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  • JPA ManyToMany referencing issue

    - by dharga
    I have three tables. AvailableOptions and PlanTypeRef with a ManyToMany association table called AvailOptionPlanTypeAssoc. The trimmed down schemas look like this CREATE TABLE [dbo].[AvailableOptions]( [SourceApplication] [char](8) NOT NULL, [OptionId] [int] IDENTITY(1,1) NOT NULL, ... ) CREATE TABLE [dbo].[AvailOptionPlanTypeAssoc]( [SourceApplication] [char](8) NOT NULL, [OptionId] [int] NOT NULL, [PlanTypeCd] [char](2) NOT NULL, ) CREATE TABLE [dbo].[PlanTypeRef]( [PlanTypeCd] [char](2) NOT NULL, [PlanTypeDesc] [varchar](32) NOT NULL, ) And the Java code looks like this. //AvailableOption.java @ManyToMany(cascade={CascadeType.ALL}, fetch=FetchType.EAGER) @JoinTable( name = "AvailOptionPlanTypeAssoc", joinColumns = { @JoinColumn(name = "OptionId"), @JoinColumn(name="SourceApplication")}, inverseJoinColumns=@JoinColumn(name="PlanTypeCd")) List<PlanType> planTypes = new ArrayList<PlanType>(); //PlanType.java @ManyToMany @JoinTable( name = "AvailOptionPlanTypeAssoc", joinColumns = { @JoinColumn(name = "PlanTypeCd")}, inverseJoinColumns={@JoinColumn(name="OptionId"), @JoinColumn(name="SourceApplication")}) List<AvailableOption> options = new ArrayList<AvailableOption>(); The problem arises when making a select on AvailableOptions it joins back onto itself. Note the following SQL code from the backtrace. The second inner join should be on PlanTypeRef. SELECT t0.OptionId, t0.SourceApplication, t2.PlanTypeCd, t2.EffectiveDate, t2.PlanTypeDesc, t2.SysLstTrxDtm, t2.SysLstUpdtUserId, t2.TermDate FROM dbo.AvailableOptions t0 INNER JOIN dbo.AvailOptionPlanTypeAssoc t1 ON t0.OptionId = t1.OptionId AND t0.SourceApplication = t1.SourceApplication INNER JOIN dbo.AvailableOptions t2 ON t1.PlanTypeCd = t2.PlanTypeCd WHERE (t0.SourceApplication = ? AND t0.OptionType = ?) ORDER BY t0.OptionId ASC, t0.SourceApplication ASC [params=(String) testApp, (String) junit0]}

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  • Map enum in JPA with fixed values ?

    - by Kartoch
    I'm looking for the different ways to map an enum using JPA. I especially want to set the integer value of each enum entry and to save only the integer value. @Entity @Table(name = "AUTHORITY_") public class Authority implements Serializable { public enum Right { READ(100), WRITE(200), EDITOR (300); private int value; Right(int value) { this.value = value; } public int getValue() { return value; } }; @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "AUTHORITY_ID") private Long id; // the enum to map : private Right right; } A simple solution is to use the Enumerated annotation with EnumType.ORDINAL: @Column(name = "RIGHT") @Enumerated(EnumType.ORDINAL) private Right right; But in this case JPA maps the enum index (0,1,2) and not the value I want (100,200,300). Th two solutions I found do not seem simple... First Solution A solution, proposed here, uses @PrePersist and @PostLoad to convert the enum to an other field and mark the enum field as transient: @Basic private int intValueForAnEnum; @PrePersist void populateDBFields() { intValueForAnEnum = right.getValue(); } @PostLoad void populateTransientFields() { right = Right.valueOf(intValueForAnEnum); } Second Solution The second solution proposed here proposed a generic conversion object, but still seems heavy and hibernate-oriented (@Type doesn't seem to exist in JEE): @Type( type = "org.appfuse.tutorial.commons.hibernate.GenericEnumUserType", parameters = { @Parameter( name = "enumClass", value = "Authority$Right"), @Parameter( name = "identifierMethod", value = "toInt"), @Parameter( name = "valueOfMethod", value = "fromInt") } ) Is there any other solutions ? I've several ideas in mind but I don't know if they exist in JPA: use the setter and getter methods of right member of Authority Class when loading and saving the Authority object an equivalent idea would be to tell JPA what are the methods of Right enum to convert enum to int and int to enum Because I'm using Spring, is there any way to tell JPA to use a specific converter (RightEditor) ?

