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  • Optimize INSERT / UPDATE / DELETE operation

    - by clime
    I wonder if the following script can be optimized somehow. It does write a lot to disk because it deletes possibly up-to-date rows and reinserts them. I was thinking about applying something like "insert ... on duplicate key update" and found some possibilities for single-row updates but I don't know how to apply it in the context of INSERT INTO ... SELECT query. CREATE OR REPLACE FUNCTION update_member_search_index() RETURNS VOID AS $$ DECLARE member_content_type_id INTEGER; BEGIN member_content_type_id := (SELECT id FROM django_content_type WHERE app_label='web' AND model='member'); DELETE FROM watson_searchentry WHERE content_type_id = member_content_type_id; INSERT INTO watson_searchentry (engine_slug, content_type_id, object_id, object_id_int, title, description, content, url, meta_encoded) SELECT 'default', member_content_type_id, web_member.id, web_member.id, web_member.name, '', web_user.email||' '||web_member.normalized_name||' '||web_country.name, '', '{}' FROM web_member INNER JOIN web_user ON (web_member.user_id = web_user.id) INNER JOIN web_country ON (web_member.country_id = web_country.id) WHERE web_user.is_active=TRUE; END; $$ LANGUAGE plpgsql; EDIT: Schemas of web_member, watson_searchentry, web_user, web_country: http://pastebin.com/3tRVPPVi. (content_type_id, object_id_int) in watson_searchentry is unique pair in the table but atm the index is not present (there is no use for it). This script should be run at most once a day for full rebuilds of search index.

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  • How can I dynamically call the named route in a :partial in rails?

    - by Angela
    I have the following partial. It can be called from three different times in a view as follows: <%= render :partial => "contact_event", :collection => @contacts, :locals => {:event => email} %> Second time: <%= render :partial => "contact_event", :collection => @contacts, :locals => {:event => call} %> Third time: <%= render :partial => "contact_event", :collection => @contacts, :locals => {:event => letter} %> In each instance, call, email, letter refer to a specific instance of a Model Call, Email, or Letter. Here is what I tried to do and conceptually what I'd like to do: assign the route based on the class name that has been passed to the :event from the :partial. What I did was create what the actual url should be. The 'text' of it is correct, but doesn't seem to recognize it as a named route. <% url = "skip_contact_#{event.class.name.tableize.singularize}_url" % <%= link_to_remote "Skip #{url} Remote", :url = skip_contact_email_url(contact_event, event), :update = "update-area-#{contact_event.id}-#{event.id}" % ' My challenge: skip_contact_email_url only works when the event refers to an email. How can I dynamically define skip_contact_email_url to be skip_contact_letter_url if the local variable is letter? Even better, how can I have a single named route that would do the appropriate action?

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  • EF4 querying through the generations

    - by Hans Kesting
    I have a model withs Parents, Children and Grandchildren, in a many-to-many relationship. Using this article I created POCO classes that work fine, except for one thing I can't yet figure out. When I query the Parents or Children directly using LINQ, the SQL reflects the LINQ query (a .Count() executes a COUNT in the database and so on) - fine. The Parent class has a Children property, to access it's children. But (and now for the problem) this doesn't expose an IQueryable interface but an ICollection. So when I access the Children property on a particular parent all the Parent's Children are read. Even worse, when I access the Grandchildren (theParent.Children.SelectMany(child => child.GrandChildren).Count()) then for each and every child a separate request is issued to select it's grandchildren. Changing the type of the Children property from ICollection to IQueryable doesn't solve this. Apart from missing needed methods like Add() and Remove(), EF just doesn't recognize the property then. Are there correct ways (as in: low database interaction) of querying through children (and what are they)? Or is this just not possible?

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  • Dynamic Views based on view models

    - by Joe
    I have an asp.net mvc 2 app. I need to display the same page to each user. But each user has different rights to the data. IE some can see but not edit some data, some cannot edit nor see the data. Ideally data that cannot be seen nor edited is whitespace on the view. For security reasons I want my viewmodels to be sparse as possible. By that I mean if a field cannot be seen nor edited , that field should not be on the viewmodel. Obviously I can write view for each view model but that seems wasteful. So here is my idea/wishlist Can I decorate the viewmodel with attributes and hook into a pre render event of the html helpers and tell it to do &nbsp; instead??? Can I have the html helpers output &nbsp; for entries not found on the viewmodel?? or can I easily convert a view built into code then programaticlly build the markup and then put into the render engine to be processed and viewd as html on client side??

