I am having the difficulty to understand NHibernate an petapoco loading mechanism. Actually I did a test to compare how both behave upon a query.
My class is as follows:
UserTest.cs with the following properties:
private string name;
private int id;
private int customerId;
public int ID
{
get { return id; }
set { id = value; }
}
public string Name
{
get { return name; }
set { name = value; }
}
public int? CustomerID
{
get { return customerId; }
set
{
if (value != customerId)
{
customerId = value;
if (this.ID > 0)
{
DoSomeOtherWork();
}
}
}
}
When I do a User.Load in NHibernate, I have observed that DoSomeOtherWork is never called whereas in PetaPoco, when I do a query from loading User such as Connection.db.Fetch<UserTest>(...) or Connection.db.Query<UserTest>(...), I can see that DoSomeOtherWork is called.
Why is that so?
Is there a way to avoid calling DoSomeOherWork when using PetaPoco such that it has the same behaviour as NHibernate? I dont want to usePetaPoco.Ignoreas I need to get and set theCustomerID`.
PetaPoco it a micro-ORM (much lighter than Nhibernate) and materializes your POCO object when you fetch the record. There is no other magic than that, so the answer is:
No, you can't avoid calling the setter of the property.
Related
I'm using Linq2NHibernate 3.0 with sybase ASE 15.
My first problem was that the dialect does not support limits ("select top 5 ..."). As a consequence, I made a custom dialect overriding those methods :
public override bool SupportsLimit
{
get { return true; }
}
public override bool SupportsLimitOffset
{
get { return true; }
}
public override bool SupportsVariableLimit
{
get
{
return true;
}
}
public new int GetLimitValue(int offset, int limit)
{
//TOOK FROM ANOTHER DIALECT
if (limit == int.MaxValue)
return int.MaxValue;
if (UseMaxForLimit)
return GetOffsetValue(offset) + limit;
return limit;
}
public override SqlString GetLimitString(SqlString sql, SqlString offset, SqlString limit)
{
//TOOK FROM ANOTHER DIALECT EXCEPT THAT I CALL ANOTHER CUSTOM CLASS
}
NOTE : I USE ANOTHER CLASS TO PASS THE LIMIT VALUE INTO GetLimitString USING LOCKS (I did not find a better alternative)
I thought it worked fine but GetLimitString is only called once, as a result, if I change the limit value, it is not taken into account.
So, my problem can be solved two ways: you have a better custom dialect for Sybase, or you know why GetLimitString is only called once.
Thanks in advance
The issue is that I can't understand how to make a OneToOne relation between two objects the way for the first object to have a link to the second and for the second to have a link to the first. Here's the code:
[MapTo("Model")]
public class Model : CSObject<Model, int>
{
[OneToOne(LocalKey = "ModelID", ForeignKey = "ModelID")]
public Product Product { get { return (Product)GetField ("Product"); } set { SetField ("Product", value); } }
}
[MapTo("Product")]
public class Product : CSObject<Product, int>
{
[OneToOne(LocalKey = "ProductID", ForeignKey = "ProductID")]
public Model Model { get { return (Model)GetField ("Model"); } set { SetField ("Model", value); } }
}
The thing is that when I create a product and a model and set the model's property "Product" to the created one and save it, the product's "Model" property doesn't get set and remains NULL. I've already tried making all the local and foreign keys for both Product's and Model's properties the same (e.g. "ModelID") but it didn't solve the problem. What is the right way of doing this?
I guess making one of them [OneToMany] will do the trick but will return a collection while I need a single object to be returned by a property.
Update
Here comes a simple solution one would call a crutch:
[OneToMany]
public CSList<Product> _ProductList { get { return (CSList<Product>)GetField ("_ProductList"); } set { SetField ("_ProductList", value); } }
[NotMapped]
public Product Product {
get {
CSList<Product> list = this._ProductList;
if (list.Count > 0)
return list [0];
return null;
}
set {
if (value != null) {
CSList<Product> list = this._ProductList;
list.RemoveAll ();
list.Add (value);
}
}
}
You can make both relations [ManyToOne]. That will work in your scenario.