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  • Hibernate - query caching/second level cache does not work by value object containing subitems

    - by Zoltan Hamori
    Hi! I have been struggling with the following problem: I have a value object containing different panels. Each panel has a list of fields. Mapping: <class name="com.aviseurope.core.application.RACountryPanels" table="CTRY" schema="DBDEV1A" where="PEARL_CTRY='Y'" lazy="join"> <cache usage="read-only"/> <id name="ctryCode"> <column name="CTRY_CD_ID" sql-type="VARCHAR2(2)" not-null="true"/> </id> <bag name="panelPE" table="RA_COUNTRY_MAPPING" fetch="join" where="MANDATORY_FLAG!='N'"> <key column="COUNTRY_LOCATION_ID"/> <many-to-many class="com.aviseurope.core.application.RAFieldVO" column="RA_FIELD_MID" where="PANEL_ID='PE'"/> </bag> </class> I use the following criteria to get the value object: Session m_Session = HibernateUtil.currentSession(); m_Criteria = m_Session.createCriteria(RACountryPanels.class); m_Criteria.add(Expression.eq("ctryCode", p_Country)); m_Criteria.setCacheable(true); As I see the query cache contains only the main select like select * from CTRY where ctry_cd_id=? Both RACountryPanels and RAFieldVO are second level cached. If I check the 2nd level cache content I can see that it cointains the RAFields and the RACountryPanels as well and I can see the select .. from CTRY where ctry_cd_id=... in query cache region as well. When I call the servlet it seems that it is using the cache, but second time not. If I check the content of the cache using JMX, everything seems to be ok, but when I measure the object access time, it seems that it does not always use the cache. Cheers Zoltan

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  • What's best practice to check if an object is part of a ManyToMany relationship in Django

    - by PhilGo20
    from an instance of Site with a ManyToMany relationship to Kiosk, i'd like to check if a Kiosk object is part of the relationship. I could do self.apps.get(id=app_id).exists() and check if True or self.apps.get(id=app_id) and catch the ObjectDoesNotExist error or self.apps.filter(id=app_id) and check if True If I have to catch a possible ObjectDoesNotExist error, I may as well use the second one I can do the second but doesnt seem super clean can use the third one but using filter on a unique ID seems wrong to me You can tell me to use whatever works and that'll be a valid answer ;-)

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  • When is lazy evaluation not useful?

    - by Cherian
    Delay execution is almost always a boon. But then there are cases when it’s a problem and you resort to “fetch” (in Nhibernate) to eager fetch it. Do you know practical situations when lazy evaluation can bite you back…?

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  • Embed a Python persistance layer into a C++ application - good idea?

    - by Rickard
    say I'm about to write an application with a thin GUI layer, a really fat calculation layer (doing computationally heavy calibrations and other long-running stuff) and fairly simple persistance layer. I'm looking at building the GUI + calculation layer in C++ (using Qt for the gui parts). Now - would it be a crazy idea to build the persistance layer in Python, using sqlalchemy, and embed it into the C++ application, letting the layers interface with eachother through lightweigth data transfer objects (written in C++ but accessible from python)? (the other alternative I'm leaning towards would probably be to write the app in Python from the start, using the PyQt wrapper, and then calling into C++ for the computational tasks) Thanks, Rickard

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  • JPA Cascade delete.

    - by Win Man
    Hi, I am new to JPA/Hibernate. Currently using EJB3, Hibernate/JPA. I have an inheritacnce structure as follows.. @Entity @DiscriminatorColumn(name = "form_type") @Inheritance(strategy = InheritanceType.JOINED) @GenericGenerator(name = "FORMS_SEQ", strategy = "sequence-identity", parameters = @Parameter(name = "sequence", value = "FORMS_SEQ")) @Table(name = "Forms") public abstract class Form{ //code for Form } @Entity @Table(name = "CREDIT_CARDS") @PrimaryKeyJoinColumn(name="CREDIT_CARD_ID") public class CreditCardForm extends Form { //Code for CreditCards. } When I add a row with save the rows are properly inserted into the parent and the child table. However when I try to delete I get an error - 10:19:35,465 ERROR [TxPolicy] javax.ejb.EJBTransactionRolledbackException: Removing a detached instance com.data.entities.form.financial.CreditCard#159? I am using a simple for loop to determine the inheritance type - CreditCard or DebitCard and then calling entityManager.remove(entity). What am I doing wrong? Code for delete.. for(Form content: contents){ if(content.getType()==Type.CREDIT_CARD){ creditCardService.delete((CreditCard)content); } Thanks. WM