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  • JPA Problems mapping relationships

    - by Rosen Martev
    Hello. I have a problem when I try to persist my model. An exception is thrown when creating the EntityManagerFactory: Blockquote javax.persistence.PersistenceException: [PersistenceUnit: NIF] Unable to build EntityManagerFactory at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:677) at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:126) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:52) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:34) at project.serealization.util.PersistentManager.createSession(PersistentManager.java:24) at project.serealization.SerializationTest.testProject(SerializationTest.java:25) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at junit.framework.TestCase.runTest(TestCase.java:168) at junit.framework.TestCase.runBare(TestCase.java:134) at junit.framework.TestResult$1.protect(TestResult.java:110) at junit.framework.TestResult.runProtected(TestResult.java:128) at junit.framework.TestResult.run(TestResult.java:113) at junit.framework.TestCase.run(TestCase.java:124) at junit.framework.TestSuite.runTest(TestSuite.java:232) at junit.framework.TestSuite.run(TestSuite.java:227) at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:79) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) Caused by: org.hibernate.HibernateException: Wrong column type in nif.action_element for column FLOW_ID. Found: double, expected: bigint at org.hibernate.mapping.Table.validateColumns(Table.java:284) at org.hibernate.cfg.Configuration.validateSchema(Configuration.java:1116) at org.hibernate.tool.hbm2ddl.SchemaValidator.validate(SchemaValidator.java:139) at org.hibernate.impl.SessionFactoryImpl.(SessionFactoryImpl.java:349) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1327) at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:867) at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:669) ... 24 more The code for SimpleActionElement and SimpleFlow is as follows: @Entity public class SimpleActionElement { @OneToOne(cascade = CascadeType.ALL, targetEntity = SimpleFlow.class) @JoinColumn(name = "FLOW_ID") private SimpleFlow<T> flow; ... } @Entity public class SimpleFlow<T> { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "ELEMENT_ID") private Long element_id; ... }

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  • How to calculate Content-Length for a file download within Kohana PHP?

    - by moritzd
    I'm trying to send a file from within a Kohana model to the browser, but as soon as I add a Content-Length header, the file doesn't start downloading right away. Now the problem seems to be that Kohana is already outputting buffers. An ob_clean at the begin of the script doesn't help this though. Also adding ob_get_length() to the Content-Length isn't helping since this just returns 0. The getFileSize() function returns the right number: if I run the script outside of Kohana, it works. I read that exit() still calls all destructors and it might be that something is outputted by Kohana afterwards, but I can't find out what exactly. Hope someone can help me out here... This is the piece of code I'm using: public function download() { header("Expires: ".gmdate("D, d M Y H:i:s",time()+(3600*7))." GMT\n"); header("Content-Type: ".$this->getFileType()."\n"); header("Content-Transfer-Encoding: binary\n"); header("Last-Modified: " . gmdate("D, d M Y H:i:s",$this->getCreateTime()) . " GMT\n"); header("Content-Length: ".($this->getFileSize()+ob_get_length().";\n"); header('Content-Disposition: attachment; filename="'.basename($this->getFileName())."\"\n\n"); ob_end_flush(); readfile($this->getFilePath()); exit(); }

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  • C++ reinterpret cast ?

    - by Ian
    I would like to cast one object of the class PointsList to another object Points3DList (and vice versa) where: template <class T> class PointsList { protected: std::vector <Point <T> *> points; //Only illustration, not possible with templaes }; and template <class T> class Points3DList { protected: std::vector <Point3D<T> *> points; //Only illustration, not possible with templaes }; Between Point and Point3D there is no relationship (inheritance nor composition)... template <class T> class Point { protected: T x; T y; }; template <class T> class Point3D { protected: T x; T y; T z; }; What do you think about conversion Points3DList <T> *pl3D = new Points3DList <T> (); ... PointsList <T> *pl = reinterpret_cast < PointList <T> * > ( pl3D ); where pl3D represents pointer to Points3DList object.. Can reinterpret_cast be used in this case or it is better to create a conversion function? Data model in this case can not be changed...

