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• Recover data from physically damaged harddrive. What are my options?

  - by Michael Kniskern

  I was trying to replace the power supply in my desktop PC and ended up physically damaging the data connection from the hard drive to the motherboard. The plastic shelf for the copper prongs on the hard drive broke into the cable. Here is a picture of my handy work: I went to Best Buy Geek Squad to discuss my options and they said that they will need to send it to the recover center it could cost anywhere between $250 to $1600 USD to recover the data out the hard drive Is this reasonable for data recovery from a physically damaged hard drive? Are there any other options I can explore? I am going to talk to the data doctors to see what my options are. Update I took the HD to Data Doctors, and they told me that the SATA connection was broken to they would need to replaced the data connector and then copy the data to a brand new hard drive. So, with the initial analysis, cost of replacement parts, and data recovery fee it came out to $865.00 USD. The technician specifically stated if this was an older hard drive that would just need to replace the data connector. But because there is specific information related to the individual hard drive in the flash ROM, they need to transfer the data to a brand new hard drive.

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• Dell XPS 15 L502X hard drive Partition

  - by Mohan Gajula

  I have a situation here. I got my new Dell XPS 15 Laptop. The configuration of hard drive is as below : Volume 1: (OEM Partition): 133MB Volume 2: OS (C:): 685.25 GB Volume 3: Recovery : 13.25 GB Now, I am trying to re-partition my C Drive to have a C: drive with 100 GB and a new drive with 585 GB. Earlier, I tried using the Windows 7 Disk Management to shrink and extend the volume. That lead to the OS and hard drive not working. Dell Tech support tried to fix the issue, but they were not able to fix the issue online. Later a Dell Technician arrived my place, and replaced the hard drive with a new hard drive. Please help me re-partition the C: Drive with 100 GB, and new D drive with 585 GB. I don't want to lose my Recovery Partition. SOLUTION As Suggested by KCotreau below , I have done exactly. I have resized the C drive to 100 GB. And then applied the changes. Windows got restarted. On the boot screen, the partition was taking place. It took around 30 mins ( approx. ). Once after restart, I can see my C drive is 100 GB. Now opened the Easeus again. And created a new partition for the free space ( 585 GB ) this took 10 seconds to create. Here goes the screenshot after partitioning. Thanks to KCotreau. You are amazing.

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• Exchange 2003: recover mailbox when migrated to 2007

  - by lyngsie

  We have migrated almost all of our mailboxes from Exchange 2003 to 2007 so both are still up and co-existing in our domain. One mailbox is missing some mails, and I tried to recover from an Exchange 2003 backup using ExMerge as usual, but it throws an error: Error opening message store (MSEMS). Verify that the Microsoft Exchange Information Store service is running and that you have the correct permissions to log on. (0x8004011d) This should be normal when a mailbox has been migrated to 2007 and you try to recover a 2003 backup as stated here: http://www.petri.co.il/restoring-exchange-2003-mailboxes-exchange-2007-exmerge.htm We then tried the solution given in the article (copying the value "homemdb" for the user and pasting this in "msExchOrigMDB" for the Recovery Storage Group object in adsiedit). The error unfortuntely persists. So my question is, how can I extract a .pst from a mailbox in the recovery storage group when both Exchange 2003 and 2007 are running? I assume this is why the solution in the article didn't work. If no solution is possible using regular tools (exmerge, eseutil, etc.) which third-party tool should we choose - preferably the cheapest as we only need this one mailbox recovered.

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• How I can recover files when the folder shows empty but the files are not deleted?

  - by Borror0

  Yesterday, my laptop caught a virus which caused massive damage. Since them, I have been trying to recover important files before reformatting my computer, a task the virus has not made easy. Restoration points predating the attack have been deleted. Most of my folders show empty. My Start menu is essentially empty, with the exception of Trillian and Mirror's Edge. The same goes for my Desktop, which only has programs which were installed after the attack. Searching for files though my computer is pretty much useless, as it only rarely brings up anything. I suspect most of my files have not been deleted. While my folders show empty, uTorrent still does display them and I can open them from here. Unfortunately, when I select Open Containing Folder, the folder still shows as completely empty even if I'm currently watching a video from that very folder. Further adding evidence to the not-deleted, just-missing theory, the data recovery software I'm using (Restoration) cannot find only find an handful of the missing files. If they were deleted, I could do a forensic recovery to get them back but since they're probably still somewhere on my computer, just out out of my reach, I can't find them. Under those circumstances, is there a way I can recover those files?

