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  • FileInputStream and FileOutputStream to the same file: Is a read() guaranteed to see all write()s that "happened before"?

    - by user946850
    I am using a file as a cache for big data. One thread writes to it sequentially, another thread reads it sequentially. Can I be sure that all data that has been written (by write()) in one thread can be read() from another thread, assuming a proper "happens-before" relationship in terms of the Java memory model? Is this behavior documented? EDIT: In my JDK, FileOutputSream does not override flush(), and OutputStream.flush() is empty. That's why I'm wondering... EDIT^2: The streams in question are owned exclusively by a class that I have full control of. Each stream is guaranteed to be accesses by one thread only. My tests show that it works as expected, but I'm still wondering if this is guaranteed and documented. See also this related discussion: http://chat.stackoverflow.com/rooms/17598/discussion-between-hussain-al-mutawa-and-user946850

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  • how do I integrate the aspnet_users table that comes with asp.net membership into my existing databa

    - by ooo
    i have a database that already has a users table COLUMNS: userID - int loginName - string First - string Last - string i just installed the asp.net membership table. Right now all of my tables are joined into my users table foreign keyed into the "userId" field How do i integrate asp.net_users table into my schema? here are the ideas i thought of: Add a membership_id field to my users table and on new inserts, include that new field in my users table. This seems like the cleanest way as i dont need to break any existing relationships. break all existing relationship and move all of the fields in my user table into the asp.net_users table. This seems like a pain but ultimately will lead to the most simple, normalized solution any thoughts?

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  • How to handle Many-To-Many In Grails without belongsTo?

    - by nute
    I need to create a many-to-many relationship in Grails. I have a "Question" domain and a "Tag" domain. A Question can have 0 or more tags. A Tag can have 0 or more Questions. If I put a "hasMany" on each sides, it gives me an error saying I need a "belongTo" somewhere. However, adding a belongsTo means that the owner must exist... Like I said, a Tag could have 0 questions, and a Question could have 0 tags. There is no concept of an owner, it's a many-to-many! What am I supposed to do?

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  • Rails object inheritence with belongs_to

    - by Rabbott
    I have a simple has_many/belongs_to relationship between Report and Chart. The issue I'm having is that my Chart model is a parent that has children. So in my Report model I have class Report < ActiveRecord::Base has_many :charts end And my Chart model is a parent, where Pie, Line, Bar all inherit from Chart. I'm not sure where the belongs_to :report belongs within the chart model, or children of chart model. I get errors when I attempt to access chart.report because the object is of type "Class" undefined local variable or method `report' for #< Class:0x104974b90 The Chart model uses STI so its pulling say.. 'Pie' from the chart_type column in the charts table.. what am I missing?

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  • Accessing individual HABTM records in a form

    - by Pichan
    I'm building a form in my CakePHP project that lets you edit a company's information. Among all other things, every company has at least one geographical area in which the company operates, but it may have more. The areas are selected individually using select dropdowns. The relationship between companies and areas is HABTM, because I need to be able to change the amount of associated areas without modifying the database. Currently the associations and corresponding data are handled separately, which isn't really a problem but I was wondering how it could be done using as much Cake's own 'automagic' functionality as possible?

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  • Sum of distinc rows after a 1-many table join

    - by Lock
    I have 2 tables that I am joining. Table 1 has 1-many relationship with table 2. That is, table 2 can return multiple rows for a single row of table 1. Because of this, the records of table 1 is duplicated for as many rows as are on table 2.. which is expected. Now, I have a sum on one of the columns from table 1, but because of the multiple rows that get returned on the join, the sum is obviously multiplying. Is there a way to get this number back to its original number? I tried dividing by the count of rows from table 2 but this didnt quite give me the expected result. Are there any analytical functions that could do this? I almost want something like "if this row has not yet been counted in the sum, add it to the sum"

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  • Cakephp, Retreive Data for HABTM Models using conditional find

    - by ion
    There are 2 Models: Project & Category that are bind with HABTM relationship. I would like to perform a search from projects controller that can do the following: FIND all DISTINCT Project.scedule WHERE Category.slug != 'uncategorised' Apologies for the syntax, I'm no sequel expert. What I have managed to do is to retrieve all projects that do not belong to Category uncategorised into an array however I'm not sure as to how to search again the array result for DISTINCT Project.schedule values (needed to fill out a form drop down) I hope I made myself clear.