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  • What makes my code DDD (domain-driven design) qualified?

    - by oykuo
    Hi All, I'm new to DDD and am thinking about using this design technique in my project. However, what strikes me about DDD is that how basic the idea is. Unlike other design techniques such as MVC and TDD, it doesn't seems to contain any ground breaking ideas. For example, I'm sure some of you will have the same feeling that the idea of root aggregates and repositories are nothing new because when you are was writing MVC web applications you have to have one single master object (i.e. the root aggregate) that contain other minor objects (i.e. value objects and entities) in the model layer in order to send data to a strongly typed view. To me, the only new idea in DDD is probably the "Smart" entities (i.e. you are supposed to have business rules on root aggregates) Separation between value object, root aggregate and entities. Can anyone tell me if I have missed out anything here? If that's all there is to DDD, if I update one of my existing MVC application with the above 2 new ideas, can I claim it's an TDD, MVC and DDD applcation?

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  • CakePHP - Paginating an Array

    - by Ashok
    Cake handles pagination of a model with a simple $this-paginate(), but what should I use if I want to paginate a array of values? The Scenario is like this: $this->set('sitepages', $this->paginate()); This code in my index() returns an array like Array ( [0] => Array ( [Sitepage] => Array ( [id] => 13 [name] => Home [urlslug] => home [parent_id] => 1 [page_title] => Welcome to KIAMS, Pune [order] => 1 ) ) [1] => Array ( [Sitepage] => Array ( [id] => 26 [name] => About Us [urlslug] => aboutus [parent_id] => 1 [page_title] => [order] => 2 ) ) [2] => Array ( [Sitepage] => Array ( [id] => 27 [name] => Overview of KIAMS [urlslug] => aboutus/overview [parent_id] => 26 [page_title] => [order] => 2 ) ) I retrieved the same data using $this-Sitepage-find('all') and then performed some manipulations as required and form a array which is very similar to the above one, but the ordering gets changed. I want to paginate this new array and pass it to the view. I tried $this->set('sitepages',$this->paginate($newarray)) But the data is not getting paginated. Can some one please help with paginating the $newarray in CakePHP?

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  • How to create reference tables using fluent nhibernate

    - by Akk
    How can i create a 3 table schema from the following model classes. public class Product { public int Id {get; set;} public string Name {get; set;} public IList<Photo> Photos {get; set;} } public class Photo { public int Id {get; set;} public string Path {get; set;} } I want to create the following table structure in the database: Product ------- Id Name ProductPhotos ------------- ProductId (FK Products.Id) PhotoId (FK Photos.Id) Photos ------ Id Path How i can express the above Database Schema using Fluent NHibernate? I could only manage the following the Mapping but this does not get me the 3rd Photo ref table. public class ProductMap : ClassMap<Product> { public CityMap() { Id(x => x.Id); Map(x => x.Name); Table("Products"); HasMany(x => x.Photos).Table("ProductPhotos").KeyColumn("ProductId"); } }

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  • Get Form Input via Ajax

    - by user3651491
    I have a jqgrid plugin which I call via Ajax. I have index.php and a getGridData.php. How will I pass form input in getGridData.php via ajax and use it in getGridData.php? I tried serialize but I can't pass or access it on getGridData.php. I need it as parameters for mysql. Here's my code. <script language="javascript" type="text/javascript"> function jgGrid() { $(document).ready(function () { $("#grid").jqGrid({ url: "inc/Controller/getGridData.php"+$("#thisForm").serialize(), data : formData, datatype: "json", mtype: "POST", colNames: ["SiteID", "TerminalID", "TransactionType", "Amount", "ServiceStatus"], colModel: [ { name: "SiteID"}, { name: "TerminalID"}, { name: "TransactionType"}, { name: "Amount"}, { name: "ServiceStatus"}, ], pager: "#pager", rowNum: 10, rowList: [10,20], sortname: "SiteID", sortorder: "asc", height: 'auto', viewrecords: true, gridview: true, caption: "" }); }); } </script> getGridData.php include('../Model/Queries.php'); $cardnumber = $_POST['cardnumber']; $transact_type = $_POST['transact_type']; $fromdate = $_POST['fromdate']; $todate = $_POST['todate']; $loyalty = new Queries(); $get_mid = $loyalty->loyaltyConn($cardnumber); $somedata = json_encode($loyalty->nposConn($get_mid, $transact_type, $fromdate, $todate)); echo $somedata;