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• MBR seems to be gone

  - by bobobobo

  So, horror story for everyone. I bought two spanking new HDD's. MM!! Gbitage. I removed all my old HDD's, physically labelled them, and was preparing to install all new HDD's (fresh sys install included!) To make sure what HDD was what, I popped each OLD HDD (data filleD!) into a Thermaltake Blacx toaster.. surprisingly BOTH couldn't be read. I didn't have static on my hands! I'm certain of it. I touched metal, touched wood, before beginning this all. Thinking that was strage, I hauled up the new sys, installed Win XP (of course!) on the new HDD, and now the two OLD HDD's (data filled!) that were entered into the toaster cannot be read. And they had tons of data on them. I read about MBR's being nuked and it sounds like that is what it is. But I'm at a loss what to do. There are so many MBR recovery programs out there, I kind of feel overwhelmed. I don't want to lose my data by just pikcing one, yet it seems so close within reach, I'm not panicking anymore.. Anybody have a play by play that I could follow? I just don't want to spend $900 on data recovery centers if I can do this myself..

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• In need of assistance for recovering a lost partition

  - by Tek

  The program that has worked for the most part is Active@ Partition Recovery. I'm so close but yet so far from recovering my data. Okay so here's what happens. In the following screenshot (blanked out a folder and filename with profanity in case some of you guys are at work :P), it detects the partition I accidentally deleted with ALL 100% of my data listed. Of course, I didn't write ANY data to that drive after I did this. But when I click "recover" and finishes the recovery process, in Windows I click on the partition that was just was just recovered... It's EMPTY. The program seems to be able to see my lost files, but when I recover the partition windows doesn't seem to think the same =( Things I tried: I tried running a chkdsk /r /f after I recovered the partition, apparently it couldn't find any errors. Tried using other software like TestDisk to recover the partition, but they (all) act similar to Windows in that it detects the (missing) partition but when I browse it there's no files. The partition is there along with all the file and data information. The sector information is also in the screenshot, is there any way I can use this to my advantage in recovering my data? Other information: Dualboot: Win8 / Ubuntu 12.10 x64 1TB Internal desktop drive, GPT Layout, NTFS formatted drive, 64K allocation size.

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• I (stupidly) converted a TrueCrypt encrypted disk to GPT in Disk Management: now TrueCrypt won't mount it

  - by asilentfire

  Backstory: After moving a Macrium Reflect disk image from my TrueCrypt external drive (with whole disk encryption) onto a unencrypted drive and using Windows PE with Macrium Reflect to restore my internal disk to the recovery image on the external unencrypted drive, my Windows 8 failed to boot. I then went back and also recovered the System Partition (looking now, it is currently EFI), but I still couldn't boot into my backup.. I was in a hurry to get online for something so I just did a clean install of Windows 8, without the backup.. After I installed Windows 8, I went into Disk Management out of curiosity to see if there were other partitions with Windows 8 that Macruim might have missed, and there is (by default) a Recovery Partition of 100MB. My memory of this is hazy, as I was trying to get up and running for an exam at 4 AM: Something in Disk Management prompted me to convert my encrypted external drive to GPT.. I have no idea why I did this, but I went ahead and allowed it to convert my TrueCrypt drive to GPT. Now, I can't mount the drive in TrueCrypt.. Disk Management sees it as Disk 1, Basic, and Unallocated. I tried converting it back to MBR with Disk Management, but no dice with TrueCrypt :( If I try to mount the disk in TrueCrypt I get the message: Incorrect password or not a TrueCrypt volume I should never have messed with a Truecrypt drive in Disk Management, but I did. I have important college work in that drive, and fear I have lost it forever. PLEASE HELP

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• Is there a way to customize how the value for a custom Model Field is displayed in a template?

