I am using Fluent NHibernate on a project that has an Oracle 10g database. I am also using SQLite with a schema generated from my mapping for testing. The problem I am having is that, since the primary keys on my tables are generated by Oracle Sequences, to get my Add methods to work correctly I had to add .GeneratedBy.Sequence({sequence name}) to the Id field of each of my mappings so that the mappings look something like this:
public CustomerMap()
{
Id(x => x.Id)
.Column("Cust_Id")
.GeneratedBy.Sequence("SEQ_CONTNT_AREA");
...
{More Mapping Code}
...
}
Once I added the GeneratedBy.Sequece to my mappings all of my tests began to fail giving me the following errors:
----> NHibernate.MappingException : could not instantiate id generator
----> NHibernate.MappingException : Dialect does not support sequences
These errors make sense to me since SQLite does not use Oracle Sequences for Primary Key generation. However, if I change my mapping to use GeneratedBy.Native(), all of my tests pass, but when I run the application I get the following error when trying to insert a new record:
InnerException = {System.Data.OracleClient.OracleException: ORA-02289: sequence does not exist
at System.Data.OracleClient.OracleConnection.CheckError(OciErrorHandle errorHandle, Int32 rc)
at System.Data.OracleClient.OracleCommand.Execute(OciStatementHandle stateme...
Message: "could not get next sequence value[SQL: select hibernate_sequence.nextval from dual]" string
This error message indicates to me that NHibernate either couldn't find the sequence needed to create the primary key for this table or it didn't even look for it. In either case, it appears to be trying to use 'hibernate_sequence' to get the value which it obviously cannot find since it doesn't exist.
I figure I'm probably missing something pretty simple due to my being pretty new to NHibernate. It is pretty important that I get both the tests and code working soon, as I will be handing this project over to someone else who as even less NHibernate experience than I do when I leave for my new job next week.
I know this is a huge hack, but could you do something like this?
public CustomerMap()
{
if (SomeStaticClass.IsRunningUnitTests)
{
Id(x => x.Id)
.Column("Cust_Id")
.GeneratedBy.Native();
}
else
{
Id(x => x.Id)
.Column("Cust_Id")
.GeneratedBy.Sequence("SEQ_CONTNT_AREA");
}
...
{More Mapping Code}
...
}
Related
I am hoping someone can help me identify the cause of the following error when doing on update in Entity Framework.
Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.
From what I have read, it means that data has changed between the fetch and save, however this is not the case in my situation. (Single developer running the application locally. I also have viewed the data in the database before I attempt to save, and it is the exact same as when I did the fetch. Also able to reproduce this on command.)
I am not sure if this is relevant, but it seems to be the only factor that is different than other entities that are working. I have an entity that represents a table with a composite key. The value that I am updating is one of the values that makes up the composite key. There is only one record in the table at the moment, so I know there is no primary key violation stuff going on.
Does anyone know what steps I can take to find out what the actual problem is?
Thanks
If you have instead of trigger on table you are inserting to, it causes this error. You have to rewrite trigger to after insert trigger, or at the end of trigger select new generated id. Maybe for update there is similar problem. Look at query entity framework generates - it can help you to see what's going on.
EDIT:
To see generated queries set logging:
public class CustomContext : DbContext
{
public CustomContext()
: base("name=CustomString")
{
// configure writing queries to console
Database.Log = Console.Write;
}
// other context stuf ...
}
Or use some profiler (for sql server express you can use http://expressprofiler.codeplex.com/).
The problem resides in the fact that you call the method _dataContext.SaveChanges();, but nothing changed in the data. To avoid this error try this:
public void EditCustomer(Customer customer)
{
_dataContext.Customer.Attach(customer);
var entry = _dataContext.Entry(customer);
if(entry.Property(e => e.DeviceId).CurrentValue != entry.Property(e => e.DeviceId).OriginalValue)
{
entry.Property(e => e.DeviceId).IsModified = true;
}
if(entry.Property(e => e.Name).CurrentValue != entry.Property(e => e.Name).OriginalValue)
{
entry.Property(e => e.Name).IsModified = true;
}
if(entry.Property(e => e.DeviceId).IsModified || entry.Property(e => e.Name).IsModified)
{
_dataContext.SaveChanges();
}
}
I hope this helps you.
#DonPablone
I've encountered with such error message, my environment is as follows, SQL server 2016 along with ef6 database first and the issue was that the database developer did not define an identity seed column in the Id column of the table I'm inserting data into, and of course the issue solved when I updated the table design, so I'm sharing this experience in case if anyone got the same issue.
If by any chance, we have the same problem when trying to update record using Attach() and then SaveChanges() combination? This may help...
