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  • Using an embedded DB (SQLite / SQL Compact) for Message Passing within an app?

    - by wk1989
    Hello, Just out of curiosity, for applications that have a fairly complicated module tree, would something like sqlite/sql compact edition work well for message passing? So if I have modules containing data such as: \SubsystemA\SubSubSysB\ModuleB\ModuleDataC, \SubSystemB\SubSubSystemC\ModuleA\ModuleDataX Using traditional message passing/routing, you have to go through intermediate modules in order to pass a message to ModuleB to request say ModuleDataC. Instead of doing that, if we we simply store "\SubsystemA\SubSubSysB\ModuleB\ModuleDataC" in a sqlite database, getting that data is as simple as a sql query and needs no routing and passing stuff around. Has anyone done this before? Even if you haven't, do you foresee any issues & performance impact? The only concern I have right now would be the passing of custom types, e.g. if ModuleDataC is a custom data structure or a pointer, I'll need some way of storing the data structure into the DB or storing the pointer into the DB. Thanks, JW EDIT One usage case I haven't thought about is when you want to send a message from ModuleA to ModuleB to get ModuleB to do something rather than just getting/setting data. Is it possible to do this using an embedded DB? I believe callback from the DB would be needed, how feasible is this?

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  • Copy a LinkedList that has a Random Pointer in it

    - by Bragaadeesh
    Hi, First of all this is not a homework, this is an interview question that I got from a company I attended today. You have a singly linked list with the Node structure as the following class Node{ int data; Node next; Node random; } You have a typical singly linked list of length n. The random pointer in each node in the linkedlist randomly points to some Node within the linked list. The Question is to create a copy of the linked list efficiently into a different LinkedList. I said that I will first calculate the Random pointer's position in the linked list and store it in an array. Then create a new linked list normally. Then iterate through the linked list by setting the random pointer where they belong by reading the values stored from the array. I know its a very brute force technique and the interviewer asked me to come up with a better solution but I couldnt. Please can someone answer this? I can explain if the question is not clear.

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  • object not getting released in iphone

    - by Jaimin
    i m writing this code in my code to store the data in database.. Search *objSearchDetail = [[Search alloc] init]; objSearchDetail = [xmlResponseDetail objectAtIndex:i]; sql = "INSERT INTO tblsearchdetail(tblrecentsearch_id,name,address,email,url,street,postcode,city,telephone,mobile) VALUES(?,?,?,?,?,?,?,?,?,?)"; returnValue = sqlite3_prepare_v2(database, sql, -1, &insertStatement, NULL); if(returnValue == SQLITE_OK){ sqlite3_bind_int(insertStatement, 1, intLastRecentSearchId); sqlite3_bind_text(insertStatement, 2, [objSearchDetail.strName UTF8String], -1,SQLITE_TRANSIENT); sqlite3_bind_text(insertStatement, 3, [objSearchDetail.strAddress UTF8String], -1,SQLITE_TRANSIENT); sqlite3_bind_text(insertStatement, 4, [objSearchDetail.strEmail UTF8String], -1,SQLITE_TRANSIENT); sqlite3_bind_text(insertStatement, 5, [objSearchDetail.strUrl UTF8String], -1,SQLITE_TRANSIENT); sqlite3_bind_text(insertStatement, 6, [objSearchDetail.strStreet UTF8String], -1,SQLITE_TRANSIENT); sqlite3_bind_text(insertStatement, 7, [objSearchDetail.strPostCode UTF8String], -1,SQLITE_TRANSIENT); sqlite3_bind_text(insertStatement, 8, [objSearchDetail.strPlace UTF8String], -1,SQLITE_TRANSIENT); sqlite3_bind_text(insertStatement, 9, [objSearchDetail.strTelephone UTF8String], -1,SQLITE_TRANSIENT); sqlite3_bind_text(insertStatement, 10, [objSearchDetail.strMobile UTF8String], -1,SQLITE_TRANSIENT); if(sqlite3_step(insertStatement)==SQLITE_DONE) { //Data; } } NSLog(@"count %d",[objSearchDetail retainCount]); [objSearchDetail release]; now the nslog shows refrence count as 2 so even if i release the refrence count will still be one and the object will not be destroyed.. plz help me....

