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  • Resetting Objects vs. Constructing New Objects

    - by byronh
    Is it considered better practice and/or more efficient to create a 'reset' function for a particular object that clears/defaults all the necessary member variables to allow for further operations, or to simply construct a new object from outside? I've seen both methods employed a lot, but I can't decide which one is better. Of course, for classes that represent database connections, you'd have to use a reset method rather than constructing a new one resulting in needless connecting/disconnecting, but I'm talking more in terms of abstraction classes. Can anyone give me some real-world examples of when to use each method? In my particular case I'm thinking mostly in terms of ORM or the Model in MVC. For example, if I would want to retrieve a bunch of database objects for display and modify them in one operation.

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  • session management: problem displaying username in the header

    - by aeonsleo
    hi, I am working on a simple login and logout module for my website without any security. I am using wamp on a windows xp machine. I am creating session when a user submits the login informaton it redirects to a process.php file which creates the session variables and starts session. Now if the login is successful user is redirected to the welcome page which includes a header file(which displays the header involving signin logout help options) The problem is the header is not changing the signin link to logout as the user logs successfully. The below code is from process.php which initiates a login. $username = $_POST['username']; $password = $_POST['password']; //echo "{$username}:{$password}"; $connection = mysql_connect("localhost","root",""); if(!$connection) { die("Database Connection Failed".mysql_error()); } $db_select = mysql_select_db("tester",$connection); if(!$db_select) { die("Database Selection Failed".mysql_error()); } $result = mysql_query("SELECT * FROM user",$connection); if(!$result) { die("Database Selection Failed".mysql_error()); } $q = "SELECT * FROM user " ."WHERE Name='".$username."' AND Password='".$password. "' "; // Run query $r = mysql_query($q); if ( $obj = @mysql_fetch_object($r) ) { session_start(); // Login good, create session variables $_SESSION["valid_id"] = session_id(); $_SESSION["valid_user"] = $_POST["username"]; $_SESSION["valid_time"] = time(); Header('Location: welcome.php'); The following code is from header.php which is included in welcome.php </div> <div id = "userdetail"> <?php if(isset($_SESSION["valid_user"])) { echo($_SESSION["valid_user"]." " ); echo("<a href=logout.php>Logout</a>"); } else { echo("<a href = login.php>Sign In</a>"); } ?> | Help | Search <input type = "text" name = "searchbox" value = "" /> </div> </div>

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  • MySQL driver for Rails in Windows 7 x64

    - by Darth
    I've got problem with connecting to MySQL database on my freshly installed Windows 7 machine. I'm getting this error when I try to migrate my database. !!! The bundled mysql.rb driver has been removed from Rails 2.2. Please install the mysql gem and try again: gem install mysql. rake aborted! 193: %1 is not valid Win32 application - C:/Ruby/lib/ruby/gems/1.8/gems/mysql-2.8.1-x86-mswin32/lib/1.8/mysql_api.so I currently have installed ruby 1.8.6 (2008-08-11 patchlevel 287) [i386-mswin32] mysql version 5.0.86 for Win64 gem 1.3.1 mysql-2.8.1-x86-mswin32

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  • Changing Data in ListView