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  • Django queries: Count number of objects with FK to model instance

    - by Chris Lawlor
    This should be easy but for some reason I'm having trouble finding it. I have the following: App(models.Model): ... Release(models.Model): date = models.DateTimeField() App = models.ForeignKey(App) ... How can I query for all App objects that have at least one Release? I started typing: App.objects.all().annotate(release_count=Count('??????')).filter(release_count__gt=0) Which won't work because Count doesn't span relationships, at least as far as I can tell. BONUS: Ultimately, I'd also like to be able to sort Apps by latest release date. I'm thinking of caching the latest release date in the app to make this a little easier (and cheaper), and updating it in the Release model's save method, unless of course there is a better way. Edit: I'm using Django 1.1 - not averse to migrating to dev in anticipation of 1.2 if there is a compelling reason though.

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  • error : java.lang.String cannot be cast to coldfusion.cfc.CFCBeanProxy anyone know about this ?

    - by faheem
    Hi does anyone know about this error I get when I try to insert a foreign key value in my entry entity using cf9 Hibernate ? java.lang.ClassCastException: java.lang.String cannot be cast to coldfusion.cfc.CFCBeanProxy Root cause :org.hibernate.HibernateException: java.lang.ClassCastException: java.lang.String cannot be cast to coldfusion.cfc.CFCBeanProxy Below is the code for my entity object and then for my user object.. Is there anything wrong with this ? entry.cfc /** * Entries Object */ component output="false" persistent="true"{ property name="entry_id" fieldType="id" generator="uuid"; property name="entryBody" ormType="text"; property name="title" notnull="true" type="string"; property name="time" fieldtype="timestamp"; property name="isCompleted" ormType="boolean" dbdefault="0" default="false"; property name="userID" fieldtype="many-to-one" fkcolumn="userID" cfc="user"; Entry function init() output=false{ return this; } } user.cfc /** * Users Object */ component output="false" persistent="true"{ property name="userID" fieldType="id" generator="uuid"; property name="firstName" notnull="true" type="string"; property name="lastName" notnull="true" type="string"; property name="password" notnull="true" type="string"; property name="userType" notnull="true" type="string"; //property name="entry" fieldtype="one-to-many" type="array" fkcolumn="userID" cfc="entry"; User function init() output=false{ return this; } }

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  • SqlMetal, Sql Server 2008 database, Table with HierachyID, dal cs file is created sometimes ?

    - by judek.mp
    I have 2 databases with a 2 tables with HierachyID fields. For one database I can get a dal cs file, for the other database I cannot get a dal cs file ? HBus is a database I can get the dal cs for, ... SqlMetal /server:.\SQLSERVER2008 /database:HBus /code:HBusDC.cs /views /functions /sprocs /namespace:HBusDC /context:HBusDataContext This kicks me out a file, ... which works, but excludes the HierarchyID field for the table and includes all other fields for that table. This is OK I do not mind. The above cmd line kicks out an warning but still produces a file, like so SqlMetal /server:.\SQLSERVER2008 /database:HBus /code:HBusDC.cs /views /functions /sprocs /namespace:HBusDC /context:HBusDataContext Microsoft (R) Database Mapping Generator 2008 version 1.00.30729 for Microsoft (R) .NET Framework version 3.5 Copyright (C) Microsoft Corporation. All rights reserved. Warning : SQM1021: Unable to extract column 'OrgNode' of Table 'dbo.HMsg' from SqlServer because the column's DbType is a user-defined type (UDT). Warning : SQM1021: Unable to extract column 'OrgNode' of Table 'dbo.vwHMsg' from SqlServer because the column's DbType is a user-defined type (UDT). HMsg is a table with a HierarchyID field. I have another database, Elf, almost the same thing but I get a warning and an Error when using sql metal and I do not get a dal cs file ... SqlMetal /server:.\SQLSERVER2008 /database:Elf /code:ElfDataContextDal.cs /views /functions /sprocs /namespace:HBusDC /context:HBusDataContext An error as well as the warning and the cs file fails to appear on my disc, ... :-( SqlMetal /server:.\SQLSERVER2008 /database:Elf /code:ElfDataContextDal.cs /views /functions /sprocs /namespace:HBusDC /context:HBusDataContext Microsoft (R) Database Mapping Generator 2008 version 1.00.30729 for Microsoft (R) .NET Framework version 3.5 Copyright (C) Microsoft Corporation. All rights reserved. Warning : SQM1021: Unable to extract column 'OrgNode' of Table 'dbo.EntityLink' from SqlServer because the column's DbType is a user-defined type (UDT). Error : Requested value 'ELF.SYS.HIERARCHYID' was not found. The fields are declared the same way in Elf db OrgNode [HierarchyID] null , in HBus db ... OrgNode [HierarchyID] null , Both databases are in the same instance of sql server 2008, so the HierarchyID is an inbuilt type, neither db has HierarchyID udt ,... cheers in advance for any replies ...