I am trying to create an NHibernate IUserType for the Noda Time LocalTime type which would logically map to a time type in Sql Server 2008/2012. I am able to get values saving and loading from the database. However, I can't write queries involving comparison of local times like _session.Query<SchedulingTemplate>().Where(x => x.Start < end && x.End >= start) gives the error SqlException (0x80131904): The data types time and datetime are incompatible in the less than operator.
The relevant code from my user type is:
public Type ReturnedType
{
get { return typeof(LocalTime); }
}
public override object NullSafeGet(IDataReader rs, string[] names, object owner)
{
var dbValue = NHibernateUtil.Time.NullSafeGet(rs, names);
if(dbValue == null)
return null;
return LocalDateTime.FromDateTime((DateTime)dbValue).TimeOfDay;
}
public override void NullSafeSet(IDbCommand cmd, object value, int index)
{
if(value == null)
NHibernateUtil.Time.NullSafeSet(cmd, null, index);
else
NHibernateUtil.Time.NullSafeSet(cmd, ((LocalTime)value).LocalDateTime.ToDateTimeUnspecified(), index);
}
public override SqlType[] SqlTypes
{
get { return new[] { SqlTypeFactory.Time }; }
}
The problem is that despite the above code indicating the database type is a time, it generates the following query (per Sql Profiler):
exec sp_executesql N'select [...] from [SchedulingTemplate] scheduling0_ where scheduling0_.Start<#p0 and scheduling0_.[End]>=#p1',N'#p0 datetime,#p1 datetime',#p0='1753-01-01 20:00:00',#p1='1753-01-01 06:00:00'
(note I omitted the select list for brevity)
Notice that the type and value of the parameters is being treated as datetime.
This appears to be very similar to two NH bugs that have been closed https://nhibernate.jira.com/browse/NH-2661 and https://nhibernate.jira.com/browse/NH-2660.
I tried to use NHibernateUtil.TimeAsTimeSpan and that didn't seem to work either. It generated exactly the same query which surprised me. I am thinking maybe the issue described in NH-2661 also exists for user types and was not fixed for that?
I am using NHibernate v3.3.1.400 and Noda Time 1.0.0-beta2
Following #Firo's advice, I worked from the time SqlType and came up with this:
using NHibernate;
using NHibernate.Dialect;
using NHibernate.SqlTypes;
using NHibernate.Type;
using NodaTime;
using NodaTime.Text;
using System;
using System.Data;
using System.Data.SqlClient;
[Serializable]
public class LocalTimeType : PrimitiveType, IIdentifierType
{
private readonly LocalTimePattern _timePattern = LocalTimePattern.CreateWithInvariantCulture("h:mm:ss tt");
public LocalTimeType() : base(SqlTypeFactory.Time) { }
public override string Name
{
get { return "LocalTime"; }
}
public override object Get(IDataReader rs, int index)
{
try
{
if (rs[index] is TimeSpan) //For those dialects where DbType.Time means TimeSpan.
{
var time = (TimeSpan)rs[index];
return LocalTime.Midnight + Period.FromTicks(time.Ticks);
}
var dbValue = Convert.ToDateTime(rs[index]);
return LocalDateTime.FromDateTime(dbValue).TimeOfDay;
}
catch (Exception ex)
{
throw new FormatException(string.Format("Input string '{0}' was not in the correct format.", rs[index]), ex);
}
}
public override object Get(IDataReader rs, string name)
{
return Get(rs, rs.GetOrdinal(name));
}
public override Type ReturnedClass
{
get { return typeof(LocalTime); }
}
public override void Set(IDbCommand st, object value, int index)
{
var parameter = ((SqlParameter)st.Parameters[index]);
parameter.SqlDbType = SqlDbType.Time; // HACK work around bad behavior, M$ says not ideal, but as intended, NH says this is a bug in MS may work around eventually
parameter.Value = new TimeSpan(((LocalTime)value).TickOfDay);
}
public override bool IsEqual(object x, object y)
{
return Equals(x, y);
}
public override int GetHashCode(object x, EntityMode entityMode)
{
return x.GetHashCode();
}
public override string ToString(object val)
{
return _timePattern.Format((LocalTime)val);
}
public object StringToObject(string xml)
{
return string.IsNullOrEmpty(xml) ? null : FromStringValue(xml);
}
public override object FromStringValue(string xml)
{
return _timePattern.Parse(xml).Value;
}
public override Type PrimitiveClass
{
get { return typeof(LocalTime); }
}
public override object DefaultValue
{
get { return new LocalTime(); }
}
public override string ObjectToSQLString(object value, Dialect dialect)
{
return "'" + _timePattern.Format((LocalTime)value) + "'";
}
}
The key code is in the Set method where is says:
var parameter = ((SqlParameter)st.Parameters[index]);
parameter.SqlDbType = SqlDbType.Time;
This is needed because the MS data provider takes setting the DbType to DbType.Time to mean the underlying type should be DateTime. You must set the SqlDbType to time for it to work.