    - by legr3c
    Hi In my app I use a ListView to display data from the database. The data changes sometimes, for example when the user applies new filters or changes the sorting method. I use AsyncTask to get the databsase cursor that points to the new data set because sometimes data needs to be loaded from the net which can take some time. What I do now looks something like this: private class updateTask extends AsyncTask<Void, Void, Void> { /* * runs on the UI thread before doInBackground */ @Override protected void onPreExecute(){ // prepare some stuff... } /* * runs in a separate thread * used for time-consuming loading operation */ @Override protected Void doInBackground() { //get new database cursor mCursor = mDbAdapter.getCursor(); return null; } /* * runs on the UI thread after doInBackground */ @Override protected void onPostExecute(Void result){ if(mCursor!=null){ MyActivity.this.startManagingCursor(mCursor); mCursorAdapter = new MyCustomCursorAdapter(MyActivity.this, mCursor); mListView.setAdapter(mCursorAdapter); } } } This works so far but I realize that creating a new CursorAdapter and calling setAdapter on my ListView each time isn't the correct way to do it. Also, after setAdapter the scroll position of the list is set back to the top. I found this post which describes how to do it properly. So now I want to do something like this: onCreate(){ // ... // create the CursorAdapter using null as the initial cursor MyCustomCursorAdapter cursorAdapter = new MyCustomCursorAdapter(this, null); mListView.setAdapter(cursorAdapter); // ... } private class updateTask extends AsyncTask<Void, Void, Void> { /* * runs on the UI thread before doInBackground */ @Override protected void onPreExecute(){ // prepare some stuff... } /* * runs in a separate thread * used for time-consuming loading operation */ @Override protected Void doInBackground() { //get new database cursor mCursor = mDbAdapter.getCursor(); return null; } /* * runs on the UI thread after doInBackground */ @Override protected void onPostExecute(Void result){ // this returns null! MyCustomCursorAdapter cursorAdapter = (MyCustomCursorAdapter)mListView.getAdapter(); Cursor oldCursor = cursorAdapter.getCursor(); if(oldCursor!=null){ MyActivity.this.stopManagingCursor(oldCursor); oldCursor.close(); } if(mCursor!=null){ MyActivity.this.startManagingCursor(mCursor); cursorAdapter.changeCursor(mCursor); } } } This however doesn't work for me because (MyCustomCursorAdapter)mListView.getAdapter(); always returns null. Why does this happen? What am I doing wrong? Edit: Some additional information: my adapter implements SectionIndexer. I don't really think that this has anything to do with my problem but it has caused me some troubles before so I thought I'd mention it.

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  • Populate FILE field with default text

    - by dclowd9901
    I'm trying to reutilize code that generates FILE fields for use when something is to be added to the database, and grayed out (and disabled) with data already in the database when the item in question is being edited or viewed in detail. However, I can't seem to get the text to fill the field. I'm using this: echo '<input type="file" name="small[]" value="' . $value_from_database . '" DISABLED><br>'; Am I missing anything? If not, are there any decent workarounds?

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  • Syncing a table records with a Service response frequently

    - by Karthik Dheeraj
    I am requesting data from a service whose response in stored in a database.First, I have an empty table, whenever I make my very first request the records from the service comes to my database table. from now, whenever I make second request, the service will provide me some records which may be same as my first response, may be new records, may be updated records etc. my query is to how to update my table with respect to the responses coming from the service during my second request on-wards? so that Unchanged records will remain same, New records will be added, updated records will be updated.Do I need to write any stored procedure on my DB or any workaround ?what might be the scenario if I use Nomysql DB's like mongo DB ? Thanks In Advance.

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  • Loading a datagrid with large amounts of data in silverlight?

    - by JD
    Hi I am breaking up my project in small sections and one of the sections involves loading a grid with possibily lots of records (could be up to 1000s of records in the database). Ideally I would like some sort of mechanism where as the users scrolls the grid, more data is retrieved. I have read that certain controls (datapager with RIA) do this but I would like to know how I could implement this myself or do something similiar? I was thinking about first loading 50 records at a time and when the user gets to scroll near the 50th record, then get another 50 as a start and so on. Not sure how I do this but this does not feel right or whether I should load ids of records in the grid and then get each row to load itself via an async thread but then I am hitting my database for each record? Thanks JD.

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  • How and when to log account access login with PHP?

    - by Nazgulled
    I want to implement a basic login system in some PHP app where no cookies will be involved. I mean, the user closes the browser and the login expires, it will remain active during the browser session (or if the user explicitly logs out) otherwise. I want to log all this activity and I'm thinking that every time the user refreshes the page, opens a different link or logs out, I record that time as the last access made by that user, overwriting the previous access log. But my problem is when and how should I insert another record into the database instead of overwriting the last one? Should I just define a timeout and if the last access was made above that timeout, another log should be inserted into the database? Should the session expire too after that timeout? Or is there a better way? Ideally, I would like to log the "log out action" when the browser was closed, but I don't think there's a way to detect that is there? Suggestions?