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  • How to I create an HQL query to return objects in a many to many relationship?

    - by Dave
    Hi there. I have an application that includes 2 classes Club and Article. These are mapped in Hibernate as a many to many relationship. As a result, hibernate has created a table called CLUB_ARTICLE which it uses to manage the many to many relation ship. The CLUB and ARTILCE tables have no direct reference to each other and the mapping is only represented in the CLUB_ARTICLE table. I need to create an HQL query that returns a list of articles for a particlular club. So I need to supply the club id and get back a list of Article objects that belong to it. For some reason, I just can't work out how to do this. Any help would be very much appriciated! Thanks.

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  • Why is Perl's Math::Complex taking up so much time when I try acos(1)?

    - by synapz
    While trying to profile my Perl program, I find that Math::Complex is taking up a lot of time with what looks like some kind of warning. Also, my code shouldn't have any complex numbers being generated or used, so I am not sure what it is doing in Math::Complex, anyway. Here's the FastProf output for the most expensive lines: /usr/lib/perl5/5.8.8/Math/Complex.pm:182 1.55480 276232: _cannot_make("real part", $re) unless $re =~ /^$gre$/; /usr/lib/perl5/5.8.8/Math/Complex.pm:310 1.01132 453641: sub cartesian {$_[0]->{c_dirty} ? /usr/lib/perl5/5.8.8/Math/Complex.pm:315 0.97497 562188: sub set_cartesian { $_[0]->{p_dirty}++; $_[0]->{c_dirty} = 0; /usr/lib/perl5/5.8.8/Math/Complex.pm:189 0.86302 276232: return $self; /usr/lib/perl5/5.8.8/Math/Complex.pm:1332 0.85628 293660: $self->{display_format} = { %display_format }; /usr/lib/perl5/5.8.8/Math/Complex.pm:185 0.81529 276232: _cannot_make("imaginary part", $im) unless $im =~ /^$gre$/; /usr/lib/perl5/5.8.8/Math/Complex.pm:1316 0.78749 293660: my %display_format = %DISPLAY_FORMAT; /usr/lib/perl5/5.8.8/Math/Complex.pm:1335 0.69534 293660: %{$self->{display_format}} : /usr/lib/perl5/5.8.8/Math/Complex.pm:186 0.66697 276232: $self->set_cartesian([$re, $im ]); /usr/lib/perl5/5.8.8/Math/Complex.pm:170 0.62790 276232: my $self = bless {}, shift; /usr/lib/perl5/5.8.8/Math/Complex.pm:172 0.56733 276232: if (@_ == 0) { /usr/lib/perl5/5.8.8/Math/Complex.pm:316 0.53179 281094: $_[0]->{'cartesian'} = $_[1] } /usr/lib/perl5/5.8.8/Math/Complex.pm:1324 0.48768 293660: if (@_ == 1) { /usr/lib/perl5/5.8.8/Math/Complex.pm:1319 0.44835 293660: if (exists $self->{display_format}) { /usr/lib/perl5/5.8.8/Math/Complex.pm:1318 0.40355 293660: if (ref $self) { # Called as an object method /usr/lib/perl5/5.8.8/Math/Complex.pm:187 0.39950 276232: $self->display_format('cartesian'); /usr/lib/perl5/5.8.8/Math/Complex.pm:1315 0.39312 293660: my $self = shift; /usr/lib/perl5/5.8.8/Math/Complex.pm:1331 0.38087 293660: if (ref $self) { # Called as an object method /usr/lib/perl5/5.8.8/Math/Complex.pm:184 0.35171 276232: $im ||= 0; /usr/lib/perl5/5.8.8/Math/Complex.pm:181 0.34145 276232: if (defined $re) { /usr/lib/perl5/5.8.8/Math/Complex.pm:171 0.33492 276232: my ($re, $im); /usr/lib/perl5/5.8.8/Math/Complex.pm:390 0.20658 128280: my ($z1, $z2, $regular) = @_; /usr/lib/perl5/5.8.8/Math/Complex.pm:391 0.20631 128280: if ($z1->{p_dirty} == 0 and ref $z2 and $z2->{p_dirty} == 0) { Thanks for any help!

