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• Trouble with Unions in C program.

  - by Jordan S

  I am working on a C program that uses a Union. The union definition is in FILE_A header file and looks like this... // FILE_A.h**************************************************** xdata union { long position; char bytes[4]; }CurrentPosition; If I set the value of CurrentPosition.position in FILE_A.c and then call a function in FILE_B.c that uses the union, the data in the union is back to Zero. This is demonstrated below. // FILE_A.c**************************************************** int main.c(void) { CurrentPosition.position = 12345; SomeFunctionInFileB(); } // FILE_B.c**************************************************** void SomeFunctionInFileB(void) { // After the following lines execute I see all zeros in the flash memory. WriteByteToFlash(CurrentPosition.bytes[0]; WriteByteToFlash(CurrentPosition.bytes[1]; WriteByteToFlash(CurrentPosition.bytes[2]; WriteByteToFlash(CurrentPosition.bytes[3]; } Now, If I pass a long to SomeFunctionInFileB(long temp) and then store it into CurrentPosition.bytes within that function, and finally call WriteBytesToFlash(CurrentPosition.bytes[n]... it works just fine. It appears as though the CurrentPosition Union is not global. So I tried changing the union definition in the header file to include the extern keyword like this... extern xdata union { long position; char bytes[4]; }CurrentPosition; and then putting this in the source (.c) file... xdata union { long position; char bytes[4]; }CurrentPosition; but this causes a compile error that says: C:\SiLabs\Optec Programs\AgosRot\MotionControl.c:76: error 91: extern definition for 'CurrentPosition' mismatches with declaration. C:\SiLabs\Optec Programs\AgosRot\/MotionControl.h:48: error 177: previously defined here So what am I doing wrong? How do I make the union global?

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• Handling responses in libcurl

  - by sfactor

  i have a code to send a Form Post with login credentials to a webpage. it looks like this CURL *curl; CURLcode res; struct curl_httppost *formpost=NULL; struct curl_httppost *lastptr=NULL; struct curl_slist *headerlist=NULL; static const char buf[] = "Expect:"; curl_global_init(CURL_GLOBAL_ALL); /* Fill in the username */ curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "user", CURLFORM_COPYCONTENTS, "username", CURLFORM_END); /* Fill in the password */ curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "pass", CURLFORM_COPYCONTENTS, "password", CURLFORM_END); /* Fill in the submit field too, even if this is rarely needed */ curl_formadd(&formpost, &lastptr, CURLFORM_COPYNAME, "submit", CURLFORM_COPYCONTENTS, "send", CURLFORM_END); curl = curl_easy_init(); /* initalize custom header list (stating that Expect: 100-continue is not wanted */ headerlist = curl_slist_append(headerlist, buf); if(curl) { /* what URL that receives this POST */ curl_easy_setopt(curl, CURLOPT_URL, "http://127.0.0.1:8000/index.html"); /* only disable 100-continue header if explicitly requested */ curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist); curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost); res = curl_easy_perform(curl); /* always cleanup */ curl_easy_cleanup(curl); /* then cleanup the formpost chain */ curl_formfree(formpost); /* free slist */ curl_slist_free_all (headerlist); } now i need to know is how do i handle the responses i get back from the server? i need to store the response into a string and then work on it.

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• How to implement generic callbacks in C++

  - by Kylotan

  Forgive my ignorance in asking this basic question but I've become so used to using Python where this sort of thing is trivial that I've completely forgotten how I would attempt this in C++. I want to be able to pass a callback to a function that performs a slow process in the background, and have it called later when the process is complete. This callback could be a free function, a static function, or a member function. I'd also like to be able to inject some arbitrary arguments in there for context. (ie. Implementing a very poor man's coroutine, in a way.) On top of that, this function will always take a std::string, which is the output of the process. I don't mind if the position of this argument in the final callback parameter list is fixed. I get the feeling that the answer will involve boost::bind and boost::function but I can't work out the precise invocations that would be necessary in order to create arbitrary callables (while currying them to just take a single string), store them in the background process, and invoke the callable correctly with the string parameter.

