I have an entity, with a field of type enum, that is persisted as an integer in my database.
When retrieving objects from the database using ICriteria, I wish to restrict the results to those with the field being a member of a collection of enum values. Does Restrictions.In work with a collection of enums?
The following does not work. Do I have to perform something like type-casting at the "restrictions.in" part of the query?
var myEnumCollection = new MyEnum[] { MyEnum.One };
return FindAll<MyType>(Restrictions.In("EnumProperty", myEnumCollection));
FindAll is a method encapsulating
criteria.GetExecutableCriteria(Session).List<MyType>()
My initial guess would be that you'll need to compare against the integer values of the enum members (assuming that you're mapping the enum as an integer); so something like:
var myEnumCollection = new int[] { MyEnum.One };
return FindAll<MyType>(Restrictions.In("EnumProperty", myEnumCollection));
May be the solution that you're after. If you update your post with further details (mapping of the enum member and the sql being generated by the query), I may be able to provide further assistance.
Related
I am getting an error:
Property or Indexer cannot be assigned to "--" it is read only
when trying to update two columns with the same name in two tables in a join query. How do I get this to work? Thanks!
The anonymous object created in your projection ("select new" part) is read-only and its properties are not tracked by data context by any means.
Instead, you can try this:
//...
select new
{
p1 = p,
p2 = t
}
foreach (var row in updates)
{
row.p1.Processed = true;
row.p2.Processed = true;
}
In order to improve performance you may also want to take a look at batch update capabilities of Entity Framework Extensions (if you are using Entity Framework): https://entityframework-extensions.net/overview
Yes, that's due to anonymous type properties are read only, from documentation:
Anonymous types provide a convenient way to encapsulate a set of
read-only properties into a single object without having to explicitly
define a type first.
I suggest you to create a custom class with the two entities you need (a DTO):
public class PassengerDTO
{
public Passenger Passenger {get;set}
public PassengerItinerary PassengerItinerary {get;set}
}
And use it in your projection, You need the entity instances and not just the properties you want to modify because, when you modify the Processed property in the foreach the proxy class that represent your entity is going to change the status of you entity to Updated.
All the examples I am finding for using the AliasToBean transformer use the sessions CreateSqlQuery method rather than the CreateQuery method. They also only return the basic value types, and not any object's of the existing mapped types.
I was hoping it would be possible that my DTO have a property of one of my mapped Domain objects, like below, but I am not getting traction. I get the following exception:
Could not find a setter for property '0' in class 'namespace.DtoClass'
My select looks like the following on my mapped classes (I have confirmed the mappings pull correctly):
SELECT
fcs.MeasurementPoint,
fcs.Form,
fcs.MeasurementPoint.IsUnscheduled as ""IsVisitUnscheduled"",
fcs.MultipleEntryAllowed
FROM FormCollectionSchedule fcs
My end query will be more complex, but I wanted to confirm if this AliasToBean method can return mapped domain objects as well as basic field values from tables retrieved via sql.
the query execution looks like the following:
var result = session.CreateQuery(hqlQuery.ToString())
.SetResultTransformer(NHibernate.Transform.Transformers.AliasToBean(typeof (VisitFormCollectionResult)))
.List<VisitFormCollectionResult>();
note: the VisitFormCollectionResult DTO has more properties, but I wanted to know if I could populate the domain object properties matching the names
update found my problem! I have to explicitly alias each of the fields. once I added an alias, even though the member property on the class matched my DTO's property name, the hydration of the object worked correctly.
The answer to my own question was that each of the individual fields in the select needed an explicit alias matching the property, regardless if the field name already matched the property name of the DTO object:
SELECT
fcs.MeasurementPoint as "MeasurementPoint",
fcs.Form as "Form",
fcs.MeasurementPoint.IsUnscheduled as "IsVisitUnscheduled",
fcs.MultipleEntryAllowed as "MultipleEntryAllowed"
FROM FormCollectionSchedule fcs
Is it possible to configure NHibernate (specifically Fluent NHibernate) to serialize an array of simple types to a single database column? I seem to remember that this was possible but its been a while since I've used NHibernate.
Essentially I need to store the days of week that a person works (int[]) and would rather not have a separate table just for this purpose.
It is possible.
You need to implement a IUserType that takes care of mapping between your array and a data column (google that first; it's possible that somebody already implemented it)
Alternatively, you can do the conversion in your entity class, and map the single-field representation instead of the property. For example:
string numbers;
public int[] Numbers
{
get { return numbers.Split(','); }
set { numbers = string.Join(",", value.Select(x => x.ToString())); }
}
Yes. There's UserType for scenarios like that. You could also use enum and bit flag.
I am having a problem determining how c# and LINQ solve the common problem of handling a data structure that does not necessarily return a table structure, but instead a resultset.