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  • Use of Hibernate 3.0 with EJB 3.0 & JPA

    - by SOA Nerd
    Where I'm working the guys that are sitting across from me are working on a project. This is a JavaEE app which uses Struts, Spring, EJB 3.0, JPA, and Hibernate 3.0. They are using EJB 3.0 entity beans with annotations. I've been asking them why Hibernate 3.0 is in this mix and noone can seem to tell me. It feels like they've included Hibernate 3.0 because they were told to but are not using it for anything that they can't get from EJB 3.0 entity beans/JPA. They're using CMP and accessing all of the database functions via EJBs. Can Hibernate give you anything in this setup that can't be provided by EJB 3.0/JPA?

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  • Eclipse plugins for Spring / Hibernate development?

    - by es11
    I have a running dynamic web project in Eclipse (Java EE + Maven + Spring). I am at the point where I need to integrate a persistence layer and want to use Hibernate with a mySql database. I am wonder what plugins would be useful for me at this point? For Hibernate should I install hibernate tools or is it not necessary? Are then any plugins that are most widely use for connecting / exploring database connections that would be appropriate for the type of project I am working on? Thanks.

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  • Attching a Behaviour to a dynamically created table in Doctrine

    - by Cesare Contini
    How do I programmatically attach a Doctrine Behaviour programmatically to a table dynamically created through $conn->export->createTable('MyTable', $definition)? For example, if I have the following code: $definition = array( 'id' => array( 'type' => 'integer', 'primary' => true, 'autoincrement' => true ), 'name' => array( 'type' => 'string', 'length' => 255 ) ); $conn->export->createTable('MyTable', $definition) ; At this point I would need to attach a doctrine typical behaviour like Timestampable or Versionable to the newly created 'MyTable' table. Is it possible at all?

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  • Persistence classes in Qt

