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• SQLAlchemy DetachedInstanceError with regular attribute (not a relation)

  - by haridsv

  I just started using SQLAlchemy and get a DetachedInstanceError and can't find much information on this anywhere. I am using the instance outside a session, so it is natural that SQLAlchemy is unable to load any relations if they are not already loaded, however, the attribute I am accessing is not a relation, in fact this object has no relations at all. I found solutions such as eager loading, but I can't apply to this because this is not a relation. I even tried "touching" this attribute before closing the session, but it still doesn't prevent the exception. What could be causing this exception for a non-relational property even after it has been successfully accessed once before? Any help in debugging this issue is appreciated. I will meanwhile try to get a reproducible stand-alone scenario and update here. Update: This is the actual exception message with a few stacks: File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/attributes.py", line 159, in __get__ return self.impl.get(instance_state(instance), instance_dict(instance)) File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/attributes.py", line 377, in get value = callable_(passive=passive) File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/state.py", line 280, in __call__ self.manager.deferred_scalar_loader(self, toload) File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/mapper.py", line 2323, in _load_scalar_attributes (state_str(state))) DetachedInstanceError: Instance <ReportingJob at 0xa41cd8c> is not bound to a Session; attribute refresh operation cannot proceed The partial model looks like this: metadata = MetaData() ModelBase = declarative_base(metadata=metadata) class ReportingJob(ModelBase): __tablename__ = 'reporting_job' job_id = Column(BigInteger, Sequence('job_id_sequence'), primary_key=True) client_id = Column(BigInteger, nullable=True) And the field client_id is what is causing this exception with a usage like the below: Query: jobs = session \ .query(ReportingJob) \ .filter(ReportingJob.job_id == job_id) \ .all() if jobs: # FIXME(Hari): Workaround for the attribute getting lazy-loaded. jobs[0].client_id return jobs[0] This is what triggers the exception later out of the session scope: msg = msg + ", client_id: %s" % job.client_id

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• Entity Framework Custom Query Function

  - by Josh

  I have an Entity Framework 4.0 Entity Object called Revision w/ Nullable DateEffectiveFrom and DateEffectiveTo dates. I was wondering if there was a short-hand way of querying an object's RevisionHistory based on a particular QueryDate date instead of having to use the following query structure: var results = EntityObject.Revisions.Where(x => (x.DateEffectiveFrom == null && x.DateEffectiveTo == null) || (x.DateEffectiveFrom == null && x.DateEffectiveTo >= QueryDate) || (x.DateEffectiveFrom <= QueryDate && x.DateEffectiveTo == null) || (x.DateEffectiveFrom <= QueryDate && x.DateEffectiveTo >= QueryDate)); I've tried creating the following boolean function in the Revision class: partial class Revision { public bool IsEffectiveOn(DateTime date) { return (x.DateEffectiveFrom == null && x.DateEffectiveTo == null) || (x.DateEffectiveFrom == null && x.DateEffectiveTo >= date) || (x.DateEffectiveFrom <= date && x.DateEffectiveTo == null) || (x.DateEffectiveFrom <= date && x.DateEffectiveTo >= date)); } ... } And then updating the query to: var results = EntityObject.Revisions.Where(x => x.IsEffectiveOn(QueryDate)); but this obviously doesn't translate to SQL. Any ideas would be much appreciated.

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• toString method for varargs contructor

  - by owca

  I have a varargs contructor like this : public class Sentence { public String[] str; public Sentence(Object... text){ StringBuilder sb = new StringBuilder(); for (Object o : text) { sb.append(o.toString()) .append(" "); } System.out.println(sb.toString()); } } Contructor can get various types of data (ints, strings, and Sentence objects as well). How to do a proper toString method for such class ?

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• Hibernate triggering constraint violations using orphanRemoval