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  • Hibernate one-to-one: getId() without fetching entire object

    - by Rob
    I want to fetch the id of a one-to-one relationship without loading the entire object. I thought I could do this using lazy loading as follows: class Foo { @OneToOne(fetch = FetchType.LAZY, optional = false) private Bar bar; } Foo f = session.get(Foo.class, fooId); // Hibernate fetches Foo f.getBar(); // Hibernate fetches full Bar object f.getBar().getId(); // No further fetch, returns id I want f.getBar() to not trigger another fetch. I want hibernate to give me a proxy object that allows me to call .getId() without actually fetching the Bar object. What am I doing wrong?

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  • nsfetchedresultscontroller with empty sections

    - by WearyMonkey
    I have a database of People and pets, with a one to many relationship Person Pet Name Name Pet <----- Owner I am using a UITableView backed by Core data and a nsfetchedresultscontroller to display the list of pets, grouped into sections by the owner. NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; fetchRequest.entity = [NSEntityDescription entityFromName:@"Pet" inManagedObjectContext:context] NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"Owner.name" ascending:YES]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; NSFetchedResultsController *controller = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:context sectionNameKeyPath:@"Owner.name" cacheName:@"Root"]; This works to display all pets under their owners section, however I also want to display the empty sections of People who do not have any pets? Is this possible? Thanks for any help.

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  • Entity Framework 4 Hiding Underlying Resolver Tables when model is generated from database

    - by grrrrrrrrrrrrr
    When creating an entity framework model from scratch it is possible to specify a Many to Many relationship in the model. e.g Entity1 * ----- * Entity2 When a database is then generated from this, a resolver table is then created automatically between the two entities, this is hidden in the code model, allowing direct access to each of the entities via properties. e.g. Entity1 ----* ResolverEntity *----- Entity2 My question is, when a model is generated from an existing database, which contains resolver tables, is it possible to create the same effect so the resolver tables do not appear in the generated object model? When I have attempted this, the entity framework appears to create entities in the model for the resolver tables with no obvious way of hiding them in the object model. Thanks.

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  • how do I integrate the aspnet_users table (asp.net membership) into my existing database

    - by ooo
    i have a database that already has a users table COLUMNS: userID - int loginName - string First - string Last - string i just installed the asp.net membership table. Right now all of my tables are joined into my users table foreign keyed into the "userId" field How do i integrate asp.net_users table into my schema? here are the ideas i thought of: Add a membership_id field to my users table and on new inserts, include that new field in my users table. This seems like the cleanest way as i dont need to break any existing relationships. break all existing relationship and move all of the fields in my user table into the asp.net_users table. This seems like a pain but ultimately will lead to the most simple, normalized solution any thoughts?

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  • Want to save data field from form into two columns of two models.

    - by vette982
    I have a Profile model with a hasOne relationship to a Detail model. I have a registration form that saves data into both model's tables, but I want the username field from the profile model to be copied over to the usernamefield in the details model so that each has the same username. function new_account() { if(!empty($this->data)) { $this->Profile->modified = date("Y-m-d H:i:s"); if($this->Profile->save($this->data)) { $this->data['Detail']['profile_id'] = $this->Profile->id; $this->data['Detail']['username'] = $this->Profile->username; $this->Profile->Detail->save($this->data); $this->Session->setFlash('Your registration was successful.'); $this->redirect(array('action'=>'index')); } } } This code in my Profile controller gives me the error: Undefined property: Profile::$username Any ideas?

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  • Check boxes for a has_many and belongs_to association.

    - by Thomas
    I have a has_many and belongs_to association. class Link < ActiveRecord::Base has_and_belongs_to_many :categories belongs_to :property end class Property < ActiveRecord::Base has_many :links end In the index and show I have <%= link.property.name %> and it will show the Property that I assigned to the link with the console just fine. I have a problem with figuring out how to show check boxes in the _form that assign a property to the link (a drop down would work as well). It seems everyone who has had this question before has ether a has_many :through or a HABTM relationship and I can't seem to adapt their answers.

