I got a legacy database where the value of 0 was used in FK columns to indicate that no relation have been specified.
This is not something that I can change in a trivial way. Is it possible to tell NHibernate to treat 0 as null in specified columns?
Edit
I know about not-found, but I just want to ignore those with 0.
This solution worked great for us: http://nhibernate.info/blog/2011/01/28/how-to-use-0-instead-of-null-for-foreign-keys.html
In short:
Add the following class:
public class NullableTuplizer : PocoEntityTuplizer
{
public NullableTuplizer(EntityMetamodel entityMetamodel, PersistentClass mappedEntity)
: base(entityMetamodel, mappedEntity)
{
}
public override object[] GetPropertyValuesToInsert(
object entity, IDictionary mergeMap, ISessionImplementor session)
{
object[] values = base.GetPropertyValuesToInsert(entity, mergeMap, session);
//dirty hack 1
for (int i = 0; i < values.Length; i++)
{
if (values[i ] == null && typeof (IEntity).IsAssignableFrom(getters[i ].ReturnType))
{
values[i ] = ProxyFactory.GetProxy(0, null);
}
}
return values;
}
public override object[] GetPropertyValues(object entity)
{
object[] values = base.GetPropertyValues(entity);
//dirty hack 2
for (int i = 0; i < values.Length; i++)
{
if (values[i ] == null && typeof (IEntity).IsAssignableFrom(getters[i ].ReturnType))
{
values[i ] = ProxyFactory.GetProxy(0, null);
}
}
return values;
}
public override void SetPropertyValues(object entity, object[] values)
{
//dirty hack 3.
for (int i = 0; i < values.Length; i++)
{
if (typeof (IEntity).IsAssignableFrom(getters[i ].ReturnType)
&& ((IEntity) values[i ]).Id == 0)
{
values[i ] = null;
}
}
base.SetPropertyValues(entity, values);
}
}
Then register it for every relevant mapping:
foreach (var persistentClass in configuration.ClassMappings)
{
persistentClass.AddTuplizer(EntityMode.Poco, typeof(NullableTuplizer).AssemblyQualifiedName);
}
There is a similar question: NHibernate Saving 0 to many-to-one column instead of null. There is an interesting, but a bit weird solution by Noel Kennedy.
I would probably store a record with the ID 0 in the database, which represents a Null Object.
Related
How to delete custom XML files with its property and relationship files?, I've used clear() method. But it's not working. Help me out.
wordMLPackage.getCustomXmlDataStorageParts().clear();
https://github.com/plutext/docx4j/blob/master/docx4j-core/src/main/java/org/docx4j/Docx4J.java#L643 shows you how to do this. To remove them all, it would be:
protected static void removeDefinedCustomXmlParts(WordprocessingMLPackage wmlPackage) {
List<PartName> partsToRemove = new ArrayList<PartName>();
RelationshipsPart relationshipsPart = wmlPackage.getMainDocumentPart().getRelationshipsPart();
List<Relationship> relationshipsList = ((relationshipsPart != null) &&
(relationshipsPart.getRelationships() != null) ?
relationshipsPart.getRelationships().getRelationship() : null);
Part part = null;
if (relationshipsList != null) {
for (Relationship relationship : relationshipsList) {
if (Namespaces.CUSTOM_XML_DATA_STORAGE.equals(relationship.getType())) {
part = relationshipsPart.getPart(relationship);
partsToRemove.add(part.getPartName());
}
}
}
if (!partsToRemove.isEmpty()) {
for (int i=0; i<partsToRemove.size(); i++) {
relationshipsPart.removePart(partsToRemove.get(i));
}
}
}
An integral part of our architecture as our system must provide a dashboard for users to explicitly publish data changes from environment to another. We looked at NH Evers, but we needed to many domain specific things to be baked into the architecture. We've been successfully using NHibernate's eventing model to track and log state changes (to another table) in our system, but recently stumbled across a snag with Components. When IPostInsertEventListener and IPostUpdateEventListener is fired it publishes a value arrays that denote the current state of the entity. In the case of updates, it publishes an array denoting previous state as well. We are using these arrays to save off "before" and "after" state into our table. When the property is a Component, the actual value (item in the area) is the component instance itself - i.e. an untyped complex object. Short of cross referencing the metamodel mapper and reflecting on that to pull out the individual values, how can I get at the actual values that make up the component? I'm able to get at the column names that map to the Component's members, but not the before and after values.
