I have a generic group members table with a GUID for a "group type" and a GUID for "referenced object". An example would be if I have a table of customers(each having a GUID) I can group them under "already paid" by creating a group GUID and in my "Group members table" referencing every customer by their respective GUID. This allows for any type of group to be added to the model as we expand(without adding extra tables).
Here is the problem. I have created a subquery in an entity in order to filter the universal group members table for a certain group and what "items" are and are not in that group; like so:
partial void ElementsNotMemberOfGroup_PreprocessQuery(int? UniversalGroupTypeIDParameter, int? UniversalGroupsIDParameter, ref IQueryable<UniversalGroupMember> query)
{
query = query.Where(x => x.UniversalGroup.UniversalGroupType.UniversalGroupTypeID == UniversalGroupTypeIDParameter);
query = query.Where(x => x.UniversalGroup.UniversalGroupsID != UniversalGroupsIDParameter);
}
This returns the GUIDs for the referenced object in the group, but for a user that's useless. I need to join this table and my customers table at runtime on the GUID so I can extract the customer info and display it.
Any Ideas?
LightSwitch wasn't really created with this kind of scenario in mind. LightSwitch makes things very easy for you when you create relationships between tables that are, well, "related". When you do this, you never need manual joins between entities.
While it's possible to do something similar to what you're describing (see the link below), it's a lot more work to achieve it, and in my opinion it isn't really worth the extra trouble. Not only that, but as you're discovering, it complicates even the most simple operations.
In essence, you're working against LightSwitch, instead of with it. My advice to you would be that if you really must do this type of manual optimization, then LightSwitch may not be the best product for you to use.
Beth Massi has a blog article, Using Different Edit Screens Based on Record Types (Table Inheritance), which isn't exactly what you're doing, but it may give you some ideas if you decide to still use LightSwitch for your project.
Related
I am new to lightswitch as well as linq, i am using LS 2015. I want to know how to display the data of one table in other table's screen.
For example I have job vacancies, where I want to show candidate professional information who has applied for job. These two tables are related through Candidate personal ID, means a foreign key between candidate personal table and professional table.
The relation is as follows
JobVacancies->CandidatePersonalInfor->candidateProfessionalInfo. They are many to one related.
I have written a linq query to fetch data, where i have included some other tables also, my code is as follows
Any help is appreciated.
Have you defined the relationships you describe between the entities? If so, you'll have the ability to add and drop the details you require onto the form in the designer. The entities and their properties will be in the left pane of the screen designer.
If the join operation is more complex, you can use a WCF RIA Service to create a composite entity, as described in http://lightswitchhelpwebsite.com/Blog/tabid/61/EntryId/2226/Creating-a-WCF-RIA-Service-for-Visual-Studio-2013.aspx
Hi I have a question that is braking my mind for some days.
I have my SQL server Database and my C# application.
In the DB I have differemt tables, let me show you a simple ex
Tables:
Person
Relationship
City
Business Rules:
The person are from a City, so the person has IdCity
A person has a relationship with other person, and about that relationship you need to save the starting date.
In other projects I already did something like that, but in this proyect this is not working for me.
When I retrieved with LinQ the information about the person, the city is not coming, and an error appears when I try "person.city.description", for ex.
I try using Include("City") in the linq query, but it didn't work. Besides that, I don't know how to manage the circular reference to the person to person relationship.
One important thing, that I think that can be the problem, is that I rename all the tables from the DataModel, for example, the table in database is called Prd_City, so I change the Name and the Entity Set Name for City in c# project. So in the included I have to use the real table name, in other case the query fail, but if I use the real name nothing happens.
using (var context = new MyContext())
{
List<Person> oPeople = (from p in context.Person.Include("Prd_City")
select p).ToList();
return oPeople ;
}
Any help will be welcome.
Thanks!
"It didn't work" is never a good description of your problem. But from the rest of your question I can infer that Person has a navigation property named "Prd_City", while you expected it to be "City". The thing is: you renamed the entities, but not the navigation properties in the entities.
My advice (for what it's worth): it seems that your work database-first. If you can, change to code-first and manually map the POCO classes to their table names, and properties to their database columns. It may be a considerable amount of work (depending on the size of your data model), but after that you will never run the risk of EF "un-renaming" your entities. Besides, the DbContext API is easier to use than ObjectContext. Currently, it's the preferred EF API.
I am trying to bring some data from Dynamics CRM 2011 using LINQ. The goal is to bring all Contact records that have changes since certain date OR have a child entity (PERC files) changed since that same date. The query looks like that:
// Bring all students who have changes (at Contact entity) after specific date
// momentInTime or the status of any of their perc files has been changed since
// that date
var students = (from c in ContactSet
join pl in cga_portallogonSet on c.Id equals pl.cga_ContactId.Id
join ef in cga_percfileSet on c.Id equals ef.cga_StudentId.Id
where
(pl.cga_PortalLogonRole.Value == 284970000) // student
where
(c.ModifiedOn >= momentInTime || c.CreatedOn > momentInTime)
||
(ef.cga_statuschangedate >= momentInTime)
select c.cga_StudentNumber).Distinct().ToList();
This produces the following error message:
'Contact' entity doesn't contain attribute with Name = 'cga_statuschangedate'.
