I am attempting to use JMSSerializerBundle to consume JSON into Doctrine entities. I need to both create new entities where they do not already exist in the database, and update existing entities when they do already exist. I am using the DoctrineObjectConstructor included in the JMSSerializer package to help with this. When I consume JSON which contains a property designated as an identifier, such as:
{
"id": 1,
"some_other_attribute": "stuff"
}
by attempting to deserialize it, JMSSerializer causes warnings and eventually dies with an exception for attempting to utilize reflection to set properties on a null value. The warnings all look like this:
PHP Warning: ReflectionProperty::setValue() expects parameter 1 to be object, null given in /Users/cdonadeo/Repos/Ubertester/vendor/jms/serializer/src/JMS/Serializer/GenericDeserializationVisitor.php on line 176
If I manually insert an entity with ID 1 in my database and make another attempt then I receive no errors and everything appears to be working correctly, but I'm now short half my functionality. I looked at the code for the DoctrineObjectConstructor class, and at the top is a comment:
/**
* Doctrine object constructor for new (or existing) objects during deserialization.
*/
But I don't see how it could possibly create a new a new entity because after the construct() function has done all of its checks, at the end it calls:
$object = $objectManager->find($metadata->name, $identifierList);
And since the identifier does not exist in the database the result is null which is ultimately what gets returned from the function. This explains why inserting a row in the database with the appropriate ID makes things work: find() now returns a proper Entity object, which is what the rest of the library expects.
Am I using the library wrong or is it broken? I forked the Git repo and made an edit, and trying it out everything seems to work more or less the way I expected. That edit does have some drawbacks that make me wonder if I'm not just making this more difficult than it has to be. The biggest issue I see is that it will cause persisted and unpersisted entities to be mixed together with no way to tell which ones are which, but I don't know if that's even a big deal.
For Doctrine entities use configuration:
jms_serializer:
object_constructors:
doctrine:
fallback_strategy: "fallback" # possible values ("null" | "exception" | "fallback")
see configuration reference https://jmsyst.com/bundles/JMSSerializerBundle/master/configuration
Related
I used the CRUD generator from a legacy database. When searching for a column value I get the following error:
htmlspecialchars() expects parameter 1 to be string, array given (/usr/local/share/yii/framework/web/helpers/CHtml.php:103)
The problem is that the model has an existing column named "attributes" which is creating a conflict. I removed the entry from the _search.php and commented out all instances in the model hoping to at least get it working but no luck. Any suggestions would be appreciated.
Thanks.
Every CActiveRecord instance (or CModel instance for that matter) has a getter/setter named attributes with which all the attributes can be set. This leads to a conflict because the generated crud code uses the attributes attribute expecting it works as described before.
The controller does something like:
$model->attributes=$_POST['ModelClassName'];
// or
$model->attributes=$_GET['ModelClassName'];
This is meant to set al the (safe) attributes of the model at once. Instead this overwrites the database attribute attributes of your legacy DB model.
This in turn leads to the error you describe, because $_GET['ModelClassName'] and $_POST['ModelClassName'] typically contain arrays of data.
I guess the easiest fix would be to directly call the setter function for the "normal" attributes behavior which would lead to replacing the lines mentioned above with something like the following:
// in the controller
$model->setAttributes($_POST['ModelClassName']);
// and
$model->setAttributes($_GET['ModelClassName']);
I think rest of the generated CRUD code (the views) could and should be left untouched to make it work.
If you want to know how and why this works, it's best to do some research into the __get and __set magic functions and how they're used in the yii framework.
I have a Android java project with quite complex datatypes including ArrayLists of other complex datatypes. I’m trying to store my data in a database using ORMLite (4.42).
I have major problems converting between ArrayLists and ForeignCollection, has anyone manage to do this?
I don’t want a continuous sync with the database, instead I have a save method that saves the entire structure and a read method that restores the entire method. After an object is restored from the database, the object is sent via interfaces where the receiver expects a ArrayLists and not orm lite ForeignCollections.
My approach is the following. For each ArrayList I have a complementary ForeignCollection. Before storing an object to the database, the content of the ArrayList is copied to the ForeignCollection, and when read back, vice versa.
When I read out a data structure from the database, I want the ensure that the entire structure is restored since later on, the object will be sent to users that are not aware about orm lite package, thus I set eager = true.