  - by Jordan Reiter

  I am storing dates as an integer field in the format YYYYMMDD, where month or day is optional. I have the following function for formatting the number: def flexibledateformat(value): import datetime, re try: value = str(int(value)) except: return None match = re.match(r'(\d{4})(\d\d)(\d\d)$',str(value)) if match: year_val, month_val, day_val = [int(v) for v in match.groups()] if day_val: return datetime.datetime.strftime(datetime.date(year_val,month_val,day_val),'%b %e, %Y') elif month_val: return datetime.datetime.strftime(datetime.date(year_val,month_val,1),'%B %Y') else: return str(year_val) Which results in the following outputs: >>> flexibledateformat(20100415) 'Apr 15, 2010' >>> flexibledateformat(20100400) 'April 2010' >>> flexibledateformat(20100000) '2010' So I'm wondering if there's a function I can add under the model field class that would automatically call flexibledateformat. So if there's a record r = DataRecord(name='foo',date=20100400) when processed in the form the value would be 20100400 but when output in a template using {{ r.date }} it shows up as "April 2010". Further clarification I do normally use datetime for storing date/time values. In this specific case, I need to record non-specific dates: "x happened in 2009", "y happened sometime in June 1996". The easiest way to do this while still preserving most of the functionality of a date field, including sorting and filtering, is by using an integer in the format of yyyymmdd. That is why I am using an IntegerField instead of a DateTimeField. This is what I would like to happen: I store what I call a "Flexible Date" in a FlexibleDateField as an integer with the format yyyymmdd. I render a form that includes a FlexibleDateField, and the value remains an integer so that functions necessary for validating it and rendering it in widgets work correctly. I call it in a template, as in {{ object.flexibledate }} and it is formatted according to the flexibledateformat rules: 20100416 - April 16, 2010; 20100400 - April 2010; 20100000 - 2010. This also applies when I'm not calling it directly, such as when it's used as a header in admin (http://example.org/admin/app_name/model_name/). I'm not aware if these specific things are possible.

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• [Database] How to model this one-to-one relation?

  - by pbean

  I have several entities which respresent different types of users who need to be able to log in to a particular system. Additionally, they have different types of information associated with them. For example: a "general user", which has an e-mail address and "admin user", which has a workstation number (note that this a hypothetical case). Both entities also share common properties like first name, surname, address and telephone number. Finally, they naturally need to have a (unique) user name and a password to log in. In the application, the user just has to fill in his user name and password, and the functionality of the application changes slightly according to the type of the user. You can imagine that the username needs to be unique for this work. How should I model this effectively? I can't just create two tables, because then I can't force a unique constaint on the user name. I also can't put them all in just one table, because they have different types of specific information associated to them. I think I might need 3 seperate tables, one for "users" (with user name and password), one for the "general users" and another one for the "admin users", but how would the relations between these work? Or is there another solution? (By the way, the target DBMS is MySQL, so I don't think generalization is supported in the database system itself).

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• How to do an additional search on archive in rails if record not found, by extending model?

  - by Nick Gorbikoff

  Hello, I was wondering if somebody knows an elegant solution to the following: Suppose I have a table that holds orders, with a bunch of data. So I'm at 1M records, and searches begin to take time. So I want to speed it up by archiving some data that is more than 3 years old - saving it into a table called orders-archive, and then purging them from the orders table. So if we need to research something or customer wants to pull older information - they still can, but 99% of the lookups are done on the orders no older than a year and a half - so there is no reason to keep looking through older data all the time. These move & purge operations can be then croned to be done on a weekly basis. I already did some tests and I know that I will slash my search times by about 4 times. So far so good, right? However I was thinking about how to implement older archival lookups and the only reasonable thing I can think of is some sort of if-else If not found in orders, do a search in orders-archive. However - I have about 20 tables that I want to archive and god knows how many searches / finds are done through out the code, that I don't want to modify. So I was wondering if there is an elegant rails-way solution to this problem, by extending a model somehow? Has anyone dealt with similar case before? Thank you.

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• What do you call a generalized (non-GUI-related) "Model-View-Controller" architecture?