  - by ptomli

  I'm having trouble with a JPA/Hibernate (3.5.3) setup, where I have an entity, an "Account" class, which has a list of child entities, "Contact" instances. I'm trying to be able to add/remove instances of Contact into a List<Contact> property of Account. Adding a new instance into the set and calling saveOrUpdate(account) persists everything lovely. If I then choose to remove the contact from the list and again call saveOrUpdate, the SQL Hibernate seems to produce involves setting the account_id column to null, which violates a database constraint. What am I doing wrong? The code below is clearly a simplified abstract but I think it covers the problem as I'm seeing the same results in different code, which really is about this simple. SQL: CREATE TABLE account ( INT account_id ); CREATE TABLE contact ( INT contact_id, INT account_id REFERENCES account (account_id) ); Java: @Entity class Account { @Id @Column public Long id; @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true) @JoinColumn(name = "account_id") public List<Contact> contacts; } @Entity class Contact { @Id @Column public Long id; @ManyToOne(optional = false) @JoinColumn(name = "account_id", nullable = false) public Account account; } Account account = new Account(); Contact contact = new Contact(); account.contacts.add(contact); saveOrUpdate(account); // some time later, like another servlet request.... account.contacts.remove(contact); saveOrUpdate(account); Result: UPDATE contact SET account_id = null WHERE contact_id = ? Edit #1: It might be that this is actually a bug http://opensource.atlassian.com/projects/hibernate/browse/HHH-5091

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• Java Date vs Calendar

  - by Marty Pitt

  Could someone please advise the current "best practice" around Date and Calendar types. When writing new code, is it best to always favour Calendar over Date, or are there circumstances where Date is the more appropriate datatype?

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• new line in a multi-line string

  - by Zka

  Trying to override a tostring in one of my classes. return string.Format(@" name = {0} ID = {1} sec nr = {2} acc nr = {3}", string, int, int ,int); // types But the thing is, the result isn't aligned when printed out: name = test ID = 42 sec nr = 11 acc nr = 55 Trying to add \n just prints it out without formating. Guessing it has something to do with @"" which I'm using for multi-lining. Would like it to print out : name = test ID = 42 sec nr = 11 acc nr = 55

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• Elegantly handling constraint violations in EJB/JPA environment?

  - by hallidave

  I'm working with EJB and JPA on a Glassfish v3 app server. I have an Entity class where I'm forcing one of the fields to be unique with a @Column annotation. @Entity public class MyEntity implements Serializable { private String uniqueName; public MyEntity() { } @Column(unique = true, nullable = false) public String getUniqueName() { return uniqueName; } public void setUniqueName(String uniqueName) { this.uniqueName = uniqueName; } } When I try to persist an object with this field set to a non-unique value I get an exception (as expected) when the transaction managed by the EJB container commits. I have two problems I'd like to solve: 1) The exception I get is the unhelpful "javax.ejb.EJBException: Transaction aborted". If I recursively call getCause() enough times, I eventually reach the more useful "java.sql.SQLIntegrityConstraintViolationException", but this exception is part of the EclipseLink implementation and I'm not really comfortable relying on it's existence. Is there a better way to get detailed error information with JPA? 2) The EJB container insists on logging this error even though I catch it and handle it. Is there a better way to handle this error which will stop Glassfish from cluttering up my logs with useless exception information? Thanks.

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• TypeConverters on the compact framework

  - by Rowland Shaw

  I'm working on a compact framework project and whilst most of the properties are fairly straight forward (I.e. mark them as browsable in the xmta file), I'm struggling to get this to work for more complex types - on the full framework, I'd just implement a custom TypeConverter and go from there, but it seems the CF TypeConverter doesn't have any of the type converting methods to override, which has left me a little stuck? It probably should be blindingly obvious but how would I go about supporting design time property support for more complex type?

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• Good Name for a Music Player (like Spotify)

  - by LnDCobra

  I can't think of anywhere else to ask therefore I thought asking here would be the ideal place. Reason I'm asking is because for my Dissertation in my report I pretty much got told my name sucks. I ain't going to argue as its just "My Music Player" so any suggestions would be highly appreciated! I know it's pretty subjective but ANY help would be appreciated! I am not of the creative types of people :(

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• Get script of SQL Server data

  - by Jared

  I'm looking for a way to do something analogous to the MySql dump from SQL Server. I need to be able to pick the tables and export the schema and the data (or I can export the schema via SQL Server Management Studio and export the data separately somehow). I need this data to be able to turn around and go back into SQL Server so it needs to maintain GUIDs/uniqueidentifiers and other column types. Does anyone know of a good tool for this?

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• XQuery vs XSLT for transfroming data

  - by metdos

  Which one of them do you use in your applications in order to transform XML data to other data types? WHY?

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• EnvDTE Retrieving the data type from a CodeElement

  - by chrischu

  I am using EnvDTE to generate some code in my latest project. I have a reference to a CodeClass-Object for a given C#-Class but now I wanted to loop through all of its members (in codeClass.Members) and check their types. However I can't manage to retrieve the type of the given member from the CodeElement-Object that I get when looping through codeClass.Members. How can I retrieve the type (int, string etc.)? PS: Reflection is not an option for my usecase.

