After running SQL Profiler, I realized that NHibernate was mapping strings to nvarchar(4000). I fixed it by specifying type=AnsiString and length=... in the hbm file. It is now generating varchar(8000) statements, and it is ignoring the length. How come?!
hbm file:
<property name="EmailAddress" column="EMAIL_ADDRESS" type="AnsiString" length="120" />
database field:
[EMAIL_ADDRESS] [varchar](120) NULL,
TIA
Actually in previous versions of nhibernate the check against length was implemented also for query creation.
But, the current implementation of the SqlDriver got a change last year,
see https://nhibernate.jira.com/browse/NH-3036 for details of the fix.
Bugfix:
// Used from SqlServerCeDriver as well
public static void SetVariableLengthParameterSize(IDbDataParameter dbParam, SqlType sqlType)
{
SetDefaultParameterSize(dbParam, sqlType);
// no longer override the defaults using data from SqlType, since LIKE expressions needs larger columns
// https://nhibernate.jira.com/browse/NH-3036
//if (sqlType.LengthDefined && !IsText(dbParam, sqlType) && !IsBlob(dbParam, sqlType))
//{
// dbParam.Size = sqlType.Length;
//}
if (sqlType.PrecisionDefined)
{
dbParam.Precision = sqlType.Precision;
dbParam.Scale = sqlType.Scale;
}
}
The defaults are what you see (4000/8000) dependent on the data type...
Related
I am trying to manually clear the level 2 cache for a specific region. I found the method posted in answer to this question. While this is working to clear my entities, for some reason the querycache is not getting cleared. This results in a separate query for each entity the next time the entities are retrieved from the database. If does work when I call sessionFactory.EvictQueries() without any parameters. It is only not working when I am passing in a specific region name. Any ideas as to what is going wrong?
Code is from the above link:
private void ClearRegion(string regionName)
{
_sessionFactory.EvictQueries(regionName);
foreach (var collectionMetaData in _sessionFactory.GetAllCollectionMetadata().Values)
{
var collectionPersister = collectionMetaData as NHibernate.Persister.Collection.ICollectionPersister;
if (collectionPersister != null)
{
if ((collectionPersister.Cache != null) && (collectionPersister.Cache.RegionName == regionName))
{
_sessionFactory.EvictCollection(collectionPersister.Role);
}
}
}
foreach (var classMetaData in _sessionFactory.GetAllClassMetadata().Values)
{
var entityPersister = classMetaData as NHibernate.Persister.Entity.IEntityPersister;
if (entityPersister != null)
{
if ((entityPersister.Cache != null) && (entityPersister.Cache.RegionName == regionName))
{
_sessionFactory.EvictEntity(entityPersister.EntityName);
}
}
}
}
Caching is working and verified using NHProfiler.
Ok, so I figured out my issue. I did not realize that it is necessary to specify a cache region when querying the data, aside from specifying it in the entity mapping. After adding .CacheRegion("regionName") to my queries everything works. By not adding the region when querying, it was going into the query cache without a region name. That is why it worked when I called.EvictQueries() without a region name parameter.
To sum it up, it is necessary to add the region name when mapping the entities (.Region("regionName") when using Fluent) and when querying with isession using .CacheRegion("regionName").
Thank you for you responses.
If you do not have experience with or aren't currently using EntitySpaces ("ES") ORM this question is not meant for you.
I have a 10 year old application that after 4 years now needs my attention. My application uses a now defunct ORM called EntitySpaces and I'm hoping if you're reading this you have experience or maybe still use it too! Switching to another ORM is not an option at this time so I need to find a way to make this work.