I am using SQLite DB and its EF provider (the same code works in SQLServer DB without problem).
I found out, when your DB column has GUID (or UniqueIdentity) in SQLite and your model is nvarchar, SQLIte EF treats it as Binary(i.e., byte[]) by default. So when SQLite EF provider tries to convert GUID into the model (string in my case) it will fail as it will convert to byte[]. The fix is to tell the SQLite EF to treat GUID as TEXT (and therefore conversion is into strings, not byte[]) by defining "BinaryGUID=false;" in the connectionstring (or metadata, if you're using database first) like so:
<connectionStrings>
<add name="Entities" connectionString="metadata=res://savetyping...=System.Data.SQLite.EF6;provider connection string="data source=C:\...\db.sqlite3;Version=3;BinaryGUID=false;App=EntityFramework"" providerName="System.Data.EntityClient" />
</connectionStrings>
Link to the solution that worked for me:
How does the SQLite Entity Framework 6 provider handle Guids?
I've got a table called AdministratorPrivilages that has the following fields:
ID
List item
MemberId
Value
MemberType
Now, the members can be of two types (Enterprise and Express). Enterprise members live in the enterprise table. Express members live in the expressmember table. I've tried to do my fluent mapping like so.
public class AdministratorPrivilegesMapping : ClassMap<AdministratorPrivileges>
{
public AdministratorPrivilegesMapping()
{
Id(x=>x.Id);
Map(x => x.Value).Column("Value");
ReferencesAny(x => x.Member)
.EntityTypeColumn("MemberType")
.EntityIdentifierColumn("MemberId")
.IdentityType<Int32>()
.AddMetaValue<ExpressMember>("Express")
.AddMetaValue<Member>("Enterprise");
}
}
Both member tables have integer ids with ascending values. When I try to pull back the privilages associated with enterprise member 10, I'm getting the permission set associated with Express Member 10. Both other tables are mapped with the old school hbm mapping files.
Am I missing something obvious? I'm using NHibernate 2.1 and FluentNhibernate 1.1
I actually found the solution using .Where().
My situation is a little different, I have objectA and objectB.
objectA contains objectB, but objectB also contains a collection of objectBs.
"objectA":{
"someProp" : "(string)",
"objectB":{
"someProp" : "(string)",
"comeCol" : [
"(objectB)"
]
}
}
So the "Parent" property of objectB can either be of type objectB or objectA, which is why I needed to use ReferencesAny in the mapping of objectB.
Mapping looks like
ReferencesAny( x => x.Parent )
.IdentityType< int >()
.MetaType< string >()
.EntityTypeColumn( "ParentType" )
.EntityIdentifierColumn( "ParentId" )
.AddMetaValue< objectA >( "E" )
.AddMetaValue< objectB >( "S" )
.Access.Property()
.LazyLoad()
.Cascade.All();
All this works well when saving, however, my problem occured when retrieving, because the framework wasn't told what to retrieve and simply retrieved everything.
So now here is the mapping of the collection that fixed the problem:
HasMany( x => x.objectBs )
.KeyColumn( "ParentId" )
.Where( "ParentType = 'S'" )
.Cascade.All()
.LazyLoad();
Hope it will help anyone in the same situation :)
As seems to always be the case when I post on Stackoverflow, I'm being a complete goober and missing something glaringly obvious that cleared itself up with a good night's rest and some caffeine. I needed to look into the mappings for the ExpressMember and Member classes. Turns out the bag declarations there didn't filter by the type of object appropriately. Initially, I thought I had made the breaking change, when in fact it was actually a very old issue. The collision in id numbers between the two different types of members was not an issue for a very long time, as express members typically have either all the permissions or none, as do most of the older members (which were created first under an admin/plebe scheme with privileges being broken out later).
I finished following the summer of nhibernate screen casts and am trying to convert it to fluent, just for the sake of knowledge.
I have two classes (very simple)
public class Customer { ... }
public class PreferredCustomer : Customer { ... }
These follow table per sub class strategy and so the fluent mapping is so:
CustomerMap -
//nothing related to PreferredCustomer - the spec says not required
public class PreferredCustomerMap : SubclassMap<PreferredCustomer>
{
Map(x => x.CustomerSince);
Map(x => x.OrderDiscountRate);
}
Thats it.