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  • Insert only adds upto 1000 records and ignoresall records after that.

    - by user560559
    i have a large database where the client stores personal messages and fire email notifications [if allowed by the users]. certain users have the option of sending messages to their entire network of friends. some users have over 5000 friends in their network so if they select the whole network they'll be sending messages to over 5000 friends and system will store all the messages into a table. the problem is this that it does not insert more than 1000 records and ignores all inserts after the first 1000. i have increased the packet size, bulk_insert_buffer_size but still no luck. since the system stores some of the info in another table for reports, every insert returns its new message id. due to this i can not use the "insert into table (column1,column2) values (value1,value2) , (value1,value2)....etc." table engine is innodb, mysql version is 5.1.3 and is hosted on amazon web services. all i want is to fix this issue of inserting more than 1000 records at a time. as mentioned earlier, it works fine but only up to 1000 records and simply ignores all the records after that. i'm using php foreach(){} to insert message for each friend and if email is available, send notification to the user. this foreach(){} also inserts the same record in another table [with only 3 columns] for generating reports.

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  • How to control the "flow" of an ASP.NET MVC (3.0) web app that relies on Facebook membership, with Facebook C# SDK?

    - by Chad
    I want to totally remove the standard ASP.NET membership system and use Facebook only for my web app's membership. Note, this is not a Facebook canvas app question. Typically, in an ASP.NET app you have some key properties & methods to control the "flow" of an app. Notably: Request.IsAuthenticated, [Authorize] (in MVC apps), Membership.GetUser() and Roles.IsUserInRole(), among others. It looks like [FacebookAuthorize] is equivalent to [Authorize]. Also, there's some standard work I do across all controllers in my site. So I built a BaseController that overrides OnActionExecuting(FilterContext). Typically, I populate ViewData with the user's profile within this action. Would performance suffer if I made a call to fbApp.Get("me") in this action? I use the Facebook Javascript SDK to do registration, which is nice and easy. But that's all client-side, and I'm having a hard time wrapping my mind around when to use client-side facebook calls versus server-side. There will be a point when I need to grab the user's facebook uid and store it in a "profile" table along with a few other bits of data. That would probably be best handled on the return url from the registration plugin... correct? On a side note, what data is returned from fbApp.Get("me")?

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  • R Tree 50,000 foot overview?

    - by roufamatic
    I'm working on a school project that involves taking a lat/long point and finding the top five closest points in a known list of places. The list is to be stored in memory, with the caveat that we must choose an "appropriate data structure" -- that is, we cannot simply store all the places in an array and compare distances one-by-one in a linear fashion. The teacher suggested grouping the place data by US State to prevent calculating the distance for places that are obviously too far away. I think I can do better. From my research online it seems like an R-Tree or one of its variants might be a neat solution. Unfortunately, that sentence is as far as I've gotten with understanding the actual technique, as the literature is simply too dense for my non-academic head. Can somebody give me a really high overview of what the process is for populating an R-Tree with lat/long data, and then traversing the tree to find those 5 nearest neighbors of a given point? Additionally the project is in C, and I don't have to reinvent the wheel on this, so if you've used an existing open source C implementation of an R Tree I'd be interested in your experiences.