Between the time I last actively worked on my application and now (ES Version 2012-09-30), EntitySpaces ("ES") has gone through a significant change in the underlying ADO.net back-end. The scenario that I'm seeking help on is when an entity collection is loaded with only a subset of the columns:
_products = new ProductCollection();
_products.Query.SelectAllExcept(_products.Query.ImageData);
_products.LoadAll();
I then override the properties that weren't loaded in the initial select so that I may lazyload them in the accessor. Here is an example of one such lazy-loaded property that used to work perfectly.
public override byte[] ImageData
{
get
{
bool rowIsDirty = base.es.RowState != DataRowState.Unchanged;
// Check if we have loaded the blob data
if(base.Row.Table != null && base.Row.Table.Columns.Contains(ProductMetadata.ColumnNames.ImageData) == false)
{
// add the column before we can save data to the entity
this.Row.Table.Columns.Add(ProductMetadata.ColumnNames.ImageData, typeof(byte[]));
}
if(base.Row[ProductMetadata.ColumnNames.ImageData] is System.DBNull)
{
// Need to load the data
Product product = new Product();
product.Query.Select(product.Query.ImageData).Where(product.Query.ProductID == base.ProductID);
if(product.Query.Load())
{
if (product.Row[ProductMetadata.ColumnNames.ImageData] is System.DBNull == false)
{
base.ImageData = product.ImageData;
if (rowIsDirty == false)
{
base.AcceptChanges();
}
}
}
}
return base.ImageData;
}
set
{
base.ImageData = value;
}
}
The interesting part is where I add the column to the underlying DataTable DataColumn collection:
this.Row.Table.Columns.Add(ProductMetadata.ColumnNames.ImageData, typeof(byte[]));
I had to comment out all the ADO.net related stuff from that accessor when I updated to the current (and open source) edition of ES (version 2012-09-30). That means that the "ImageData" column isn't properly configured and when I change it's data and attempt to save the entity I receive the following error:
Column 'ImageData' does not belong to table .
I've spent a few days looking through the ES source and experimenting and it appears that they no longer use a DataTable to back the entities, but instead are using a 'esSmartDictionary'.
My question is: Is there a known, supported way to accomplish the same lazy loaded behavior that used to work in the new version of ES? Where I can update a property (i.e. column) that wasn't included in the initial select by telling the ORM to add it to the entity backing store?
After analyzing how ES constructs the DataTable that is uses for updates it became clear that columns not included in the initial select (i.e. load) operation needed to be added to the esEntityCollectionBase.SelectedColumns dictionary. I added the following method to handle this.
/// <summary>
/// Appends the specified column to the SelectedColumns dictionary. The selected columns collection is
/// important as it serves as the basis for DataTable creation when updating an entity collection. If you've
/// lazy loaded a column (i.e. it wasn't included in the initial select) it will not be automatically
/// included in the selected columns collection. If you want to update the collection including the lazy
/// loaded column you need to use this method to add the column to the Select Columns list.
/// </summary>
/// <param name="columnName">The lazy loaded column name. Note: Use the {yourentityname}Metadata.ColumnNames
/// class to access the column names.</param>
public void AddLazyLoadedColumn(string columnName)
{
if(this.selectedColumns == null)
{
throw new Exception(
"You can only append a lazy-loaded Column to a partially selected entity collection");
}
if (this.selectedColumns.ContainsKey(columnName))
{
return;
}
else
{
// Using the count because I can't determine what the value is supposed to be or how it's used. From
// I can tell it's just the number of the column as it was selected: if 8 colums were selected the
// value would be 1 through 8 - ??
int columnValue = selectedColumns.Count;
this.selectedColumns.Add(columnName, columnValue);
}
}
You would use this method like this:
public override System.Byte[] ImageData
{
get
{
var collection = this.GetCollection();
if(collection != null)
{
collection.AddLazyLoadedColumn(ProductMetadata.ColumnNames.ImageData);
}
...
It's a shame that nobody is interested in the open source EntitySpaces. I'd be happy to work on it if I thought it had a future, but it doesn't appear so. :(
I'm still interested in any other approaches or insight from other users.
