I don't understand why Q2 would not return results if Q1 does. Am I missing something?
var q1 = session.Query<Comp>().Where(x => x.ptype=="RTC"||x.ptype=="FLT"); //works
var q2 = session.Query<Comp>().Where(x => x.ptype.In(new string[] {"RTC","FLT"})); //does not
This was happening because I was using a 2.0 client against a db on RavenHQ (which is using v1.0).
Related
I have a Cypher query like that
MATCH (n: learningPaths)
WHERE any(x IN n.modules WHERE x = "any course")
RETURN n
How can I write this query in .net core API to get the results
Previously I have a query like that
MATCH (n:learningPaths)-[]->(m:modules)
WHERE m.id = "any course"
RETURN n;
and I write below in .net core API
var result = (
await _graphClient.Cypher
.Match(#"(n:learningPaths)-[]->(m:modules)")
.Where<modules>(m => m.id == "any course")
.Return((n)=> n.As<learningPaths>())
.ResultsAsync)
.ToList();
Have you tried just doing:
var query = client.Cypher
.Match("MATCH (n:learningPaths)-->(m:modules)")
.Where("any(x IN n.modules WHERE x = 'any course')"
.Return( n => n.As<learningPaths>());
I have a system with two database servers I am working with:
One of them is database first - a database managed by a legacy enterprise application and I don't have full control over changing the database structure.
The second is code first and I have full control in the code first database to make changes.
Security policies prevent me from making a view that joins tables from the two database servers in the code first DB which might be a way to make this better according to what i've seen on SO posts.
I have one context for each database since they are separate.
The data and structure in the code first tables is designed to be able to join to the non-code first database as if they were all in one database.
I CAN get what I need working using this set of queries:
// Set up EF tables
var person = await _context1.Person.ToListAsync();
var labor = await _context1.Labor.ToListAsync();
var laborCraftRate = await context1.LaborCraftRate.ToListAsync();
var webUsers = await context2.WebUsers.ToListAsync();
var workOrders = await _context1.Workorder
.Where(r => r.Status == "LAPPR" || r.Status == "APPR" || r.Status == "REC")
.ToListAsync();
var specialRequests = await _context1.SwSpecialRequest
.Where(r => r.Requestdate > DateTime.Now)
.ToListAsync();
var distributionListQuery = (
from l in labor
from p in person.Where(p => p.Personid == l.Laborcode).DefaultIfEmpty()
from wu in webUsers.Where(wu => wu.Laborcode == l.Laborcode).DefaultIfEmpty()
from lcr in laborCraftRate.Where(lcr => lcr.Laborcode == l.Laborcode).DefaultIfEmpty()
select new
{
Laborcode = l.Laborcode,
Displayname = p.Displayname,
Craft = lcr.Craft,
Crew = l.Crewid,
Active = wu.Active,
Admin = wu.FrIsAdmin,
FrDistLocation = wu.FrDistLocation,
}).Where(r => r.Active == "Y" && (r.FrDistLocation == "IPC" || r.FrDistLocation == "IPC2" || r.FrDistLocation == "both"))
.OrderBy(r => r.Craft)
.ThenBy(r => r.Displayname);
// Build a subquery for the next query to use
var ptoSubQuery =
from webUser in webUsers
join workOrder in workOrders on webUser.Laborcode equals workOrder.Wolablnk
join specialRequest in specialRequests on workOrder.Wonum equals specialRequest.Wonum
select new
{
workOrder.Wonum,
Laborcode = workOrder.Wolablnk,
specialRequest.Requestdate
};
// Build the PTO query to join with the distribution list
var ptoQuery =
from a in ptoSubQuery
group a by a.Wonum into g
select new
{
Wonum = g.Key,
StartDate = g.Min(x => x.Requestdate),
EndDate = g.Max(x => x.Requestdate),
Laborcode = g.Min(x => x.Laborcode)
};
// Join the distribution list and the object list to return
// list items with PTO information
var joinedQuery = from dl in distributionListQuery
join fl in ptoQuery on dl.Laborcode equals fl.Laborcode
select new
{
dl.Laborcode,
dl.Displayname,
dl.Craft,
dl.Crew,
dl.Active,
dl.Admin,
dl.FrDistLocation,
fl.StartDate,
fl.EndDate
};
// There are multiple records that result from the join,
// strip out all but the first instance of PTO for all users
var distributionList = joinedQuery.GroupBy(r => r.Laborcode)
.Select(r => r.FirstOrDefault()).OrderByDescending(r => r.Laborcode).ToList();
Again, this works and gets my data back in a reasonable but clearly not optimal timeframe that I can work with in my UI that needs this by preloading the data before it is needed. Not the best, but works.
If I change the variable declarations to not be async which I was told I should do in another SO post, this turns into a cross db query and netcore says no:
// Set up EF tables
var person = _context1.Person;
var labor = _context1.Labor;
var laborCraftRate = context1.LaborCraftRate;
var webUsers = context2.WebUsers;
var workOrders = _context1.Workorder
.Where(r => r.Status == "LAPPR" || r.Status == "APPR" || r.Status == "REC");
var specialRequests = _context1.SwSpecialRequest
.Where(r => r.Requestdate > DateTime.Now);
Adding ToListAsync() is what allows the join functionality I need to work.