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  • Storing an encrypted cookie with Rails

    - by J. Pablo Fernández
    I need to store a small piece of data (less than 10 characters) in a cookie in Rails and I need it to be secure. I don't want anybody being able to read that piece of data or injecting their own piece of data (as that would open up the app to many kinds of attacks). I think encrypting the contents of the cookie is the way to go (should I also sign it?). What is the best way to do it? Right now I'm doing this, which looks secure, but many things looked secure to people that knew much more than I about security and then it was discovered it wasn't really secure. I'm saving the secret in this way: encryptor = ActiveSupport::MessageEncryptor.new(Example::Application.config.secret_token) cookies[:secret] = { :value => encryptor.encrypt(secret), :domain => "example.com", :secure => !(Rails.env.test? || Rails.env.development?) } and then I'm reading it like this: encryptor = ActiveSupport::MessageEncryptor.new(Example::Application.config.secret_token) secret = encryptor.decrypt(cookies[:secret]) Is that secure? Any better ways of doing it? Update: I know about Rails' session and how it is secure, both by signing the cookie and by optionally storing the contents of the session server side and I do use the session for what it is for. But my question here is about storing a cookie, a piece of information I do not want in the session but I still need it to be secure.

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  • If Statements Skipping or Evaluating Strangely, JavaScript and jquery

    - by tlm2021
    So in jQuery, I have a global variable "currentSubNav" that stores a current visible element. The following code executes on "mouseenter". I need it to get store element's ID, check to see if there was one. If there wasn't, set the new visible element to the default. $('#mainMenu a').mouseenter(function() { var newName = $(this).attr("id"); if(newName == ''){ var newName = "default"; } Then it checks to see if the new element matches the current one. If so, it returns. If not, it performs the animations to bring in the new one. if(newName == currentSubNav){ return; }else{ $("div[name=" + currentSubNav + "]").animate({"left": "+=600px", "opacity": "toggle"}, "slow"); $("div[name=" + newName + "]").css({"margin-top": "0"}); $("div[name=" + newName + "]").fadeIn(2000); $("div[name=" + currentSubNav + "]").animate({"left": "-=600px"}, 0); currentSubNav = newName; return; } }); I'm using Chrome at the moment, and according to the dev tools that isn't what happens. Problem #1 "$(this).attr("id");" isn't returning undefined as the documentation claims. It seems to be returning "". BUT, when I have the if statement as I do above, it skips over the statement entirely. I set a breakpoint, but it never pauses execuation, so the statement is never evaluated. Problem #2 After the animations occur, instead of using the return at the end of the statements it goes back and uses the return for the "newName == currentSubNav" if statement. I guess that not a big deal, but it's not the intended behavior. I'm fairly new to JavaScript, and it appears I'm missing something about how JavaScript works. But I can't find what anywhere. Any help? Blockquote

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  • How can I make this simple C# generics factory work?

    - by Kevin Brassen
    I have this design: public interface IFactory<T> { T Create(); T CreateWithSensibleDefaults(); } public class AppleFactory : IFactory<Apple> { ... } public class BananaFactory : IFactory<Banana> { ... } // ... The fictitious Apple and Banana here do not necessarily share any common types (other than object, of course). I don't want clients to have to depend on specific factories, so instead, you can just ask a FactoryManager for a new type. It has a FactoryForType method: IFactory<T> FactoryForType<T>(); Now you can invoke the appropriate interface methods with something like FactoryForType<Apple>().Create(). So far, so good. But there's a problem at the implementation level: how do I store this mapping from types to IFactory<T>s? The naive answer is an IDictionary<Type, IFactory<T>>, but that doesn't work since there's no type covariance on the T (I'm using C# 3.5). Am I just stuck with an IDictionary<Type, object> and doing the casting manually?

