Linq How to group joined queries - linq

I am newbee and can join two datasets. I want to group these by OrderNo query. How can I manage that?
var result = context.Order
.Join(context.OrderDetails
, od => od.OrderId
, o => o.OrderId
, (o, od) => new {
o.OrderNo, od.ProductName, o.OrderDate
})
.Select(s => s);


try this
var result = context.Order
.Join(context.OrderDetails
, od => od.OrderId
, o => o.OrderId
, (o, od) => new {
o.OrderNo, od.ProductName, o.OrderDate
})
.GroupBy(p => new{
o.OrderNo
})
.Select(s => s);

Related

Nest multisearch query writing as object initializer Syntax

I have a multiSearch query as below. Basically I query product and category types. I would like to make this query optional without writing same code again.
Basically in some cases I want to query only product type, that means that it will not multisearch but a search query. How can I split this query into 2 search queries. Something like below I think.
return Client.MultiSearch(ms => ms
.Search<Product>("products", s => s
.Index(IndexName)
.Explain(explain)
.Query(q => q
.Bool(b => b
.Should(
sh => sh.MultiMatch(qs => qs
.Fields(d => d
.Field(Name + ".raw", NameBoost + 0.5)
.Field(Name, NameBoost)
.Type(TextQueryType.BestFields)
.Query(key))
))).From(startfrom).Size(size))
.Search<Category>("categories", s => s
.Index(IndexName)
.Explain(explain)
.Query(q => q.
Bool(b => b.
Should(sh => sh.
MultiMatch(m => m
.Fields(d => d
.Field(f => f.Name, NameBoost)
.Field(p => p.Name.Suffix("raw"), NameBoost + 0.5)).Type(TextQueryType.BestFields)
.Query(key)
)
))).From(startfrom).Size(size))
);
something like this below. I guess that it is called object initializer Syntax according to this article
Client.MultiSearch (SearchProductQuery && SearchCategoryQuery)
is it possible?

This fluent API multi search
client.MultiSearch(ms => ms
.Search<Product>("products", s => s
.Index(IndexName)
.Explain(explain)
.Query(q => q
.Bool(b => b
.Should(sh => sh
.MultiMatch(qs => qs
.Fields(d => d
.Field(Name + ".raw", NameBoost + 0.5)
.Field(Name, NameBoost)
)
.Type(TextQueryType.BestFields)
.Query(key)
)
)
)
)
.From(startfrom)
.Size(size)
)
.Search<Category>("categories", s => s
.Index(IndexName)
.Explain(explain)
.Query(q => q
.Bool(b => b
.Should(sh => sh
.MultiMatch(m => m
.Fields(d => d
.Field(f => f.Name, NameBoost)
.Field(p => p.Name.Suffix("raw"), NameBoost + 0.5)
)
.Type(TextQueryType.BestFields)
.Query(key)
)
)
)
)
.From(startfrom)
.Size(size)
)
);
would be this OIS API multi search
var multiSearch = new MultiSearchRequest
{
Operations = new Dictionary<string, ISearchRequest>
{
{ "products", new SearchRequest<Product>(IndexName)
{
Explain = true,
Query = new BoolQuery
{
Should = new QueryContainer[] {
new MultiMatchQuery
{
Fields =
((Fields)Field.Create(Name + ".raw", NameBoost + 0.5))
.And(Name, NameBoost),
Type = TextQueryType.BestFields,
Query = key
}
}
},
From = startfrom,
Size = size
}
},
{ "categories", new SearchRequest<Category>(IndexName)
{
Explain = true,
Query = new BoolQuery
{
Should = new QueryContainer[] {
new MultiMatchQuery
{
Fields =
((Fields)Infer.Field<Category>(f => f.Name, NameBoost))
.And<Category>(f => f.Name.Suffix("raw"), NameBoost + 0.5),
Type = TextQueryType.BestFields,
Query = key
}
}
},
From = startfrom,
Size = size
}
},
}
};
client.MultiSearch(multiSearch);
Take a look at the multi search integration tests for another example. I'll look at getting this added to the documentation.

Query expressions to Lambda Syntax?

How can I change this query expression to lambda expression:
var dataUser = from cm in ConsumerName
join c in Consumer on cm.ConsumerId equals c.Id
join cua in ConsumerAccount on cm.ConsumerId equals cua.ConsumerId
join bd in BankDetail on cm.ConsumerId equals bd.ConsumerId
join cpm in CardPayment on cm.ConsumerId equals cpm.ConsumerId
where cm.ConsumerId == consumerId
select new { AccountNumber=bd.AccountNumber,CardNumber= cpm.CardNumber, Name = cm.FirstName + " " + cm.MiddleName + " " + cm.LastName, Email = c.Email, AccountId = cua.AccountId };

