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  • Problem persisting inheritance tree

    - by alaiseca
    I have a problem trying to map an inheritance tree. A simplified version of my model is like this: @MappedSuperclass @Embeddable public class BaseEmbedded implements Serializable { @Column(name="BE_FIELD") private String beField; // Getters and setters follow } @MappedSuperclass @Embeddable public class DerivedEmbedded extends BaseEmbedded { @Column(name="DE_FIELD") private String deField; // Getters and setters follow } @MappedSuperclass public abstract class BaseClass implements Serializable { @Embedded protected BaseEmbedded embedded; public BaseClass() { this.embedded = new BaseEmbedded(); } // Getters and setters follow } @Entity @Table(name="MYTABLE") @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @DiscriminatorColumn(name="TYPE", discriminatorType=DiscriminatorType.STRING) public class DerivedClass extends BaseClass { @Id @Column(name="ID", nullable=false) private Long id; @Column(name="TYPE", nullable=false, insertable=false, updatable=false) private String type; public DerivedClass() { this.embedded = new DerivedClass(); } // Getters and setters follow } @Entity @DiscriminatorValue("A") public class DerivedClassA extends DerivedClass { @Embeddable public static NestedClassA extends DerivedEmbedded { @Column(name="FIELD_CLASS_A") private String fieldClassA; } public DerivedClassA() { this.embedded = new NestedClassA(); } // Getters and setters follow } @Entity @DiscriminatorValue("B") public class DerivedClassB extends DerivedClass { @Embeddable public static NestedClassB extends DerivedEmbedded { @Column(name="FIELD_CLASS_B") private String fieldClassB; } public DerivedClassB() { this.embedded = new NestedClassB(); } // Getters and setters follow } At Java level, this model is working fine, and I believe is the appropriate one. My problem comes up when it's time to persist an object. At runtime, I can create an object which could be an instance of DerivedClass, DerivedClassA or DerivedClassB. As you can see, each one of the derived classes introduces a new field which only makes sense for that specific derived class. All the classes share the same physical table in the database. If I persist an object of type DerivedClass, I expect fields BE_FIELD, DE_FIELD, ID and TYPE to be persisted with their values and the remaining fields to be null. If I persist an object of type DerivedClass A, I expect those same fields plus the FIELD_CLASS_A field to be persisted with their values and field FIELD_CLASS_B to be null. Something equivalent for an object of type DerivedClassB. Since the @Embedded annotation is at the BaseClass only, Hibernate is only persisting the fields up to that level in the tree. I don't know how to tell Hibernate that I want to persist up to the appropriate level in the tree, depending on the actual type of the embedded property. I cannot have another @Embedded property in the subclasses since this would duplicate data that is already present in the superclass and would also break the Java model. I cannot declare the embedded property to be of a more specific type either, since it's only at runtime when the actual object is created and I don't have a single branch in the hierarchy. Is it possible to solve my problem? Or should I resignate myself to accept that there is no way to persist the Java model as it is? Any help will be greatly appreciated.

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  • Dojo treemodel- adding large number of items

    - by Ashley
    I am trying to add a large number of items (100+) to my tree via ForestStoreModel by calling newItem in a loop. This seems to be quite slow and locks up the browser. Is there any way I can do something similar to grid's beginUpdate & endUpdate? I want to basically 'turn off' my tree, add 100 items in a batch, then 'turn on' my tree. Any ideas? Thanks!

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  • How to implement a unit converter in java

    - by Mohit Deshpande
    How could I possibly implement a unit converter in Java??? I was thinking of having a abstract base class: public abstract class Unit { ... public void ConvertTo(Unit unit); } Then having each class like Meter Kilometer Inch Centimeter Millimeter ... derive from that base Unit class. All the units of length would be in a package called com.unitconverter.distance, then a package, com.unitconverter.energy, for energy etc. etc. So is this the best way to implement a unit converter? Or is there a better or more easier way?

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  • Find node level in a tree

    - by Álvaro G. Vicario
    I have a tree (nested categories) stored as follows: CREATE TABLE `category` ( `category_id` int(10) unsigned NOT NULL AUTO_INCREMENT, `category_name` varchar(100) NOT NULL, `parent_id` int(10) unsigned DEFAULT NULL, PRIMARY KEY (`category_id`), UNIQUE KEY `category_name_UNIQUE` (`category_name`,`parent_id`), KEY `fk_category_category1` (`parent_id`,`category_id`), CONSTRAINT `fk_category_category1` FOREIGN KEY (`parent_id`) REFERENCES `category` (`category_id`) ON DELETE SET NULL ON UPDATE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_spanish_ci I need to feed my client-side language (PHP) with node information (child+parent) so it can build the tree in memory. I can tweak my PHP code but I think the operation would be way simpler if I could just retrieve the rows in such an order that all parents come before their children. I could do that if I knew the level for each node: SELECT category_id, category_name, parent_id FROM category ORDER BY level -- No `level` column so far :( Can you think of a way (view, stored routine or whatever...) to calculate the node level? I guess it's okay if it's not real-time and I need to recalculate it on node modification.