My complex datatype looks like this:
#DatabaseTable(tableName = "accounts")
public class Account {
#DatabaseField(generatedId = true)
private int id;
#ForeignCollectionField (eager = true, maxEagerLevel = 2)
private ForeignCollection<Order> ordersFoC;
private ArrayList<Order> ordersArL;
The Problem
Before storing the Account to the database, I tried to do the following. My hope was to copy the objects in the ArrayList to the ForeignCollection and the update the database with the Account object. The object myAccount has the same id as an object in the database so I expect an update of that object.
ordersFoC.addAll(orderArL);
myDao.createOrUpdate(myAccount);
No luck. The addAll method does directly write the orders to the database so I end up with duplicates of all orders since “addAll” adds and does not update any existing records.
So I tried to first remove all the orders from the database, but again with no luck:
ordersFoC.clear(); // Also tried: ordersFoC.removeAll(ordersFoC);
ordersFoC.addAll(orderArL);
myDao.createOrUpdate(myAccount);
The objects are not removed from the database. I read at groups.google.com (by Philip Fu) that this is a “known” problem with ormlite, that eager ForeignCollection does not play well with removeAll() or clear().
Is there a pattern that I have missed that allows me to work with objects that includes ArrayLists of complex types using the ormlite framework?
I've got my code working with ArrayLists ok. I declared my fields like this:
#ForeignCollectionField(eager = true, maxEagerForeignCollectionLevel = 99)
private Collection<PersonalNameStructure> personalnamestructures = new ArrayList<>();
and the getter as
public List<PersonalNameStructure> getPersonalNameStructures() {
return new ArrayList<>(personalnamestructures) ;
}
so it creates the ArrayList on the fly rather than trying to maintain it.
Obviously you may realise this already, but you also need to be careful around writing the objects as the eager setting affects reading foreign collections, it doesn't do anything for foreign fields or when writing a record.
I am taking over a project that was written by third party consultants who have already left.
I come from EF backgournd. One of the DAO class has the following which I find very hard to get my head around on details of what is exactly happening step by step. If anyone could kindly help me to understand this code section will be much appreciated.
return HibernateTemplate.Execute(
delegate(ISession hbSession) // <<--What is this code actually trying to do?
{
string queryText = "from {0} x where x.Code = :Code";
queryText = string.Format(queryText, typeof(Product));
IQuery query = hbSession.CreateQuery(queryText);
query.SetParameter("Code", productCode);
query.SetCacheable(true);
query.SetCacheRegion(CoreCacheConstants.ProductQueryCacheRegion); // <-- What is this code trying to do.
var fund = query.UniqueResult(); // <-- Is this similar to DISTINCT keyword in LINQ?
if (fund == null)
throw new ArgumentException(String.Format("No product found with productcode: {0}", productCode: ));
NHibernateUtil.Initialize(((Product)Product).Details); // <--What is this code trying to do. And where is the execute method for above queries.
return fund;
}
) as Product
Basically I am confused with delegate part and why delegate is being used instead of simple query to database. And what is the benefit of above approach.
Also I cant see any nHibernate ORM mapping xml. Does Spring.NET requires mapping files in order to pass data from/to data source?In order words how does ISession knows which database to connect to and which table to use etc
This is what in the spring documents is referred to as Classic Hibernate Usage. It is not the currently recommended approach to work with NHibernate, which is described in the chapter on object relational mappers.
The "convenient" usage of delegates here is basically done to provide the HibernateTemplate the means to manage a session and hand this managed session over to other custom methods (in this particular case an anonymous method). (I think it's an implementation of the visitor pattern, btw).
Using this approach, the classic HibernateTemplate can provide functionality to methods it doesn't "know of", such as opening and closing sessions correctly and participating in transactions.
The query is actually being executed by HibernateTemplate.Execute(myMethod); I imagine it creates and initializes a session for you, does transaction management, executes your method with the managed session and cleans everything up.
I've never used HibernateTemplate, but I'm sure it would require mapping files and a SessionFactory, so if this code is hit during execution and doesn't throw any exceptions, the configuration for those has to be there somewhere!
With respect to the questions (besides the delegate part) within your posted code: the use of NHibernateTemplate hasn't really got anything to do with it: you can just as well run this code in any piece of code where you've got hold of a valid ISession instance:
the session executes a HQL query; this query is added to the query cache. I've never used SetCacheRegion myself, but apparently it gives you "fine-grained control over query cache expiration policies".
query.UniqueResult
NHibernateUtil.Initialize
I use LinqToEntitiesDomainService class to update database with Silverlight 4 client.
