Is it possible to generate table indexes along with the rest of the database schema with Fluent NHibernate? I would like to be able to generate the complete database DDL via an automated build process.
In more recent versions of Fluent NHibernate, you can call the Index() method to do this rather than using SetAttribute (which no longer exists):
Map(x => x.Prop1).Index("idx__Prop1");
Do you mean indexes on columns?
You can do it manually in your ClassMap<...> files by appending .SetAttribute("index", "nameOfMyIndex"), e.g. like so:
Map(c => c.FirstName).SetAttribute("index", "idx__firstname");
or you can do it by using the attribute features of the automapper - e.g. like so:
After having created your persistence model:
{
var model = new AutoPersistenceModel
{
(...)
}
model.Conventions.ForAttribute<IndexedAttribute>(ApplyIndex);
}
void ApplyIndex(IndexedAttribute attr, IProperty info)
{
info.SetAttribute("index", "idx__" + info.Property.Name");
}
and then do this to your entities:
[Indexed]
public virtual string FirstName { get; set; }
I like the latter. Is is a good compromise between not being non-instrusive to your domain model, yet still being very effective and clear on what is happening.
Mookid's answer is great and helped me a lot, but meanwhile the ever evolving Fluent NHibernate API has changed.
So, the right way to write mookid sample now is the following:
//...
model.ConventionDiscovery.Setup(s =>
{
s.Add<IndexedPropertyConvention>();
//other conventions to add...
});
where IndexedPropertyConvention is the following:
public class IndexedPropertyConvention : AttributePropertyConvention<IndexedAttribute>
{
protected override void Apply(IndexedAttribute attribute, IProperty target)
{
target.SetAttribute("index", "idx__" + target.Property.Name);
}
}
The [Indexed] attribute works the same way now.
Related
We're using convention based mapping with Fluent NHibernate. The mapping looks like so:
.Conventions.Add
(
Table.Is(x => string.Concat(x.EntityType.Name.ToLower(), "s")),
PrimaryKey.Name.Is(x => "Id"),
DefaultLazy.Always(),
DefaultCascade.SaveUpdate(),
AutoImport.Never(),
Cache.Is(x => x.ReadWrite())
)
For most of our objects this is perfect but on certain objects I wish to disable the 2nd level cache. However it doesn't appear that I can do this. There is no fluent option for Cache.None. I've even tried Not.Cache() but that didn't work either.
Has anyone got any ideas on how I can disable the cache for certain selected model objects?
Ok, I managed to find it after some digging around jogged an idea:
Remove the shortcut Cache.Is(x => x.ReadWrite()
Create a new convention class:
public class CacheableConvention: IClassConventionAcceptance, IClassConvention
{
public void Accept(IAcceptanceCriteria criteria)
{
criteria.Expect(x => x.EntityType.IsNotAny(typeof(Content), typeof(InstanceSetting), typeof(Profanity)));
}
public void Apply(IClassInstance instance)
{
instance.Cache.ReadWrite();
}
}
Add the convention to the AutoMappings.
Done!
I have a class which I would like to map as a component onto any table which contains it:
public class Time
{
public int Hours { get; set; }
public int Minutes { get; set; }
public int Seconds { get; set; }
}
I would like to store this class as a bigint in the database - the same as how TimeSpan is stored but my class has completely different behaviour so I decided to create my own.
I'm using FLH's automapper and have this class set as a component (other classes have Time as a property). I've got as far as creating an override but am not sure how to go about mapping it:
I gave it a try this way:
public class TimeMappingOverride : IAutoMappingOverride<Time>
{
public void Override(AutoMapping<Time> mapping)
{
mapping.Map(x => x.ToTimeSpan());
mapping.IgnoreProperty(x => x.Hours);
mapping.IgnoreProperty(x => x.Minutes);
mapping.IgnoreProperty(x => x.Seconds);
}
}
But got this error:
Unable to cast object of type 'System.Linq.Expressions.UnaryExpression' to type 'System.Linq.Expressions.MethodCallExpression'.
How should I go about this?
Details of components can be found here: http://wiki.fluentnhibernate.org/Fluent_mapping#Components
But first of all, you can't map a method.
Assuming you change ToTimeSpan() to a property AsTimeSpan, there are two ways to do it, only the harder of which will work for you because you are using automapping:
Create a ComponentMap<Time> -- once done, your existing mapping will just work. This is not compatible with automapping.
Declare the component mapping inline:
mapping.Component(x => x.AsTimeSpan, component => {
component.Map(Hours);
component.Map(Minutes);
component.Map(Seconds);
});
You'll have to do this every time, though.