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• What is your custom exception hierrarchy?

  - by bonefisher

  My question is: how would you create exception hierarchy in your application? Designing the architecture of an application, from my perspective, we could have three types of exceptions: the built-in (e.g.: InvalidOperationException) custom internal system faults (DB transaction failed on commit, DbTransactionFailedException) custom business exceptions (BusinessRuleViolationException) Class hierarchy: Exception MyAppInternalException DbTransactionFailedException MyServerTimeoutException ... MyAppBusinessRuleViolationException UsernameAlreadyExistsException ... where only MyAppInternalException & MyAppBusinessRuleViolationException would be catched.

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• Pie, Bar, Line charts in java?

  - by Mandar

  I want to use Pie, Bar, Line charts in java. What is the best API to use them? Is there any API by Sun to create these types of charts?

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• Generics and collections ... struggling with an implementation

  - by mattruma

  I am trying to figure out a way to leverage generics so I can make the property Value be an actual type that initialized (not sure if this is the correct way of saying it) when my collection class is created. I would like to have the syntax be something like: var list = new ListItemCollection<Guid>(parameters would go here); I have the following class: [Serializable] public class ListItem { public object Value { get; set; } public string Text { get; set; } public object DataContext { get; set; } public Nullable<bool> Checked { get; set; } public ListItem() { this.Checked = false; } } I have the following collection: [Serializable] public class ListItemCollection : List<ListItem> { public ListItem this[object value] { get { foreach (var child in this) { if (child.Value.Equals(value)) return child; } return null; } } public bool Contains(object value) { foreach (var child in this) { if (child.Value.Equals(value)) return true; } return false; } public void Add(object value, string text) { this.Add(value, text, null); } public void Add(object value, string text, object dataContext) { var child = new ListItem(); child.Value = value; child.Text = text; child.DataContext = dataContext; this.Add(child); } public ListItemCollection() { } public ListItemCollection(IEnumerable items, string displayMember, string valueMember, bool showEmptyItem, string emptyItemText, object emptyItemValue) { if (showEmptyItem) { this.Add(emptyItemValue, emptyItemText); } foreach (object item in items) { object text = null; object value = null; text = item.GetType().GetProperty(displayMember).GetValue(item, null); value = item.GetType().GetProperty(valueMember).GetValue(item, null); // Add the item this.Add(value, text.ToString(), item); } } }

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• Visual Studio 'SQL Server 2008 Server Project' vs. 'Sql Server 2008 Database project' ?

  - by user193189

  I can't see to find a quick explanation of the differences so I can figure out which to use. One is for a server one is for a Database? Im not sure what that means.. Basically we are doing a new web app and I want to see what these project types can offer me in terms of tracking the DB code/schema etc..

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• Loading a Reusable UITableViewCell from a Nib

  - by Greg Martin

  I am able to design custom UITableViewCells and load them just fine using the technique described in the thread found at http://forums.macrumors.com/showthread.php?t=545061. However, using that method no longer allows you to init the cell with a reuseIdentifier which means you have to create whole new instances of each cell at every call. Has anyone figured out a good way to still cache particular cell types for reuses, but still be able to design them in Interface Builder?

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• SQL Server backward compatibility in Entity Framework?

  - by shake

  Is there any backward compatibility in the entity framework between SQL Server 2008 and 2005? It seems the framework forces you to use the same provider for all the .edmx files in a solution. If you use the 2008 provider, data types like DateTime2 and functions like SysDateTime that are emitted by the framework to the underlying SQL query make it useless to use them against a SQL 2005 Server. Any way around this?

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• What is common architecture of notification system on the web-forum, PMB and etc.?

  - by glaz666

  What I need is - list of new stuff from last visit - when user has already checked out some new entity since his last visit (ex. post on forum), mark this entity as read in the list - count different types of entities - private messages, posts, comments and etc. There are lot of websites using this technique for private messaging, listing new stuff and etc (ex. phpBB, this one and etc). Are there any common pattern, description of the system core which will events, making lists?