I've been digging through the NH source, and I'm not finding how to pull out these values, but obviously NH knows how to do this internally as it's able to publish the sql properly. Here's a modified/verbose version of the code I currently have that highlights the issue:
public static RowChangedReport Load(IChangeTrackable trackable, object entityId, AbstractEntityPersister persister, object[] state, object[] oldState)
{
var report = new RowChangedReport
{
Entity = trackable,
EntityTypeFullName = persister.EntityName,
TableName = new TableName(persister.GetTableName()),
EntityId = entityId,
};
var authContext = AuthenticationContext.Current;
if (authContext != null)
report.SecurityContextUserId = authContext.UserId;
if (persister.PropertyNames != null && state != null)
{
report.ChangedType = oldState == null ? RowChangedTypes.New : RowChangedTypes.Modified;
for (var index = 0; index < persister.PropertyNames.Length; index++)
{
var propertyName = persister.PropertyNames[index];
IType propertyType = persister.PropertyTypes[index];
if (!propertyType.IsCollectionType)
{
AddColumnChangeReport(persister, state, oldState, index, propertyName, report);
}
}
}
report.FinalizeState();
return report;
}
private static void AddColumnChangeReport(AbstractEntityPersister persister, object[] state, object[] oldState, int index, string propertyName, RowChangedReport report)
{
var currentValue = state[index];
// for simple properties, this is always a single element array
// for components, this is an array with an element for each member on the component - i.e. how the component is mapped
string[] columns = persister.GetPropertyColumnNames(propertyName);
var previousValue = oldState == null ? null : oldState[index];
if (!Equals(currentValue, previousValue))
{
if (report.ChangedType == RowChangedTypes.Modified && propertyName == IsActivePropertyName)
report.FlagAsDeleted();
foreach (var column in columns)
{
// if this is a component, both the currentValue and the previousValue are complex objects
// need to have a way to get the actual member value per column!
report.AddChange(new ColumnChangedReport(report, propertyName, column, previousValue, currentValue));
}
}
}
OK, after a few hours reading the NH code, I stumbled across Tuplizers and tracked them back to the property Type. So the solution is pretty simple - for components, you need to detect them as such, cast to the ComponentType Type and then ask ComponentType for the property values. Here some code that's working for me:
public static RowChangedReport Load(IChangeTrackable trackable, object entityId, AbstractEntityPersister persister, object[] state, object[] oldState)
{
var report = new RowChangedReport
{
Entity = trackable,
EntityTypeFullName = persister.EntityName,
TableName = new TableName(persister.GetTableName()),
EntityId = entityId,
};
var authContext = AuthenticationContext.Current;
if (authContext != null)
report.SecurityContextUserId = authContext.UserId;
if (persister.PropertyNames != null && state != null)
{
report.ChangedType = oldState == null ? RowChangedTypes.New : RowChangedTypes.Modified;
for (var index = 0; index < persister.PropertyNames.Length; index++)
{
var propertyName = persister.PropertyNames[index];
IType propertyType = persister.PropertyTypes[index];
if (!propertyType.IsCollectionType)
{
AddColumnChangeReport(persister, state, oldState, index, propertyName, propertyType, report);
}
}
}
report.FinalizeState();
return report;
}
private static void AddColumnChangeReport(AbstractEntityPersister persister, object[] state, object[] oldState, int index, string propertyName, IType propertyType, RowChangedReport report)
{
var currentValue = state[index];
string[] columns = persister.GetPropertyColumnNames(propertyName);
var previousValue = oldState == null ? null : oldState[index];
if (!Equals(currentValue, previousValue))
{
if (report.ChangedType == RowChangedTypes.Modified && propertyName == IsActivePropertyName)
report.FlagAsDeleted();
if (propertyType.IsComponentType)
{
ComponentType component = (ComponentType)propertyType;
object[] componentCurrentValues = null;
if (currentValue != null)
componentCurrentValues = component.GetPropertyValues(currentValue, EntityMode.Poco);
object[] componentPreviousValues = null;
if (currentValue != null)
componentPreviousValues = component.GetPropertyValues(previousValue, EntityMode.Poco);
if ((componentCurrentValues != null && componentCurrentValues.Length != columns.Length) ||
(componentPreviousValues != null && componentPreviousValues.Length != columns.Length))
throw new ConventionViolationException(GetComponentArraysExceptionMessage(persister, propertyName, columns, componentPreviousValues, componentCurrentValues));
for (int i = 0; i < columns.Length; i++)
{
var column = columns[i];
var componentPreviousValue = componentPreviousValues == null ? null : componentPreviousValues[i];
var componentCurrnetValue = componentCurrentValues == null ? null : componentCurrentValues[i];
report.AddChange(new ColumnChangedReport(report, propertyName, column, componentPreviousValue, componentCurrnetValue));
}
}
else
{
if (columns.Length > 1)
throw new ConventionViolationException("Expected only component properties to have multiple columns. Property '{0}' on entity {1} is violating that assumption.".FormatWith(propertyName, persister.EntityName));
report.AddChange(new ColumnChangedReport(report, propertyName, columns[0], previousValue, currentValue));
}
}
}
Is hibernatetemplate's bulkUpdate actually doing a bulkUpdate? I looked at the code, and it doesn't seem to be doing bulkUpdate. Or maybe am I missing something?
