Is it possible to use AutoMapper to avoid the manual mapping bellow that gets executes a join on 2 tables in the select statement?
private IQueryable<HHDrawingNumber> GetDrawingNumbers()
{
var drawingNumbers = from dn in _unitOfWork.DrawingNumbers.Get()
join ld in _unitOfWork.CfgLocDrawing.Get() on dn.LocDrawingNum equals ld.DrawingsId
join ar in _unitOfWork.AssetReg.Get() on dn.AssetId equals ar.LastData
select new HHDrawingNumber
{
TagNumber = dn.TagNumber ?? string.Empty,
DrawingsId = ld.DrawingsId,
DrawingsCode = ld.DrawingsCode ?? string.Empty,
DrawingsDescription = ld.DrawingsDescription ?? string.Empty
};
return drawingNumbers;
}
Related
I'm converting from EF6 to EF Core 3.1 and this LINQ query is failing with a runtime exception stating 'The LINQ expression ... could not be translated.
The group by is what is causing the issue, but I'm not sure how to rewrite it to work with EF Core and keep the result in a nested list.
Notification notification = new Notification()
{
ProductReminders = new List<List<ProductNotification>>(),
ProductStats = new List<StatResult>()
};
var profileCode = 123;
notification.ProductReminders =
(from ng in ProductNotification
where ng.UserProfileCode == profileCode
orderby ng.EndDate ?? DateTime.MaxValue
group ng by ng.GroupGUID into groupG
select (from pn in ProductNotification
join p in Product on pn.ProductID equals p.ProductID
where pn.UserProfileCode == profileCode
&& pn.GroupGUID == groupG.Key
orderby pn.EndDate ?? DateTime.MaxValue
select new ProductNotification()
{
ProductDetail = new ProductDetail()
{
ProductId = pn.ProductID ?? 0,
Upc = p.UPC,
Brand = p.Description,
Manufacturer = p.Name,
ProfileCode = p.ProfileCode,
},
EndDate = pn.EndDate,
NotificationId = pn.NotificationID,
Status = pn.Status,
GroupGuid = pn.GroupGUID
})
.ToList())
.ToList();
Since grouping operator has limitations, I would suggest to read all needed data and provide grouping on the client side. Query in your case will be much effective:
// select only needed data from database
var minimalRequiredData =
from pn in ProductNotification
join p in Product on pn.ProductID equals p.ProductID
where pn.UserProfileCode == profileCode
select new ProductNotification
{
ProductDetail = new ProductDetail
{
ProductId = pn.ProductID ?? 0,
Upc = p.UPC,
Brand = p.Description,
Manufacturer = p.Name,
ProfileCode = p.ProfileCode,
},
EndDate = pn.EndDate,
NotificationId = pn.NotificationID,
Status = pn.Status,
GroupGuid = pn.GroupGUID
};
// materialize result
var materialized = minimalRequiredData.ToList();
// form required result shape using IEnumerable<T>
var resultQuery =
from m in materialized
orderby ng.EndDate ?? DateTime.MaxValue
group m by new m.GroupGUID into g
select g.Orderby(x => x.EndDate ?? ng.EndDate).ToList();
notification.ProductReminders = resultQuery.ToList();
I have this Linq to entity query that returns a list of visitors with joins.
I want a similar query to return a single record without the query being a List collection, but changing it to a basic select with FirstOrDefaultAsync gets the error "A query body must end with a select clause or a group clause"
public async Task<List<VisitorDetail>> GetOneVisitor(int visitorId)
{
var query = await (from v in _context.Visitors
where v.Id == visitorId
join d in _context.Categories on v.VisitCategoryId equals d.Id
join c in _context.Counters on v.AssignedCounter equals c.Host into counterGroup
from cg in counterGroup.DefaultIfEmpty()
select new
{
FirstName = v.FirstName,
LastName = v.LastName,
CounterDescription = cg.Description,
VisitCategory = d.Description
}).ToListAsync();
List<VisitorDetail> visitors = new();
foreach (var p in query)
{
visitors.Add(new VisitorDetail
{
FirstName = p.FirstName,
LastName = p.LastName,
CounterDescription = p.CounterDescription,
CategoryDescription = p.VisitCategory
});
}
return visitors;
}
If you want to keep DRY with LINQ to Entities, return IQueryable for your common queries and invoke materialization only when it is needed.