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  • Stop writing blank line at the end of CSV file (using MATLAB)

    - by Grant M.
    Hello all ... I'm using MATLAB to open a batch of CSV files containing column headers and data (using the 'importdata' function), then I manipulate the data a bit and write the headers and data to new CSV files using the 'dlmwrite' function. I'm using the '-append' and 'newline' attributes of 'dlmwrite' to add each line of text/data on a new line. Each of my new CSV files has a blank line at the end, whereas this blank line was not there before when I read in the data ... and I'm not using 'newline' on my final call of 'dlmwrite'. Does anyone know how I can keep from writing this blank line to the end of my CSV files? Thanks for your help, Grant EDITED 5/18/10 1:35PM CST - Added information about code and text file per request ... you'll notice after performing the procedure below that there appears to be a carriage return at the end of the last line in the new text file. Consider a text file named 'textfile.txt' that looks like this: Column1, Column2, Column3, Column4, Column 5 1, 2, 3, 4, 5 1, 2, 3, 4, 5 1, 2, 3, 4, 5 1, 2, 3, 4, 5 1, 2, 3, 4, 5 Here's a sample of the code I am using: % import data importedData = importdata('textfile.txt'); % manipulate data importedData.data(:,1) = 100; % store column headers into single comma-delimited % character array (for easy writing later) columnHeaders = importedData.textdata{1}; for counter = 2:size(importedData.textdata,2) columnHeaders = horzcat(columnHeaders,',',importedData.textdata{counter}); end % write column headers to new file dlmwrite('textfile_updated.txt',columnHeaders,'Delimiter','','newline','pc') % append all but last line of data to new file for dataCounter = 1:(size(importedData.data,2)-1) dlmwrite('textfile_updated.txt',importedData.data(dataCounter,:),'Delimiter',',','newline','pc','-append') end % append last line of data to new file, not % creating new line at end dlmwrite('textfile_updated.txt',importedData.data(end,:),'Delimiter',',','-append')

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  • WIN32 Logon question

    - by Lalit_M
    We have developed a ASP.NET 3.5 web application with Web Server 2008 and has implemented a custom authentication solution using active directory as the credentials store. Our front end application uses a normal login form to capture the user name and password and leverages the Win32 LogonUser method to authenticate the user’s credentials. When we are calling the LogonUser method, we are using the LOGON32_LOGON_NETWORK as the logon type. The issue we have found is that user profile folders are being created under the C:\Users folder of the web server. The folder seems to be created when a new user who has never logged on before is logging in for the first time. As the number of new users logging into the application grows, disk space is shrinking due to the large number of new user folders getting created. I need to get the token back after the authentication (authenticated \ password locked \ wrong password ) its futher use and based on logic showing different web pages Has anyone seen this behavior with the Win32 LogonUser method? Please answer the following issue: Is it possible to disable this behavior to create the folder as taking 2.78 MB of space for every new user and it eating my disck space? I have tried LOGON32_LOGON_BATCH but it was giving an error 1385 in authentication user. For any solution related to LOGON32_LOGON_BATCH, can you please confirm if that will stop creating the folders at location C:\users. Also for any possible solution I need either I am able to disable the folder to be created at C:\user or Any other option to authenticated user which will not creat folders.

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  • how close a connection from server side that created by ajax from client side

    - by saeid
    I have this sample php code: <?php function response($a) { @ob_end_clean(); header("Connection: close"); ob_start(); echo $a; $length = ob_get_length(); header("Content-Length: $length"); ob_end_flush(); flush(); } response("test1"); sleep(5); echo "test2"; ?> now I make a connection to server from client by ajax. now I want to server only send "test1" to me and then close the connection. but connection not closed and wait 5 seconds and send me "test1 test2" !! this is response headers from server to me : X-Powered-By: PHP/5.3.27 Connection: close Vary: Accept-Encoding,User-Agent Content-Encoding: gzip Cache-Control: private, no-cache, no-store, ------revalidate, no-transform Transfer-Encoding: chunked Content-Type: text/html in response headers I do not see Content-Length header. is problem for this ?? or if not what I must do now for solving problem ??

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  • std::bad_cast from parent to child?