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  • Skip subdirectory in python import

    - by jstaab
    Ok, so I'm trying to change this: app/ - lib.py - models.py - blah.py Into this: app/ - __init__.py - lib.py - models/ - __init__.py - user.py - account.py - banana.py - blah.py And still be able to import my models using from app.models import User rather than having to change it to from app.models.user import User all over the place. Basically, I want everything to treat the package as a single module, but be able to navigate the code in separate files for development ease. The reason I can't do something like add for file in __all__: from file import * into init.py is I have circular references between the model files. A fix I don't want is to import those models from within the functions that use them. But that's super ugly. Let me give you an example: user.py ... from app.models import Banana ... banana.py ... from app.models import User ... I wrote a quick pre-processing script that grabs all the files, re-writes them to put imports at the top, and puts it into models.py, but that's hardly an improvement, since now my stack traces don't show the line number I actually need to change. Any ideas? I always though init was probably magical but now that I dig into it, I can't find anything that lets me provide myself this really simple convenience.

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  • The elements do not fall into document('').

    - by Kalinin
    xslt: <my:translations xmlns:my="my:my"> <w e="name" r="????????"/> <w e="model" r="??????"/> <w e="year" r="???"/> <w e="glass_type" r="???"/> <w e="scancode" r="???????"/> <w e="eurocode" r="???????"/> <w e="comment" r="???????????"/> <w e="glass_size" r="??????"/> <w e="vendor" r="?????????????"/> <w e="trademark" r="???????? ?????"/> <w e="fprice" r="????"/> </my:translations> <xsl:value-of select="count(document('')//w)"/> returns 0. In what may be the problem?

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  • Mercurial "server"

    - by user85116
    I've been using mercurial for a little while, but mainly for my own usage. Now though, I have a project I'm working on where two of us are building the same project, and we will probably be modifiying each other's files. I would like to setup a mercurial repo on a server, make that repo the "server", so my changes and the other editor's changes both push to that server (so basically the subversion / cvs model); I like mercurial though, and don't want to switch to something like subversion. Here in my own network, everything is done on linux, and my "server" has openssh installed. So pushing my changes (I work on multiple computers) from one computer to the server is just a matter of "hg push"; the protocol used is ssh for transfering the changes. The problem is that I use linux, the server will be windows (so no openssh, right?) and the other editor will be using windows too. As far as I know, the best way of working in mercurial in these types of setups is for the repo to pull changes from the source, rather then the source pushing to the "server". I'm behind several firewall's (not entirely my network) and my computer won't be visible from the server, and I'm assuming the other editor will be behind a firewall too (so we can't just start up the local mercurial http server and get the "server" computer to pull from that). What's the best way for both editors to get our changes to the server repo? (I should add that the server is a server on the internet, so just as visible as something like google.com. It's a hosted windows server, but I would probably have permission to install software if needed for this)

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  • best way to avoid sql injection

    - by aauser
    I got similar domain model 1) User. Every user got many cities. @OneToMany(targetEntity=adv.domain.City.class...) 2) City. Every city got many districts @OneToMany(targetEntity=adv.domain.Distinct.class) 3) Distintc My goal is to delete distinct when user press delete button in browser. After that controller get id of distinct and pass it to bussiness layer. Where method DistinctService.deleteDistinct(Long distinctId) should delegate deliting to DAO layer. So my question is where to put security restrictions and what is the best way to accomplish it. I want to be sure that i delete distinct of the real user, that is the real owner of city, and city is the real owner of distinct. So nobody exept the owner can't delete ditinct using simple url like localhost/deleteDistinct/5. I can get user from httpSession in my controller and pass it to bussiness layer. After that i can get all cities of this user and itrate over them to be sure, that of the citie.id == distinct.city_id and then delete distinct. But it's rather ridiculous in my opinion. Also i can write sql query like this ... delete from t_distinct where t_distinct.city_id in (select t_city.id from t_city left join t_user on t_user.id = t_city.owner_id where t_user.id = ?) and t_distinct.id = ? So what is the best practice to add restrictions like this. I'm using Hibernate, Spring, Spring MVC by the way.. Thank you