Your method can be rewritten in the following way:
public IQueryable<VisitorDetail> GetVisitorDetails(int visitorId)
{
var query =
from v in _context.Visitors
where v.Id == visitorId
join d in _context.Categories on v.VisitCategoryId equals d.Id
join c in _context.Counters on v.AssignedCounter equals c.Host into counterGroup
from cg in counterGroup.DefaultIfEmpty()
select new VisitorDetail
{
FirstName = v.FirstName,
LastName = v.LastName,
CounterDescription = cg.Description,
CategoryDescription = d.Description
};
return query;
}
var many = await GetVisitorDetails(visitorId).ToListAsync();
var one = await GetVisitorDetails(visitorId).FirstOrDefaultAsync();
trying to do LINQ Update query using join with on condition also And condition
Following my SQL Query
UPDATE tbl_gs_related_orders
SET RelatedCOI = sop.ServiceOrderNo
FROM tbl_service_order_progress sop
JOIN tbl_gs_related_orders ro ON sop.parentid = ro.RelatedOrderParentId
AND ro.RelatedCOIIdentifier collate database_default = sop.InstanceIdentifier collate database_default
WHERE ro.ParentId = #PARENTID
AND ro.relatedorderparentid IS NOT NULL
This Query i want to convert into LINQ SO following my update LINQ query but getting some error like "the type of one of the expressions in the join clause is incorrect type inference failed in the call to join"
var updateQuery = (from c in ctxParser.TBL_SERVICE_ORDER_PROGRESS
join o in ctxParser.tbl_GS_Related_Orders on new { ParentId = c.ParentId, InstanceIdentifier = c.InstanceIdentifier }
equals new { RelatedOrderParentId = o.RelatedOrderParentId, RelatedCOIIdentifier = o.RelatedCOIIdentifier }
where ro.RelatedOrderParentId == sParentId && ro.RelatedOrderParentId != null
select new
{
ServiceOrderNo = c.ServiceOrderNo,
Order = o
});
foreach (var item in updateQuery)
{
item.Order.RelatedCOI = item.ServiceOrderNo;
}
ctxParser.SaveChanges();
Use same aliases when creating Anonymous type for equals clause:
from c in ctxParser.TBL_SERVICE_ORDER_PROGRESS
join o in ctxParser.tbl_GS_Related_Orders on new { ParentId = c.ParentId, InstanceIdentifier = c.InstanceIdentifier }
equals new { ParentId = o.RelatedOrderParentId, InstanceIdentifier = o.RelatedCOIIdentifier }
The EntityModel is defined as:
Personnel has a link to a Country
When executing this code in LinqPad, I see that the SQL which is generated is not optimized (all fields are returned) in the first query ? What am I missing here or doing wrong ?
Query 1 LINQ
var Country = Countries.FirstOrDefault(o => o.Id == 100000581);
var personnelIds = Country.Personnels.Select(p => p.Id).ToArray();
personnelIds.Dump();
Query 1 SQL
exec sp_executesql N'SELECT [t0].[Id], [t0].[Version], [t0].[Identifier], [t0].[Name], , [t0].[UpdatedBy] FROM [Personnel] AS [t0] WHERE [t0].[Country_Id] = #p0',N'#p0 bigint',#p0=100000581
Query 2 LINQ
var Country = Countries.FirstOrDefault(o => o.Id == 100000581);
var personnelIds2 = Personnels.Where(p => p.Country == Country).Select(p => p.Id).ToArray();
personnelIds2.Dump();
Query 2 SQL
exec sp_executesql N'SELECT [t0].[Id] FROM [Personnel] AS [t0] WHERE [t0].[Country_Id] = #p0',N'#p0 bigint',#p0=100000581
The database used is SQL Express 2008. And LinqPad version is 4.43.06
//var Country = Countries.FirstOrDefault(o => o.Id == 100000581);
var personnelIds = context.Personnels
.Where(p => p.Country.Id == 100000581)
.Select(p => p.Id)
.ToArray();
personnelIds.Dump();
Try this, it should be better.
Personnels collection will be populated via lazy loading when accessed, hence retrieving all of the fields from the DB. Here's what's happening...
// retrieves data and builds the single Country entity (if not null result)
var Country = Countries.FirstOrDefault(o => o.Id == 100000581);
// Country.Personnels accessor will lazy load and construct all Personnel entity objects related to this country entity object
// hence loading all of the fields
var personnelIds = Country.Personnels.Select(p => p.Id).ToArray();
You want something more like this:
// build base query projecting desired data
var personnelIdsQuery = dbContext.Countries
.Where( c => c.Id == 100000581 )
.Select( c => new
{
CountryId = c.Id,
PersonnelIds = c.Personnels.Select( p => p.Id )
}
// now do enumeration
// your example shows FirstOrDefault without OrderBy
// either use SingleOrDefault or specify an OrderBy prior to using FirstOrDefaul
var result = personnelIdsQuery.OrderBy( item => item.CountryId ).FirstOrDefault();
OR:
var result = personnelIdsQuery.SingleOrDefault();
Then get the array of IDs if not null
if( null != result )
{
var personnelIds = result.PersonnelIds;
}
Try can also try grouping personnel into a single query
var groups =
(from p in Personnel
group p by p.CountryId into g
select new
{
CountryId = g.Key
PersonnelIds = p.Select(x => x.Id)
});
var personnelIds = groups.FirstOrDefault(g => g.Key == 100000581);
Do you have the ForeignKey explicitly defined in your POCO for Personnel? It's common to leave it out in EF, but adding it would massively simplify both this code and the resulting SQL:
public class Personnel
{
public Country Country { get; set; }
[ForeignKey("Country")]
public int CountryId { get; set; }
. . .