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  • Using Durable Services for saving wcf instances

    - by miker169
    I am currently creating a service which connects to a DAL and that can run a few stored procedures, one of the issues I am facing is that for certain times of the month, we can't update the database, (at the moment this is done manually. This is done via the user adding a note to their calendar) But I would like to automate this process, one of the possible solutions I can think of using is a durable service. When the date is lets say the 1st of the month, the Update/Insert/Delete instances can get saved to a database, and then ran after that date in a batch. Is this the intended use of durable services ? Is there a better route I could possibly take ?

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  • Converting "fr_FR" into "French (France)" in both directions. (Objective-C iPhone)

    - by Janice
    I can easily change a short region-code (en_US) into a longer string... but it there an easy way to also move in the other direction? [displayInEnglish displayNameForKey:NSLocaleIdentifier value:regionCountryCode]; "en_US" becomes "English (United States)". "English (United States)" becomes "en_US". I currently store the short region-code in a database.... but when I show some aggregate results... I need to display the longer strings to the user. Or should I just store the longer strings right in the database... and not even worry about "converting" them later? I'm trying to show a "dollars total" for each country. If you were a user... which would you more likely wish to see (for a currency-total list)? A "French" total A "France" total A "French (France)" total A "fr_Fr" total?

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  • Auto increment with a Unit Of Work

    - by Derick
    Context I'm building a persistence layer to abstract different types of databases that I'll be needing. On the relational part I have mySQL, Oracle and PostgreSQL. Let's take the following simplified MySQL tables: CREATE TABLE Contact ( ID varchar(15), NAME varchar(30) ); CREATE TABLE Address ( ID varchar(15), CONTACT_ID varchar(15), NAME varchar(50) ); I use code to generate system specific alpha numeric unique ID's fitting 15 chars in this case. Thus, if I insert a Contact record with it's Addresses I have my generated Contact.ID and Address.CONTACT_IDs before committing. I've created a Unit of Work (amongst others) as per Martin Fowler's patterns to add transaction support. I'm using a key based Identity Map in the UoW to track the changed records in memory. It works like a charm for the scenario above, all pretty standard stuff so far. The question scenario comes in when I have a database that is not under my control and the ID fields are auto-increment (or in Oracle sequences). In this case I do not have the db generated Contact.ID beforehand, so when I create my Address I do not have a value for Address.CONTACT_ID. The transaction has not been started on the DB session since all is kept in the Identity Map in memory. Question: What is a good approach to address this? (Avoiding unnecessary db round trips) Some ideas: Retrieve the last ID: I can do a call to the database to retrieve the last Id like: SELECT Auto_increment FROM information_schema.tables WHERE table_name='Contact'; But this is MySQL specific and probably something similar can be done for the other databases. If do this then would need to do the 1st insert, get the ID and then update the children (Address.CONTACT_IDs) – all in the current transaction context.

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  • From comma separated list to individual item result set. *mysql

    - by Raziel
    I'm doing some data migration from a horribly designed database to a less horribly designed database. There is a many to many relationship that has a primary key in one table that corresponds to a comma separated list in another. FK_ID | data ------------- 1,2 | foo 3 | bar 1,3,2 | blarg Is there a way to output the FK_ID field with each comma separated element as a single line in the result set? result set FK_ID | data ------------- 1 | foo 2 | foo 3 | bar 1 | blarg 2 | blarg 3 | blarg I'm thinking this would require some sort of recursive query which I don't think mysql has. Thanks in advance.

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  • LINQ in SQLite for Windows store app does not have 'ThenBy' to order by multiple columns

    - by user1131657
    I have a Windows 8 store application and I'm using the latest version on SQLite for my database. So I want to return some records from the database and I want to order them by more that one column. However SQLite doesn't seem to have the ThenBy statement? So my LINQ statement is below: from i in connection.Table<MyTable>() where i.Type == type orderby i.Usage_Counter // ThenBy i.ID select i); So how do I sort by multiple columns in SQLite without doing another LINQ statement?

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  • How can I convert German characters during XML read and PHP write into mysql?