Simple, auto-converted by Resharper
var dataUser =
ConsumerName.Join(Consumer, cm => cm.ConsumerId, c => c.Id, (cm, c) => new { cm, c })
.Join(ConsumerAccount, #t => cm.ConsumerId, cua => cua.ConsumerId, (#t, cua) => new { #t, cua })
.Join(BankDetail, #t => cm.ConsumerId, bd => bd.ConsumerId, (#t, bd) => new { #t, bd })
.Join(CardPayment, #t => cm.ConsumerId, cpm => cpm.ConsumerId, (#t, cpm) => new { #t, cpm })
.Where(#t => cm.ConsumerId == consumerId)
.Select(
#t =>
new
{
AccountNumber = bd.AccountNumber,
CardNumber = cpm.CardNumber,
Name = cm.FirstName + " " + cm.MiddleName + " " + cm.LastName,
Email = c.Email,
AccountId = cua.AccountId
});

How to get EF Framework to generate this group by query

I tried a few different ways and I am not impressed with the generated output query. It seems so inefficient. It needs to be efficient and shouldn't bring back all the rows into the app layer
select year(datetaken) as yr,
month(datetaken) as mth,
day(datetaken) as dy,
count(*) as totalpics
from photos
where photos.dateTaken <= #cutoffdate
group by year(datetaken), month(datetaken), day(datetaken)
order by yr asc, mth asc, dy asc
LINQ query:
var query = ctx.Photos.Where(p => p.DateTaken <= maxCutOffDate)
.GroupBy(p => new { p.DateTaken.Year, p.DateTaken.Month, p.DateTaken.Day })
.Select(grp => grp);
var results = query.ToList();

Select only the grouping key (grp.Key):
var query = ctx.Photos.Where(p => p.DateTaken <= maxCutOffDate)
.GroupBy(p => new { p.DateTaken.Year, p.DateTaken.Month, p.DateTaken.Day })
.Select(grp => grp.Key);
var results = query.ToList();
Edit
Or, including the count of totalpics:
var query = ctx.Photos.Where(p => p.DateTaken <= maxCutOffDate)
.GroupBy(p => new { p.DateTaken.Year, p.DateTaken.Month, p.DateTaken.Day })
.Select(grp => new
{
Date = grp.Key,
TotalPics = grp.Count()
});
var results = query.ToList();

You can access the key properties through grp.Key and the count through grp.Count().
var query = ctx.Photos.Where(p => p.DateTaken <= maxCutOffDate)
.GroupBy(p => new { p.DateTaken.Year, p.DateTaken.Month, p.DateTaken.Day })
.Select(grp => new
{
grp.Key.Year,
grp.Key.Month,
grp.Key.Day,
Count = grp.Count()
});
var results = query.ToList();

LINQ - Group by lambda expression

Say I have the following:
var OrderCounts = from o in Orders
group o by o.CustomerID into g
select new {
CustomerID = g.Key,
TotalOrders = g.Count()
};
How can this be converted to a Lambda expression

var OrderCounts = customers
.GroupBy (o => o.CustomerID)
.Select (o => new { CustomerID = o.Key, TotalOrders = o.Count () })

LINQ lambda expression for many-to-one inner join involving max()

I have the following schema:
Table1
ID int
Table2
ID int
Table1ID int
Datetime datetime
Table3
ID int
Table2ID int
Name varchar(255)
All columns are not null. How do I write the following SQL query in LINQ using lambda expressions?
select Table1.*
from Table2
inner join (
select Table1ID, max(Datetime) as Datetime
from Table2
group by Table1ID
) a on Table2.Table1ID = a.Table1ID and Table2.Datetime = a.Datetime
inner join Table3 on Table2.ID = Table3.Table2ID
inner join Table1 on Table1.ID = Table2.Table1ID
where Name = 'me'
EDIT:
I am using LINQ to EF. I have tried
var myEntities = new MyEntities();
var a = myEntities.Table2.Select(x => new { x.Id, x.Datetime }).GroupBy(x => x.Id).Select(x => new { Id = x.Key, Datetime = x.Max(y => y.Datetime) });
var b = myEntities.Table2.Join(a.ToList(), x => new { Id = x.Table1Id, x.Datetime }, y => new { y.Id, y.Datetime }, (x, y) => x.Id);
return myEntities.Table3.Where(x => x.Name == "me" && b.Contains(x.Table2Id)).Select(x => x.Table2.Table1).ToList();
but it comes back with
System.NotSupportedException: Unable to create a constant value of type 'Anonymous type'. Only primitive types ('such as Int32, String, and Guid') are supported in this context.
highlighting the last line above. The stack trace shows it is ToList() throwing this exception.

I figured it out; it was that
var b = myEntities.Table2.Join(a.ToList(),
should be
var b = myEntities.Table2.Join(a,
Also, the query should be
var myEntities = new MyEntities();
var a = myEntities.Table2.Select(x => new { x.Table1Id, x.Datetime }).GroupBy(x => x.Table1Id).Select(x => new { Table1Id = x.Key, Datetime = x.Max(y => y.Datetime) });
var b = myEntities.Table2.Join(a, x => new { x.Table1Id, x.Datetime }, y => new { y.Table1Id, y.Datetime }, (x, y) => x);
return b.Join(myEntities.Table3, x => x.Id, y => y.Table2Id, (x, y) => new { x.Table1, y.Name }).Where(x => x.Name == "me").Select(x => x.Table1).ToList();

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