    - by polyglot
    For simplicity, class Parent {} class Child1 : Parent {} class Child2 : Parent {} Elsewhere, I created instances of Child1 and Child2 and store it in same vector under Parent: // . . . in .h file, for example vector<Parent> vector_of_parent; // . . . in one particular method Child1 c1(); Child2 c2(); vector_of_parent.push_back(c1); vector_of_parent.push_back(c2); // . . . Then in another method which has access to vector_of_parent, I tried void doSomething(Parent& some_child) { // wrapped in a try block somehow... Child1& c = dynamic_cast<Child1&> some_child; // do something if the cast is successful } void otherMethod() { doSomething(vector_of_parent.at(0)); // vector_of_parent.at(0) is a Child1 } Why is there a std:bad_cast when I call otherMethod()?

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  • Stable/repeatable random sort (MySQL, Rails)

    - by Matt Rogish
    I'd like to paginate through a randomly sorted list of ActiveRecord models (rows from MySQL database). However, this randomization needs to persist on a per-session basis, so that other people that visit the website also receive a random, paginate-able list of records. Let's say there are enough entities (tens of thousands) that storing the randomly sorted ID values in either the session or a cookie is too large, so I must temporarily persist it in some other way (MySQL, file, etc.). Initially I thought I could create a function based on the session ID and the page ID (returning the object IDs for that page) however since the object ID values in MySQL are not sequential (there are gaps), that seemed to fall apart as I was poking at it. The nice thing is that it would require no/minimal storage but the downsides are that it is likely pretty complex to implement and probably CPU intensive. My feeling is I should create an intersection table, something like: random_sorts( sort_id, created_at, user_id NULL if guest) random_sort_items( sort_id, item_id, position ) And then simply store the 'sort_id' in the session. Then, I can paginate the random_sorts WHERE sort_id = n ORDER BY position LIMIT... as usual. Of course, I'd have to put some sort of a reaper in there to remove them after some period of inactivity (based on random_sorts.created_at). Unfortunately, I'd have to invalidate the sort as new objects were created (and/or old objects being removed, although deletion is very rare). And, as load increases the size/performance of this table (even properly indexed) drops. It seems like this ought to be a solved problem but I can't find any rails plugins that do this... Any ideas? Thanks!!

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  • Matlab GUI: How to Save the Results of Functions (states of application)

    - by niko
    Hi, I would like to create an animation which enables the user to go backward and forward through the steps of simulation. An animation has to simulate the iterative process of channel decoding (a receiver receives a block of bits, performs an operation and then checks if the block corresponds to parity rules. If the block doesn't correspond the operation is performed again and the process finally ends when the code corresponds to a given rules). I have written the functions which perform the decoding process and return a m x n x i matrix where m x n is the block of data and i is the iteration index. So if it takes 3 iterations to decode the data the function returns a m x n x 3 matrix with each step is stired. In the GUI (.fig file) I put a "decode" button which runs the method for decoding and there are buttons "back" and "forward" which have to enable the user to switch between the data of recorded steps. I have stored the "decodedData" matrix and currentStep value as a global variable so by clicking "forward" and "next" buttons the indices have to change and point to appropriate step states. When I tried to debug the application the method returned the decoded data but when I tried to click "back" and "next" the decoded data appeared not to be declared. Does anyone know how is it possible to access (or store) the results of the functions in order to enable the described logic which I want to implement in Matlab GUI?

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  • Creating new image in a loop using OpenCV

    - by user565415
    I am programing some image conversion code with OpenCV and I don't know how can I create image memory buffer to load image on every iteration. I have number of iteration (maxImNumber) and I have an input image. In every loop program must create image that is resized and modified input image. Here is some basic code (concept). for (int imageIndex = 0; imageIndex < maxImNumber; imageIndex++){ cvCopy(inputImage, images[imageIndex], 0); cvReleaseImage(&inputImage); images[imageIndex+1] = cvCreateImage(cvSize((image[imageIndex]->width)/2, image[imageIndex]->height), IPL_DEPTH_8U, 1); for (i=1; i < image[imageIndex]->height; i++) { index = 0; // for(j=0; j < image[imageIndex]->width ; j=j+2){ // doing some basic matematical operation on image content and store it to new image images[imageIndex+1][i][index] = (image[imageIndex][i][j] + image[imageIndex][i][j+2])/2; index++ } } inputImage = cvCreateImage(cvSize((image[imageIndex+1]->width), image[imageIndex]->height), IPL_DEPTH_8U, 1); cvCopy(images[imageIndex+1], inputImage, 0); } Can somebody, please, explain how can I create this image buffer (images[]) and allocate memory for it. Also how can I access any image in this buffer? Thank you very much in advance!