    - by kitenski
    Morning, I am inputting data from an XML file into my database, but have any isse with German words (that are in the XML by mistake) For example the word für appears in my XML as für and thus appears the same in my database. I know I could do a simple search/replace for that exact phrase, but I was wondering if there was a smarter way to do it as I can't predict if any other German words may one day appear in the XML? ADDING SOME MORE DETAIL The XML source says: and in my PHP I have $domString = utf8_encode($dom-saveXML($element)); If I look into the XML file before I start reading it, it has - <title> - <![CDATA[ CoPilot Live v8 Europa für Android 8.0.0.644 ]]> </title> Thanks. Greg

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  • Trouble using South with Django and Heroku

    - by Dan
    I had an existing Django project that I've just added South to. I ran syncdb locally. I ran manage.py schemamigration app_name locally I ran manage.py migrate app_name --fake locally I commit and pushed to heroku master I ran syncdb on heroku I ran manage.py schemamigration app_name on heroku I ran manage.py migrate app_name on heroku I then receive this: $ heroku run python notecard/manage.py migrate notecards Running python notecard/manage.py migrate notecards attached to terminal... up, run.1 Running migrations for notecards: - Migrating forwards to 0005_initial. > notecards:0003_initial Traceback (most recent call last): File "notecard/manage.py", line 14, in <module> execute_manager(settings) File "/app/lib/python2.7/site-packages/django/core/management/__init__.py", line 438, in execute_manager utility.execute() File "/app/lib/python2.7/site-packages/django/core/management/__init__.py", line 379, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File "/app/lib/python2.7/site-packages/django/core/management/base.py", line 191, in run_from_argv self.execute(*args, **options.__dict__) File "/app/lib/python2.7/site-packages/django/core/management/base.py", line 220, in execute output = self.handle(*args, **options) File "/app/lib/python2.7/site-packages/south/management/commands/migrate.py", line 105, in handle ignore_ghosts = ignore_ghosts, File "/app/lib/python2.7/site-packages/south/migration/__init__.py", line 191, in migrate_app success = migrator.migrate_many(target, workplan, database) File "/app/lib/python2.7/site-packages/south/migration/migrators.py", line 221, in migrate_many result = migrator.__class__.migrate_many(migrator, target, migrations, database) File "/app/lib/python2.7/site-packages/south/migration/migrators.py", line 292, in migrate_many result = self.migrate(migration, database) File "/app/lib/python2.7/site-packages/south/migration/migrators.py", line 125, in migrate result = self.run(migration) File "/app/lib/python2.7/site-packages/south/migration/migrators.py", line 99, in run return self.run_migration(migration) File "/app/lib/python2.7/site-packages/south/migration/migrators.py", line 81, in run_migration migration_function() File "/app/lib/python2.7/site-packages/south/migration/migrators.py", line 57, in <lambda> return (lambda: direction(orm)) File "/app/notecard/notecards/migrations/0003_initial.py", line 15, in forwards ('user', self.gf('django.db.models.fields.related.ForeignKey')(to=orm['auth.User'])), File "/app/lib/python2.7/site-packages/south/db/generic.py", line 226, in create_table ', '.join([col for col in columns if col]), File "/app/lib/python2.7/site-packages/south/db/generic.py", line 150, in execute cursor.execute(sql, params) File "/app/lib/python2.7/site-packages/django/db/backends/util.py", line 34, in execute return self.cursor.execute(sql, params) File "/app/lib/python2.7/site-packages/django/db/backends/postgresql_psycopg2/base.py", line 44, in execute return self.cursor.execute(query, args) django.db.utils.DatabaseError: relation "notecards_semester" already exists I have 3 models. Section, Semester, and Notecards. I've added one field to the Notecards model and I cannot get it added on Heroku. Thank you.

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  • Django paging object has issues with Postgresql QuerySets

    - by pivotal
    I have some django code that runs fine on a SQLite database or on a MySQL database, but it runs into problems with Postgres, and it's making me crazy that no one has has this issue before. I think it may also be related to the way querysets are evaluated by the pager. In a view I have: def index(request, page=1): latest_posts = Post.objects.all().order_by('-pub_date') paginator = Paginator(latest_posts, 5) try: posts = paginator.page(page) except (EmptyPage, InvalidPage): posts = paginator.page(paginator.num_pages) return render_to_response('blog/index.html', {'posts' : posts}) And inside the template: {% for post in posts.object_list %} {# some rendering jazz #} {% endfor %} This works fine with SQLite, but Postgres gives me: Caught TypeError while rendering: 'NoneType' object is not callable To further complicate things, when I switch the Queryset call to: latest_posts = Post.objects.all() Everything works great. I've tried re-reading the documentation, but found nothing, although I admit I'm a bit clouded by frustration at this point. What am I missing? Thanks in advance.