  - by dcuccia

  I am currently refactoring code that coordinates multiple hardware components for data acquisition, and feeling a bit like I'm recreating the wheel. In particular, an MVC-like pattern seems to be emerging. Except, this has nothing to do with a GUI and I'm worried that I'm forcing this particular pattern where another might be more appropriate. Here's my scenario: Individual hardware "component" classes obey interface contracts for each hardware type. Previously, component instances were orchestrated by a single monolithic InstrumentController class, which relied heavily on configuration + branching logic for executing a specific acquisition sequence. After an iteration, I have a separate controller for each component, with these controllers all managed by a small InstrumentControllerBase (or its derivatives). The composite system will receive "input" either programmatically or via inter-hardware component triggering - in either case these interactions are routed to, and handled by, the appropriate controller. So, I have something that feels MVC-esque, but I don't know if that's because I'm forcing the point. With little direct MVC experience in application development, it's hard to know if I'm just trying to make my scenario fit MVC, where another pattern might be a good alternative or complimentary. My problem is, search results and wiki documentation of these family of patterns seems to immediately drop me into GUI-specific discussions. I understand "M means Model data and the V means View" - but do you call the superset pattern? Component-Commander-Controller? Whence can I exhume examples exemplary?

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• Implement password recovery best practice

  - by Enrique

  Hello I want to to implement password recovery in my web application. I'd like to avoid using secret questions. I could just send the password by e-mail but I think it would be risky. Maybe I could generate a new temporary random password and send it by e-mail but I think it is as risky as the above point. Can I send a url by e-mail for example http://mysite.com/token=xxxx where xxxx is a random token associated with the user. So when the user navigates to that url he/she can reset the password. Any ideas?

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• integrating tinymce with asp .net MVC 4.0

  - by user1865670

  using ASP .NET MVC 4.0 , VS2012. In one of my page, I tried to integrate a WYSIWYG editor "TinyMCE". To integrate, I followed the following URL : .tugberkugurlu.com My view page is like : @model AboutModels @using FileUploadDemo.Models <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.js"></script> <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script> <script src="Scripts/tinymce/jquery.tinymce.js" type="text/javascript"></script> @{ ViewBag.Title = "About"; } @using (Html.BeginForm()) { @Html.ValidationSummary(true) <fieldset> <legend>About</legend> <div class="editor-label"> @Html.LabelFor(model => model.Title) </div> <div class="editor-field"> @Html.EditorFor(model => model.Title) @Html.ValidationMessageFor(model => model.Title) </div> <div class="editor-label"> @Html.LabelFor(model => model.PostedOn) </div> <div class="editor-field"> @Html.EditorFor(model => model.PostedOn) @Html.ValidationMessageFor(model => model.PostedOn) </div> <div class="editor-label"> @Html.LabelFor(model => model.Tags) </div> <div class="editor-field"> @Html.EditorFor(model => model.Tags) @Html.ValidationMessageFor(model => model.Tags) </div> <div class="editor-label"> @Html.LabelFor(model => model.Content) </div> <div class="editor-field"> @Html.EditorFor(model => model.Content) @Html.ValidationMessageFor(model => model.Content) </div> <p> <input type="submit" value="Create" /> </p> <p> Posted Content : @ViewBag.HtmlContent </p> </fieldset> } Here my Model is like : public class AboutModels { public string Title { get; set; } public DateTime PostedOn { get; set; } public string Tags { get; set; } [UIHint("tinymce_jquery_full"), AllowHtml] public string Content { get; set; } } My about page loads with all features. "@html.EditorFor(model=>model.content)" also loads fine. but no "WYSIWYG" pane(i donno what it is called, the pane is used to edit my text written in the textarea(HTml.editorFor())) is loaded. In the runtime, Exception is thrown in jquery.tinymce.js file. Error Message : `Unhandled exception at line 86, column 11 in http://localhost:1706/Home/About 0x800a01b6 - Microsoft JScript runtime error: Object doesn't support this property or method` And give me two options, Continue or Break . If i continue, the page loads with features as i mentioned earlier. If i Break, then it stays in the jquery.tinymce.js file with a yellow text-background. I have no experience with Javascript/jquery. And new in ASP .NET MVC 4.0, actually this is my first try of web application in .net. I updated jquery from nuGet. What could be the possible ways to solve it?

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• Example of an ASP.NET MVC post model?