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  • Javascript object properties access functions in parent constructor?

    - by Bob Spryn
    So I'm using this pretty standard jquery plugin pattern whereby you can grab an api after applying the jquery function to a specific instance. This API is essentially a javascript object with a bunch of methods and data. So I wanted to essentially create some private internal methods for the object only to manipulate data etc, which just doesn't need to be available as part of the API. So I tried this: // API returned with new $.TranslationUI(options, container) $.TranslationUI = function (options, container) { // private function? function monkey(){ console.log("blah blah blah"); } // extend the default settings with the options object passed this.settings = $.extend({},$.TranslationUI.defaultSettings,options); // set a reference for the container dom element this.container = container; // call the init function this.init(); }; The problem I'm running into is that init can't call that function "monkey". I'm not understanding the explanation behind why it can't. Is it because init is a prototype method?($.TranslationUI's prototype is extended with a bunch of methods including init elsewhere in the code) $.extend($.TranslationUI, { prototype: { init : function(){ // doesn't work monkey(); // editing flag this.editing = false; // init event delegates here for // languagepicker $(this.settings.languageSelector, this.container).bind("click", {self: this}, this.selectLanguage); } } }); Any explanations would be helpful. Would love other thoughts on creating private methods with this model too. These particular functions don't HAVE to be in prototype, and I don't NEED private methods protected from being used externally, but I want to know how should I have that requirement in the future.

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  • Rails - Update a single attribute : link with custom action or form with hidden fields?

    - by MrRuru
    Let's say I have a User model, with a facebook_uid field corresponding to the user's facebook id. I want to allow the user to unlink his facebook account. Do do so, I need to set this attribute to nil. I currently see 2 ways of doing this First way : create a custom action and link to it # app/controllers/users_controller.rb def unlink_facebook_account @user = User.find params[:id] # Authorization checks go here @user.facebook_uid = nil @user.save # Redirection go here end # config/routes.rb ressources :users do get 'unlink_fb', :on => :member, :as => unlink_fb end # in a view = link_to "Unlink your facebook account", unlink_fb_path(@user) Second way : create a form to the existing update action # app/views/user/_unlink_fb_form.html.haml = form_for @user, :method => "post" do |f| = f.hidden_field :facebook_uid, :value => nil = f.submit "Unlink Facebook account" I'm not a big fan of either way. In the first one, I have to add a new action for something that the update controller already can do. In the second one, I cannot set the facebook_uid to nil without customizing the update action, and I cannot have a link instead of a button without adding some javascript. Still, what would you recommend as the best and most elegant solution for this context? Did I miss a third alternative?

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  • getting active records to display as a plist

    - by phil swenson
    I'm trying to get a list of active record results to display as a plist for being consumed by the iphone. I'm using the plist gem v 3.0. My model is called Post. And I want Post.all (or any array or Posts) to display correctly as a Plist. I have it working fine for one Post instance: [http://pastie.org/580902][1] that is correct, what I would expect. To get that behavior I had to do this: class Post < ActiveRecord::Base def to_plist attributes.to_plist end end However, when I do a Post.all, I can't get it to display what I want. Here is what happens: http://pastie.org/580909 I get marshalling. I want output more like this: [http://pastie.org/580914][2] I suppose I could just iterate the result set and append the plist strings. But seems ugly, I'm sure there is a more elegant way to do this. I am rusty on Ruby right now, so the elegant way isn't obvious to me. Seems like I should be able to override ActiveRecord and make result-sets that pull back more than one record take the ActiveRecord::Base to_plist and make another to_plist implementation. In rails, this would go in environment.rb, right?