By default, WCF deserializes missing elements into default values like null, 0 or false. The problem with this approach is that if it's a basic type like number 0 I'm not sure whether it means the real value sent by an external system or a default value generated by WCF.
So my question is: Is it possible to find out at run-time whether the default value means "I didn't send anything".
This is crucial because we can't update and overwrite existing data in the database with the default values just because the external system didn't send a particular element this time (data corruption).
Microsoft's short answer is "It is up to the receiving endpoint to appropriately interpret a missing element."
Data member default values
http://msdn.microsoft.com/en-us/library/aa347792.aspx
Can somebody please clarify what's that supposed to mean?
Thanks
If you define your data members as properties, you can use whether the setter was called or not to decide whether some value was sent. The code below shows one data contract which knows whether it deserialized its fields.
public class Post_51ca1ead_2f0a_4912_a451_374daab0101b
{
[DataContract(Name = "Person", Namespace = "")]
public class Person
{
string name;
int age;
bool nameWasSent;
bool ageWasSent;
[DataMember]
public string Name
{
get
{
return this.name;
}
set
{
this.nameWasSent = true;
this.name = value;
}
}
[DataMember]
public int Age
{
get
{
return this.age;
}
set
{
this.ageWasSent = true;
this.age = value;
}
}
[OnDeserializing]
void OnDeserializing(StreamingContext ctx)
{
this.ageWasSent = false;
this.nameWasSent = false;
}
public override string ToString()
{
return string.Format("Person[Name={0},Age={1}]",
nameWasSent ? name : "UNSPECIFIED",
ageWasSent ? age.ToString() : "UNSPECIFIED");
}
}
public static void Test()
{
MemoryStream ms = new MemoryStream();
DataContractSerializer dcs = new DataContractSerializer(typeof(Person));
dcs.WriteObject(ms, new Person { Name = "John", Age = 30 });
Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));
string noAge = "<Person><Name>John</Name></Person>";
ms = new MemoryStream(Encoding.UTF8.GetBytes(noAge));
object p = dcs.ReadObject(ms);
Console.WriteLine("No age: {0}", p);
string noName = "<Person><Age>45</Age></Person>";
ms = new MemoryStream(Encoding.UTF8.GetBytes(noName));
p = dcs.ReadObject(ms);
Console.WriteLine("No name: {0}", p);
}
}
given a query in the form of an ICriteria object, I would like to use NHibernate (by means of a projection?) to find an element's order,
in a manner equivalent to using
SELECT ROW_NUMBER() OVER (...)
to find a specific item's index in the query.
(I need this for a "jump to page" functionality in paging)
any suggestions?
NOTE: I don't want to go to a page given it's number yet - I know how to do that - I want to get the item's INDEX so I can divide it by page size and get the page index.
After looking at the sources for NHibernate, I'm fairly sure that there exists no such functionality.
I wouldn't mind, however, for someone to prove me wrong.
In my specific setting, I did solve this problem by writing a method that takes a couple of lambdas (representing the key column, and an optional column to filter by - all properties of a specific domain entity). This method then builds the sql and calls session.CreateSQLQuery(...).UniqueResult(); I'm not claiming that this is a general purpose solution.
To avoid the use of magic strings, I borrowed a copy of PropertyHelper<T> from this answer.