Of course, this doesn't address "I would like to store this class as bigint…"
Are you saying you want to persist it as seconds only? If so, scratch everything at the top and again you have two options:
Implement NHibernate IUserType (ugh)
Create a private property or field that stores the value as seconds only, and wire only this up to NHibernate. The getters and setters of the pubic properties will have to convert to/from seconds.
I personally haven't worked with AutoMappings yet, but my suggestion would be to look into NHibernate's IUserType to change how a type is being persisted. I believe that's a cleaner way of defining your custom mapping of Time <-> bigint.
Reading the code above, Map(x => x.ToTimeSpan()) will not work as you cannot embed application-to-database transformation code into your mappings. Even if that would be possible, the declaration misses the transformation from the database to the application. A IUserType, on the other hand, can do custom transformations in the NullSafeGet and NullSafeSet methods.
I´m using Nhibernate 2.1.2.4000 GA with Nhibernate.Linq 1.0 and latest version of FluentNhibernate downloaded from master on github.
Im doing some tests and whenever I try to delete a entity retrieved by a linq query i´m getting this error:
No persister for: NHibernate.Linq.Query`1[[Employees.Core.Entities.Employee, Employees.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]
All other operations (insert, update and select) looks fine;
My Entity class:
public class Employee
{
public Employee()
{
}
public virtual Int32 Id { get; private set; }
public virtual String Name { get; set; }
public virtual String SayHello()
{
return String.Format("'Hello World!', said {0}.", Name);
}
}
Mapping class:
public class EmployeeMap : ClassMap<Employee>
{
public EmployeeMap()
{
Id(x => x.Id);
Map(x => x.Name)
.Not.Nullable()
.Length(50);
}
}
Configuration:
Assembly mappingsAssemly = Assembly.GetExecutingAssembly();
return Fluently.Configure()
.Database( MsSqlConfiguration.MsSql2008
.ConnectionString(connectionString)
.ProxyFactoryFactory(typeof(ProxyFactoryFactory))
.ShowSql())
.Mappings( m => m.FluentMappings.AddFromAssembly(mappingsAssemly))
.BuildSessionFactory();
And the code that does not work:
public void RemoveAll()
{
var q = from employee in _session.Linq<Employee>()
select employee;
foreach (var employee in q.ToList())
{
_session.Delete(q);
}
}
Any thoughts?
We all missed it!
Sorry guys and thanks for all your help but I just figured.
If you pay attention to the RemoveAll() method you will see that I´m trying to delete the "q" object which is not an entity, but a IQueriable instead of passing "employee". It was lack of attention.
The right code would be:
public void RemoveAll()
{
var q = from employee in _session.Linq()
select employee;
var p = q.ToList();
foreach (var employee in p)
{
_session.Delete(employee);
}
}
Are you certain the assembly you're supplying to FNH (Assembly.GetExecutingAssembly()) is actually the one containing your mappings?
Modify your Mappings call to include the ExportTo method, which'll export any mappings FNH finds to a specified folder; check out the contents of that folder and see if all the mappings are in there. If they are, then chances are it's not a FNH issue and might be a problem with the Linq provider (as Michael said).
Mappings(
m => m.FluentMappings
.AddFromAssembly(mappingsAssemly)
.ExportTo(#"C:\"));
Another thing you can check is the NHibernate Configuration instance that NH is actually using. To do that, use BuildConfiguration instead of BuildSessionFactory and inspect the result; there's a ClassMappings collection (or some variation of that), which should contain all the mapped entities.
If that looks fine, then try creating your query using the Criteria API or HQL instead, see if that fixes your problem (and in that case it's almost certain to be the linq provider).
It may just be a bug in the Linq provider. You may want to try to reproduce the problem against the latest NHibernate trunk which includes a new/different Linq provider. Alternatively, if you (successfully) remove Fluent NHibernate from the equation, you can probably (relatively easily) submit a test case / bug report against the Linq provider.
Having successfully gotten a sample program working, I'm now starting
to do Real Work with Fluent NHibernate - trying to use Automapping on my project's class
heirarchy.
It's a scientific instrumentation application, and the classes I'm
mapping have several properties that are arrays of floats e.g.
private float[] _rawY;
public virtual float[] RawY
{
get
{
return _rawY;
}
set
{
_rawY = value;
}
}
These arrays can contain a maximum of 500 values.