  - by Anthony Potts

  I was watching the HaHaa presentation on ASP.NET MVC from MIX and they mentioned using a Post Model where I guess they were saying you could use a model that was ONLY for posting. I have tried looking for examples for this. Am I not understanding what they are saying? Does anyone have an example of how this might work in a strongly typed view where the view model and post model are not of the same type?

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• Django User model, adding function

  - by Hellnar

  Hello, I want to add a new function to the default User model of Django for retrieveing a related list of Model type. Such Foo model: class Foo(models.Model): owner = models.ForeignKey(User, related_name="owner") likes = models.ForeignKey(User, related_name="likes") ........ #at some view user = request.user foos= user.get_related_foo_models() Hwo can this be achieved ?

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• Backup & recovery of multiple MySQL databases (InnoDB & MyISAM)

  - by Cymon

  I am working on nightly and hourly backups of MySQL Databases. There are multiple MySQL databases which are either InnoDB or MyISAM (Note: Each database is either InnoDB or MyISAM for a reason). With the 2 different types I want to make sure I am grabbing everything that is needed for backup and recovery. Here is my current plan Nightly -mysqldump of each DB which is stored locally and remotely. Hourly -flush binary logs and store them locally and remotely. Weekly -expire binary logs older than a week. I feel like I am grabbing everything that is needed for the MyISAM databases but I am concerned about the InnoDB databases and the log files (ib_logfile0, ib_logfile1, ibdata1) they create. Should I backup these files? Nightly? Hourly? Both? Do I really need them if I am already doing the above nightly and hourly backups?

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• Options for keeping models and the UI in sync (in a desktop application context)

  - by Benju

  In my experience I have only had 2 patterns work for large-scale desktop application development when trying to keep the model and UI in sync. 1-An eventbus approach via a shared eventbus command objects are fired (ie:UserDemographicsUpdatedEvent) and have various parts of the UI update if they are bound to the same user object updated in this event. 2-Attempt to bind the UI directly to the model adding listeners to the model itself as needed. I find this approach rather clunky as it pollutes the domain model. Does anybody have other suggestions? In a web application with something like JSP binding to the model is easy as you ussually only care about the state of the model at the time your request comes in, not so in a desktop type application. Any ideas?

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• C#: Inheritance, Overriding, and Hiding

  - by Rosarch

  I'm having difficulty with an architectural decision for my C# XNA game. The basic entity in the world, such as a tree, zombie, or the player, is represented as a GameObject. Each GameObject is composed of at least a GameObjectController, GameObjectModel, and GameObjectView. These three are enough for simple entities, like inanimate trees or rocks. However, as I try to keep the functionality as factored out as possible, the inheritance begins to feel unwieldy. Syntactically, I'm not even sure how best to accomplish my goals. Here is the GameObjectController: public class GameObjectController { protected GameObjectModel model; protected GameObjectView view; public GameObjectController(GameObjectManager gameObjectManager) { this.gameObjectManager = gameObjectManager; model = new GameObjectModel(this); view = new GameObjectView(this); } public GameObjectManager GameObjectManager { get { return gameObjectManager; } } public virtual GameObjectView View { get { return view; } } public virtual GameObjectModel Model { get { return model; } } public virtual void Update(long tick) { } } I want to specify that each subclass of GameObjectController will have accessible at least a GameObjectView and GameObjectModel. If subclasses are fine using those classes, but perhaps are overriding for a more sophisticated Update() method, I don't want them to have to duplicate the code to produce those dependencies. So, the GameObjectController constructor sets those objects up. However, some objects do want to override the model and view. This is where the trouble comes in. Some objects need to fight, so they are CombatantGameObjects: public class CombatantGameObject : GameObjectController { protected new readonly CombatantGameModel model; public new virtual CombatantGameModel Model { get { return model; } } protected readonly CombatEngine combatEngine; public CombatantGameObject(GameObjectManager gameObjectManager, CombatEngine combatEngine) : base(gameObjectManager) { model = new CombatantGameModel(this); this.combatEngine = combatEngine; } public override void Update(long tick) { if (model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); } base.Update(tick); } } Still pretty simple. Is my use of new to hide instance variables correct? Note that I'm assigning CombatantObjectController.model here, even though GameObjectController.Model was already set. And, combatants don't need any special view functionality, so they leave GameObjectController.View alone. Then I get down to the PlayerController, at which a bug is found. public class PlayerController : CombatantGameObject { private readonly IInputReader inputReader; private new readonly PlayerModel model; public new PlayerModel Model { get { return model; } } private float lastInventoryIndexAt; private float lastThrowAt; public PlayerController(GameObjectManager gameObjectManager, IInputReader inputReader, CombatEngine combatEngine) : base(gameObjectManager, combatEngine) { this.inputReader = inputReader; model = new PlayerModel(this); Model.Health = Constants.PLAYER_HEALTH; } public override void Update(long tick) { if (Model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); for (int i = 0; i < 10; i++) { Debug.WriteLine("YOU DEAD SON!!!"); } return; } UpdateFromInput(tick); // .... } } The first time that this line is executed, I get a null reference exception: model.Body.ApplyImpulse(movementImpulse, model.Position); model.Position looks at model.Body, which is null. This is a function that initializes GameObjects before they are deployed into the world: public void Initialize(GameObjectController controller, IDictionary<string, string> data, WorldState worldState) { controller.View.read(data); controller.View.createSpriteAnimations(data, _assets); controller.Model.read(data); SetUpPhysics(controller, worldState, controller.Model.BoundingCircleRadius, Single.Parse(data["x"]), Single.Parse(data["y"]), bool.Parse(data["isBullet"])); } Every object is passed as a GameObjectController. Does that mean that if the object is really a PlayerController, controller.Model will refer to the base's GameObjectModel and not the PlayerController's overriden PlayerObjectModel? In response to rh: This means that now for a PlayerModel p, p.Model is not equivalent to ((CombatantGameObject)p).Model, and also not equivalent to ((GameObjectController)p).Model. That is exactly what I do not want. I want: PlayerController p; p.Model == ((CombatantGameObject)p).Model p.Model == ((GameObjectController)p).Model How can I do this? override?