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  • In B-trees which element gets promoted when the node splits

    - by Phenom
    Let's say there is a B-tree of order 8. This means it can have 8 pointers and 7 elements. Say the letters A through G are stored in this B-tree. So this B-tree is just a single node containing 7 elements. Then you try to insert J into the tree. There's no room, so you have to split the node and create a new root node. Which element gets promoted up into the root node?

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  • Cannot instantiate abstract class or interface : problem while persisting

    - by sammy
    i have a class campaign that maintains a list of AdGroupInterfaces. im going to persist its implementation @Entity @Table(name = "campaigns") public class Campaign implements Serializable,Comparable<Object>,CampaignInterface { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @OneToMany ( cascade = {CascadeType.ALL}, fetch = FetchType.EAGER, targetEntity=AdGroupInterface.class ) @org.hibernate.annotations.Cascade( value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN ) @org.hibernate.annotations.IndexColumn(name = "CHOICE_POSITION") private List<AdGroupInterface> AdGroup; public Campaign() { super(); } public List<AdGroupInterface> getAdGroup() { return AdGroup; } public void setAdGroup(List<AdGroupInterface> adGroup) { AdGroup = adGroup; } public void set1AdGroup(AdGroupInterface adGroup) { if(AdGroup==null) AdGroup=new LinkedList<AdGroupInterface>(); AdGroup.add(adGroup); } } AdGroupInterface's implementation is AdGroups. when i add an adgroup to the list in campaign, campaign c; c.getAdGroupList().add(new AdGroups()), etc and save campaign it says"Cannot instantiate abstract class or interface :" AdGroupInterface its not recognizing the implementation just before persisting... Whereas Persisting adGroups separately works. when it is a member of another entity, it doesnt get persisted. import java.io.Serializable; import java.util.List; import javax.persistence.*; @Entity @DiscriminatorValue("1") @Table(name = "AdGroups") public class AdGroups implements Serializable,Comparable,AdGroupInterface{ /** * */ private static final long serialVersionUID = 1L; private Long Id; private String Name; private CampaignInterface Campaign; private MonetaryValue DefaultBid; public AdGroups(){ super(); } public AdGroups( String name, CampaignInterface campaign) { super(); this.Campaign=new Campaign(); Name = name; this.Campaign = campaign; DefaultBid = defaultBid; AdList=adList; } @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name="AdGroup_Id") public Long getId() { return Id; } public void setId(Long id) { Id = id; } @Column(name="AdGroup_Name") public String getName() { return Name; } public void setName(String name) { Name = name; } @ManyToOne @JoinColumn (name="Cam_ID", nullable = true,insertable = false) public CampaignInterface getCampaign() { return Campaign; } public void setCampaign(CampaignInterface campaign) { this.Campaign = campaign; } } what am i missing?? please look into it ...

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  • Syntax Error with MySql Workbench and IF Statement

    - by Hugo S.
    Hey guys, Im migrating from T-SQL to MySql syntax and don't know how to get over this syntax error given by Workbench 5.1.18: -- -------------------------------------------------------------------------------- -- Routine DDL -- -------------------------------------------------------------------------------- DELIMITER // CREATE PROCEDURE `SysTicket`.`GetProductionLines` (aId INT, aActive INT, aResponsible VARCHAR(8000)) BEGIN IF(aId > 0) THEN SELECT * FROM ProductionLine WHERE Id = @Id; ELSE IF( aActive <> -1 AND aResponsible = '|$EMPTYARG$|') THEN SELECT * FROM ProductionLine; ELSE IF(aResponsible = '|$EMPTYARG&|') THEN SELECT * FROM ProductionLine WHERE Active = aActive; ELSE SELECT * FROM ProductionLine WHERE Active = aActive AND Responsible LIKE CONCAT('%', aResponsible, '%'); END IF; END// It says Syntax error near END (last line) ty in advance.