    - by zarzych
    Hi, I'm porting a medium-sized CRUD application from .Net to Qt and I'm looking for a pattern for creating persistence classes. In .Net I usually created abstract persistence class with basic methods (insert, update, delete, select) for example: public class DAOBase<T> { public T GetByPrimaryKey(object primaryKey) {...} public void DeleteByPrimaryKey(object primaryKey) {...} public List<T> GetByField(string fieldName, object value) {...} public void Insert(T dto) {...} public void Update(T dto) {...} } Then, I subclassed it for specific tables/DTOs and added attributes for DB table layout: [DBTable("note", "note_id", NpgsqlTypes.NpgsqlDbType.Integer)] [DbField("note_id", NpgsqlTypes.NpgsqlDbType.Integer, "NoteId")] [DbField("client_id", NpgsqlTypes.NpgsqlDbType.Integer, "ClientId")] [DbField("title", NpgsqlTypes.NpgsqlDbType.Text, "Title", "")] [DbField("body", NpgsqlTypes.NpgsqlDbType.Text, "Body", "")] [DbField("date_added", NpgsqlTypes.NpgsqlDbType.Date, "DateAdded")] class NoteDAO : DAOBase<NoteDTO> { } Thanks to .Net reflection system I was able to achieve heavy code reuse and easy creation of new ORMs. The simplest way to do this kind of stuff in Qt seems to be using model classes from QtSql module. Unfortunately, in my case they provide too abstract an interface. I need at least transactions support and control over individual commits which QSqlTableModel doesn't provide. Could you give me some hints about solving this problem using Qt or point me to some reference materials? Update: Based on Harald's clues I've implemented a solution that is quite similar to the .Net classes above. Now I have two classes. UniversalDAO that inherits QObject and deals with QObject DTOs using metatype system: class UniversalDAO : public QObject { Q_OBJECT public: UniversalDAO(QSqlDatabase dataBase, QObject *parent = 0); virtual ~UniversalDAO(); void insert(const QObject &dto); void update(const QObject &dto); void remove(const QObject &dto); void getByPrimaryKey(QObject &dto, const QVariant &key); }; And a generic SpecializedDAO that casts data obtained from UniversalDAO to appropriate type: template<class DTO> class SpecializedDAO { public: SpecializedDAO(UniversalDAO *universalDao) virtual ~SpecializedDAO() {} DTO defaultDto() const { return DTO; } void insert(DTO dto) { dao->insert(dto); } void update(DTO dto) { dao->update(dto); } void remove(DTO dto) { dao->remove(dto); } DTO getByPrimaryKey(const QVariant &key); }; Using the above, I declare the concrete DAO class as following: class ClientDAO : public QObject, public SpecializedDAO<ClientDTO> { Q_OBJECT public: ClientDAO(UniversalDAO *dao, QObject *parent = 0) : QObject(parent), SpecializedDAO<ClientDTO>(dao) {} }; From within ClientDAO I have to set some database information for UniversalDAO. That's where my implementation gets ugly because I do it like this: QMap<QString, QString> fieldMapper; fieldMapper["client_id"] = "clientId"; fieldMapper["name"] = "firstName"; /* ...all column <-> field pairs in here... */ dao->setFieldMapper(fieldMapper); dao->setTable("client"); dao->setPrimaryKey("client_id"); I do it in constructor so it's not visible at a first glance for someone browsing through the header. In .Net version it was easy to spot and understand. Do you have some ideas how I could make it better?

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  • Blob in Java/Hibernate/sql-server 2005

    - by Ramy
    Hi, I'm trying to insert an HTML blob into our sql-server2005 database. i've been using the data-type [text] for the field the blob will eventually live in. i've also put a '@Lob' annotation on the field in the domain model. The problem comes in when the HTML blob I'm attempting to store is larger than 65536 characters. Its seems that is the caracter-limit for a text data type when using the @Lob annotation. Ideally I'd like to keep the whole blob in tact rather than chunk it up into multiple rows in the database. I appreciate any help or insight that might be provided. Thanks! _Ramy Allow me to clarify annotation: @Lob @Column(length = Integer. MAX_VALUE) //per an answer on stackoverflow private String htmlBlob; database side (sql-server-2005): CREATE TABLE dbo.IndustrySectorTearSheetBlob( ... htmlBlob text NULL ... ) Still seeing truncation after 65536 characters... EDIT: i've printed out the contents of all possible strings (only 10 right now) that would be inserted into the Database. Each string seems to contain all cahracters, judging by the fact that the close html tag is present at the end of the string....

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  • Using Hibernate to do a query involving two tables

    - by Nathan Spears
    I'm inexperienced with sql in general, so using Hibernate is like looking for an answer before I know exactly what the question is. Please feel free to correct any misunderstandings I have. I am on a project where I have to use Hibernate. Most of what I am doing is pretty basic and I could copy and modify. Now I would like to do something different and I'm not sure how configuration and syntax need to come together. Let's say I have two tables. Table A has two (relevant) columns, user GUID and manager GUID. Obviously managers can have more than one user under them, so queries on manager can return more than one row. Additionally, a manager can be managing the same user on multiple projects, so the same user can be returned multiple times for the same manager query. Table B has two columns, user GUID and user full name. One-to-one mapping there. I want to do a query on manager GUID from Table A, group them by unique User GUID (so the same User isn't in the results twice), then return those users' full names from Table B. I could do this in sql without too much trouble but I want to use Hibernate so I don't have to parse the sql results by hand. That's one of the points of using Hibernate, isn't it? Right now I have Hibernate mappings that map each column in Table A to a field (well the get/set methods I guess) in a DAO object that I wrote just to hold that Table's data. I could also use the Hibernate DAOs I have to access each table separately and do each of the things I mentioned above in separate steps, but that would be less efficient (I assume) that doing one query. I wrote a Service object to hold the data that gets returned from the query (my example is simplified - I'm going to keep some other data from Table A and get multiple columns from Table B) but I'm at a loss for how to write a DAO that can do the join, or use the DAOs I have to do the join. FYI, here is a sample of my hibernate config file (simplified to match my example): <hibernate-mapping package="com.my.dao"> <class name="TableA" table="table_a"> <id name="pkIndex" column="pk_index" /> <property name="userGuid" column="user_guid" /> <property name="managerGuid" column="manager_guid" /> </class> </hibernate-mapping> So then I have a DAOImplementation class that does queries and returns lists like public List<TableA> findByHQL(String hql, Map<String, String> params) etc. I'm not sure how "best practice" that is either.