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  • JavaCard monitoring folder

    - by GxG
    I want to write a two way application: applet for javacard and an application in C#. I've got the C# covered but i want to know if with JavaCard i can monitor a folder on the memory and how would i go about doing that. I have a shared folder let's call it temp in which i want to store buffer information between the simulated smartcard and the C# application. The C# application will only read from that folder and display the information, but also it will write requests towards the smartcard. For example i simulate entering the PIN for the card. The applet will write a file containing available options and the C# application will read that file and display those options; from the C# app i will chose and option and write a request file in the same folder. This is when the smartcard which is monitoring that folder will read the request and issue a response. Can i make the smartcard monitor that folder? I was thinking of using encrypted XML files for the request/response operations. But simple .txt files are good to. I am limited to using JavaCard v2.2.1, and every operation has to be encrypted/decrypted. (with the ciphering i have no problem)

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  • Best solution for __autoload

    - by tpk
    As our PHP5 OO application grew (in both size and traffic), we decided to revisit the __autoload() strategy. We always name the file by the class definition it contains, so class Customer would be contained within Customer.php. We used to list the directories in which a file can potentially exist, until the right .php file was found. This is quite inefficient, because you're potentially going through a number of directories which you don't need to, and doing so on every request (thus, making loads of stat() calls). Solutions that come to my mind... -use a naming convention that dictates the directory name (similar to PEAR). Disadvantages: doesn't scale too great, resulting in horrible class names. -come up with some kind of pre-built array of the locations (propel does this for its __autoload). Disadvantage: requires a rebuild before any deploy of new code. -build the array "on the fly" and cache it. This seems to be the best solution, as it allows for any class names and directory structure you want, and is fully flexible in that new files just get added to the list. The concerns are: where to store it and what about deleted/moved files. For storage we chose APC, as it doesn't have the disk I/O overhead. With regards to file deletes, it doesn't matter, as you probably don't wanna require them anywhere anyway. As to moves... that's unresolved (we ignore it as historically it didn't happen very often for us). Any other solutions?

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  • Simple jQuery syntax help, don't know where I've gone wrong

    - by Jascination
    I'm having trouble with a jQuery code at the moment, I know WHERE the problem lies, but I don't know what the problem is exactly. Probably very basic, but I'm new to this. You can see a (non)working fiddle here: http://www.jsfiddle.net/CvZeQ/ Basically I want to set different .click function based on whatever is selected (I have 5 image maps, each with a different #mapname, and want each to pertain to a different variable (answer1, answer2, answer3...) so as to store the selected 'answer' for each map.) Here is the code I'm using for one of the maps: $(window).load(function(){ //Get cookies when page loaded var useranswers=$.cookie('survery'); useranswers= JSON.parse (useranswers); // do something with previous answers //#shape functions $('#shape area').hover( function(e){ $('#'+ this.alt).addClass('hover'); }, function(e){ $('#'+ this.alt).removeClass('hover'); } ).click( function(e){ $('img.selected-region').removeClass('selected-region'); }, function(e){ $('#'+ this.alt).addClass('selected-region'); }, function(e){ var answer1 = $(this).attr("class"); }); }); I know the problem lies somewhere with the .click function, but I'm not entirely sure what I've done wrong. Any help would be greatly appreciated.