There's AttachAsModified extended method for entity framework ObjectContext which allows you supply original entity property values:
Order original = this.ChangeSet.GetOriginal(currentOrder);
this.ObjectContext.Orders.AttachAsModified(currentOrder, original);
By default, WCF RIA Services doesn't send original values to the server, so one needs to
apply [RoundtripOriginal()] attribute to his/her entity.
However, even if I supply original values, SQL generated by Entity framework updates all columns, not only changed ones. Since AttachAsModified() method isn't native ObjectContext class method (it's extended method defined in ObjectContextExtensions class), I tried to use
ApplyOriginalValues method which is defined in ObjectSet class. No change.
It seems entity framework 4.1, which was released recently may have solution (not sure). How about entity framework 4? Is it possible EF to generate sql to update only changed columns?
AttachAsModified will mark the entity as modified. Subsequently (quote from MSDN):
When you change the EntityState of an
entity object entry to Modified, all
of the properties of the object are
marked as modified, regardless of the
current or original values.
Caveat; I haven't done this but, it should work.
Instead of using AttachAsModified, mark the entity as UnChanged using the ChangeState method.
Then use the SetModifiedProperty method on the properties that have changed to have them included in an update.
EDIT: If you want a way to find which properties have changed, there are a couple of articles out there explaining how to do so using the ObjectStateManager such as this one
I did ask similar question on MSDN forums, and it is confirmed that WCF RIA Services will change all columns. Alternative is,
You can fetch a copy from database, compare and mark SetModifiedProperty manually by using reflection.
// change state of entity as Unmodified/Unchanged...
original.EntityState = Unchanged;
// this is copy form database...
// Use different context
MyOrderContext context = new MyOrderContext();
Order dbOriginal = context.Orders.First( x=>x.OrderID == original.OrderID);
foreach(PropertyInfo p in copy.GetTypes().GetProperties()){
Object originalValue = p.GetValue(dbOriginal);
Object newValue = p.GetValue(original);
if(originalValue!=null && newValue!=null
&& originalValue.Equals(newValue)){
continue;
}
// resetting this will
// make entity's only current
// property as changed
p.SetValue(original,originalValue);
p.SetValue(original,newValue);
}
You may have to change code as per situation, check if property is readonly or not and this is just a sample but it will help you to build upon it.
I managed to do this by first attaching the object and then calling ApplyOriginalValues on the EntitySet. You'll need an object with the original values to do this. This method can also be used to prevent a column from being updated, e.g. for row level security.
NOTE: This unfortunately does not work without retrieving the original entity from the database first. Otherwise only properties that are set to its default value are excluded from the update...
The setup
Some of the "old old old" tables of our database use an exotic primary key generation scheme [1] and I'm trying to overlay this part of the database with NHibernate. This generation scheme is mostly hidden away in a stored procedure called, say, 'ShootMeInTheFace.GetNextSeededId'.
I have written an IIdentifierGenerator that calls this stored proc:
public class LegacyIdentityGenerator : IIdentifierGenerator, IConfigurable
{
// ... snip ...
public object Generate(ISessionImplementor session, object obj)
{
var connection = session.Connection;
using (var command = connection.CreateCommand())
{
SqlParameter param;
session.ConnectionManager.Transaction.Enlist(command);
command.CommandText = "ShootMeInTheFace.GetNextSeededId";
command.CommandType = CommandType.StoredProcedure;
param = command.CreateParameter() as SqlParameter;
param.Direction = ParameterDirection.Input;
param.ParameterName = "#sTableName";
param.SqlDbType = SqlDbType.VarChar;
param.Value = this.table;
command.Parameters.Add(param);
// ... snip ...
command.ExecuteNonQuery();
// ... snip ...
return ((IDataParameter)command
.Parameters["#sTrimmedNewId"]).Value as string);
}
}
The problem
I can map this in the XML mapping files and it works great, BUT....
It doesn't work when NHibernate tries to batch inserts, such as in a cascade, or when the session is not Flush()ed after every call to Save() on a transient entity that depends on this generator.
That's because NHibernate seems to be doing something like
for (each thing that I need to save)
{
[generate its id]
[add it to the batch]
}
[execute the sql in one big batch]
This doesn't work because, since the generator is asking the database every time, NHibernate just ends up getting the same ID generated multiple times, since it hasn't actually saved anything yet.
