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• What Can A 'TreeDict' (Or Treemap) Be Used For In Practice?

  - by Seun Osewa

  I'm developing a 'TreeDict' class in Python. This is a basically a dict that allows you to retrieve its key-value pairs in sorted order, just like the Treemap collection class in Java. I've implemented some functionality based on the way unique indexes in relational databases can be used, e.g. functions to let you retrieve values corresponding to a range of keys, keys greater than, less than or equal to a particular value in sorted order, strings or tuples that have a specific prefix in sorted order, etc. Unfortunately, I can't think of any real life problem that will require a class like this. I suspect that the reason we don't have sorted dicts in Python is that in practice they aren't required often enough to be worth it, but I want to be proved wrong. Can you think of any specific applications of a 'TreeDict'? Any real life problem that would be best solved by this data structure? I just want to know for sure whether this is worth it.

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• Can I grant explicit Javascript methods to a different-host iframe?

  - by Matchu

  I'm thinking about a system in which I allow users to create Javascript-empowered widgets for other users to embed in their dashboard on my website. I'd like to limit these widgets fairly strictly, so each would exist as an iframe kept on its own unique hostname: the widget with ID #47 would be accessible at w47.widgets.example.com, for example. It would be helpful, for permission-granting dialogs and the like, to allow the widget to call very specific methods explicitly granted by the parent window, without authorizing the iframe to do whatever it likes with the parent frame on the user's behalf. Is it possible for a parent document to explicitly allow certain method calls to a child document on a different host?

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• Two entities with @ManyToOne joins the same table

  - by Ivan Yatskevich

  I have the following entities Student @Entity public class Student implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Teacher @Entity public class Teacher implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Task @Entity public class Task implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "student_id") }) private Student author; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "teacher_id") }) private Teacher curator; //getters and setters } Consider that author and curator are already stored in DB and both are in the attached state. I'm trying to persist my Task: Task task = new Task(); task.setAuthor(author); task.setCurator(curator); entityManager.persist(task); Hibernate executes the following SQL: insert into student_task (teacher_id, id) values (?, ?) which, of course, leads to null value in column "student_id" violates not-null constraint Can anyone explain this issue and possible ways to resolve it?

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• Linq-to-XML explicit casting in a generic method

  - by vlad

  I've looked for a similar question, but the only one that was close didn't help me in the end. I have an XML file that looks like this: <Fields> <Field name="abc" value="2011-01-01" /> <Field name="xyz" value="" /> <Field name="tuv" value="123.456" /> </Fields> I'm trying to use Linq-to-XML to get the values from these fields. The values can be of type Decimal, DateTime, String and Int32. I was able to get the fields one by one using a relatively simple query. For example, I'm getting the 'value' from the field with the name 'abc' using the following: private DateTime GetValueFromAttribute(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == "abc" select (DateTime)field.Attribute("value")).FirstOrDefault() } this is placed in a separate function that simply returns this value, and everything works fine (since I know that there is only one element with the name attribute set to 'abc'). however, since I have to do this for decimals and integers and dates, I was wondering if I can make a generic function that works in all cases. this is where I got stuck. here's what I have so far: private T GetValueFromAttribute<T>(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == attName select (T)field.Attribute("value").Value).FirstOrDefault(); } this doesn't compile because it doesn't know how to convert from String to T. I tried boxing and unboxing (i.e. select (T) (Object) field.Attribute("value").Value but that throws a runtime Specified cast is not valid exception as it's trying to convert the String to a DateTime, for instance. Is this possible in a generic function? can I put a constraint on the generic function to make it work? or do I have to have separate functions to take advantage of Linq-to-XML's explicit cast operators?

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• [jquery] Appending to Second Last element

  - by Shishant

  Hello, This is the final output My HTML <li id='$id'>TEXT <ul class='indent'> <li id='$id'>TEXT</li> <li id='$id'>TEXT</li> <li class='formContainer'> FORM </li> </ul> </li> I want to append a li between form after all other li So in this example new li will be appended between Test141 APPEND Input Box The $id are db ids of li which are unique

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• Django and a referrer system question

  - by Hellnar

  Hello, I am trying develop a basic referrer system to my Django website, system will be generating a unique url for each users to share with their friends. Once these friends enter this website, system somehow keep the data that "this user is browsing by the reference of X user" and once this invited person decided to register for an account, system will save this information (maybe as an extra Foreign Key of the inviting user in the UserProfile model) Now how can I keep track of the inviting user from the moment entering using the referred link to the point where he/she registers to the site. Would session framework work on this? If not how could this be done ?