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• function pointers callbacks C

  - by robUK

  Hello, I have started to review callbacks. I found this link: http://stackoverflow.com/questions/142789/what-is-a-callback-in-c-and-how-are-they-implemented which has a good example of callback which is very similar to what we use at work. However, I have tried to get it to work, but I have many errors. #include <stdio.h> /* Is the actual function pointer? */ typedef void (*event_cb_t)(const struct event *evt, void *user_data); struct event_cb { event_cb_t cb; void *data; }; int event_cb_register(event_ct_t cb, void *user_data); static void my_event_cb(const struct event *evt, void *data) { /* do some stuff */ } int main(void) { event_cb_register(my_event_cb, &my_custom_data); struct event_cb *callback; callback->cb(event, callback->data); return 0; } I know that callback use function pointers to store an address of a function. But there is a few things that I find I don't understand. That is what is meet by "registering the callback" and "event dispatcher"? Many thanks for any advice,

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• Recycle Freed Objects

  - by uray

  suppose I need to allocate and delete object on heap frequently (of arbitrary size), is there any performance benefit if instead of deleting those objects, I will return it back to some "pool" to be reused later? would it give benefit by reduce heap allocation/deallocation?, or it will be slower compared to memory allocator performance, since the "pool" need to manage a dynamic collection of pointers. my use case: suppose I create a queue container based on linked list, and each node of that list are allocated on the heap, so every call to push() and pop() will allocate and deallocate that node: ` template <typename T> struct QueueNode { QueueNode<T>* next; T object; } template <typename T> class Queue { void push(T object) { QueueNode<T>* newNode = QueueNodePool<T>::get(); //get recycled node if(!newNode) { newNode = new QueueNode<T>(object); } // push newNode routine here.. } T pop() { //pop routine here... QueueNodePool<T>::store(unusedNode); //recycle node return unusedNode->object; } } `

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• How to troubleshoot memcache set method always fail issue?

  - by Morgan Cheng

  I have XAMPP 1.7.3 installed on Windows 7. The PHP version is 5.3.1. I have successfully installed memcache for win32 from http://www.splinedancer.com/memcached-win32. I got PHP extension php_memcache.dll from http://downloads.php.net/pierre. Restarting apache and checking phpinfo() shows memcache is OK. When I test it with below PHP page. It always fail in set method. <?php $memcache = new Memcache; $memcache->connect('127.0.0.1', 11211) or die ("Could not connect"); $version = $memcache->getVersion(); echo "Server's version: ".$version." \n"; $tmp_object = new stdClass; $tmp_object->str_attr = 'test'; $tmp_object->int_attr = 123; $memcache->set('key', $tmp_object, false, 10) or die ("Failed to save data at the server"); echo "Store data in the cache (data will expire in 10 seconds)\n"; $get_result = $memcache->get('key'); echo "Data from the cache: \n" ?> The set method always return false so it constantly output Server's version: Failed to save data at the server I'm stuck. I don't know which way to trouble shoot this issue. Anybody has any idea about possible direction? Thanks.

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• Content Management Systems for Adaptive Content [closed]