My test is failing, upon inspection, its complaining that sql cant find column customer_id
this is the sql produced by hibernate:
SELECT customer0_.CustomerId as CustomerId1_0_,
customer0_.Version as Version1_0_,
customer0_.Firstname as Firstname1_0_,
customer0_.Lastname as Lastname1_0_,
customer0_1_.CustomerSince as Customer2_2_0_,
customer0_1_.OrderDiscountRate as OrderDis3_2_0_,
//here, customer0_1_.customer_id needs to be CustomerID really.
case when customer0_1_.Customer_id is not null then 1 when customer0_.CustomerId is not null then 0 end as clazz_0_
FROM [Customer] customer0_ left outer join [PreferredCustomer] customer0_1_ on customer0_.CustomerId=customer0_1_.Customerid
WHERE customer0_.Customer_Id=1
Its clearly doing that only on PreferredCustomer joined table. Cant find what needs to be done.
Any Ideas please?
edit: how do I read the xml's produced by fluent? that could be a good start.
You need a call to KeyColumn("CustomerID"); in your SubclassMaps.
I'm trying to map a many-to-many collection with Fluent NHibnernate. My model class has this property:
public virtual IList<Resource> Screenshots
{
get { return _screenshots; }
protected set { _screenshots = value; }
}
And my fluent mapping is:
HasManyToMany(x => x.Screenshots)
.AsList(x => x.WithColumn("Index"))
.Cascade.AllDeleteOrphan();
When I run my application, I get the following exception message:
The element 'list' in namespace
'urn:nhibernate-mapping-2.2' has
invalid child element 'many-to-many'
in namespace
'urn:nhibernate-mapping-2.2'. List of
possible elements expected: 'index,
list-index' in namespace
'urn:nhibernate-mapping-2.2'.
There should be a way to do this. Does anyone know what I am doing wrong?
The current FluentNHibernate syntax for this is as follows:
HasManyToMany(x => x.Screenshots)
.AsList(i => i.Column("`Index`"));
The index column defaults to Index, but that's a reserved word on SQL Server (and probably other databases too), so you must quote it with back-ticks.
Also, I'd recommend against setting a cascade on this relationship. Consider the following code:
x.Screenshots.Remove(s);
session.SaveOrUpdate(x);
NHibernate will correctly delete rows from the linking table even without a cascade specified. However, if you specify AllDeleteOrphan, then NHibernate will delete the row from the linking table and also delete Resource s. I doubt this is the behavior you want on a many-to-many relationship.
I am using: NHibernate, NHibernate.Linq and Fluent NHibernate on SQL Server Express 2008. I am selecting an entity using a predicate on a referenced property (many-one mapping). I have fetch=join, unique=true, lazy-load=false. I enabled the log4net log and when any such query executes it logs two identical SQL queries. Running the query returns one row, and when I attempt to use the IQueryable.Single extension method it throws the exception stating there is more than one row returned. I also tried running the query using the standard IQuery.UniqueResult method with the same result, it ends up logging and actually running the query twice, then throwing an exception stating that there were multiple rows, however running the actual query in management studio returns only one result. When I disable logging I receive the same error.
The entities and mappings are declared as follows (proper access modifiers and member type variance are implied)
class User
{
int ID;
string UserName;
}
class Client
{
int ID;
User User;
Person Person;
Address Address;
}
class UserMap : ClassMap<User>
{
public UserMap()
{
Id(x => x.ID);
Map(x => x.UserName);
}
}
class ClientMap : ClassMap<Client>
{
public ClientMap()
{
Id(x => x.ID);
References(x => x.User).Unique();
...
}
}
Then I invoke a queries such as the following:
ISession s = GetNHibernateSession();
...
var client = s.Linq<Client>().SingleOrDefault(x => x.User.ID = 17);
or
var client = s.Linq<Client>().Where(x => x.User.ID = 17);
or
var client = s.CreateQuery("from Client as c where c.User.ID = 17").UniqueResult<Client>();
In all cases executes two identical queries. When I enable lazy load, the client is again loaded using two queries, however upon accessing a member, such as Person, only one additional query is executed.
Is this possibly a result of Fluent generating an improper mapping? Or SQL Server Express edition not being used properly by NHibernate?
The problem was caused by another mapping I had declared. I had a class inheriting from Client which had an associated mapping. This is what caused NHibernate to query twice. I noticed this because when using Linq() it returned the subclass, not Client itself. This particular instance of inheritance and mapping was a design flaw on my part and was the root of the whole problem!
NHibernate doesn't have any trouble with SQL Express, I've used it fairly extensively. Similarily, it's unlikely Fluent NHibernate is generating invalid mappings in this simple scenario (but not unheard of).
A shot in the dark, but I believe NHibernate reserves the name Id as an identifier name, so when it sees Id in the query it knows to just look at the foreign key instead of the actual joined entity. Perhaps your naming of ID instead of Id is throwing it off?
You could try using the excellent NHibernate profiler for a more detailed view of what is happening. It comes with a 30 day trial license and while in Beta there is a discount on the full license cost