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  • Manually Building a Tree in CakePHP

    - by mabwi
    I'm currently working on building an application in CakePHP. There's a quite extensive existing data set that's conceptually a tree, but wasn't previously stored as one. What I mean by that, is there's no real relationship defined in the data. The problem I'm having is getting it to work correctly with the CakePHP tree behaviour. Because I have to set all the values on existing data - as opposed to Cake setting up the structure as elements are inserted - I need to understand how the lft/rght values work. So, I guess the question is: How does the structure data work, specifically the lft/rght values? How do I set it up so that the data comes out rationally, without inserting them one at a time? It's a 2 level tree, with Sections and sub-sections. Thanks for the help

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  • After C++ - Python or Java?

    - by carleeto
    I'm fast approaching the point in my coding where I would like to quickly write object oriented code in languages other than C++ for a variety of reasons. After a lot of research, my choices have pretty much narrowed down to Python and Java. I'm leaning towards Python because of its relationship to C, but with Java, from what I can see, I get a good introduction to using and creating test suites with Eclipse - there is also Processing which is pulling me towards Java. I'm not the kind of guy to tackle two languages at once, so which one would you recommend and why? What I want at the end is to have an additional language I can use for rapid development. Ease of learning isn't important to me as I'm willing to put in the time regardless. Ability to use the new language widely is.

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  • has_many conditions

    - by user305270
    c = "(f.profile_id = #{self.id} OR f.friend_id = #{self.id})" c += AND + "(CASE WHEN f.profile_id=#{self.id} THEN f.friend_id ELSE f.profile_id END = p.id)" c += AND + "(CASE WHEN f.profile_id=#{self.id} THEN f.profile_rejected ELSE f.friend_rejected END = 1)" c += AND + "(p.banned = 0)" I need this to be used in a has_many relationship like this: has_many :removed_friends, :conditions => ??? how do i set there the self.id?, or how do i pass there the id? Then i want to use the will_paginate plugin: @profile.removed_friends.paginate(:page => 1, :per_page => 20) Thanks for your help

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  • Rails: Best practice to store user settings?

    - by ole_berlin
    Hi, I'm wondering what the best way is to store user settings? For a web 2.0 app I want users to be able to select certain settings. At the moment is it only when to receive email notifications. The easiest way would be to just create a Model "Settings" and have a column for every setting and then have a 1-1 relationship with users. But is there a pattern to solve this better? Is it maybe better to store the info in the user table itself? Or should I use a table with "settings_name" and "settings_value" to be completely open about the type of settings stored there (without having to run any migrations when adding options)? What is your opinion? Thanks

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  • Storing Data as XML BLOB

    - by NBrowne
    Hi, At the moment the team i am working with is looking into the possibility of storing data which is entered by users from a series of input wizard screens as an XML blob in the database. the main reason for this being that i would like to write the input wizard as a component which can be brought into a number of systems without having to bring with it a large table structure. To try to clarify if the wizard has 100 input fields (for example) then if i go with the normal relational db structure then their will be a 1 to 1 relationship so will have 100 columns in database. So to get this working in another system will have to bring the tables,strore procedures etc into the new system. I have a number of reservations about this but i would like peoples opinions?? thanks

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  • user_objects oracle

    - by mysticfalls
    I would just like to ask what is the difference between user_constraints and user_objects. I have this two database. I run a script on both DB that resulted a unique constraint error. To solve the problem I delete the constraint on user_constraint table for both DB. After that DB1 run without error.. DB2 however failed, I checked the user_constraint for both db and the constraints was deleted. I was asked to check the user_objects.. and found that DB2 has that same constraint_name as the object_name in user_objects table.. Any info regarding their relationship, use, similarites, etc will be appreciated ... Thanks..

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  • SQL SELECT using in() but excluding others.

    - by Pickledegg
    I have a table called 'countries' linked to another table 'networks' with a many to many relationship: countries countries_networks networks +-------------+----------+ +-------------+----------+ +-------------+---------------+ | Field | Type | | Field | Type | | Field | Type | +-------------+----------+ +-------------+----------+ +-------------+---------------+ | id | int(11) | | id | int(11) | | id | int(11) | | countryName | char(35) | | country_id | int(11) | | name | varchar(100) | +-------------+----------+ | network_id | int(11) | | description | varchar(255) | To retrieve all countries that have a network_id of 6 & 7, I just do the following: ( I could go further to use the networks.name but I know the countries_networks.network_id so i just use those to reduce SQL.) SELECT DISTINCT countryName FROM countries AS Country INNER JOIN countries_networks AS n ON Country.id = n.country_id WHERE n.network_id IN (6,7) This is fine, but I then want to retrieve the countries with a network_id of JUST 8, and no others. I'ver tried the following but its still returning networks with 6 & 7 in. Is it something to do with my JOIN? SELECT DISTINCT countryName FROM countries AS Country INNER JOIN countries_networks AS n ON Country.id = n.country_id WHERE n.network_id IN (8) AND n.network_id not IN(6,7) Thanks.