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  • Why the good append syntax is so ugly, asks python newbie

    - by Cawas
    Now following my series of "python newbie questions" and based on another question. Go to http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html#other-languages-have-variables and scroll down to "Default Parameter Values". There you can find the following: def bad_append(new_item, a_list=[]): a_list.append(new_item) return a_list def good_append(new_item, a_list=None): if a_list is None: a_list = [] a_list.append(new_item) return a_list So, question here is: why is the "good" syntax over a known issue ugly like that in a programming language that promotes "elegant syntax" and "easy-to-use"? Why not just something in the definition itself, that the "argument" name is attached to a "localized" mutable object like: def better_append(new_item, a_list=[].local): a_list.append(new_item) return a_list I'm sure there would be a better way to do this syntax, but I'm also almost positive there's a good reason to why it hasn't been done. So, anyone happens to know why?

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  • try...else...except syntax error

    - by iform
    I can't understand this... Cannot get this code to run and I've no idea why it is a syntax error. try: newT.read() #existingArtist = newT['Exif.Image.Artist'].value #existingKeywords = newT['Xmp.dc.subject'].value except KeyError: print "KeyError" else: #Program will NOT remove existing values newT.read() if existingArtist != "" : newT['Exif.Image.Artist'] = artistString print existingKeywords keywords = os.path.normpath(relativePath).split(os.sep) print keywords newT['Xmp.dc.subject'] = existingKeywords + keywords newT.write() except: print "Cannot write tags to ",filePath Syntax error occurs on the last "except:". Again...I have no idea why python is throwing a syntax error (spent ~3hrs on this problem).

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  • Test For CSS3 Radial Gradient Vendor Syntax

    - by Scott Christopherson
    I'm having an issue where I'm trying to update the background gradient of an element with JavaScript based on values I specify. I tried this route: elem.style.backgroundImage = '-webkit-gradient(radial, '+x+' '+y+', 0, '+x+' '+y+', 800, from(#ccc), to(#333)), -moz-radial-gradient('+x+'px '+y+'px, circle cover, #ccc 0, #333 100%)'; Since Webkit and Gecko have two different syntaxes for CSS3 gradients, I need to specify both. However, the above code doesn't work. It works if I only have just the Gecko syntax or just the Webkit syntax, not both. I think you can check for CSS gradient support, but my question is, is there a way to check which syntax needs to be used without browser sniffing? Keep in mind that I need to set my gradients this way since the x and y coordinates of the gradient change dynamically. Hope this makes sense, thanks.

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  • Why the "mutable default argument fix" syntax is so ugly, asks python newbie

    - by Cawas
    Now following my series of "python newbie questions" and based on another question. Go to http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html#other-languages-have-variables and scroll down to "Default Parameter Values". There you can find the following: def bad_append(new_item, a_list=[]): a_list.append(new_item) return a_list def good_append(new_item, a_list=None): if a_list is None: a_list = [] a_list.append(new_item) return a_list So, question here is: why is the "good" syntax over a known issue ugly like that in a programming language that promotes "elegant syntax" and "easy-to-use"? Why not just something in the definition itself, that the "argument" name is attached to a "localized" mutable object like: def better_append(new_item, a_list=[].local): a_list.append(new_item) return a_list I'm sure there would be a better way to do this syntax, but I'm also almost positive there's a good reason to why it hasn't been done. So, anyone happens to know why?

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  • How to convert JavaScript dictionary into Python syntax

    - by Sputnix
    Writing out javascript dictionary from inside of JavaScript- enabled application (such as Adobe) into external .jsx file (or any other .txt file) the context of resulted file dictionary looks like: ({one:"1", two:"2"}) (Please note that each dictionary keys are written as they are the variables name (which is not true). A next step is to read this .jsx file with Python. I need to find a way to convert ({one:"1", two:"2"}) into Python dictionary syntax such as: {'one':"1", 'two':"2"} It has been already suggested that instead of using JavaScript's built-in dict.toSource() it would make more sense to use JSON which would write a dictionary content in similar to Python syntax. But unfortunately using JSON is not an option for me. I need to find a way to convert ({one:"1", two:"2"}) into {'one':"1", 'two':"2"} using Python alone. Any suggestions on how to achieve it? Once again, the problem mostly in dictionary keys syntax which inside of Python look like variable names instead of strings-like dictionary keys names: one vs "one"

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  • WPF - Correct Syntax for Using Coverter with Current Binding

    - by Andy T
    Hi, I have a collection of hex strings that represent colours and I am binding a combobox's ItemsSource to that collection. The combobox items are templated to have a filled rectangle with the relevant colour. I therefore need to use a converter to convert the hex value to a string. Easy enough. However, Blend is telling me that this syntax is incorrect in my XAML: Fill="{Binding, Converter={StaticResource StringToBrush}}" Apparently, I can't use a converter against plain old 'Binding'. Blend says that something like this is syntactically correct: Fill="{Binding Value, Converter={StaticResource StringToBrush}}" ...However that obviously doesn't work. I'm not quite au fait with binding syntax yet, so obviously I'm getting it wrong. Can anyone advise the correct syntax to achieve what I'm trying to do (convert my bound String using the coverter StringToBrush)? Thanks in advance! AT

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  • What, if any, is wrong with this definition of letrec in Scheme?