  - by andrewap

  Content management systems (CMS) allow us to easily maintain blogs, news sites, general websites, and so on. Many of them are designed to manage pages of content, and provide tools to organize and customize how that content is displayed on the web. However, as explained by Mark Boulton in his Adaptive Content Management article, and by Karen McGrane in her talk on Adapting Ourselves to Adaptive Content, we are increasingly delivering content not just to the web, but also to other platforms and channels. We need tools to manage pieces of content with meaningful metadata attached. Create once, publish everywhere. The main idea is to store content cleanly, without intertwining it with presentation markup specific to the web. Because pieces of content is compartmentalized semantically, it can easily adapt to fit in different platforms and channels. Hence, it's called adaptive content. Let's look at a quick example to compare: Say I manage news articles and events. To create a news article, I would tell the CMS the type of content I'm creating, and be asked to fill in a form with individual fields tailored to news articles (e.g. headline, subtitle, full text, short snippet, and images). — i.e. pieces of content With a traditional web publishing tool, I would probably have had to create a new page under News, and then type in and format the news article in a blank WYSIWYG text editor. — i.e. pages of content As you can see, the first design allows me to individually specify content in its smallest semantic unit. When I want to display or consume it, the system can easily provide the pieces I need. So here's my question: Is there a CMS that is designed specifically with adaptive content in mind, and that is decoupled with the presentation layer? Note: This is not a discussion about the best CMS, or which CMS I should use. I am asking whether a very specific type of tool — CMS designed for adaptive content — exists for developers to use.

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• Google Analytics Script inside XML File

  - by mnml

  Hi, I would like to know If I can add my ecommerce analytics tags inside an xml formated file? <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <script type="text/javascript"> var _gaq = _gaq || []; _gaq.push(['_setAccount', 'UA-XXXXX-X']); _gaq.push(['_trackPageview']); _gaq.push(['_addTrans', '1234', // order ID - required 'Acme Clothing', // affiliation or store name '11.99', // total - required '1.29', // tax '5', // shipping 'San Jose', // city 'California', // state or province 'USA' // country ]); // add item might be called for every item in the shopping cart // where your ecommerce engine loops through each item in the cart and // prints out _addItem for each _gaq.push(['_addItem', '1234', // order ID - required 'DD44', // SKU/code 'T-Shirt', // product name 'Green Medium', // category or variation '11.99', // unit price - required '1' // quantity - required ]); _gaq.push(['_trackTrans']); //submits transaction to the Analytics servers (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(ga); })(); </script>

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• Downloading Spreadsheets From Google Docs

  - by jeremynealbrown

  Hello, I am working on an Android app that uses the gdata-java-client to download documents for display only. So far I have an application that authenticates with the services and displays a list of user documents. When the user selects a document another query is made for the documents itself. A request for txt, html, rtf and doc files works well, however when I request a spreadsheet in either .csv or .xsl format the result is unexpected. I'm using an HTTPResponse object to store the result of a an HTTPRequest. When I request a document in .csv or .xsl format the HTTPResponse.parseAsString() method produces an entire html page which appears to be the Google Docs home page. Sounds strange, but the result is the actual html for the login page. The HTTPResponse.getStatusMessage returns a 200. Seems like I am missing something simple here. Is there another property of the HTTPResponse that contains the .csv data? I am pretty sure that I am using the correct uri for downloading spreadsheets because it works when I download through my browser. In any case here is an example uri: https://spreadsheets.google.com/feeds/download/spreadsheets/Export?key=0AsE_6_YIr797dHBTUWlHMUFXeTV4ZzJlUGxWRnJXanc&exportFormat=csv Thanks in advance for any help :)

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• How to change scope data in controller?

  - by Derooie

  I am a real newbie at angular. I created something now which will let me retrieve and add items via angular and get/put them in mongodb. I use express and mongoose in the app The question is, how can i modify the data before it reaches the DOM in the controller. In this example i have created a way to retrieve data, and i get it exactly as it is stored in mongodb. What i would like is that the field where i store 1 or 0 in the database, to be shown as text. So if mongo has a value 1 i get "the value in mongo is 1" and when the field has a value of 0 get "the value is zero". (just as an example, i like other texts, but it illustrate what i want) I post my controller, html and current output. Any help would be appreciated. Controller function getGuests($scope, $http) { $scope.formData = {}; $http.get('/api/guests') .success(function(data) { $scope.x = data; }) .error(function(data) { console.log('Error: ' + data); }); } HTML <div ng-controller="getGuests"> <div ng-repeat="guest in x"> {{ guest.voornaam }} {{ guest.aanwezig }} </div> </div> The current scope output, what i see in HTML. I like to change only the value of "aanwezig" in case the value of aanwezig is 0 or 1. firstname1 1 firstname2 0 Something else, but would be great to learn, is how i can do a specific mongodb query by the push of a button and get that result.