Q - Can anyone elaborate on possible downsides and problems with what I am doing?
Thank you for helping me understand!
It's not that calling ToList() "doesn't work." The problem is that it materializes (I think that's the right word) the query and returns a potentially larger than intended amount of data to the client. Any further LINQ operations are done on the client side. This can increase the load on the database and network. In your case, it works because you're bringing all that data to the client side. At that point, it no longer matters that it was a cross-database query.
This was a frequent concern during the transition from .NET Core 2.x to 3.x. If an operation could not be performed server side, .NET Core 2.x would silently insert something like ToList(). (Well, not completely silently. I think it was logged somewhere. But many developers weren't aware of it.) 3.x stopped doing that and would give you an error. When people tried to upgrade to 3.x, they often found it difficult to convert the queries into something that could run server side. And people resisted throwing in an explicit ToList() because muh performance. But remember, that's what it was always doing. If there wasn't a performance issue before, there isn't one now. And at least now you're aware of what it's actually doing, and can fix it if you really need to.
I have a query that i compose it from some options, like this
string q1 ="SELEC * from MyTable";
string q2 =string .Empty;
if(options1)
q2+=" Condition_1 ";
if(options2)
q2+=" Condition_2";
if(!String.IsNullOrEmpty(q2))
q1+=" WHERE"+q2;
cmd.Execute(...
How can i do that against LINQ over entity-framework-6 in just one attempt?
You can do that by working with a IQueryAble.
This example may help you :
//Define your query without executing it.
IQueryable<YourEntityType> query= (from s in Context.MyTable select s);
if(options1)
//Add a where clause to your IQueryable
query= query.Where(p=> p.SomeProperty == "Something");
if(options2)
//Add another where clause to your IQueryable
query= query.Where(p=> p.SomeProperty == "Something else");
//Executes the query depending your options.
var Result = query.ToList();
Yes, you can. You can chain several .Where operations. So you can write smt like
var set = MySet;
if (cond_1) {
set = set.Where(a=>...);
}
if (cond_2) {
set = set.Where(a=>...);
}
set.ToList()
etc
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 am trying to write a Breeze query for the Northwind database to show orders that contain all three products that a user specifies. So if a user selects ProductID 41, 51, and 65 from drop downs, the query would return order id 10250.
This is just a sample scenario that I am looking to base another query on in a project I am working on, but I thought using Northwind to explain it would be easier than describing the project. I can easily do it in T-SQL using derived tables, but I need to get the parameters from the client. Any thoughts? Thanks in advance!
If you're still interested in doing this on the client, you can try the following Breeze query.
var listOfProductIds = [41, 51, 65];
var preds = listOfProductIds.map(function (id) {
return Predicate.create("OrderDetails", "any", "ProductID", "==", id);
});
var whereClause = Predicate.and(preds);
var query = EntityQuery.from('Orders').where(whereClause);
This will retrieve all Orders that have at least all 3 of the Products specified.
To further filter this so you have all Orders that have only all 3 of the Products specified, you can write,
entityManager.executeQuery(query)
.then(filterOrders);
//once you get results on the client
function filterOrders(data) {
var allOrders = data.results;
var filteredOrders = allOrders.filter(function (o) {
return o.OrderDetails.length == listOfProductIds.length;
});
}
You can only filter on the client since OData doesn't yet support the Aggregate Count function like Linq to Entities does. This is probably not ideal but it's an option if you decide not to do it on the server.
Sorry in my comment I said look at the and() method but in actuality for your use you needed to look at the or() method -
var p1 = breeze.Predicate("Product.ProductID", "==", 41);
var p2 = breeze.Predicate("Product.ProductID", "==", 51);
var p3 = breeze.Predicate("Product.ProductID", "==", 65);
var newPred = breeze.Predicate.or(p1, p2, p3);
var query = EntityQuery.from('Order_Details').select('Order.OrderID').where(newPred);
The only issue with these queries on the client is that depending on how you are building them client-side and how many predicates you are adding they can get very long in some situations, such as select all 200 records except 1 id type queries which can bite you on IE8.
You can use the EntityQuery.withParameters method to call a server side query that has your linq query. i.e. something like this.
// On the client
var query = EntityQuery.from("GetOrdersWithProductIds")
.withParameters({ productIds: [41, 51, 65] });
// On the server
[HttpGet]
public IQueryable<Order> GetOrdersWithProductIds([FromUri] int[] productIds) {
return ContextProvider.Context.Orders.Where(... your linq query here ...);
}
or you might try using the support for 'any'/'all' query operators. i.e. something like this.
var predicate = breeze.Predicate("ProductID", "==", 41)
.or("ProductID", "==", 51)
.or("ProductID", "==", 65);
var query = EntityQuery.from("Orders")
.where("OrderDetails", "all", predicate)