}
> update-database -f -verbose
var ids = db.Personnel.Where(p => p.CountryId == 100000581).Select(p => p.Id).ToArray();
Because of some business decisions I need to change a bit of what I was doing. Yay me. :)
Currently, I have:
public IOrderedQueryable<ProductDetail> GetProductList(string productGroupName, string productTypeName, Dictionary<string,List<string>> filterDictionary)
{
string whereClause = "ProductGroupName='" + productGroupName + "' AND ProductTypeName='" + productTypeName + "'";
string comma = "";
foreach (KeyValuePair<string, List<string>> myKVP in filterDictionary)
{
comma = "";
if (myKVP.Value.Count > 0)
{
whereClause = String.Format("{0} AND FieldName = {1} AND FieldValue IN (", whereClause, myKVP.Key);
foreach (string value in myKVP.Value)
{
whereClause = String.Format("{0}{1}'{2}'", whereClause, comma, value);
comma = ",";
}
whereClause = String.Format("{0})", whereClause);
}
}
var q = db.ProductDetail
.Where (whereClause)
.OrderBy ("ProductTypeName");
return q;
}
Instead of foing this directly, I now need to join through 2 other tables to apply the filter correctly. I'm trying to figure out how to correctly join in a dynamic LINQ query. In TSQL it would be something like:
SELECT pd.*
FROM ProductDetail pd
INNER JOIN ProductFilterAssignment pfa ON pd.ProductID = pfs.ProductID
INNER JOIN ProductFilter pf ON pfs.FIlterID = pf.FIlterID
WHERE pf.FieldName = 'var1' AND pf.FieldValue IN ('var1a','var1b','var1c',etc)
AND pf.FieldName = 'var2' AND pf.FieldValue IN ('var2a','var2b','var2c',etc)
Ouch. Yeah, that's a complicated requirement. You know, lambdas are cumulative, so you can do this much simpler if you use successive linq expressions. Note that subsequent linq expressions are using the prior expression result and the entire isn't actually executed until iterated.
public IOrderedQueryable<ProductDetail> GetProductList(string productGroupName, string productTypeName, Dictionary<string,List<string>> filterDictionary)
{
// Initial select on productGroupName and productTypeName
var products = from product in db.ProductDetail
where product.ProductGroupName == productGroupName && product.ProductTypeName == productTypeName
select product;
// Now add each filter item present.
foreach (KeyValuePair<string, List<string>> myKVP in filterDictionary)
{
products = from product in products
join pfa in db.ProductFilterAssignment on product.ProductID equals pfa.ProductID
join pf in db.Product on pfa.FilterID equals pf.FilterId
where pf.FieldName == myKVP.Key && myKVP.Value.Contains(pf.FieldValue)
select product;
}
return products.OrderBy ("ProductTypeName");
}
I don't have a good "answer" for you, but more of an aside. Check out LINQPad. You might even see an ad on the right-hand side of this page, too. It is very slick for writing LINQ queries. It might help in writing and validating this and any other future LINQ query you write.
Try to use Spolty Framework. It helps to do dynamic query for Linq To SQL and Entity Framework. You can dynamically create left/inner join, add conditions, orderings and other things. If you use Spolty Framework then your code will be look like below:
public IQueryable<ProductDetail> GetProductList(string productGroupName, string productTypeName, Dictionary<string, List<string>> filterDictionary)
{
// create root node
JoinNode productDetailNode = new JoinNode(typeof(ProductDetail));
productDetailNode.AddConditions(new Condition("ProductGroupName", productGroupName),
new Condition("ProductTypeName", productTypeName));
// if there are conditions than we create joins
if (filterDictionary.Count > 0)
{
// create joinNode
// INNER JOIN ProductFilterAssignment pfa ON pd.ProductID = pfs.ProductID
JoinNode productFilterAssignmentNode = new JoinNode(typeof(ProductFilterAssignment));
productDetailNode.AddChildren(productFilterAssignmentNode);
// create joinNode
// INNER JOIN ProductFilter pf ON pfs.FIlterID = pf.FIlterID
JoinNode productFilterNode = new JoinNode(typeof(ProductFilter));
productFilterNode.AddChildren(productFilterNode);
foreach (KeyValuePair<string, List<string>> myKVP in filterDictionary)
{
// create condition pf.FieldName = {1} And AND pf.FieldValue IN ('var1a','var1b','var1c',etc)
productFilterNode.AddConditions(new Condition("FieldName", myKVP.Key),
OrCondition.Create("FieldValue", myKVP.Value.ToArray()));
}
}
// create result query by JoinNode productDetailNode
QueryDesigner queryDesigner = new QueryDesigner(db, productDetailNode).
OrderBy(new Ordering("ProductTypeName"));
return queryDesigner.Cast<ProductDetail>();
}