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  • Tools for Automated Source Code Editing

    - by Steve
    I'm working on a research project to automatically modify code to include advanced mathematical concepts (like adding random effects into a loop or encapsulating an existing function with a new function that adds in a more advanced physical model). My question to the community is: are there are any good tools for manipulating source code directly? I want to do things like Swap out functions Add variable declarations wherever they are required Determine if a function is multiplied by anything Determine what functions are called on a line of code See what parameters are passed to a function and replace them with alternatives Introduce new function calls on certain lines of code Wherever possible just leaving the rest of the code untouched and write out the results I never want to actually compile the code I only want to understand what symbols are used, replace and add in a syntactically correct way, and be able to declare variables at the right position. I've been using a minimal flex/bison approach with some success but I do not feel the it is robust. I hate to take on writing a full language parser just to add some new info to the end of a line or the top of a function. It seems like this is almost what is going to be required but it also seems like there should be some tools out there to do these types of manipulations already. The code to be changed is in a variety of languages, but I'm particularly interested in FORTRAN. Any thoughts?

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  • Position a div relative to a top-level container?

    - by Seifeddine Dridi
    I'm trying to model an HTML document which only contains div elements positioned in absolute. For each div, properties left and top are precalculated wrt. the top-level div, but a problem occurs with nested divs since according to the CSS standard an element is positioned relative to its first ancestral element whose positioning is either relative or absolute. Does anyone know any workaround? EDIT: small code snippet that demonstrates the problem <html> <body style="background-color: #444444"> <div style="position: relative; background-color: white;"> <div style="position: absolute; background-color: red; width: 4cm; height: 3cm; top: 1cm">div 1 <div style="position: absolute; background-color: green; top: 4cm"> div 1.1</div> </div> </div> </body> </html> The green div is expected to be positioned right after the red div, instead there is a gap of 1cm in between.

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  • has_many :through default values

    - by David Lyod
    I have a need to design a system to track users memberships to groups with varying roles (currently three). class Group < ActiveRecord::Base has_many :memberships has_many :users, :through => :memberships end class Role < ActiveRecord::Base has_many :memberships has_many :users, :through => :memberships end class Membership < ActiveRecord::Base belongs_to :user belongs_to :role belongs_to :group end class User < ActiveRecord::Base has_many :memberships has_many :groups, :through => :memberships end Ideally what I want is to simply set @group.users << @user and have the membership have the correct role. I can use :conditions to select data that has been manually inserted as such : :conditions => ["memberships.grouprole_id= ? ", Grouprole.find_by_name('user')] But when creating the membership to the group the grouprole_id is not being set. Is there a way to do this as at present I have a somewhat repetitive piece of code for each user role in my Group model.

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  • Can anyone give me a sample java socket programming for doing a peer to peer for 3 systems?

    - by Sadesh Kumar N
    I am doing an university project. I need some sample programs on peer to peer programs in java socket programming. Every where people are telling to add a server socket in the client program. I am in a confusion. Can a single program having server socket and client socket will do or i have to create two programs of one initiating a system and another peer program running thrice to solve the problem. or i need to create three programs for three peer systems. I am not clear on the architecture of building peer to peer programs using java sockets. Can some one help me giving a simple program on how to create a peer to peer connection between three systems. I know how to do a socket program for client server model and clear on the concept. But creating a peer to peer architecture sounds complex for me to understand. I also referred this thread. developing peer to peer in java The person commented second says" To make peer2peer app each client opens server socket too. When client A wishes to connect to client B it just connects to its socket. " Need some more sample and an explanation on how peer to peer java socket program works I dont want any external api like jxta to do this task. I need a clear picture on how it works alone with an example.

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  • Comparing lists of field-hashes with equivalent AR-objects.