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• Silverlight Socket Constantly Returns With Empty Buffer

  - by Benny

  I am using Silverlight to interact with a proxy application that I have developed but, without the proxy sending a message to the Silverlight application, it executes the receive completed handler with an empty buffer ('\0's). Is there something I'm doing wrong? It is causing a major memory leak. this._rawBuffer = new Byte[this.BUFFER_SIZE]; SocketAsyncEventArgs receiveArgs = new SocketAsyncEventArgs(); receiveArgs.SetBuffer(_rawBuffer, 0, _rawBuffer.Length); receiveArgs.Completed += new EventHandler<SocketAsyncEventArgs>(ReceiveComplete); this._client.ReceiveAsync(receiveArgs); if (args.SocketError == SocketError.Success && args.LastOperation == SocketAsyncOperation.Receive) { // Read the current bytes from the stream buffer int bytesRecieved = this._client.ReceiveBufferSize; // If there are bytes to process else the connection is lost if (bytesRecieved > 0) { try { //Find out what we just received string messagePart = UTF8Encoding.UTF8.GetString(_rawBuffer, 0, _rawBuffer.GetLength(0)); //Take out any trailing empty characters from the message messagePart = messagePart.Replace('\0'.ToString(), ""); //Concatenate our current message with any leftovers from previous receipts string fullMessage = _theRest + messagePart; int seperator; //While the index of the seperator (LINE_END defined & initiated as private member) while ((seperator = fullMessage.IndexOf((char)Messages.MessageSeperator.Terminator)) > 0) { //Pull out the first message available (up to the seperator index string message = fullMessage.Substring(0, seperator); //Queue up our new message _messageQueue.Enqueue(message); //Take out our line end character fullMessage = fullMessage.Remove(0, seperator + 1); } //Save whatever was NOT a full message to the private variable used to store the rest _theRest = fullMessage; //Empty the queue of messages if there are any while (this._messageQueue.Count > 0) { ... } } catch (Exception e) { throw e; } // Wait for a new message if (this._isClosing != true) Receive(); } } Thanks in advance.

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• Drupal Studs help me with my form_alter hook ( I am almost there)

  - by user363036

  So I think I am almost there conceptually but need some missing pointers. Objective is to add a few more fields to the normal user registration form, style it a little, then submit it with storing the extra fields in a table. This is what I have so far. Can someone give me the final nudge and get me going. Please help me. Also how do I apply some minor styling like aligning the new form fields ? Thank you so much !!!!!!!!! function module_menu() { $items = array(); $items['school/registration'] = array( 'title' = 'Upgraded Registration Form', 'page callback' ='module_school_register', 'type' = MENU_CALLBACK ); return $items; }//end of the function function module_school_register(){ return drupal_get_form('form_school_register'); }//end of the function function module_school_form_alter(&$form, $form_state, $form_id) { dsm($form_id); if ($form_id == 'user_registration_form') { // modify the "#submit" form property by prepending another submit handler array $form['#submit'] = array_merge( array('_module_registration_submit' = array()), $form['#submit'] ); } } function _module_registration_submit($form_id, $form_values) { // store extra data in different table } function module_registration_validate($form, &$form_state) { $error=0; //Validation stuff here, set $error to true if something went wrong, or however u want to do this. Completely up to u in how u set errors. if ($error) { form_set_error('new_field_name', 'AHH SOMETHING WRONG!'); } }

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• PHP: What is an efficient way to parse a text file containing very long lines?