public int bulkUpdate(final String queryString, final Object... values) throws DataAccessException {
return executeWithNativeSession(new HibernateCallback<Integer>() {
public Integer doInHibernate(Session session) throws HibernateException {
Query queryObject = session.createQuery(queryString);
prepareQuery(queryObject);
if (values != null) {
for (int i = 0; i < values.length; i++) {
queryObject.setParameter(i, values[i]);
}
}
return queryObject.executeUpdate();
}
});
}
whereas JdbcTemplate batchUpdate (looks like) is doing a batchUpdate
public int[] batchUpdate(final String[] sql) throws DataAccessException {
Assert.notEmpty(sql, "SQL array must not be empty");
if (logger.isDebugEnabled()) {
logger.debug("Executing SQL batch update of " + sql.length + " statements");
}
class BatchUpdateStatementCallback implements StatementCallback<int[]>, SqlProvider {
private String currSql;
public int[] doInStatement(Statement stmt) throws SQLException, DataAccessException {
int[] rowsAffected = new int[sql.length];
if (JdbcUtils.supportsBatchUpdates(stmt.getConnection())) {
for (String sqlStmt : sql) {
this.currSql = sqlStmt;
stmt.addBatch(sqlStmt);
}
rowsAffected = stmt.executeBatch();
}
else {
for (int i = 0; i < sql.length; i++) {
this.currSql = sql[i];
if (!stmt.execute(sql[i])) {
rowsAffected[i] = stmt.getUpdateCount();
}
else {
throw new InvalidDataAccessApiUsageException("Invalid batch SQL statement: " + sql[i]);
}
}
}
return rowsAffected;
}
public String getSql() {
return this.currSql;
}
}
return execute(new BatchUpdateStatementCallback());
}
Yes, it is doing bulk update. As you see, DELETE and INSERT queries executed in bulkUpdate method can affect multiple rows. That's why they are called bulk operations.
Point is to have handy method to execute update and execute query and return number of rows affected in bulk operation. Additionally it wraps exceptions to DataAccessException.
Is any way, how to create two classes, which will be referenced both way and will use only one FK? This interest me in One-to-One as like as One-to-Many cases.
f.e.:
Class First: Entity
{
Second second;
}
Class Second: Entity
{
First first;
}
String TwoWayReference()
{
First Fir = new First();
Second Sec = new Second();
Fir.second = Sec; // I need it is equivalent to: Sec.first = Fir;
if (Sec.first == Fir)
return "Is any way how to do this code works and code return this string?";
else
return "Or it is impossible?"
}
simplest would be
class First : Entity
{
private Second second;
public virtual Second Second
{
get { return this.second; }
set {
if (value != null)
{
value.First = this;
this.second = value;
}
}
}
}
class Second : Entity
{
private First first;
public virtual First First
{
get { return this.first; }
set {
if (value != null && value.Second != this)
{
value.Second = this;
this.first = value;
}
}
}
}
I am interfacing with a PostgreSQL database with NHibernate.
Background
I made some simple tests...it seems it's taking 2 seconds to persist 300 records.
I have a Perl program with identical functionality, but issue direct SQL instead, takes only 70% of the time.
I am not sure if this is expected. I thought C#/NHibernate would be faster or at least on par.
Questions
One of my observation is that (with show_sql turned on), the NHibernate is issuing INSERTs a few hundreds times, instead of doing bulk INSERT that take cares of multiple rows. And note I am assigning the primary key myself, not using the "native" generator.
Is that expected? Is there anyway I could make it issue bulk INSERT statement instead? It seems to me that this could be one of the area I could speed up the performance.
As stachu found out correctly: NHibernate does not have *BatchingBatcher(Factory) for PostgreSQL(Npgsql)
As stachu askes: Did anybody managed to force Nhibarnate to do batch inserts to PostgreSQL
I wrote a Batcher that doesn't use any Npgsql batching stuff, but does manipulate the SQL String "oldschool style" (INSERT INTO [..] VALUES (...),(...), ...)
using System;
using System.Collections;
using System.Data;
using System.Diagnostics;
using System.Text;
using Npgsql;
namespace NHibernate.AdoNet
{
public class PostgresClientBatchingBatcherFactory : IBatcherFactory
{
public virtual IBatcher CreateBatcher(ConnectionManager connectionManager, IInterceptor interceptor)
{
return new PostgresClientBatchingBatcher(connectionManager, interceptor);
}
}
/// <summary>
/// Summary description for PostgresClientBatchingBatcher.