    - by Lajla
    R5RS gives proposed macro definitions for library forms of syntax: http://schemers.org/Documents/Standards/R5RS/HTML/r5rs-Z-H-10.html#%_sec_7.3 Which also defines letrec, in a very complicated way, certainly not how I would define it, I would simply use: (define-syntax letrec2 (syntax-rules () ((letrec2 ((name val) ...) body bodies ...) ((lambda () (define name val) ... body bodies ...))))) As far as I understand the semantics of letrec, which I use very often as a named let. It works in this way, however as I've had my fair share of debates with philosophers who think they can just disprove special relativity or established phonological theories, I know that when you think you have a simple solution to a complex problem, it's probably WRONG. There has got to be some point where this macro does not satify the semantics of letrec else they'd probably have used it. In this definition, the definitions are local to the body of the letrec, they can refer to each other for mutual recursion, I'm not quite sure what (if any) is wrong.

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  • mysql - offset problem

    - by Phil Jackson
    Hi, I recently posted a question about getting last 3 results in table in the correct order. I now want the get all comments apart from the last 3 in the correct order. Here is my syntax; SELECT * FROM (SELECT * FROM $table ORDER BY ID DESC OFFSET 3) AS T ORDER BY TIME_STAMP the error i am receiving is; You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'OFFSET, 3) AS T ORDER BY TIME_STAMP' at line 1 I can't seem to get it to work. Any help much appreciated.

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  • MYSQL -Incorrect Syntax

    - by user1854392
    WHILE x > 1 DO SET x = x - 1; SET totalTime = SELECT CONCAT(FLOOR(HOUR(TIMEDIFF(end_time,start_time)) / 24), ' days ', MOD(HOUR(TIMEDIFF(end_time,start_time)), 24), ' hrs ', MINUTE(TIMEDIFF(end_time,start_time)), ' minutes ') AS total_Time I don't see why I am having a syntax error? It is part of a bigger procedure but is pointing to this aas being incorrect Error message: SQL Error (1064): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT CONCAT(FLOOR(HOUR(TIMEDIFF(end_time,start_time)) / 24,' days',' at line 11 and totalTime is declared as a VARCHAR(50)

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  • Prevent .htaccess syntax error

    - by seengee
    Hi, As part of one our system's we enable a user in the backoffice to add a block of 301 redirects should they need to. This is just a textarea which then populates a specific area of a .htaccess file. As much as this may seem insecure it has only previously used internally by people who know what they are doing but for various reasons they cannot access the specific file. We need now to allow more access to this function, not for the general public, but for people that probably have far less knowledge of regexp etc and syntax in htaccess files. Obviously the major concern here is the user enters some bad syntax and makes their entire site, including the backoffice where they could fix the issue, totally inaccessible without manual intervention. What approaches can i take to make sure that they do not break their site? A htaccess syntax check? copy the file elsewhere and check it doesnt generate a 500 error (with cURL or similar)?. Would welcome any ideas. Thanks.

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  • Emacs check syntax of file before saving

    - by astropanic
    How I can prevent Emacs from saving my buffer when it contains syntax errors ? It would by especially useful for editing source code. I'm writing some source code into the buffer, hit C-x C-s and Emacs should position the cursor on the line containing the error. I'm correcting the error, hit the save command again, and Emacs should save the file.

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  • Emacs check syntax of file before saving

    - by astropanic
    How I can prevent Emacs from saving my buffer when it contains syntax errors ? It would by especially useful for editing source code. I'm writing some source code into the buffer, hit C-x C-s and Emacs should position the cursor on the line containing the error. I'm correcting the error, hit the save command again, and Emacs should save the file.

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  • Syntax for DBCC CHECKTABLE on all indexes?

    - by GuinnessFan
    Just want to check the syntax to make sure this is for one table and all indexes (default?). --must be single user ALTER DATABASE database_name SET SINGLE_USER; DBCC CHECKTABLE ( "table_name" , REPAIR_ALLOW_DATA_LOSS ) WITH ALL_ERRORMSGS; -- TURN BACK MULTI USER ALTER DATABASE database_name SET MULTI_USER; Also, should I be in the database containing the table to repair or should I be in master?

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