Is there any way to set a default value for max_lo that will take effect for all mapped entities? All of my entities are currently mapped via Xml. I know the default is 32678, but I would like to reduce this to 1000.
I've had a look through the NH configuration xsd and I can't see any settings in there. I think that you should be able to achieve this ok if you are mapping by code, but I am currently using Xml and don't fancy changing across.
Thanks.
you can also override the value on SessionFactory generation, which is only done once:
private void InitSessionFactory()
{
var cfg = new Configuration().Configure();
foreach (var cm in cfg.ClassMappings) {
if (cm.Identifier.IsSimpleValue) {
var simpleVal = cm.Identifier as SimpleValue;
if (simpleVal.IdentifierGeneratorStrategy == "hilo"){
simpleVal.IdentifierGeneratorProperties["max_lo"] = "1000";
}
}
}
sessionFactory = cfg.BuildSessionFactory();
}
this NH2 code so for NH3 there might be some differences
No way to configure default/global from hbm. Int16.MaxValue is simply hardcoded in NHibernate (as of 3.2). TableHiLoGenerator source:
public override void Configure(IType type, ...)
{
...
maxLo = PropertiesHelper.GetInt64(MaxLo, parms, Int16.MaxValue);
...
}
I guess you can open feature request here.
It looks like it may be possible to do this by extending the NH hilo generator as per http://daniel.wertheim.se/2011/03/08/nhibernate-custom-id-generator/
I have a sql2008 db that has a column type of xml.
Using NHibernate 2.5 I can save to this column no problems.
I've dropped in the NHibernate 3.0 dlls and suddenly I'm getting the above errors?
My mapping file doesn't have a type against that column so surely NHibernate should pick up the xml data type (I'm using the sql 2008 dialect) ?
4000 just seems to be a suspicious length, i.e the length of a varchar column in sql.
I see there are a few articles about mapping xml columns using custom UserTypes, etc.
How come this just worked in 2.5 and now doesn't in 3.0 ? I don't need any special handling. That column gets used as a string everywhere.
The reason this behavior changed from 2.x to 3.0.0 was due to a code commit on NHibernate.Driver.SqlClientDriver, which effectively turned on some of the behavior of enabling the prepare_sql configuration in order to resolve an issue with the caching of query plans.
A C# string property mapped to a column that has no other type specified in its mapping will get treated as a NHibernate.SqlTypes.StringSqlType and given a 4000 character limit by the driver:
From NHibernate.SqlTypes.StringSqlType:
/// <remarks>
/// This can store the length of the string that the <see cref="IDbDataParameter"/> can hold.
/// If no value is provided for the length then the <c>Driver</c> is responsible for
/// setting the properties on the <see cref="IDbDataParameter"/> correctly.
/// </remarks>
So, you can see that the code below from the driver (NHibernate.Driver.SqlClientDriver), maps a default string property to a length of 4000 characters.
/* SNIP */
private const int MaxAnsiStringSize = 8000;
private const int MaxBinarySize = MaxAnsiStringSize;
private const int MaxStringSize = MaxAnsiStringSize / 2;
private const int MaxBinaryBlobSize = int.MaxValue;
private const int MaxStringClobSize = MaxBinaryBlobSize / 2;
/* SNIP */
private static void SetDefaultParameterSize(IDbDataParameter dbParam, SqlType sqlType)
{
switch (dbParam.DbType)
{
/* SNIP */
case DbType.String:
case DbType.StringFixedLength:
dbParam.Size = IsText(dbParam, sqlType) ? MaxStringClobSize : MaxStringSize;
break;
/* SNIP */
}
}
For configurations with prepare_sql set to false, NH 3.0.0 now brings the SetDefaultParameterSize method into play where it was not before
As you noted, you can use NH-3.0.0-native support for the SQL Server XML datatype (thanks to NH-866), like so:
<property name="Data" type="xml" not-null="true" />
or more explicitly, but equivalently:
<property name="Data" type="XmlDoc" not-null="true">
<column name="DATA" sql-type="XmlSql" />
</property>
But using NHibernate.Type.XmlDocType expects the property type to be of C# type XmlDocument - leading to a cast exception.