  - by Shaun

  I'm working on a parser in php which is designed to extract MySQL records out of a text file. A particular line might begin with a string corresponding to which table the records (rows) need to be inserted into, followed by the records themselves. The records are delimited by a backslash and the fields (columns) are separated by commas. For the sake of simplicity, let's assume that we have a table representing people in our database, with fields being First Name, Last Name, and Occupation. Thus, one line of the file might be as follows [People] = "\Han,Solo,Smuggler\Luke,Skywalker,Jedi..." Where the ellipses (...) could be additional people. One straightforward approach might be to use fgets() to extract a line from the file, and use preg_match() to extract the table name, records, and fields from that line. However, let's suppose that we have an awful lot of Star Wars characters to track. So many, in fact, that this line ends up being 200,000+ characters/bytes long. In such a case, taking the above approach to extract the database information seems a bit inefficient. You have to first read hundreds of thousands of characters into memory, then read back over those same characters to find regex matches. Is there a way, similar to the Java String next(String pattern) method of the Scanner class constructed using a file, that allows you to match patterns in-line while scanning through the file? The idea is that you don't have to scan through the same text twice (to read it from the file into a string, and then to match patterns) or store the text redundantly in memory (in both the file line string and the matched patterns). Would this even yield a significant increase in performance? It's hard to tell exactly what PHP or Java are doing behind the scenes.

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• Having trouble creating vectors of System::String^

  - by Justen

  So I have a regex expression to parse certain parts of a file name. I'm trying to store each part in its own vector until I use it later, but it won't let me. One error I get when I try making a vector of System::String^ is that error C3698: 'System::String ^' : cannot use this type as argument of 'new' Then, when I try just making a vector of std::string, it can't implicitly convert to type System::String^, and casting won't work either. void parseData() { System::String^ pattern = "(\\D+)(\\d+)(\\w{1})(\\d+)\\.(\\D{3})"; std::vector < System::String^ > x, y, filename, separator; Regex re( pattern ); for ( int i = 0; i < openFileDialog1->FileNames->Length; i++ ) { Match^ m = re.Match( openFileDialog1->FileNames[i] ); filename.push_back( m->Groups[0]->Value );/* x.push_back( m->Groups[1]->Value ); separator.push_back( m->Groups[2]->Value ); y.push_back( m->Groups[3]->Value );*/ } }

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• Working with complex objects in Prevayler commands

  - by alexantd

  The demos included in the Prevayler distribution show how to pass in a couple strings (or something simple like that) into a command constructor in order to create or update an object. The problem is that I have an object called MyObject that has a lot of fields. If I had to pass all of them into the CreateMyObject command manually, it would be a pain. So an alternative I thought of is to pass my business object itself into the command, but to hang onto a clone of it (keeping in mind that I can't store the BO directly in the command). Of course after executing this command, I would need to make sure to dispose of the original copy that I passed in. public class CreateMyObject implements TransactionWithQuery { private MyObject object; public CreateMyObject(MyObject business_obj) { this.object = (MyObject) business_obj.clone(); } public Object executeAndQuery(...) throws Exception { ... } } The Prevayler wiki says: Transactions can't carry direct object references (pointers) to business objects. This has become known as the baptism problem because it's a common beginner pitfall. Direct object references don't work because once a transaction has been serialized to the journal and then deserialized for execution its object references no longer refer to the intended objects - - any objects they may have referred to at first will have been copied by the serialization process! Therefore, a transaction must carry some kind of string or numeric identifiers for any objects it wants to refer to, and it must look up the objects when it is executed. I think by cloning the passed-in object I will be getting around the "direct object pointer" problem, but I still don't know whether or not this is a good idea...

