This works in v.717 (IComponentConvention) :
public void Apply(IComponentInstance instance)
{
if (instance.Type == typeof(EmailAddress))
{
instance.Properties.First(property => property.Name == "FullAddress")).Column(instance.Name);
}
}
Using the above convention I can map the name of my database column to the name of the component property. But in v.727 the hbm suddenly looks like this:
<component name="DefaultMailAddressForAlerts" class="EmailAddress">
<property name="FullAddress" type="System.String">
<column name="DefaultMailAddressForAlertsDefaultMailAddressForAlerts"/>
</property>
</component>
Making the column name in the database the name of the component property x 2. Is there a new way of creating component conventions in v727 of fluent nhibernate?
This looks like a bug. I've raised an issue in our bugtracker, see Fluent NHibernate #161.
Related
Consider this class that represents a node in a hierarchical structure:
public class Node
{
public Node()
{
Children = new List<Node>();
}
public virtual int Id { get; set; }
public virtual IList<Node> Children { get; set; }
public virtual Node Parent { get; set; }
public virtual int Position
{
get { return Parent == null ? -1 : Parent.Children.IndexOf(this); }
set { }
}
}
The mapping looks like this (as NHibernate does not support lists in bidirectional associations, I use a bag here and have the children determine their position automatically):
<?xml version="1.0" encoding="utf-8"?>
<hibernate-mapping xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" namespace="AmbiguousColumn" assembly="AmbiguousColumn" xmlns="urn:nhibernate-mapping-2.2">
<class name="Node">
<id name="Id" type="Int32">
<generator class="identity" />
</id>
<bag name="Children" inverse="true" cascade="all" order-by="Position">
<key column="Parent" />
<one-to-many class="Node" />
</bag>
<many-to-one name="Parent" />
<property name="Position" />
</class>
</hibernate-mapping>
To get all nodes with their children loaded I'd use a query like this:
var nodes = session.QueryOver<Node>()
.Fetch(x => x.Children).Eager
.List();
However, executing this results in an exception:
NHibernate.Exceptions.GenericADOException: could not execute query
[...(sql)...] ---> System.Data.SqlClient.SqlException: Ambiguous column name 'Position'.
The SQL:
SELECT
this_.Id as Id0_1_,
this_.Parent as Parent0_1_,
this_.Position as Position0_1_,
children2_.Parent as Parent3_,
children2_.Id as Id3_,
children2_.Id as Id0_0_,
children2_.Parent as Parent0_0_,
children2_.Position as Position0_0_
FROM
Node this_
left outer join
Node children2_
on this_.Id=children2_.Parent
ORDER BY
Position
I understand why this happens: NH joins the same table twice, but uses the order clause without qualifying the column name.
The question is: how can I make this scenario work? Resorting to instead of is probably difficult as I'd like to have a bidirectional relation.
There are a couple of similar question on SO, but nowhere did I find an actual solution.
Update: the error is database/driver specific. Using the Sql Server CE (e.g. SqlServerCeDriver and MsSqlCe40Dialect) I get the proper query. Using Sql Server (e.g. Sql2008ClientDriver and MsSql2012Dialect) produces the unqualified queries.
According to my own tests, this behavior still exists in the master branch on github.
A gist with a test case: https://gist.github.com/anonymous/5377535
I think I found the cause of the problem and viable workarounds:
The cause of the issue is the fact that the column is called "Position", which is a reserved word in ODBC according to http://msdn.microsoft.com/en-us/library/ms189822.aspx
This combined with the fact that the default value for NH's hbm2ddl.keywords property is set to "keywords" somehow caused NH not to qualify the order-by clause, probably because it though "Position" was a keyword, not a column.
http://nhforge.org/blogs/nhibernate/archive/2009/06/24/auto-quote-table-column-names.aspx
Ways to fix it:
1) Use a different name for the property - one that isn't a keyword. In this case, PositionInParent would have worked without any issues.
2) Quote the order by clause properly using back-ticks.
<bag name="Children" inverse="true" cascade="all" order-by="`Position`">
Or whatever it takes in your mapping API of choice, e.g. in mapping by code:
cls.Bag(x => x.Children,
map =>
{
map.Inverse(true);
map.Cascade(Cascade.All);
map.Key(key => key.Column("Parent"));
map.OrderBy("`Position`"); // note that you must not use a lambda expression in this case
},
map => map.OneToMany());
3) Disable keyword auto import, ie. set hbm2ddl.keywords to none (neither keywords nor auto-quote will work):
<property name="hbm2ddl.keywords">none</property>
Or programmatically:
config.DataBaseIntegration(db => db.KeywordsAutoImport = Hbm2DDLKeyWords.None);
You can still auto-quote reserved words by calling SchemaMetadataUpdater.QuoteTableAndColumns just before building the session factory.
SchemaMetadataUpdater.QuoteTableAndColumns(config);
I'll stick with approach 3 for now as it is the most painless so far.