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• ASP.MVC 2 Model Data Persistance

  - by toccig

  I'm and MVC1 programmer, new to the MVC2. The data will not persist to the database in an edit scenario. Create works fine. Controller: // // POST: /Attendee/Edit/5 [Authorize(Roles = "Admin")] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(Attendee attendee) { if (ModelState.IsValid) { UpdateModel(attendee, "Attendee"); repository.Save(); return RedirectToAction("Details", attendee); } else { return View(attendee); } } Model: [MetadataType(typeof(Attendee_Validation))] public partial class Attendee { } public class Attendee_Validation { [HiddenInput(DisplayValue = false)] public int attendee_id { get; set; } [HiddenInput(DisplayValue = false)] public int attendee_pin { get; set; } [Required(ErrorMessage = "* required")] [StringLength(50, ErrorMessage = "* Must be under 50 characters")] public string attendee_fname { get; set; } [StringLength(50, ErrorMessage = "* Must be under 50 characters")] public string attendee_mname { get; set; } } I tried to add [Bind(Exclude="attendee_id")] above the Class declaration, but then the value of the attendee_id attribute is set to '0'. View (Strongly-Typed): <% using (Html.BeginForm()) {%> ... <%=Html.Hidden("attendee_id", Model.attendee_id) %> ... <%=Html.SubmitButton("btnSubmit", "Save") %> <% } %> Basically, the repository.Save(); function seems to do nothing. I imagine it has something to do with a primary key constraint violation. But I'm not getting any errors from SQL Server. The application appears to runs fine, but the data is never persisted to the Database.

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• How to perform a join with CodeIgniter's Active Record class on a multicolumn key?

  - by Scott Southworth

  I've been able to make this code work using CodeIgniter's db->query as follows: $sql = 'SELECT mapping_code,zone_name,installation_name FROM installations,appearances,zones WHERE installations.installation_id = zones.installation_fk_id AND appearances.installation_fk_id = installations.installation_id AND appearances.zone_fk_id = zones.zone_id AND appearances.barcode = ? '; return $this->db->query($sql,array($barcode)); The 'appearances' table throws a 'not unique table' error if I try this using the Active Record class. I need to join appearances on both the zone and installations tables. How can I do this?

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• share image with url from database

  - by LauroSkr

  In my PHP web site will have a text converted to jpeg file,so it is a image. I want that i give users option to share the image. every image will have unique url so they can share image on facebook,twitter , do i need to put images with their url in mysql database or you do it in cloud? user will write text and then script will convert it to image and show it as image. then i want to provide user that he/she can share their created image. It would be great if you could provide me with a link or tutorial for my problem. Dont be hard on beginners,you were all in the same boat.. Thanks, LauroSkr

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• Determining the order of a list of numbers (possibly without sorting)

  - by Victor Liu

  I have an array of unique integers (e.g. val[i]), in arbitrary order, and I would like to populate another array (ord[i]) with the the sorted indexes of the integers. In other words, val[ord[i]] is in sorted order for increasing i. Right now, I just fill in ord with 0, ..., N, then sort it based on the value array, but I am wondering if we can be more efficient about it since ord is not populated to begin with. This is more of a question out of curiousity; I don't really care about the extra overhead from having to prepopulate a list and then sort it (it's small, I use insertion sort). This may be a silly question with an obvious answer, but I couldn't find anything online.

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• ModelName(django.contrib.auth.models.User) vs ModelName(models.Model)

  - by amr.negm

  I am developing a django project. I created some apps, some of those are related to User model, for instance, I have a feeds app that handles user feeds, and another app that deals with extra user data like age, contacts, and friends. for each of these, I created a table that should be connected to the User model, which I using for storing and authenticating users. I found two ways to deal with this issue. One, is through extending User model to be like this: ModelName(User): friends = models.ManyToMany('self') ..... Two, is through adding a foreign key to the new table like this: ModelName(models.Model): user = models.ForeignKey(User, unique=True) friends = friends = models.ManyToMany('self') ...... I can't decide which to use in which case. in other words, what are the core differences between both?

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• More than one profile in Django?

  - by JPC

  Is it possible to use Django's user authentication features with more than one profile? Currently I have a settings.py file that has this in it: AUTH_PROFILE_MODULE = 'auth.UserProfileA' and a models.py file that has this in it: from django.db import models from django.contrib.auth.models import User class UserProfileA(models.Model): company = models.CharField(max_length=30) user = models.ForeignKey(User, unique=True) that way, if a user logs in, I can easily get the profile because the User has a get_profile() method. However, I would like to add UserProfileB. From looking around a bit, it seems that the starting point is to create a superclass to use as the AUTH_PROFILE_MODULE and have both UserProfileA and UserProfileB inherit from that superclass. The problem is, I don't think the get_profile() method returns the correct profile. It would return an instance of the superclass. I come from a java background (polymorphism) so I'm not sure exactly what I should be doing. Thanks!

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• ASP.NET: How to assign ID to a field in DetailsView?