Here's the code:
public abstract class RepositoryBase<T> where T : DomainEntityBase
{
public long GetIndexOf<TUnique, TWhere>(T entity, Expression<Func<T, TUnique>> uniqueSelector, Expression<Func<T, TWhere>> whereSelector, TWhere whereValue) where TWhere : DomainEntityBase
{
if (entity == null || entity.Id == Guid.Empty)
{
return -1;
}
var entityType = typeof(T).Name;
var keyField = PropertyHelper<T>.GetProperty(uniqueSelector).Name;
var keyValue = uniqueSelector.Compile()(entity);
var innerWhere = string.Empty;
if (whereSelector != null)
{
// Builds a column name that adheres to our naming conventions!
var filterField = PropertyHelper<T>.GetProperty(whereSelector).Name + "Id";
if (whereValue == null)
{
innerWhere = string.Format(" where [{0}] is null", filterField);
}
else
{
innerWhere = string.Format(" where [{0}] = :filterValue", filterField);
}
}
var innerQuery = string.Format("(select [{0}], row_number() over (order by {0}) as RowNum from [{1}]{2}) X", keyField, entityType, innerWhere);
var outerQuery = string.Format("select RowNum from {0} where {1} = :keyValue", innerQuery, keyField);
var query = _session
.CreateSQLQuery(outerQuery)
.SetParameter("keyValue", keyValue);
if (whereValue != null)
{
query = query.SetParameter("filterValue", whereValue.Id);
}
var sqlRowNumber = query.UniqueResult<long>();
// The row_number() function is one-based. Our index should be zero-based.
sqlRowNumber -= 1;
return sqlRowNumber;
}
public long GetIndexOf<TUnique>(T entity, Expression<Func<T, TUnique>> uniqueSelector)
{
return GetIndexOf(entity, uniqueSelector, null, (DomainEntityBase)null);
}
public long GetIndexOf<TUnique, TWhere>(T entity, Expression<Func<T, TUnique>> uniqueSelector, Expression<Func<T, TWhere>> whereSelector) where TWhere : DomainEntityBase
{
return GetIndexOf(entity, uniqueSelector, whereSelector, whereSelector.Compile()(entity));
}
}
public abstract class DomainEntityBase
{
public virtual Guid Id { get; protected set; }
}
And you use it like so:
...
public class Book : DomainEntityBase
{
public virtual string Title { get; set; }
public virtual Category Category { get; set; }
...
}
public class Category : DomainEntityBase { ... }
public class BookRepository : RepositoryBase<Book> { ... }
...
var repository = new BookRepository();
var book = ... a persisted book ...
// Get the index of the book, sorted by title.
var index = repository.GetIndexOf(book, b => b.Title);
// Get the index of the book, sorted by title and filtered by that book's category.
var indexInCategory = repository.GetIndexOf(book, b => b.Title, b => b.Category);
As I said, this works for me. I'll definitely tweak it as I move forward. YMMV.
Now, if the OP has solved this himself, then I would love to see his solution! :-)
ICriteria has this 2 functions:
SetFirstResult()
and
SetMaxResults()
which transform your SQL statement into using ROW_NUMBER (in sql server) or limit in MySql.
So if you want 25 records on the third page you could use:
.SetFirstResult(2*25)
.SetMaxResults(25)
After trying to find an NHibernate based solution for this myself, I ultimately just added a column to the view I happened to be using:
CREATE VIEW vw_paged AS
SELECT ROW_NUMBER() OVER (ORDER BY Id) AS [Row], p.column1, p.column2
FROM paged_table p
This doesn't really help if you need complex sorting options, but it does work for simple cases.
A Criteria query, of course, would look something like this:
public static IList<Paged> GetRange(string search, int rows)
{
var match = DbSession.Current.CreateCriteria<Job>()
.Add(Restrictions.Like("Id", search + '%'))
.AddOrder(Order.Asc("Id"))
.SetMaxResults(1)
.UniqueResult<Paged>();
if (match == null)
return new List<Paged>();
if (rows == 1)
return new List<Paged> {match};
return DbSession.Current.CreateCriteria<Paged>()
.Add(Restrictions.Like("Id", search + '%'))
.Add(Restrictions.Ge("Row", match.Row))
.AddOrder(Order.Asc("Id"))
.SetMaxResults(rows)
.List<Paged>();
}