I have a problem when using Hibernate Criteria API:
var query = session.QueryOver<MyClass>().Where(param => param.Name == "myFilterName").List<MyClass>();
If a run this statement, a NHibernate.QueryException is thrown:
could not resolve property: Name of: MyClass
And in the StackTrace:
at NHibernate.Persister.Entity.AbstractPropertyMapping.ToType(String
propertyName)
MyClass.hbm.xml file has the property mapped of this way:
<property name="name" access="field">
<column name="NAME" length="50" not-null="true" />
</property>
I think that the problem comes because hibernate can not access the property "Name" of MyClass because is mapped with access="field", but I can not change this way to access the property due application design requirements.
The idea is create querys by using Criteria API with lambda expressions in order to avoid hardcoded string property names.
Also I´ve tried with a Expression with the same exception result:
var criterion = Expression.Where<MyClass>(param => param.Name == "myFilterName");
var result = session.CreateCriteria<MyClass>().Add(criterion).List<MyClass>();
Somebody knows how I can indicate to Criteria API that MyClass has the properties mapped as access="field"?
Help very appreciated.
Not sure of what you want to achieve, having the class code might help.
Anyway, from what you provided, I guess the mapping should be :
<property name="Name" access="field.camelcase">
see http://www.nhforge.org/doc/nh/en/#mapping-declaration-property
I've seen several questions related to properly mapping an enum type using NHibernate.
This article by Jeff Palermo showed me how to do that properly by creating a custom type. I use Schema Export to create my DB during my dev cycles, but this method breaks my export statement. Is there a way to specify the type of the column on export?
Here is my enum code:
public enum OperatorCode
{
CodeA,
CodeB,
CodeC,
CodeD
}
Here is my custom type:
public class OperatorCodeType:EnumStringType
{
public OperatorCodeType():base(typeof(OperatorCode),20)
{
}
}
Here is my property in my mapping file:
<property name="OperatorCode" column="OperatorCode" type="OperatorCodeType" />
And finally here is my class declaration for that property:
public virtual OperatorCode OperatorCode { get; set; }
Is it even possible to do this?
I have not tested it, but you can use the Column declaration within a property to specify the sql type. Example from the docs:
<property name="Foo" type="String">
<column name="foo" length="64" not-null="true" sql-type="text"/>
</property>
Granted this is a string, but you may want to try it with the type of OperatorCodeType, column sql-type as text or nvarchar or whatever works.
If you try it, let me know? Not near my dev machine at the moment.
I have a class which contains a collection of Points (PointF's rather).
I want to be able to persist instances of that class using NHibernate.
My class looks somewhat like this (simplified):
public class MyClass
{
public IDictionary<string, PointF> Points = new Dictionary<string, PointF>();
public void AddPoint( location, PointF position )
{
Points.Add(location, position);
}
}
The mapping of this collection looks like this (simplified):
<map name="Points" table="Locations">
<key column="MyClassId" />
<index column="LocationName" />
<composite-element class="System.Drawing.PointF, System.Drawing">
<property name="X" column="X" />
<property name="Y" column="Y" />
</composite-element>
</map>
The problem now is, that NHibernate throws an error while processing the mapping file, since PointF is not a known (mapped) entity.
How can I solve this in the most simple way ?
How can I make sure that NHibernate is able to persist my collection of locations (with their coordinates (point) ?
The problem is not that you didn't map the type PointF - because you map it as composite-element, which is correct.
When mapping such types you need to make sure
that properties are writable (which is luckily the case here)
that it has a default constructor, which is not the case here.
So how should NH create new instances when there is not default constructor? It can't.
Your options are:
implement an interceptor or NH event. I think it is possible to inject code there which creates instances of certain types, but I don't know how.
implement a NH user type (derived from ICompositeUserType), which is not too hard to do
map another type (eg. a wrapper to PointF)
For mapping component in nhibernate , is there a way in the hmb file we can indicate a overlaoded constructor to be used instead of default one.
In below mapping nHibernate will use the default constructor of MyClass when reading data from database - I am wondering if we can instruct nhibernate to use a overloaded constructor instead ?
<component name="MyProperty" class="MyClass" >
<property name="Member1" column="member_1" />
<property name="Member2" column="member_2" />
<property name="Member3" column="member_3" />
</component >
Edit #1
Alternatively , does nHibernate allow to map a static value to a property instead of a column ?
Something like below:
<component name="MyProperty" class="MyClass" >
<property name="Member1" column="member_1" />
<property name="Member2" column="member_2" />
<property name="Member3" **value="555"** />
</component >
NHibernate will always use the default constructor to instantiate an object of the type, (unless you want to create some kind of DTO and retrieve it via HQL) and then it will use the properties (or backing fields if specified) to populate the object.
If you have a type for which you do not want to expose a default (no-args) constructor, but you want to make sure that you can only instantiate the type via a specific constructor, then I always do it like this:
public class MyClass
{
private MyClass()
{
// Default constructor has been made private, so it is not usable
// by user code, but NHibernate requires a default constructor
// (it may be private)
}
public MyClass( int member1, int member2, string member3 )
{
}
}
The only standard way you can use constructor with parameters in NHibernate using select new HQL construct:
select new Family(mother, mate, offspr)
from Eg.DomesticCat as mother
join mother.Mate as mate
left join mother.Kittens as offspr
Otherwise it uses parameterless constructors for all purposes. I'm not sure whether this can be altered by hacking NHibernate internals (IClassPersister, IInterceptor, etc.)