long parentID =Convert.ToInt64(parentTagID[0]);
Now i want the query out of the above code as:
INSERT INTO TUPLE_MAP (TagId,ParentTagId,ParentTagname,MinOccur,MaxOccur,Order)
VALUES (TagIdToInsert,ParentTagId,ParentTagname,MinOccur,MaxOccur,Order)
Please help me I don't know how to write SQL queries using linq
Maybe something like this:
using(var db=new DataContext("YourConnectionStringHERE"))
{
db.TUPLE_MAP.InsertAllOnSubmit(tags.Select (t =>
new TUPLE_MAP()
{
TagId=t.TagIdToInsert,
ParentTagId=t.ParentTagId,
ParentTagname=t.ParentTagname,
MinOccur=t.MinOccur,
MaxOccur=t.MaxOccur,
Order=t.Order
}));
db.SubmitChanges();
}
Or if you want to use the parentID then something like this:
using(var db=new DataContext("YourConnectionStringHERE"))
{
db.TUPLE_MAP.InsertAllOnSubmit(tags.Select (t =>
new TUPLE_MAP()
{
TagId=t.TagIdToInsert,
ParentTagId=parentID,
ParentTagname=t.ParentTagname,
MinOccur=t.MinOccur,
MaxOccur=t.MaxOccur,
Order=t.Order
}));
db.SubmitChanges();
}
where db is your linq data context
Useful references:
How to: Insert Rows Into the Database (LINQ to SQL)
EDIT
So if you are using the Compact database 3.5 then many something like this:
using (var conn =new SqlCeConnection("Data Source = test.sdf; Password ='pass'"))
{
foreach (var tag in tags)
{
using(var cmd = conn.CreateCommand())
{
cmd.CommandText = #"INSERT INTO TUPLE_MAP (TagId,ParentTagId,ParentTagname,MinOccur,MaxOccur,Order)
VALUES (#TagIdToInsert,#ParentTagId,#ParentTagname,#MinOccur,#MaxOccur,#Order)";
cmd.Parameters.AddWithValue("#TagIdToInsert", tag.TagIdToInsert);
cmd.Parameters.AddWithValue("#ParentTagId", tag.ParentTagId);
cmd.Parameters.AddWithValue("#ParentTagname", tag.ParentTagname);
cmd.Parameters.AddWithValue("#MinOccur", tag.MinOccur);
cmd.Parameters.AddWithValue("#MaxOccur", tag.MaxOccur);
cmd.Parameters.AddWithValue("#Order", tag.Order);
cmd.ExecuteNonQuery();
}
}
}
Useful references:
Why can't I insert a record into my SQL Compact 3.5 database?
SqlCeCommand.Parameters Property
SqlCeCommand Class
SqlParameterCollection.AddWithValue Method
Use linq Pad or sql profiler to see the generated SQL.
You can also use visual studio for that purpose. In the debug mode,hold cursor on the variable "tags", you will be able to see the SQL.
I am assuming you are using Linq to SQL, if you are doing so you would have entity called Tuple_map in you xxxDataContext. Then you would just have to create object of that entity something like this....
using (XXXDataContext context = new XXXDataContext())
{
Tuple_map obj = new Tuple_map();
//Populate obj properties like obj.tabid = from objects you got it from above query
context.Tuple_map.InsertOnSubmit(obj);
context.SubmitChanges();
}
I have a scenario where I have to update an entity if it exists or add a new one if it doesn't.
I would like to execute a single method for this (it would be great if it were a single trip to the server).
Is there something like that in EF?
Right now my code looks like this:
var entity = db.Entities.FirstOrDefault(e => e.Id == myId);
if (entity == null)
{
entity = db.Entities.CreateObject();
entity.Id = myId;
}
entity.Value = "my modified value";
db.SaveChanges();
But I would like to avoid the first query, something like this:
var entity = new Entity();
entity.Id = myId;
entity.Value = "my modified value";
db.AddOrAttach(entity);
db.SaveChanges();
Is there anything similar? or do I have to perform the first query no matter what?
Thanks
You have to perform the first query no matter what, unfortunately.
One option would be to write a stored procedure that performs a T-SQL MERGE then map it to a function import, though that would require that you pass the scalar values of the entity as parameters (and support for navigation properties would be done), but it would accomplish what you're after.
I ran some quick test code for editing in MVC 3 with EF 4 and it seems to work for edit with following code:
using (var context = new TestStackOverFlowEntities())
{
Person p = new Person();
p.Id = long.Parse(collection["Id"]);
p.FirstName = collection["FirstName"];
p.LastName = collection["LastName"];
context.People.Attach(p);
context.ObjectStateManager.ChangeObjectState(p, System.Data.EntityState.Modified);
context.SaveChanges();
return RedirectToAction("Index");
}
Edit: I checked with creating new object too, you need to change this
context.ObjectStateManager.ChangeObjectState(p, System.Data.EntityState.Added);
when Id == 0 //ie new object.
Quick and dirty code to add new is this:
using (var context = new TestStackOverFlowEntities())
{
Person p = new Person();
p.Id = 0;
p.FirstName = collection["FirstName"];
p.LastName = collection["LastName"];
context.People.Attach(p);
context.ObjectStateManager.ChangeObjectState(p, System.Data.EntityState.Added);
context.SaveChanges();
return RedirectToAction("Index");
}
If you are just trying to limit code to clarify your controllers:
db.Attach(model);
db.SaveChanges(model);
Will update if the Entity Key exists, and create if it does not.
I am using the System.Linq.Data library provided here - http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx
I have the following query which works great and returns an Iqueryable
IQueryable customer =
ctx.Customers.Where(cust => true).Select("new("Name,Address")");
However, how do I access these returned columns? I cannot access them using a lambda expression as follows:
var test = customer.Where(cust=>cust.Name == "Mike").First();
"cust.Name" in the above case cannot be resolved. It does not exist in the list of methods/properties for "cust".
Am i assuming something wrong here. I understand that I am working with an anonymous type. Do I have to create a DTO in this case?
For any IQueryable you have property called ElementType.
You can use it to get the properties as explained below
IQueryable query = from t in db.Cities
selec new
{
Id = t.Id,
CityName = t.Name
};
if(query!=null)
{
Type elementType = query.ElementType;
foreach(PropertyInfo pi in elementType.GetProperties())
{
}
}
Try foreach loop:
var a = _context.SENDERS.Select(x=>new { Address=x.ADDRESS, Company=x.COMPANY });
foreach(var obj in a)
{
Console.WriteLine(obj.Address);
Console.WriteLine(obj.Company);
}