I have a stored procedure that works, and have included it in my DBML
[Function(Name="dbo.p_GetObject")]
public int p_GetObject([Parameter(Name="ObjectType", DbType="NVarChar(200)")] string objectType, [Parameter(Name="ItemState", DbType="Bit")] System.Nullable<bool> itemState, [Parameter(Name="IsPublished", DbType="Bit")] System.Nullable<bool> isPublished)
{
IExecuteResult result = this.ExecuteMethodCall(this, ((MethodInfo)(MethodInfo.GetCurrentMethod())), objectType, itemState, isPublished);
return ((int)(result.ReturnValue));
}
The dbml says that the return type is (None) and this could be the crux issue. However I don't have a DBML object that matches the resultset.
The SP takes three parameters, and returns a result set with three columns (ID, Name, Value) with multple rows. I can create a data object for this, and call it resultSet
When I write a function call for this, I get stuck:
public List<resultset> GetObject(string objectType, bool itemState, bool isPublished)
{
MyDataContext.p_GetObject(objectType, itemState, isPublished);
}
My questions are:
how do I have the data context call to the stored procedure populate my resultSet object? Is there a better approach? What should the return type be? A SQL view? Looking for good suggestions...
If it simply isn't understanding your SP, that could be the SET FMT_ONLY issue... try generating the data from a simplified version of the SP?
Normally, SPs / UDFs that don't map 1:1 with an existing entity would expose themselves in a generated type. You can rename this in the DBML file (not in the designer), but personally I wouldn't; I tend to mark the SP as private, and write my own method that projects into my own POCO type (defined for the repository):
var typed = from row in cxt.SomeFunction(123)
select new MyType {Id = row.Id, Name = row.Name, ...}
The reason for this is partly for repository purity, and partly to guard against the designer's habit of re-writing the DBML in unexpected ways ;-p See here for more.
I want to run a query against two tables (which happen to be mapped in ActiveRecord). The query returns a result list that cannot be mapped to an ActiveRecord object (as it is custom aggregate information).
For instance
Dim query_str as string = "Select distinct d.ID, (select count(1) as exp from Sales_Leads where date_created <= :todays_date) as NbrLeads from Dealer d"
Dim q As Queries.HqlBasedQuery = New Queries.HqlBasedQuery(GetType(ICollection), query_str)
q.SetParameter("todays_date", DateTime.Today)
Dim i As ICollection = ActiveRecordMediator.ExecuteQuery(q)
What I'm looking for is simple execution of SQL, without an ActiveRecord object returned.
So, ideally, I'd be able to look at i("NbrResults") for each item in the collection.
The error I am getting is:
You have accessed an ActiveRecord
class that wasn't properly
initialized. The only explanation is
that the call to
ActiveRecordStarter.Initialize()
didn't include
System.Collections.ICollection class
Well, this was asked a long time ago but I have a working answer.
public static IList<T> ExecuteQuery<T>(HqlBasedQuery query)
where T : new()
{
query.SetResultTransformer(new NHibernate.Transform.AliasToBeanResultTransformer(typeof(T)));
var results = (ArrayList)ActiveRecordMediator.ExecuteQuery(query);
List<T> list = new List<T>(results.Count);
for (int i = 0; i < results.Count; i++)
{
list.Add((T)results[i]);
}
return list;
}
This will give you back results of type T. Type T can be anything you want. Type T needs a no argument constructor and it needs public fields or properties that match the column names or aliases in the query you build.
We do this all the time. Particularly when you want to use aggregate function in HQL to produce aggregate data.
A companion function will allow you to just pass in your query as a string as well as any positional parameters you might have:
public static IList<T> ExecuteQuery<T, U>(string hqlQuery, params object[] parameters)
where T : new()
{
return ExecuteQuery<T>(new HqlBasedQuery(typeof(U), hqlQuery, parameters));
}
Type U is any type that is a valid ActiveRecord type. It doesn't even have to be one of the types you are referencing. If you want you could replace it will some type you know is gonna be valid int he session and ditch the extra parameter.
Here was my final solution:
Dim query_str As String = "SELECT DISTINCT d.ID, count( l ) from LEAD as l join l.Dealer as d where l.DateCreated >= DATEADD(day, -30, :todays_date) GROUP BY d.ID"
Then obtain the active record session (or NHibernate, still don't even know what is returned here):
Dim sess As ISession = activerecordmediator.GetSessionFactoryHolder().CreateSession(GetType(ActiveRecordBase))
Dim q As NHibernate.IQuery = sess.CreateQuery(query_str)
q.SetParameter("todays_date", DateTime.Today)
Dim i As IList = q.List() ' get results
In the .aspx page, the result can be accessed in a GridView like so:
You're stepping outside the NHibernate paradigm to call down to SQL, which is somewhat against the spirit of ORM. It's not 'bad' per-se, but I'd certainly avoid breaking the abstraction if I could to try to maintain a looser coupling.
You can do what you want with a straight HQL query, which will return a collection of tuples containing the results of your query. I explained how to do this here
Custom query with Castle ActiveRecord
which you might want to have a look at. Even though you must specify a type when you new an HQLBasedQuery, NH is smart enough to know that if you don't select a type instance it should assemble a result-set based on object tuples.
(IMNSHO it's still a bit non-pure - I'd be tempted to try to model this relationship as an object and map it accordingly, but then I'd have to bash the DB into shape to suit the object model and that's not going to fly in all cases.)