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• Replace textfields with dropdown select fields

  - by 47

  I have three model classes that look as below: class Model(models.Model): model = models.CharField(max_length=20, blank=False) manufacturer = models.ForeignKey(Manufacturer) date_added = models.DateField(default=datetime.today) def __unicode__(self): name = ''+str(self.manufacturer)+" "+str(self.model) return name class Series(models.Model): series = models.CharField(max_length=20, blank=True, null=True) model = models.ForeignKey(Model) date_added = models.DateField(default=datetime.today) def __unicode__(self): name = str(self.model)+" "+str(self.series) return name class Manufacturer(models.Model): MANUFACTURER_POPULARITY_CHOICES = ( ('1', 'Primary'), ('2', 'Secondary'), ('3', 'Tertiary'), ) manufacturer = models.CharField(max_length=15, blank=False) date_added = models.DateField(default=datetime.today) manufacturer_popularity = models.CharField(max_length=1, choices=MANUFACTURER_POPULARITY_CHOICES) def __unicode__(self): return self.manufacturer I want to have the fields for model series and manufacturer represented as dropdowns instead of text fields. I have customized the model forms as below: class SeriesForm(ModelForm): series = forms.ModelChoiceField(queryset=Series.objects.all()) class Meta: model = Series exclude = ('model', 'date_added',) class ModelForm(ModelForm): model = forms.ModelChoiceField(queryset=Model.objects.all()) class Meta: model = Model exclude = ('manufacturer', 'date_added',) class ManufacturerForm(ModelForm): manufacturer = forms.ModelChoiceField(queryset=Manufacturer.objects.all()) class Meta: model = Manufacturer exclude = ('date_added',) However, the dropdowns are populated with the unicode in the respective class...how can I further customize this to get the end result I want? Also, how can I populate the forms with the correct data for editing? Currently only SeriesForm is populated. The starting point of all this is from another class whose declaration is as below: class CommonVehicle(models.Model): year = models.ForeignKey(Year) series = models.ForeignKey(Series) .... def __unicode__(self): name = ''+str(self.year)+" "+str(self.series) return name

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• Event sourcing: Write event before or after updating the model