I cannot figure out how to do OR on two different entities. The MSDN says you need WHERE clause for each entity:
where Clause
In order to filter the result set, where clauses can be added against one or more of the >entities. Each where clause may only contain conditions against an individual entity type. >A composite condition involving multiple entities is not valid. Instead, each entity >should be filtered in separate where clauses.
http://msdn.microsoft.com/en-us/library/ff681565.aspx
Is there another way of achieving what I need?
Unfortunately you cannot achieve what you want in a single linq statement beacuse the liunq provider they use boils down to fetchXML, and fetchXML does not support the scenario you are using.
More detail... Fetch gives you condition's inside of entity's or link-entity's. These condition elements cannot have attributes in them from other linked entities, only the direct parent entity or link-entity. Here is one of many microsoft forum posts referencing this limitation of fetchXML
Probably not the answer you were looking for, eh? As an ugly alternative you you can run two separate queries and filter in memory (as damaging as that may be to performance). Or better yet if you are an on-premise deployment you can write some sql against the filtered views. Good luck.
We use CRM 4.0 at our institution and have no plans to upgrade presently as we've spend the last year and a half customising and extending the CRM to work with our processes.
A tiny part of model is a simply hierarchy, we have a group of learning rooms that has a one-to-many relationship with another entity that describes the courses available for that learning room.
Another entity has a list of all potential and enrolled students who have expressed an interest in whichever course.
That bit's all straightforward and works pretty well and is modelled into 3 custom entities.
Now, we've got an Admin application that reads the rooms and then wants to show the courses for that room, but only where there are enrolled students.
In SQL this is simplified to:
SELECT DISTINCT r.CourseName, r.OtherInformation
FROM Rooms r
INNER JOIN Students S
ON S.CourseId = r.CourseId
WHERE r.RoomId = #RoomId
And this indeed is very close to the eventual SQL that CRM generates.
We use a Crm QueryEntity, a Filter and a LinkEntity to represent this same structure.
The problem now is that the CRM normalizes the a customize entity into a Base Table which has the standard CRM entity data that all share, and then an ExtensionBase Table which has our customisations. To Give a flattened access to this, it creates a view that merges both tables.
This view is what is used by the Generated SQL.
Now the base tables have indices but the view doesn't.
The problem we have is that all we want to do is return Courses where the inner join is satisfied, it's enough to prove there are entries and CRM makes it SELECT DISTINCT, so we only get one item back for Room.
At first this worked perfectly well, but now we have thousands of queries, it takes well over 30 seconds and of course causes a timeout in anything but SMS.
I'm given to believe that we can create and alter indices on tables in CRM and that's not considered to be an unsupported modification; but what about Views ?
I know that if we alter an entity then its views are recreated, which would of course make us redo our indices when this happens.
Is there any way to hint to CRM4.0 that we want a specific index in place ?
Another source recommends that where you get problems like this, then it's best to bring data closer together, but this isn't something I'd feel comfortable in trying to engineer into our solution.
I had considered putting a new entity in that only has RoomId, CourseId and Enrolment Count in to it, but that smacks of being incredibly hacky too; After all, an index would resolve the need to duplicate this data and have some kind of trigger that updates the data after every student operation.
Lastly, whilst I know we're stuck on CRM4 at the moment, is this the kind of thing that we could expect to have resolved in CRM2011 ? It would certainly add more weight to the upgrading this 5 year old product argument.
Since views are "dynamic" (conceptually, their contents are generated on-the-fly from the base tables every time they are used), they typically can't be indexed. However, SQL Server does support something called an "indexed view". You need to create a unique clustered index on the view, and the query analyzer should be able to use it to speed up your join.
Someone asked a similar question here and I see no conclusive answer. The cited concerns from Microsoft are Referential Integrity (a non-issue here) and Upgrade complications. You mention the unsupported option of adding the view and managing it over upgrades and entity changes. That is an option, as unsupported and hackish as it is, it should work.
FetchXml does have aggregation but the query execution plans still uses the views: here is the SQL generated from a simple select count from incident:
'select
top 5000 COUNT(*) as "rowcount"
, MAX("__AggLimitExceededFlag__") as "__AggregateLimitExceeded__" from (select top 50001 case when ROW_NUMBER() over(order by (SELECT 1)) > 50000 then 1 else 0 end as "__AggLimitExceededFlag__" from Incident as "incident0" ...
I dont see a supported solution for your problem.
If you are building an outside admin app and you are hosting CRM 4 on-premise you could go directly to the database for your query bypassing the CRM API. Not supported but would allow you to solve the problem.
I'm going to add this as a potential answer although I don't believe its a sustainable or indeed valid long-term solution.
After analysing the indexes that CRM had defined automatically, I realised that selecting more information in my query would be enough to fulfil the column requirements of an Index and now the query runs in less then a second.
I'm using Linq 2 Sql and I'd like to add a custom member on one of my data type. For example: I have tables Companies, Departments and Employees. Departments has a FK in Companies and Employess has a FK in Deparments. Very simple.
My goal is to add an EmployeeCount property on Company that will, of course, returns the number of employee in the company (by suming the number of employee in company's departments).
As you may know, it's really trivial to do: just add a member on the partial class and do the stuff. The problem is, I now want to sort on this custom member.
How can I write this custom member for Linq to be able to translate the logic into a valid SQL orderby? I tried with a SPROC but did not success.
Any help appreciated!
Fabian
I guess your may need to add this column to your schema, in order for SQL server to recognize it and take in under consideration in his optimizations.
I would have add a trigger that will update this column automaticly upon changes on your data.