    - by Tim Snowhite
    I have a list of hashes, as such: incoming_links = [ {:title => 'blah1', :url => "http://blah.com/post/1"}, {:title => 'blah2', :url => "http://blah.com/post/2"}, {:title => 'blah3', :url => "http://blah.com/post/3"}] And an ActiveRecord model which has fields in the database with some matching rows, say: Link.all => [<Link#2 @title='blah2' @url='...post/2'>, <Link#3 @title='blah3' @url='...post/3'>, <Link#4 @title='blah4' @url='...post/4'>] I'd like to do set operations on Link.all with incoming_links so that I can figure out that <Link#4 ...> is not in the set of incoming_links, and {:title => 'blah1', :url =>'http://blah.com/post/1'} is not in the Link.all set, like so: #pseudocode #incoming_links = as above links = Link.all expired_links = links - incoming_links missing_links = incoming_links - links expired_links.destroy missing_links.each{|link| Link.create(link)} One route I've tried: I'd rather not rewrite Array#- and such, and I'm okay with converting incoming_links to a set of unsaved Link objects; so I've tried overwriting hash eql? and so on in Link so that it ignored the id equality that AR::Base provides by default. But this is the only place this sort of equality should be considered in the application - in other places the Link#id default identity is required. Is there some way I could subclass Link and apply the hash, eql?, etc overwriting there? The other route I've tried is to pull out the attributes hash for each Link and doing a .slice('id',...etc) to prune the hashes down. But this requires writing seperate methods for keeping track of the Link objects while doing set operations on the hashes, or writing seperate Collection classes to wrap the incoming_links hash-list and Link-list which seems a bit overkill. What is the best way to design this interaction? Extra credit for cleanliness.

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  • How to correctly pass a float from C# to C++ (dll)

    - by RavelT
    I'm getting huge differences when I pass a float from C# to C++. I'm passing a dynamic float wich changes over time. With a debuger I get this: c++ lonVel -0.036019072 float c# lonVel -0.029392920 float I did set my MSVC++2010 floating point model to /fp:fast wich should be the standard in .NET if I'm not mistaken, but this didnt help. Now I cant give out the code but I can show a fraction of it. From C# side it looks like this: namespace Example { public class Wheel { public bool loging = true; #region Members public IntPtr nativeWheelObject; #endregion Members public Wheel() { this.nativeWheelObject = Sim.Dll_Wheel_Add(); return; } #region Wrapper methods public void SetVelocity(float lonRoadVelocity,float latRoadVelocity){Sim.Dll_Wheel_SetVelocity(this.nativeWheelObject,lonRoadVelocity,latRoadVelocity);} #endregion Wrapper methods } internal class Sim { #region PInvokes [DllImport(pluginName, CallingConvention=CallingConvention.Cdecl)] public static extern void Dll_Wheel_SetVelocity(IntPtr wheel,float lonRoadVelocity,float latRoadVelocity); #endregion PInvokes } } And in C++ side @ exportFunctions.cpp: EXPORT_API void Dll_Wheel_SetVelocity(CarWheel* wheel,float lonRoadVelocity,float latRoadVelocity){ wheel->SetVelocity(lonRoadVelocity,latRoadVelocity);} So any sugestions on what I should do in order to get 1:1 results or atleast 99% correct results.

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  • How to use different providers for Linq to entities?

    - by Anders Svensson
    I'm trying to familiarize myself a bit more with database programming, and I'm looking at different ways of creating a data access layer for applications. I've tried out a few ways but there is such a jungle of different database technologies that I don't know what to learn. For instance I've tried using datasets with tableadapters. Using that I am able to switch data provider rather easily (by programming against the interfaces such as IDbConnection). This is one thing I would want to achieve. But I also know everyone's talking about LINQ, and I'm trying to get to know that a bit better too. So I have tried using Linq to Sql classes as the data access layer as well, but apparently this is not provider independent (works only for SQL Server). So then I read about the Entity Framework (which just as Linq to SQL apparently has gotten its share of bashing already...). It's supposed to be provider independent everybody says, but how? I tried out a tutorial to create an entity data model, but the only providers to choose from were SQL Server/Express. Just for learning purposes, I would like to know how to use the entity framework with MS Access/OleDb. Also, I would appreciate some input on what is the preferred database technology for data access. Is it LINQ still after all the bashing, or should you just use datasets because they are provider independent? Any pointers for what to learn would be great, because it's just too much to learn it all if I'm not going to use it in the end...!

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