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• propositional theorems

  - by gcc

  wang's theorem to prove theorems in propositonal calculus Label Sequent Comment S1: P ? Q, Q ? R, ¬R ? ¬P Initial sequent. S2: ¬P ? Q, ¬Q ? R, ¬R ? ¬P Two applications of R5. S3: ¬P ? Q, ¬Q ? R ? ¬P, R Rl. S4: ¬P, ¬Q ? R ? ¬P, R S4 and S5 are obtained from S3 with R3. Note that S4 is an axiom since P appears on both sides of the sequent ar- row at the top level. S5: Q, ¬Q ? R ? ¬P, R The other sequent generated by the ap- plication of R3. S6: Q, ¬Q ? ¬P, R S6 and S7 are obtained from S5 using R3. S7: Q, R ? ¬P, R This is an axiom. S8: Q ? ¬P, R, Q Obtained from S6 using R1. S8 is an axiom. The original sequent is now proved, since it has successfully been transformed into a set of three axioms with no unproved sequents left over. //R1,R2,R3,R4,R5 is transformation myhomework is so complicate as you can see and i must finish homework in 4 days i just want help ,can you show me how i should construct the algorithm or how i should take and store the input

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• How to stay DRY when using both Javascript and ERB templates (Rails)

  - by user94154

  I'm building a Rails app that uses Pusher to use web sockets to push updates to directly to the client. In javascript: channel.bind('tweet-create', function(tweet){ //when a tweet is created, execute the following code: $('#timeline').append("<div class='tweet'><div class='tweeter'>"+tweet.username+"</div>"+tweet.status+"</div>"); }); This is nasty mixing of code and presentation. So the natural solution would be to use a javascript template. Perhaps eco or mustache: //store this somewhere convenient, perhaps in the view folder: tweet_view = "<div class='tweet'><div class='tweeter'>{{tweet.username}}</div>{{tweet.status}}</div>" channel.bind('tweet-create', function(tweet){ //when a tweet is created, execute the following code: $('#timeline').append(Mustache.to_html(tweet_view, tweet)); //much cleaner }); This is good and all, except, I'm repeating myself. The mustache template is 99% identical to the ERB templates I already have written to render HTML from the server. The intended output/purpose of the mustache and ERB templates are 100% the same: to turn a tweet object into tweet html. What is the best way to eliminate this repetition? UPDATE: Even though I answered my own question, I really want to see other ideas/solutions from other people--hence the bounty!

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• Can I use a keyPath in a predicate?

  - by dontWatchMyProfile

  For some reason, this didn't work (although the keypath does exist): NSPredicate *predicate = [NSPredicate predicateWithFormat:@"department.departmentName == %@", departmentName]; [fetchRequest setPredicate:predicate]; NSError *fetchError = nil; NSUInteger count = [moc countForFetchRequest:fetchRequest error:&fetchError]; // execution simply stops at this line, with no error or console log Execution just stops at the last line above when asking for the count. I don't get an console log. Also I don't get any kind of exception. The execution just stops. There are no objects in the persistent store yet. So maybe it crashes because of it tries to follow a keypath in a nonexisting object? Does that make sense? The line where GDB stops is this: 0x002a31cb <+0459> test %eax,%eax Previously to that, I see a lot of NSSQLAdapter... calls in the stack trace. There's definitely something wrong. Well, but when I set the Entity to the destination of the key path and then just do something like NSPredicate *predicate = [NSPredicate predicateWithFormat:@"departmentName == %@", departmentName]; then there is no problem and count simply is 0.

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• php parsing speed optimization

  - by Arnaud

  I would like to add tooltip or generate link according to the element available in the database, for exemple if the html page printed is: to reboot your linux host in single-user mode you can ... I will use explode(" ", $row[page]) and the idea is now to lookup for every single word in the page to find out if they have a related referance in this exemple let's say i've got a table referance an one entry for reboot and one for linux reboot: restart a computeur linux: operating system now my output will look like (replaced < and by @) to @a href="ref/reboot"@reboot@/a@ your @a href="ref/linux"@linux@/a@ host in single-user mode you can ... Instead of have a static list generated when I saved the content, if I add more keyword in the future, then the text will become more interactive. My main concerne and question is how can I create a efficient enough process to do it ? Should I store all the db entry in an array and compare them ? Do an sql query for each word (seems to be crazy) Dump the table in a file and use a very long regex or a "grep -f pattern data" way of doing it? Or or or or I'm sure it must be a better way of doing it, just don't have a clue about it, or maybe this will be far too resource un-friendly and I should avoid doing such things. Cheers!