  - by jawonlee

  I have a master-detail page, in which I use GridView to display multiple rows of data, and DetailsView + jQuery dialog to display the details of a single records. only one DetailsView is open at a time. I need to be able to pull out a single field of the open DetailsView, for manipulation using JavaScript. Is there a way to give a unique ID to a given field in DetailsView, so I can use getElementByID? Or is there another way to accomplish what I'm trying to do? Thank you in advance.

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• django: Selecting questions that was not asked

  - by Oleg Tarasenko

  Hi, I am creating small django application which holds some few questions (and answers for them) What I want to do is to show user random question, but only from those which was not solved by him yet. I wonder how to do this. For now, I defined user profile model this way: class UserProfile(models.Model): rank = models.IntegerField(default = 1) solvedQ = models.ManyToManyField(Question) user = models.ForeignKey(User, unique=True) So solved problems are added this way: if user.is_authenticated(): profile = user.get_profile() profile.rank += 1 profile.solvedQ.add(Question.objects.get(id=id)) Now if the view must show random question, but not from already solved list... Is there a good way to intersect Questions and solvedQuestions.... so question is chosen from the unsolved list?

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• SQL HAVING COUNT and JOIN

  - by user1833274

  I have tried to this query: What are the doctors that work on less than 2 Hospitals. I have these tables: CREATE TABLE Hospital ( hid INT PRIMARY KEY, name VARCHAR(127) UNIQUE, country VARCHAR(127), area INT ); CREATE TABLE Doctor ( ic INT PRIMARY KEY, name VARCHAR(127), date_of_birth INT, ); CREATE TABLE Work ( hid INT, ic INT, since INT, FOREIGN KEY (hid) REFERENCES Hospital (hid), FOREIGN KEY (ic) REFERENCES Doctor (ic), PRIMARY KEY (hid,ic) ); I tried with this: SELECT DISTINCT D.ic FROM Doctor D, Work W JOIN Hospital H ON (H.hid = W.hid) WHERE D.bi = W.bi GROUP BY (D.ic) HAVING COUNT(H.hid) < 2 ;

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• Appropriate data structure for a buffer of the packets

  - by psihodelia

  How to implement a buffer of the packets where each packet is of the form: typedef struct{ int32 IP; //4-byte IP-address int16 ID; //unique sequence id }t_Packet; What should be the most appropriate data structure which: (1) allows to collect at least 8000 such packets (fast Insert and Delete operations) (2) allows very fast filtering using IP address, so that only packets with given IP will be selected (3) allows very fast find operation using ID as a key (4) allows very fast (2), then (3) within filtered results ? RAM size does matter, e.g. no huge lookup table is possible to use.

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• Can tomcat perform ssl redirection by filtering host alias?

  - by Stephen

  Hi, We have a tomcat server (6.0.20) running one web application behind two urls, e.g. www.foo and secure.foo This is configured in the server.xml as one host with a single alias: <Host name="www.foo" appBase="webapps"> <Context docBase="foo" path=""></Context> <Alias>secure.foo</Alias> </Host> Ideally we'd like any requests to secure.foo on port 80 to be automatically redirected to use ssl. However, I can only find instructions for redirecting based on the path after the hostname, so I could add a /* security constraint but then this would apply to both urls. Does anyone know if it's possible to apply the redirection by filtering on hostname requested? (We've already got the ssl connector, certificate, etc. working ok). I know we could do it by sticking an apache server in front of tomcat and handling the redirection there, but I'm curious to know if tomcat can do this on its own. Thanks

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• How does DateTime.Now.Tick exactly work?

  - by Roflcoptr

  In my application I generate files at random opportunities. To ensure a unique naming, I tried to use the nano seconds since 1.1.1970: long time = DateTime.Now.Ticks; String fileName = Convert.ToString(time); Console.WriteLine(fileName); Now I observed something weird. Why is the output like that? I mean why are the last 4 numbers always the same? I can use this as a filename, that is not the problem, but I'm just wondering about it. 634292263478068039 634292263512888039 634292263541368039 634292263603448039 634292263680078039

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• Check if DateTime in specific range

  - by katit

  Need to check if DateTime is in specific range. I think I need to calculate knowing YEAR first and last date of DST time in this year. How would I figure "Sunday of week 2 of March" date? From 1/1/2007 12:00:00 AM to 12/31/9999 12:00:00 AM Begins at 2:00 AM on Sunday of week 2 of March Ends at 2:00 AM on Sunday of week 1 of November For example, I need to check if 11/21/2011 is between Sunday of week 2 in March and Sunday of week 1 of November - answer should be NO If I pass 8/8/2011 - answer should be yes. Basically, I need to write function to check if my date belongs to daylight savings time. My only idea so far is to write loops to find 2nd week for example. So, I would loop from Day 1 in March until I hit Sunday second time. Same thing I would loop (increment days by 1) from day 1 of November until I hit Sunday first time. In another words, I need function to check if input data is in Daylight Savings time period. Time period defined by constraint above. P.S. I can't use TimeZoneInfo since it's in Silverlight P.P.S I can't use DateTime.IsDaylightSavingsTime as I don't have times with kind "local"