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  • Defining and using controller methods in ember.js

    - by OriginalEXE
    first of all, I am total noob when it comes to OOP in JS, this is new to me so treat me like a noob. I am building my first ember.js application and I am stuck (not the first time but I would get unstuck by myself, this is a tough one though). I have two models: forms entries Entries is of course in (one to many) relationship to forms, so each form can have as many properties. Form properties: id : DS.attr( 'number' ), title : DS.attr( 'string' ), views : DS.attr( 'number' ), conversion : DS.attr( 'number' ), entries : DS.hasMany( 'entry' ) Entry properties: id : DS.attr( 'number' ), parent_id: DS.belongsTo( 'form' ) Now, I have forms route that displays all forms in tabled view, and each table row has some info like form id, name etc. and that works great. What I wanted to do is display the number of entries each form has. I figured I should do that via controller, so here is my controller now: // Form controller App.FormController = Ember.ObjectController.extend({ entriescount: function() { var entries = this.get( 'store').find( 'entry' ); return entries.filterBy( 'parent_id', this.get( 'id' ) ).get( 'length' ); }.property( '[email protected]_id') }); Now for some reason, when I use {{entriescount}} in {{#each}} loop, this returns nothing. It also returns nothing in single form route. Note that in both cases, {{title}} for example works. I am wondering, am I going the right way by using controller for this, and how do I get controller to output the data. Thanks

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  • Having to insert a record, then update the same record warrants 1:1 relationship design?

    - by dianovich
    Let's say an Order has many Line items and we're storing the total cost of an order (based on the sum of prices on order lines) in the orders table. -------------- orders -------------- id ref total_cost -------------- -------------- lines -------------- id order_id price -------------- In a simple application, the order and line are created during the same step of the checkout process. So this means INSERT INTO orders .... -- Get ID of inserted order record INSERT into lines VALUES(null, order_id, ...), ... where we get the order ID after creating the order record. The problem I'm having is trying to figure out the best way to store the total cost of an order. I don't want to have to create an order create lines on an order calculate cost on order based on lines then update record created in 1. in orders table This would mean a nullable total_cost field on orders for starters... My solution thus far is to have an order_totals table with a 1:1 relationship to the orders table. But I think it's redundant. Ideally, since everything required to calculate total costs (lines on an order) is in the database, I would work out the value every time I need it, but this is very expensive. What are your thoughts?

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  • What C# container is most resource-efficient for existence for only one operation?

    - by ccornet
    I find myself often with a situation where I need to perform an operation on a set of properties. The operation can be anything from checking if a particular property matches anything in the set to a single iteration of actions. Sometimes the set is dynamically generated when the function is called, some built with a simple LINQ statement, other times it is a hard-coded set that will always remain the same. But one constant always exists: the set only exists for one single operation and has no use before or after it. My problem is, I have so many points in my application where this is necessary, but I appear to be very, very inconsistent in how I store these sets. Some of them are arrays, some are lists, and just now I've found a couple linked lists. Now, none of the operations I'm specifically concerned about have to care about indices, container size, order, or any other functionality that is bestowed by any of the individual container types. I picked resource efficiency because it's a better idea than flipping coins. I figured, since array size is configured and it's a very elementary container, that might be my best choice, but I figure it is a better idea to ask around. Alternatively, if there's a better choice not out of resource-efficiency but strictly as being a better choice for this kind of situation, that would be nice as well.

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  • how to install a file handle in perl class

    - by Haiyuan Zhang
    please looku up the following code first. #! /usr/bin/perl package foo; sub new { my $pkg = shift; my $self = {}; my $self->{_fd} = undef; bless $self, $pkg; return $self; } sub Setfd { my $self = shift; my $fd = shift; $self_->{_fd} = $fd; } sub write { my $self = shift; print $self->{_fd} "hello word"; } my $foo = new foo; My intention is to store a file handle within a class using hash. the file handle is undefined at first, but can be initilized afterwards by calling Setfd function. then write can be called to actually write string "hello word" to a file indicated by the file handle, supposed that the file handle is the result of a success "write" open. but, perl compiler just complains that there are syntax error in the "print" line. can anyone of you tells me what's wrong here? thanks in advance.