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• gen_server with a dict vs mnesia table vs ets

  - by pablo

  Hi, I'm building an erlang server. Users sends http requests to the server to update their status. The http request process on the server saves the user status message in memory. Every minute the server sends all messages to a remote server and clear the memory. If a user update his status several times in a minute, the last message overrides the previous one. It is important that between reading all the messages and clearing them no other process will be able to write a status message. What is the best way to implement it? gen_server with a dict. The key will be the userid. dict:store/3 will update or create the status. The gen_server solves the 'transaction' issue. mnesia table with ram_copies. Handle transactions and I don't need to implement a gen_server. Is there too much overhead with this solution? ETS table which is more light weight and have a gen_server. Is it possible to do the transaction in ETS? To lock the table between reading all the messages and clearing them? Thanks

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• Filtering on a left join in SQLalchemy

  - by Adam Ernst

  Using SQLalchemy I want to perform a left outer join and filter out rows that DO have a match in the joined table. I'm sending push notifications, so I have a Notification table. This means I also have a ExpiredDeviceId table to store device_ids that are no longer valid. (I don't want to just delete the affected notifications as the user might later re-install the app, at which point the notifications should resume according to Apple's docs.) CREATE TABLE Notification (device_id TEXT, time DATETIME); CREATE TABLE ExpiredDeviceId (device_id TEXT PRIMARY KEY, expiration_time DATETIME); Note: there may be multiple Notifications per device_id. There is no "Device" table for each device. So when doing SELECT FROM Notification I should filter accordingly. I can do it in SQL: SELECT * FROM Notification LEFT OUTER JOIN ExpiredDeviceId ON Notification.device_id = ExpiredDeviceId.device_id WHERE expiration_time == NULL But how can I do it in SQLalchemy? sess.query( Notification, ExpiredDeviceId ).outerjoin( (ExpiredDeviceId, Notification.device_id == ExpiredDeviceId.device_id) ).filter( ??? ) Alternately I could do this with a device_id NOT IN (SELECT device_id FROM ExpiredDeviceId) clause, but that seems way less efficient.

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• converting a timestring to a duration

  - by radman

  Hi, At the moment I am trying to read in a timestring formatted and create a duration from that. I am currently trying to use the boost date_time time_duration class to read and store the value. boost date_time provides a method time_duration duration_from_string(std::string) that allows a time_duration to be created from a time string and it accepts strings formatted appropriately ("[-]h[h][:mm][:ss][.fff]".). Now this method works fine if you use a correctly formatted time string. However if you submit something invalid like "ham_sandwich" or "100" then you will still be returned a time_duration that is not valid. Specifically if you try to pass it to a standard output stream then an assertion will occur. My question is: Does anyone know how to test the validity of the boost time_duration? and failing that can you suggest another method of reading a timestring and getting a duration from it? Note: I have tried the obvious testing methods that time_duration provides; is_not_a_date_time(), is_special() etc and they don't pick up that there is an issue. Using boost 1.38.0

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• using dummy row with NOT NULL to solve DEFAULT NULL