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• Best Practice for creating Web Services

  - by Holograham

  To preface I am new to web development. I am looking at creating a core set of RESTful web services around a valuable document library of sorts (initial CRUD abilities). In doing so I am theoretically creating a perfectly re-usable and scalable back-end to be used by unanticipated applications in the future. My question centers around the best practice for doing this. My initial requirement has me also creating a unique front end. Would I make the front end and back end completely separate projects to enhance the re-usability. It would increase overhead. Looking at using GWT, Restlet, and JEE technology stack if this influences the setup at all.

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• How to remove duplicate records in a table?

  - by Mason Wheeler

  I've got a table in a testing DB that someone apparently got a little too trigger-happy on when running INSERT scripts to set it up. The schema looks like this: ID UNIQUEIDENTIFIER TYPE_INT SMALLINT SYSTEM_VALUE SMALLINT NAME VARCHAR MAPPED_VALUE VARCHAR It's supposed to have a few dozen rows. It has about 200,000, most of which are duplicates in which TYPE_INT, SYSTEM_VALUE, NAME and MAPPED_VALUE are all identical and ID is not. Now, I could probably make a script to clean this up that creates a temporary table in memory, uses INSERT .. SELECT DISTINCT to grab all the unique values, TRUNCATE the original table and then copy everything back. But is there a simpler way to do it, like a DELETE query with something special in the WHERE clause?

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• Setting a preferred item of a many-to-one in Django

  - by Mike DeSimone

  I'm trying to create a Django model that handles the following: An Item can have several Names. One of the Names for an Item is its primary Name, i.e. the Name displayed given an Item. (The model names were changed to protect the innocent.) The models.py I've got looks like: class Item(models.Model): primaryName = models.OneToOneField("Name", verbose_name="Primary Name", related_name="_unused") def __unicode__(self): return self.primaryName.name class Name(models.Model): item = models.ForeignKey(Item) name = models.CharField(max_length=32, unique=True) def __unicode__(self): return self.name class Meta: ordering = [ 'name' ] The admin.py looks like: class NameInline(admin.TabularInline): model = Name class ItemAdmin(admin.ModelAdmin): inlines = [ NameInline ] admin.site.register(Item, ItemAdmin) It looks like the database schema is working fine, but I'm having trouble with the admin, so I'm not sure of anything at this point. My main questions are: How do I explain to the admin that primaryName needs to be one of the Names of the item being edited? Is there a way to automatically set primaryName to the first Name found, if primaryName is not set, since I'm using inline admin for the names?

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• How to determine ASP.NET's generated ID's from codebehind?

  - by Matthew Scharley

  In ASP.NET, when you give a tag an ID it generates a unique HTML id for the element based on the control hierachy, ie. <asp:Panel ID="test" runat="server"> ... </asp:Panel> <!-- Becomes... --> <div id="plc_lt_zoneContent_PagePlaceholder_PagePlaceholder_lt_test_test"> ... </div> Is there some way of determining the generated id in the codebehind file? I need to generate some Javascript that uses the id.

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• PHP/Codeigniter processing a list with javascript

  - by user270797

  I have a list of items that the user can select. I want it to be more user friendly than standard checkboxes so I have seperate div's each with a unique id. When user clicks an item, I use javascript to display a tick on top of that item and change the style to show that it is highlighted. Im trying to work out how I can pass the list of id's when the form is submitted. Remember, if the user unticks an item, it should be removed from the list, I was thinking of using comma seperated values in a hidden text field but couldnt work out how to remove items from the start of the list if they were deselected

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• Initializing new instances of a class in a loop, how can I persist an assignment to an event handler

  - by Pydroid

  This is a follow on question from http://stackoverflow.com/questions/3020960/why-is-my-prototype-function-not-returning-the-property-of-the-instance $.getJSON(myjson, function(data) { var json = data; for (i in json) { juuvies[i] = new Juuvy(i,json[i], font, keyfontsize, valfontsize, orbcol, orbkeycol, orbvalcol, paper); juuvies[i].juuv_it(); var mykey = juuvies[i].init_nodes(); juuvies[i].orb.node.onmouseover = function() { console.log(mykey);}; } }); And my init_nodes function, Juuvy.prototype.init_nodes = function() { return this.key; } At this point of time, I get only the last key in the loop, instead of a unique pass each time. Is there a way I can persist the assignment for the event handler?

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