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  • Is there an ORM that allows a "plugin" to extend the database?

    - by IP
    So, I've been searching for the answer to this, but I can't find anything I have an Entity Framework Model (MyModel1) - for now, we'll say this contains a "Users" table It's part of a big app, that has a references to an "Addresses" project The addresses project contains an Entity Framework Model (MyModel2), this contains a Users table, and an Addresses table (pointing to the same database. The main app has a control that edits the user, and in that control it has an "addresses" control which actually exists in the "Addresses" project. To make this work, the User control passes the User object down to the addresses control, however, as the User that's been passed belongs to MyModel1 and not MyModel2, another User object has to be loaded up, then it can be used. This isn't ideal as I've had to load up the User twice. Is there a way of say, MyModel2 extending MyModel1, which effectively just adds a relationship to "User". Or is there an ORM that would handle this better? Or even a design pattern that would handle this better?

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  • Is JPA + EJB to much slow (or heavy) for over Internet transactions?

    - by Xavier Callejas
    Hi, I am developing a stand-alone java client application that connects to a Glassfish v3 application for JPA/EJB facade style transactions. In other words, my client application do not connect directly to the database to CRUD, but it transfers JPA objets using EJB stateless sessions. I have scenarios where this client application will be used in an external network connected with a VPN over Internet with a client connection of 512kbp/DSL, and a simple query takes so much time, I'm seeing the traffic graph and when I merge a entity in the client application I see megabytes of traffic (I couldn't believe how a purchase order entity could weight more than 1 mb). I have LAZY fetch in almost every many-to-many relationship, but I have a lot of many-to-one relationships between entities (but this is the great advantage of JPA!). Could I do something to accelerate the the speed of transactions between JPA/EJB server and the remote java client? Thank you in advance.

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  • Generate a valid array key from an URL string in PHP

    - by John Riche
    I have a PHP array with some predefined values: $aArray = array( 0 => 'value0', 1 => 'value1' ); I need to create a function where the string input will always return the same, valid, array key so that when I call: GiveMeAKey('http://www.google.com'); // May return 0 or 1 I receive always the same key (I don't care which one) from the array. Obvisously I can't store the relationship in a database and the string passed to the GiveMeAKey method can be any URL. I wonder if there is a way of doing that ?

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  • Very basic database theory.

    - by John R
    I have a set of tables to show the relationship between organziations and supporters below. Although I have done some basic mySQL querries, I know very little about database 'design'. I plan to querry the database for: -a list of contributors to a specific organization... or, -a list of organizations that a specific suporter supports. The database tables for organiations and contributors may have other columns in the future and recieve a lesser amount of querries based on that information. A | X A | Y A | Z B | X B | Y C | X C | Z How should the tables be set up? I assume that there should be a third table, but there is still redundent information in the third table. Is there a better way of setting up the tables? +----+-------+ +-------------+----------+ +----+-------+ | id | org | | org | contr | | id | contr.| +----+-------+ +-------------+----------+ +----+-------+ | 1 | A | | 1 | 1 | | 1 | X | | 2 | B | | 1 | 2 | | 2 | Y | | 3 | C | | 1 | 3 | | 3 | Z | +----+-------+ | 2 | 1 | +----+-------+ | 2 | 2 | | 3 | 1 | | 3 | 3 | +-------------+----------+

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  • save object associate to another object automatically

    - by Luca Romagnoli
    Hi i have these classes: class Core < ActiveRecord::Base belongs_to :resource, :polymorphic => true belongs_to :image, :class_name => 'Multimedia', :foreign_key => 'image_id' end class Place < ActiveRecord::Base has_one :core, :as => :resource end If i try do launch this: a = Place.find(5) a.name ="a" a.core.image_id = 24 a.save name is saved. image_id no i want save automatically all changes in records in relationship with place class at a.save command. is possible? thanks

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