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• Problem getting correct parameters for C# P/Invoke call to C++ dll

  - by Jim Jones

  Trying to Interop a functionality from the Outside In API from Oracle. Have the following function: SCCERR EXOpenExport {VTHDOC hDoc, VTDWORD dwOutputId, VTDWORD dwSpecType, VTLPVOID pSpec, VTDWORD dwFlags, VTSYSPARAM dwReserved, VTLPVOID pCallbackFunc, VTSYSPARAM dwCallbackData, VTLPHEXPORT phExport); From the header files I reduced the parameters to: typedef VTSYSPARAM VTHDOC, VTLPHDOC * typedef DWORD_PTR VTSYSPARAM typedef unsigned long DWORD_PTR typedef unsigned long VTDWORD typedef VTVOID* VTLPVOID #define VTVOID void typedef VTHDOC VTHEXPORT, *VTLPEXPORT These are for 32 bit windows Going through the header files, the example programs, and the documentation I found: 1. That pSpec could be a pointer to a buffer or NULL, so I set it to a IntPtr.Zero (documentation). 2. That dwFlags and dwReserved according to the documentation "Must be set by the developer to 0". 3. That pCallbackFunc can be set to NULL if I don't want to handle callbacks. 4. That the last two are based on structs that I wrote C# wrappers for using the [StructLayout(LayoutKind.Sequential)]. Then instatiated an instance and generated the parameters by first creating a IntPtr with Marshal.AllocHGlobal(Marshal.SizeOf(instance)), then getting the address value which is passed as a uint for dwCallbackData and a IntPtr for phExport. The final parameter list is as follows: 1. phDoc as a IntPtr which was loaded with an address by the DAOpenDocument function called before. 2. dwOutputId as uint set to 1535 which represents FI_JPEGFIF 3. dwSpecType as int set to 2 which represents IOTYPE_ANSIPATH 4. pSpec as an IntPtr.Zero where the output will be written 5. dwFlags as uint set to 0 as directed 6. dwReserved as uint set to 0 as directed 7. pCallbackFunc as IntPtr set to NULL as I will handle results 8. dwCallBackDate as uint the address of a buffer for a struct 9. phExport as IntPtr to another struct buffer still get an undefined error from the API. Meaning that the call returns a 961 which is not defined in any of the header files. In the past I have gotten this when my choice of parameter types are incorrect. I started out using Interop Assistant which was helpful in learning how many of the parameter types get translated. It is however limited by how well I am able to glean the correct native type from the header files. For example the hDoc parameter used in the preceding function was defined as a non-filesytem handle, so attempted to use Marshal to create a handle, then used an IntPtr, and finally it turned out to be an int (actually it was &phDoc used here). So is there a more scientific way of doing this, other than trial and error? Jim

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• Creating a comma separated list from IList<string> or IEnumerable<string>

  - by Daniel Fortunov

  What is the cleanest way to create a comma-separated list of string values from an IList<string> or IEnumerable<string>? String.Join(...) operates on a string[] so can be cumbersome to work with when types such as IList<string> or IEnumerable<string> cannot easily be converted into a string array.

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• Best approach for coding ?

  - by ahmed

  What should or how should I decide the best approach for coding as a smart programmer. I have just started programming last year in VB, and I keep on listening this statement. But I never could find by myself to choose the best approach for coding. When I search for a coding example on internet I find different types of approach to achieve the same target. So help me finding the best approach. (asp.net,vb.net)

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• Scala 2.8: _ behaviour changed?

  - by Alexey Romanov

  Using XScalaWT, this compiled under Scala 2.7: class NodeView(parent: Composite) extends Composite(parent) { var nodeName: Label = null this.contains( label( nodeName = _ ) ) } With 2.8.0 RC1, I get this error: type mismatch; found : main.scala.NodeView required: org.eclipse.swt.widgets.Label The types are: label(setups: (Label => Unit)*)(parent: Composite) : Label contains(setups: (W => Unit)*) : W So it looks like _ now binds to the outer function instead of inner. Is this change intentional?

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• Linq to object - Select Distinct

  - by Ben

  Hi, I can't quite figure out why this Linq Statement isn't working as i would expect: Dim distinctSurchargesList = (From thisparent As Parent In ThisParentCollection _ From thisChild As Child In thisparent.theseChildren _ Select New With {.childId = thischild.Id}).Distinct() I would assume that this would create a new collection of anonymous types, that would be distinct. Instead it creates a collection the size of the "ThisParentCollection" with duplicate "MyAnonymousType" in it (duplicate id's). Can anyone tell me where im going wrong? Thanks

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• Can CancellationTokens be used across AppDomains

  - by Daniel Plaisted

  .NET 4 introduced some types to nicely support cooperative cancellation. I would like to be able to cancel an operation which is running in a different AppDomain. The CancellationToken type is a struct. If I pass it to another AppDomain, will it work as normal?

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