  - by Tony38

  I know having DEFAULT NULLS is not a good practice but I have many optional lookup values which are FK in the system so to solve this issue here is what i am doing: I use NOT NULL for every FK / lookup colunms. I have the first row in every lookup table which is PK id = 1 as a dummy row with just "none" in all the columns. This way I can use NOT NULL in my schema and if needed reference to the none row values PK =1 for FKs which do not have any lookup value. Is this a good design or any other work arounds? EDIT: I have: Neighborhood table Postal table. Every neighborhood has a city, so the FK can be NOT NULL. But not every postal code belongs to a neighborhood. Some do, some don't depending on the country. So if i use NOT NULL for the FK between postal and neighborhood then I will be screwed as there has to be some value entered. So what i am doing in essence is: have a row in every table to be a dummy row just to link the FKs. This way row one in neighborhood table will be: n_id = 1 name =none etc... In postal table I can have: postal_code = 3456A3 FK (city) = Moscow FK (neighborhood_id)=1 as a NOT NULL. If I don't have a dummy row in the neighborhood lookup table then I have to declare FK (neighborhood_id) as a Default null column and store blanks in the table. This is an example but there is a huge number of values which will have blanks then in many tables.

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• smallest mysql type that accomodates single decimal

  - by donpal

  Database newbie here. I'm setting up a mysql table. One of the fields will accept a value in increment of a 0.5. e.g. 0.5, 1.0, 1.5, 2.0, .... 200.5, etc. I've tried int but it doesn't capture the decimals. `value` int(10), What would be the smallest type that can accommodate this value, considering it's only a single decimal. I also was considering that because the decimal will always be 0.5 if at all, I could store it in a separate boolean field? So I would have 2 fields instead. Is this a stupid or somewhat over complicated idea? I don't know if it really saves me any memory, and it might get slower now that I'm accessing 2 fields instead of 1 `value` int(10), `half` bool, //or something similar to boolean What are your suggestions guys? Is the first option better, and what's the smallest data type in that case that would get me the 0.5?

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• ExtJs Grid in TabPanel auto Fit issue.

  - by Jinah Adam

  Hi, I am having problems redering an grid in a a tab panel (Its made with Ext Designer.). the hierarchy is as follows , Viewport. - tabPanel - Panel - Container - Grid. This is how its displayed now Here is the code for viewport mainWindowUi = Ext.extend(Ext.Viewport, { layout: 'border', id: 'mainWindow', initComponent: function() { this.items = [ { xtype: 'panel', title: 'Navigation', region: 'west', width: 200, frame: true, split: true, titleCollapse: true, collapsible: true, id: 'navigation', items: [ { flex: 1, xtype: 'mytreepanel' } ] }, { xtype: 'tabpanel', layoutOnTabChange: true, resizeTabs: true, defaults: { layout: 'fit', autoScroll: true }, region: 'center', tpl: '', id: 'mainTabPanel', layoutConfig: { deferredRender: true } } ]; mainWindowUi.superclass.initComponent.call(this); } }); here is the code to create the tab.. (created from a nav panel programmatically) var currentTab = tabPanel.findById(node.id); // If not yet created, create the tab if (!currentTab){ currentTab = tabPanel.add({ title:node.id, id:node.id, closable:true, items:[{ xtype: 'phasePanel', layout: 'fit', autoscroll: true, }], autoScroll:true, }); } // Activate tab tabPanel.setActiveTab(currentTab); here is the code for the panel/container/grid PhasePanelUi = Ext.extend(Ext.Panel, { frame: true, layout: 'anchor', autoScroll: true, autoWidth: true, defaults: '', initComponent: function() { this.items = [ { xtype: 'container', autoScroll: true, layout: 'fit', defaults: { layout: 'fit', autoScroll: true }, id: 'gridHolder', items: [ { xtype: 'grid', title: 'Current Phases', store: 'PhaseStore', autoDestroy: false, viewConfig: '', deferRowRender: false, autoLoad: '', ref: '../phaseGrid', id: 'phaseGrid', columns: [ { xtype: 'gridcolumn', header: 'Name', dataIndex: 'name', sortable: true, width: 200 }, { xtype: 'gridcolumn', header: 'Estate', dataIndex: 'estate_name', sortable: true, width: 500 } ] } ] } ]; PhasePanelUi.superclass.initComponent.call(this); } }); i have tried all sorts of combinations. but just cant get the grid to render correctly any sort of assistance will be appreciated.

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