/// </summary>
public class PostgresClientBatchingBatcher : AbstractBatcher
{
private int batchSize;
private int countOfCommands = 0;
private int totalExpectedRowsAffected;
private StringBuilder sbBatchCommand;
private int m_ParameterCounter;
private IDbCommand currentBatch;
public PostgresClientBatchingBatcher(ConnectionManager connectionManager, IInterceptor interceptor)
: base(connectionManager, interceptor)
{
batchSize = Factory.Settings.AdoBatchSize;
}
private string NextParam()
{
return ":p" + m_ParameterCounter++;
}
public override void AddToBatch(IExpectation expectation)
{
if(expectation.CanBeBatched && !(CurrentCommand.CommandText.StartsWith("INSERT INTO") && CurrentCommand.CommandText.Contains("VALUES")))
{
//NonBatching behavior
IDbCommand cmd = CurrentCommand;
LogCommand(CurrentCommand);
int rowCount = ExecuteNonQuery(cmd);
expectation.VerifyOutcomeNonBatched(rowCount, cmd);
currentBatch = null;
return;
}
totalExpectedRowsAffected += expectation.ExpectedRowCount;
log.Info("Adding to batch");
int len = CurrentCommand.CommandText.Length;
int idx = CurrentCommand.CommandText.IndexOf("VALUES");
int endidx = idx + "VALUES".Length + 2;
if (currentBatch == null)
{
// begin new batch.
currentBatch = new NpgsqlCommand();
sbBatchCommand = new StringBuilder();
m_ParameterCounter = 0;
string preCommand = CurrentCommand.CommandText.Substring(0, endidx);
sbBatchCommand.Append(preCommand);
}
else
{
//only append Values
sbBatchCommand.Append(", (");
}
//append values from CurrentCommand to sbBatchCommand
string values = CurrentCommand.CommandText.Substring(endidx, len - endidx - 1);
//get all values
string[] split = values.Split(',');
ArrayList paramName = new ArrayList(split.Length);
for (int i = 0; i < split.Length; i++ )
{
if (i != 0)
sbBatchCommand.Append(", ");
string param = null;
if (split[i].StartsWith(":")) //first named parameter
{
param = NextParam();
paramName.Add(param);
}
else if(split[i].StartsWith(" :")) //other named parameter
{
param = NextParam();
paramName.Add(param);
}
else if (split[i].StartsWith(" ")) //other fix parameter
{
param = split[i].Substring(1, split[i].Length-1);
}
else
{
param = split[i]; //first fix parameter
}
sbBatchCommand.Append(param);
}
sbBatchCommand.Append(")");
//rename & copy parameters from CurrentCommand to currentBatch
int iParam = 0;
foreach (NpgsqlParameter param in CurrentCommand.Parameters)
{
param.ParameterName = (string)paramName[iParam++];
NpgsqlParameter newParam = /*Clone()*/new NpgsqlParameter(param.ParameterName, param.NpgsqlDbType, param.Size, param.SourceColumn, param.Direction, param.IsNullable, param.Precision, param.Scale, param.SourceVersion, param.Value);
currentBatch.Parameters.Add(newParam);
}
countOfCommands++;
//check for flush
if (countOfCommands >= batchSize)
{
DoExecuteBatch(currentBatch);
}
}
protected override void DoExecuteBatch(IDbCommand ps)
{
if (currentBatch != null)
{
//Batch command now needs its terminator
sbBatchCommand.Append(";");
countOfCommands = 0;
log.Info("Executing batch");
CheckReaders();
//set prepared batchCommandText
string commandText = sbBatchCommand.ToString();
currentBatch.CommandText = commandText;
LogCommand(currentBatch);
Prepare(currentBatch);
int rowsAffected = 0;
try
{
rowsAffected = currentBatch.ExecuteNonQuery();
}
catch (Exception e)
{
if(Debugger.IsAttached)
Debugger.Break();
throw;
}
Expectations.VerifyOutcomeBatched(totalExpectedRowsAffected, rowsAffected);
totalExpectedRowsAffected = 0;
currentBatch = null;
sbBatchCommand = null;
m_ParameterCounter = 0;
}
}
protected override int CountOfStatementsInCurrentBatch
{
get { return countOfCommands; }
}
public override int BatchSize
{
get { return batchSize; }
set { batchSize = value; }
}
}
}
I also found that NHibernate is not doing batch inserts into PostgreSQL.
I identified two possible reasons:
1) Npgsql driver does not support batch inserts/updates (see forum)
2) NHibernate does not have *BatchingBatcher(Factory) for PostgreSQL(Npgsql). I tried using Devart dotConnect driver with NHibernate (I wrote custom driver for NHibernate) but it still did not worked.
I suppose this driver should also implement IEmbeddedBatcherFactoryProvider interface, but it seems not trivial for me (using one for Oracle did not worked ;) )
Did anybody managed to force Nhibarnate to do batch inserts to PostgreSQL or can confirm my conclusion?