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  • When to define SDD(System Sequence Diagram) operations System->Actor?

    - by devoured elysium
    I am having some trouble understanding how to make System Sequence Diagrams, as I don't fully grasp why in some cases one should define operations for System - Actor and in others don't. Here is an example: Let's assume the System is a Cinema Ticket Store and the Actor is a client that wants to buy a ticket. 1) The User tells the System that wants to buy some tickets, stating his client number. 2) The System confirms that the given client number is valid. 3) The User tells the System the movie that wants to see. 4) The System shows the set of available sessions and seats for that movie. 5) The System asks the user which session/seat he wants. 6) The User tells the System the chosen session/seat. This would be converted to: a) -----> tellClientNumber(clientNumber) b) <----- validClientNumber c) -----> tellMovieToSee(movie) d) <----- showsAvailableSeatsHours e) -----> tellSystemChosenSessionSeat(session, seat) I know that when we are dealing with SDD's we are still far away from coding. But I can't help trying to imagine how it how it would have been had I to convert it right away to code: I can understand 1) and 2). It's like if it was a C#/Java method with the following signature: boolean tellClientNumber(clientNumber) so I put both on the SDD. Then, we have the pair 3) 4). I can imagine that as something as: SomeDataStructureThatHoldsAvailableSessionsSeats tellSystemMovieToSee(movie) Now, the problem: From what I've come to understand, my lecturer says that we shouldn't make an operation on the SDD for 5) as we should only show operations from the Actor to the System and when the System is either presenting us data (as in c)) or validating sent data (such as in b)). I find this odd, as if I try to imagine this like a DOS app where you have to put your input sequencially, it makes sense to make an arrow even for 5). Why is this wrong? How should I try to visualize this? Thanks

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  • [Concept] How does unlink() find the file to delete?

    - by Prasad
    My app has a 'Photo' field to store URL. It uses sfWidgetFormInputFileEditable for the widget schema. To delete the old image when a new image is uploaded, I use unlink before setting the value in the over-ridden setter and it works!!! if (file_exists($this->_get('photo'))) unlink($this->_get('photo')); Photos are stored in uploads/photos and when saving 'Photo' only the file name xxx-yyy.zzz is saved (and not the full path). However, I wish to know how symfony/php knows the full path of the file to be deleted? Part 2: I am using sfThumbnailPlugin to generate thumbnails. So the actual code looks like this: public function setPhoto($value) { if(!empty($value)) { Contact::generateThumbnail($value); // delete current Photo & create thumbnail $this->_set('photo',$value); // setting new value after deleting old one } } public function generateThumbnail($value) { $uploadDir = sfConfig::get('app_photo_upload'); // path to upload folder if (file_exists($this->_get('photo'))) { unlink($this->_get('photo')); // delete full-size image // path to thumbnail $thumbpath = $uploadDir.'/thumbnails/'.$this->get('photo'); // read a blog, tried setting dir manually, doesn't work :( //chdir('/thumbnails/'); // tried closing the file too, doesn't work! :( //fclose($thumbpath) or die("can't close file"); //unlink($this->_get('photo')); // doesn't work; no error :( unlink($thumbpath); // doesn't work, no error :( } $thumbnail = new sfThumbnail(150, 150); $thumbnail->loadFile($uploadDir.'/'.$value); $thumbnail->save($uploadDir.'/thumbnails/'.$value, 'image/png'); } Why can't the thumbnail be deleted using unlink()? is the sequence of ops incorrect? Is it because the old thumbnail is displayed in the sfWidgetFormInputFileEditable widget? I've spent hours trying to figure this out, but unable to nail down the real cause. Thanks in advance.

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