The other NHibernate generators like IncrementGenerator seem to get around this by asking the database for the seed value once and then incrementing the value in memory during subsequent calls in the same session. I would rather not do this in my implementation if I have to, since all of the code that I need is sitting in the database already, just waiting for me to call it correctly.
Is there a way to make NHibernate actually issue the INSERT after each call to generating an ID for entities of a certain type? Fiddling with the batch size settings don't seem to help.
Do you have any suggestions/other workarounds besides re-implementing the generation code in memory or bolting on some triggers to the legacy database? I guess I could always treat these as "assigned" generators and try to hide that fact somehow within the guts of the domain model....
Thanks for any advice.
The update: 2 months later
It was suggested in the answers below that I use an IPreInsertEventListener to implement this functionality. While this sounds reasonable, there were a few problems with this.
The first problem was that setting the id of an entity to the AssignedGenerator and then not actually assigning anything in code (since I was expecting my new IPreInsertEventListener implementation to do the work) resulted in an exception being thrown by the AssignedGenerator, since its Generate() method essentially does nothing but check to make sure that the id is not null, throwing an exception otherwise. This is worked around easily enough by creating my own IIdentifierGenerator that is like AssignedGenerator without the exception.
The second problem was that returning null from my new IIdentifierGenerator (the one I wrote to overcome the problems with the AssignedGenerator resulted in the innards of NHibernate throwing an exception, complaining that a null id was generated. Okay, fine, I changed my IIdentifierGenerator to return a sentinel string value, say, "NOT-REALLY-THE-REAL-ID", knowing that my IPreInsertEventListener would replace it with the correct value.
The third problem, and the ultimate deal-breaker, was that IPreInsertEventListener runs so late in the process that you need to update both the actual entity object as well as an array of state values that NHibernate uses. Typically this is not a problem and you can just follow Ayende's example. But there are three issues with the id field relating to the IPreInsertEventListeners:
The property is not in the #event.State array but instead in its own Id property.
The Id property does not have a public set accessor.
Updating only the entity but not the Id property results in the "NOT-REALLY-THE-REAL-ID" sentinel value being passed through to the database since the IPreInsertEventListener was unable to insert in the right places.
So my choice at this point was to use reflection to get at that NHibernate property, or to really sit down and say "look, the tool just wasn't meant to be used this way."
So I went back to my original IIdentifierGenreator and made it work for lazy flushes: it got the high value from the database on the first call, and then I re-implemented that ID generation function in C# for subsequent calls, modeling this after the Increment generator:
private string lastGenerated;
public object Generate(ISessionImplementor session, object obj)
{
string identity;
if (this.lastGenerated == null)
{
identity = GetTheValueFromTheDatabase();
}
else
{
identity = GenerateTheNextValueInCode();
}
this.lastGenerated = identity;
return identity;
}
This seems to work fine for a while, but like the increment generator, we might as well call it the TimeBombGenerator. If there are multiple worker processes executing this code in non-serializable transactions, or if there are multiple entities mapped to the same database table (it's an old database, it happened), then we will get multiple instances of this generator with the same lastGenerated seed value, resulting in duplicate identities.
##$##$#.
My solution at this point was to make the generator cache a dictionary of WeakReferences to ISessions and their lastGenerated values. This way, the lastGenerated is effectively local to the lifetime of a particular ISession, not the lifetime of the IIdentifierGenerator, and because I'm holding WeakReferences and culling them out at the beginning of each Generate() call, this won't explode in memory consumption. And since each ISession is going to hit the database table on its first call, we'll get the necessary row locks (assuming we're in a transaction) we need to prevent duplicate identities from happening (and if they do, such as from a phantom row, only the ISession needs to be thrown away, not the entire process).
It is ugly, but more feasible than changing the primary key scheme of a 10-year-old database. FWIW.
[1] If you care to know about the ID generation, you take a substring(len - 2) of all of the values currently in the PK column, cast them to integers and find the max, add one to that number, add all of that number's digits, and append the sum of those digits as a checksum. (If the database has one row containing "1000001", then we would get max 10000, +1 equals 10001, checksum is 02, resulting new PK is "1000102". Don't ask me why.
A potential workaround is to generate and assign the ID in an event listener rather than using an IIdentifierGenerator implementation. The listener should implement IPreInsertEventListener and assign the ID in OnPreInsert.
Why dont you just make private string lastGenerated; static?