  - by Magnus

  I'm reasoning about event sourcing and often I arrive at a chicken and egg problem. Would be grateful for some hints on how to reason around this. If I execute all I/O-bound processing async (ie writing to the event log) then how do I handle, or sometimes even detect, failures? I'm using Akka Actors so processing is sequential for each event/message. I do not have any database at this time, instead I would persist all the events in an event log and then keep an aggregated state of all the events in a model stored in memory. Queries are all against this model, you can consider it to be a cache. Example Creating a new user: Validate that the user does not exist in model Persist event to journal Update model (in memory) If step 3 breaks I still have persisted my event so I can replay it at a later date. If step 2 breaks I can handle that as well gracefully. This is fine, but since step 2 is I/O-bound I figured that I should do I/O in a separate actor to free up the first actor for queries: Updating a user while allowing queries (A0 = Front end/GUI actor, A1 = Processor Actor, A2 = IO-actor, E = event bus). (A0-E-A1) Event is published to update user 'U1'. Validate that the user 'U1' exists in model (A1-A2) Persist event to journal (separate actor) (A0-E-A1-A0) Query for user 'U1' profile (A2-A1) Event is now persisted continue to update model (A0-E-A1-A0) Query for user 'U1' profile (now returns fresh data) This is appealing since queries can be processed while I/O-is churning along at it's own pace. But now I can cause myself all kinds of problems where I could have two incompatible commands (delete and then update) be persisted to the event log and crash on me when replayed up at a later date, since I do the validation before persisting the event and then update the model. My aim is to have a simple reasoning around my model (since Actor processes messages sequentially single threaded) but not be waiting for I/O-bound updates when Querying. I get the feeling I'm modeling a database which in itself is might be a problem. If things are unclear please write a comment.

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• backbone model validation error

  - by koko

  I got a validation based on backbone fundamentals by addyosmani, but when i try it on my view i can't get the error that the model generated.TIA model.js validate: function(attrs) { var errors = this.errors = {}; if (!attrs.box) errors.box= 'box value is required'; //console.log(errors.box); if (!_.isEmpty(errors)) return errors; } view.js validate: function(model) { console.log("error text--" + model.errors[this.input] || ''); },

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• create a new model instance version instead of update

  - by pablo

  Hi, I have a model with a version field - autocreate timestamp. When a model instance is being saved I want to create a new instance with a new timestamp instead of updating the old model instance. Is it possible? I thought of overriding the model save() method but I don't know how to create a new instance without creating a infinite save() loop. Thanks

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• Question about domain models & their visibility...

  - by Another SO User

  I was involved in an interesting debate about the visibility of domain models & was wondering if people here have any good guidance. Per my understanding of MDA, we need not expose the domain model throughout the application layers & tiers The reason being that any change to the domain model has an impact in the overall application The wise thing to do would be to expose light-weight object (DTO's) which are a small sub-set of the domain model to abstract the actual model On the flip side, any change to the domain model would mean changing various DTO's throughout the application for the change to be visible, while if we do expose the domain model, then the change is in a single location Hope to see some comments & thoughts about this. Appreciate all the help!

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• Spring & Hibernate SessionFactory - recovery from a down server

  - by MJB

  So pre spring, we used version of HibernateUtil that cached the SessionFactory instance if a successful raw JDBC connection was made, and threw SQLException otherwise. This allowed us to recover from initial setup of the SessionFactory being "bad" due to authentication or server connection issues. We moved to Spring and wired things in a more or less classic way with the LocalSessionFactoryBean, the C3P0 datasource, and various dao classes which have the SessionFactory injected. Now, if the SQL server appears to not be up when the web app runs, the web app never recovers. All access to the dao methods blow up because a null sessionfactory gets injected. (once the sessionfactory is made properly, the connection pool mostly handles the up/down status of the sql server fine, so recovery is possible) Now, the dao methods are wired by default to be singletons, and we could change them to prototype. I don't think that will fix the matter though - I believe the LocalSessionFactoryBean is now "stuck" and caches the null reference (I haven't tested this yet, though, I'll shamefully admit). This has to be an issue that concerns people.

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• Django Show M2M field in both model forms

  - by John

  Hi I am using the forms.ModelForm to create my form. I want to be able to show the manytomany field in both model forms, how do I do this? If the manytomany relationship is defined in the model it is fine and just appears but if it is not in the model (but is still linked via the other model) it does not appear. Hope this makes sense. How can I make it show up? Thanks

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