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  • How to use SQLAlchemy to dump an SQL file from query expressions to bulk-insert into a DBMS?

    - by Mahmoud Abdelkader
    Please bear with me as I explain the problem, how I tried to solve it, and my question on how to improve it is at the end. I have a 100,000 line csv file from an offline batch job and I needed to insert it into the database as its proper models. Ordinarily, if this is a fairly straight-forward load, this can be trivially loaded by just munging the CSV file to fit a schema, but I had to do some external processing that requires querying and it's just much more convenient to use SQLAlchemy to generate the data I want. The data I want here is 3 models that represent 3 pre-exiting tables in the database and each subsequent model depends on the previous model. For example: Model C --> Foreign Key --> Model B --> Foreign Key --> Model A So, the models must be inserted in the order A, B, and C. I came up with a producer/consumer approach: - instantiate a multiprocessing.Process which contains a threadpool of 50 persister threads that have a threadlocal connection to a database - read a line from the file using the csv DictReader - enqueue the dictionary to the process, where each thread creates the appropriate models by querying the right values and each thread persists the models in the appropriate order This was faster than a non-threaded read/persist but it is way slower than bulk-loading a file into the database. The job finished persisting after about 45 minutes. For fun, I decided to write it in SQL statements, it took 5 minutes. Writing the SQL statements took me a couple of hours, though. So my question is, could I have used a faster method to insert rows using SQLAlchemy? As I understand it, SQLAlchemy is not designed for bulk insert operations, so this is less than ideal. This follows to my question, is there a way to generate the SQL statements using SQLAlchemy, throw them in a file, and then just use a bulk-load into the database? I know about str(model_object) but it does not show the interpolated values. I would appreciate any guidance for how to do this faster. Thanks!

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  • Mongomapper query collection problem

    - by kylemac
    When I define the User has_many meetings, it automatically creates a "user_id" key/value pair to relate to the User collections. Except I can't run any mongo_mapper finds using this value, without it returning nil or []. Meeting.first(:user_id = "1234") Meeting.all(:user_id = "1234") Meeting.find(:user_id = "1234") All return nil. Is there another syntax? Basically I can't run a query on the automatically generated associative ObjectId. # Methods class User include MongoMapper::Document key :user_name, String, :required = true key :password, String many :meetings end class Meeting include MongoMapper::Document key :name, String, :required = true key :count, Integer, :default = 1 end # Sinatra get '/add' do user = User.new user.meetings "foobar") #should read: Meeting.new(:name = "foobar") user.save end get '/find' do test = Meeting.first(:user_id = "4b4f9d6d348f82370b000001") #this is the _id of the newly create user p test # WTF! returns [] end

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  • NHibernate query CreateCriteria

    - by Jacob
    Is it possible to chose what columns I want in return from Session.CreateCriteria() ? egz.: var x = session.CreateCriteria(); x.CreateAlias("EmployeePosition", "employeePosition"); x.Add(Restrictions.Eq("employeePosition.Name", "Developer")); and is there a way to add something like "select LastName" to avoid downloading the whole row.

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  • Symfony app - how to add calculated fields to Propel objects?

    - by Thomas Kohl
    What is the best way of working with calculated fields of Propel objects? Say I have an object "Customer" that has a corresponding table "customers" and each column corresponds to an attribute of my object. What I would like to do is: add a calculated attribute "Number of completed orders" to my object when using it on View A but not on Views B and C. The calculated attribute is a COUNT() of "Order" objects linked to my "Customer" object via ID. What I can do now is to first select all Customer objects, then iteratively count Orders for all of them, but I'd think doing it in a single query would improve performance. But I cannot properly "hydrate" my Propel object since it does not contain the definition of the calculated field(s). How would you approach it?

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