I didn't expect Automapping to work on arrays, but tried it anyway,
with some success at first. Each array was auto mapped to a BLOB
(using SQLite), which seemed like a viable solution.
The first problem came when I tried to call SaveOrUpdate on the
objects containing the arrays - I got "No persister for float[]"
exceptions.
So my next thought was to convert all my arrays into ILists e.g.
public virtual IList<float> RawY { get; set; }
But now I get:
NHibernate.MappingException: Association references unmapped class: System.Single
Since Automapping can deal with lists of complex objects, it never
occured to me it would not be able to map lists of basic types. But
after doing some Googling for a solution, this seems to be the case.
Some people seem to have solved the problem, but the sample code I
saw requires more knowledge of NHibernate than I have right now - I
didn't understand it.
Questions:
1. How can I make this work with Automapping?
2. Also, is it better to use arrays or lists for this application?
I can modify my app to use either if necessary (though I prefer
lists).
Edit:
I've studied the code in Mapping Collection of Strings, and I see there is test code in the source that sets up an IList of strings, e.g.
public virtual IList<string> ListOfSimpleChildren { get; set; }
[Test]
public void CanSetAsElement()
{
new MappingTester<OneToManyTarget>()
.ForMapping(m => m.HasMany(x => x.ListOfSimpleChildren).Element("columnName"))
.Element("class/bag/element").Exists();
}
so this must be possible using pure Automapping, but I've had zero luck getting anything to work, probably because I don't have the requisite knowlege of manually mapping with NHibernate.
Starting to think I'm going to have to hack this (by encoding the array of floats as a single string, or creating a class that contains a single float which I then aggregate into my lists), unless someone can tell me how to do it properly.
End Edit
Here's my CreateSessionFactory method, if that helps formulate a
reply...
private static ISessionFactory CreateSessionFactory()
{
ISessionFactory sessionFactory = null;
const string autoMapExportDir = "AutoMapExport";
if( !Directory.Exists(autoMapExportDir) )
Directory.CreateDirectory(autoMapExportDir);
try
{
var autoPersistenceModel =
AutoMap.AssemblyOf<DlsAppOverlordExportRunData>()
.Where(t => t.Namespace == "DlsAppAutomapped")
.Conventions.Add( DefaultCascade.All() )
;
sessionFactory = Fluently.Configure()
.Database(SQLiteConfiguration.Standard
.UsingFile(DbFile)
.ShowSql()
)
.Mappings(m => m.AutoMappings.Add(autoPersistenceModel)
.ExportTo(autoMapExportDir)
)
.ExposeConfiguration(BuildSchema)
.BuildSessionFactory()
;
}
catch (Exception e)
{
Debug.WriteLine(e);
}
return sessionFactory;
}
I would probably do a one to many relationship and make the list another table...
But maybe you need to rethink your object, is there also a RawX that you could compose into a RawPoint? This would make a table with 3 columns (ParentID, X, Y).
The discontinuity comes from wanting to map a List to a value that in an RDBMS won't go in a column very neatly. A table is really the method that they use to store Lists of data.
This is the whole point of using an ORM like NHibernate. When doing all the querying and SQL composition by hand in your application, adding a table had a high cost in maintenance and implementation. With NHibernate the cost is nearly 0, so take advantage of the strengths of the RDBMS and let NHibernate abstract the ugliness away.
I see your problem with mapping the array, try it with an override mapping first and see if it will work, then you could maybe create a convention override if you want the automap to work.
.Override<MyType>(map =>
{
map.HasMany(x => x.RawY).AsList();
})
Not sure if that will work, I need to get an nHibernate testing setup configured for this stuff.
Since I posted my question, the Fluent NHibernate team have fixed this problem.
You can now automap ILists of C# value types (strings, ints, floats, etc).
Just make sure you have a recent version of FNH.
Edit
I recently upgraded from FNH 1.0 to FNH 1.3.
This version will also automap arrays - float[], int[], etc.
Seems to map them as BLOBs. I assume this will be more efficient than ILists, but have not done any profiling to confirm.
I eventually got an override to work - see the end of the code listing. The key points are:
a new mapping class called DlsAppOverlordExportRunDataMap
the addition of a UseOverridesFromAssemblyOf clause in
CreateSessionFactory
Also, it turns out that (at least with v. 1.0.0.594) there is a very big gotcha with Automapping - the mapping class (e.g. DlsAppOverlordExportRunDataMap) cannot be in the same Namespace as the domain class (e.g. DlsAppOverlordExportRunData)!