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  • How to compare a string column(as DateTime) in LINQ?

    - by lyon
    I have a database with a ValidDate field - it's a string(we made a mistake, it should be a datetime, but we can't modify the database now.) and now I want to compare this filed with a parameter(validDateStart) from the website: priceList = priceList.Where(p => Convert.ToDateTime(p.ValidDate) >= Convert.ToDateTime(validDateStart)); var list = initPriceList.ToList(); But I get an error: The method ToDateTime is not implemented. Can anybody give me some help? Thanks!

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  • iPhone UITableView populating variable rows sections from flat array

    - by Biko
    I thought that would be very common and easy iPhone App. In the main app I connect to database, retrieve values from database (NSDate converted to NSString)n and put into single array. The in one of the views I populate UITableView with elements from the array. UITableView is grouped (sections). I step through array to discover number of sections (change section if new day). How do I retrieve correct element of array in cellForRowAtIndexPath? IndexPath.section and IndexPath.row seem useless as row starts count from zero for each section. If number of rows in each section was the same it would have been easy: [arryData objectAtIndex:(indexPath.row)+indexPath.section*[tblMatchesView numberOfRowsInSection:indexPath.section]]; But number of rows in each section varies... :-)

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  • Passing a formula field value into a Crystal Reports command

    - by DarkDeny
    Hello eveybody! I have a report, in which I calculate starting date via Formula Fields. Then I need to pass calculated value into a subreport, where I can use it as one of the parameters for the stored procedure in my database. The problem is that for some reason value of the corresponding parameter when the database is queried is empty (or null, I am not sure exactly). What can be wrong in my report template? The formula I use is: ToText( ShiftDateTime ({@StartDate}, {?TimeZone}, "UTC,0")) Name of this formula field is StartDate I pass it into subreport as a Pm-?@StartDateUTC (also tried Pm-@StartDateUTC). I am sure, that @StartDate has correct value (tested in preview with this field in report), also Pm-?@StartDateUTC does has a value, but when CR is accessing DB - the result is empty field value...

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  • Cannot copying tables when compiling on Device

    - by Amarpreet
    Hi guys, I am working on sqlite application with around 10 tables in database. it works fine when i run on simulator. And when i open the sqlite file from Applications folder of simulator it shows me all the tables and data. the problem arises when i run app on device. I downloaded the application from device and i checked the sqlite database files there were no tables in it. please help me solving this problem. thanks.

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  • Can we you the attached properties in C# class library?

    - by Manas Agarwal
    Hi I have implemented the Observer Pattern with lazy load. The class that requests the data from the database is a singleton class. Now I am able to load the data from one database (located in one datacenter) very easily. But I need to get the data from other data centers too and display on the same UI. I can somehow pass the address of second data center and fetch the data from there also. But once I will get the data from second data center, it will be added to earlier list only. So later it will be thought for me to distinguish between the data. So I thought of attaching a property with the result set, so that while displaying the output I can show the data for both the data centers separately but on the same UI. I thought of attached property as an option where I can attach the data center name with the list of the data obtained. How is it possible to do in C#? Thanks Manas

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  • Newline not showing correctly in textbox

    - by TheGateKeeper
    I am loading a string from my database which among other things contains line breaks (\r\n). However, this isn't being rendered as a new line but instead as \r\n. If I type it directly in instead of loading it from a string, it works just fine but I need to be able to load it from a string. Any ideas? Edit: Upon closer inspection, it looks like the string is being returned as: Changed test7\\r\\nChanged test8\\r\\nChanged test9Changed test7 From the database. I tried running a .Replace(@"\\", @"\") on it but this had no effect at all. Any ideas?

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