You could do the XmlDocument.InnerXml fix like you mentioned, but that's a lot of unnecessary transformation from string to doc and back. I've used the following mapping to keep the domain property a string:
<property name="Data" type="StringClob" not-null="true">
<column name="DATA" sql-type="XmlSql" />
</property>
Using NHibernate.Type.StringClobType will return true for the IsText(dbParam, sqlType) call in the driver snippet above, giving a max character length of int.MaxValue / 2 - something like 2GB of string data.
I solved this by changing the property type to xml in the mapping file.
Then just used the XmlDocument that is returned as XmlDocument.InnerXml to get the string value.
I'm importing data that may or may not exist already in my database. I'd like NHibernate to associate any entities with the existing db one if it exists (probably just setting the primary key/id), or create a new one if it doesn't. I'm using S#arp architecture for my framework (MVC 2, NHibernate, Fluent).
I've added the [HasUniqueDomainSignature] attribute to the class, and a [DomainSignature] attribute to the properties I want to use for comparison. The only way I can think to do it (which is not an acceptable solution and may not even work) is the following (psuedo C#):
foreach (Book importedBook in importedBooks){
foreach (Author author in importedBook.Authors){
if (!author.IsValid()){ // NHibernate Validator will check DomainSignatures
author = _authorRepository.GetByExample(author); // This would be to get the db object with the same signature,
//but I don't think I could even update this as I iterate through it.
}
}
}
As you can see, this is both messy, and non-sensical. Add to that the fact that I've got a half dozen associations on the Book (subject, format, etc), and it doesn't make any sense. There's got to be an easy way to do this that I'm missing. I'm not a novice with NHibernate, but I'm definitely not an expert.
I might not be understanding the problem, but how can the data "may or may not exist in the database"? For example, if a Book has 2 Authors, how is the relationship stored at the database level if the Author doesn't exist?
It seems as if you're trying to use NHibernate to import your data (or create an entity if it doesn't exist) which doesn't seem correct.
Most database implementations support a conditional UPDATE-or-INSERT syntax. Oracle, for example, has a MERGE command. In combination with a Hibernate <sql-insert> block in your mapping you should be able to work something out. I don't know Fluent but I assume it supports this too.
Just realize I never gave an answer or approved another's answer. I ended up just writing a new SaveOrUpdate which takes a parameter to check for existing before persisting. I also added an attribute to my domain models to overwrite when saving/updating (although in retrospect it's only on updating that it'd be overwriting).
Here's the code if it can help anyone else in this dilemma:
public TEntity SaveOrUpdate<TEntity>(TEntity entity, bool checkForExistingEntity)
{
IRepository<TEntity> repository = new Repository<TEntity>();
if (checkForExistingEntity) {
if (entity is Entity) {
IEnumerable<PropertyInfo> props = (entity as Entity).GetSignatureProperties();
Dictionary<string, object> parameters =
props.ToDictionary(propertyInfo => propertyInfo.Name, propertyInfo => propertyInfo.GetValue(entity, null));
TEntity duplicateEntity = repository.FindOne(parameters);
if (duplicateEntity != null) {
// Update any properties with the OverwriteOnSaveUpdate attribute
foreach (var property in RepositoryHelper.GetUpdatableProperties(typeof(TEntity)))
{
object initialValue = property.GetValue(entity, null);
property.SetValue(duplicateEntity, initialValue, null);
}
// Fill in any blank properties on db version
foreach (var property in typeof(TEntity).GetProperties())
{
if (property.GetValue(duplicateEntity, null) == null) {
object initialValue = property.GetValue(entity, null);
property.SetValue(duplicateEntity, initialValue, null);
}
}
return duplicateEntity;
}
}
}
return SaveOrUpdate(entity);
}