Otherwise, NHibernate will throw "NHibernate.MappingException: (XmlDocument)(2,4): XML validation error: ..." , with absolutely no indication of what or where the real problem is.
This is probably a bug, and may be fixed in later versions of Fluent NHibernate.
namespace DlsAppAutomapped
{
public class DlsAppOverlordExportRunData
{
public virtual int Id { get; set; }
// Note: List<float> needs overrides in order to be mapped by NHibernate.
// See class DlsAppOverlordExportRunDataMap.
public virtual IList<float> RawY { get; set; }
}
}
namespace FrontEnd
{
// NEW - SET UP THE OVERRIDES
// Must be in different namespace from DlsAppOverlordExportRunData!!!
public class DlsAppOverlordExportRunDataMap : IAutoMappingOverride<DlsAppOverlordExportRunData>
{
public void Override(AutoMapping<DlsAppOverlordExportRunData> mapping)
{
// Creates table called "RawY", with primary key
// "DlsAppOverlordExportRunData_Id", and numeric column "Value"
mapping.HasMany(x => x.RawY)
.Element("Value");
}
}
}
private static ISessionFactory CreateSessionFactory()
{
ISessionFactory sessionFactory = null;
const string autoMapExportDir = "AutoMapExport";
if( !Directory.Exists(autoMapExportDir) )
Directory.CreateDirectory(autoMapExportDir);
try
{
var autoPersistenceModel =
AutoMap.AssemblyOf<DlsAppOverlordExportRunData>()
.Where(t => t.Namespace == "DlsAppAutomapped")
// NEW - USE THE OVERRIDES
.UseOverridesFromAssemblyOf<DlsAppOverlordExportRunData>()
.Conventions.Add( DefaultCascade.All() )
;
sessionFactory = Fluently.Configure()
.Database(SQLiteConfiguration.Standard
.UsingFile(DbFile)
.ShowSql()
)
.Mappings(m => m.AutoMappings.Add(autoPersistenceModel)
.ExportTo(autoMapExportDir)
)
.ExposeConfiguration(BuildSchema)
.BuildSessionFactory()
;
}
catch (Exception e)
{
Debug.WriteLine(e);
}
return sessionFactory;
}
Didn't get any answers here or on the Fluent NHibernate mailing list that actually worked, so here's what I did.
It smells like a horrible hack, but it works. (Whether it will scale up to large data sets remains to be seen).
First, I wrapped a float property (called Value) in a class:
// Hack - need to embed simple types in a class before NHibernate
// will map them
public class MappableFloat
{
public virtual int Id { get; private set; }
public virtual float Value { get; set; }
}
I then declare the properties in other classes that need to be Lists of floats e.g.
public virtual IList<MappableFloat> RawYMappable { get; set; }
NHibernate creates a single database table, with multiple foreign keys, e.g.
create table "MappableFloat" (
Id integer,
Value NUMERIC,
DlsAppOverlordExportRunData_Id INTEGER,
DlsAppOverlordExportData_Id INTEGER,
primary key (Id)
)
I have a class called Entry. This class as a collection of strings called TopicsOfInterest. In my database, TopicsOfInterest is represented by a separate table since it is there is a one-to-many relationship between entries and their topics of interest. I'd like to use nhibernate to populate this collection, but since the table stores very little (only an entry id and a string), I was hoping I could somehow bypass the creation of a class to represent it and all that goes with (mappings, configuration, etc..)
Is this possible, and if so, how? I'm using Fluent Nhibernate, so something specific to that would be even more helpful.
public class Entry
{
private readonly IList<string> topicsOfInterest;
public Entry()
{
topicsOfInterest = new List<string>();
}
public virtual int Id { get; set; }
public virtual IEnumerable<string> TopicsOfInterest
{
get { return topicsOfInterest; }
}
}
public class EntryMapping : ClassMap<Entry>
{
public EntryMapping()
{
Id(entry => entry.Id);
HasMany(entry => entry.TopicsOfInterest)
.Table("TableName")
.AsList()
.Element("ColumnName")
.Cascade.All()
.Access.CamelCaseField();
}
}
I had a similar requirement to map a collection of floats.
I'm using Automapping to generate my entire relational model - you imply that you already have some tables, so this may not apply, unless you choose to switch to an Automapping approach.
Turns out that NHibernate will NOT Automap collections of basic types - you need an override.
See my answer to my own question How do you automap List or float[] with Fluent NHibernate?.
I've provided a lot of sample code - you should be able to substitute "string" for "float", and get it working. Note the gotchas in the explanatory text.