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  • Finding object count where a field is unique in Django

    - by Johnd
    I have a model that is something like this: class Input(models.Model): details = models.CharField(max_length=1000) user = models.ForeignKey(User) class Case(Input): title = models.CharField(max_length=200) views = models.IntegerField() class Argument(Input): case = models.ForeignKey(Case) side = models.BooleanField() A user can submit many arguments, per case. I want to be able to say how many users have submitted side=true arguments. I mean if 1 user had 10 arguments and another user had 2 arguments (both side=true) I'd want the count to be 2, not 12.

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  • Unique identification string in php

    - by NardCake
    Currently me and my friend are developing a website, for what we will call 'projects' we just have a basic auto increment id in the database used to navigate to projects such as oururl.com/viewproject?id=1 but we started thinking, if we have alot of posted projects thats going to be a LONG url. So we need to somehow randomly generate a alphanumerical string about 6 characters long. We want the chance of the string being duplicated being extremely low and of course we will query the database before assigning an identifier. Thanks for anyhelp, means alot!

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  • only return random number when it is unique

    - by phil
    My brain is melting today and i cannot think how to do this simple bit of code. numberList is a string of numbers seperated by commas like '2, 34, 10' etc.. when i request a random number i need to check if the string has the number, if it does i want to keep requesting a random number until the random number is definitely not in the string. i cant think what kind of loop i would do to get this to work: Random r = new Random(); public int RandomPos(int max) { int i; do { i = r.Next(max) + 1; } while (!numberList.Contains(i.ToString())); return i; }

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  • Counting unique XML element attributes using XSLT

    - by patrick_corrigan
    I've just started using XSLT and am trying to figure this out. Your help would be greatly appreciated. Example XML file <purchases> <item id = "1" customer_id = "5"> </item> <item id = "2" customer_id = "5"> </item> <item id = "7" customer_id = "4"> </item> </purchases> Desired HTML Output: <table> <tr><th>Customer ID</th><th>Number of Items Purchased</th></tr> <tr><td>5</td><td>2</td></tr> <tr><td>4</td><td>1</td></tr> </table> Customer with id number 5 has bought 2 items. Customer with id number 4 has bought 1 item.

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  • Loop through different sets of unique permutations

    - by user558610
    Hi I'm having a hard time getting started to layout code for this problem. I have a fixed amount of random numbers, in this case 8 numbers. R[] = { 1, 2, 3, 4, 5, 6, 7, 8 }; That are going to be placed in 3 sets of numbers, with the only constraint that each set contain minimum one value, and each value can only be used once. For example: R1[] = { 1, 4 } R2[] = { 2, 8, 5, 6 } R3[] = { 7, 4 } I need to loop through all possible combinations of a set R1, R2, R3. Order is not important, so if the above example happened, I don't need R1[] = { 4, 1 } R2[] = { 2, 8, 5, 6 } R3[] = { 7, 4 } NOR R1[] = { 2, 8, 5, 6 } R2[] = { 7, 4 } R3[] = { 1, 4 } What is a good method?

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  • Calculate sum of objects for each unique object property in Ruby

    - by macek
    I was helping with an answer in this question and it sparked a question of my own. Pie is an object that has a pieces array made of of PiePiece objects. Each PiePiece has a flavor attribute How do I create a hash that looks like this: # flavor => number of pieces { :cherry => 3 :apple => 1 :strawberry => 2 } This works, but I think it could be improved def inventory hash = {} pieces.each do |p| hash[p.flavor] ||= 0 hash[p.flavor] += 1 end hash end Any ideas?

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  • Many Buttons on a Page, Need to send back Unique Post Data with each

    - by CoffeeAddict
    I'm listing out a bunch of cars with a button next to them that when clicked will need to perform a GET but also sends over that item's model.Name: @using (Html.BeginForm("GetCarUrl", "Car", FormMethod.Get, new { model = Model })) { if(Model.Cars != null && Model.Cars.Count > 0) { foreach (CarContent car in Model.Cars) { <p>@car.Name</p> } <input type="button" value="Get Car Url" class="submit" /> } So the page renders a bunch of hyperlinks and buttons: [hyperlink1] [submit] [hyperlink2] [submit] [hyperlink3] [submit] [hyperlink4] [submit] [hyperlink5] [submit] ... When a user clicks on any of the submits, I need to pass back its corresponding @car.CarType for that specific hyperlink Not sure how to go about this. My action method expects a @car.CarType for that specific car hyperlink to be sent to it

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  • What relationship do software Scrum or Lean have to industrial engineering concepts like theory of constraints?

    - by DeveloperDon
    In Scrum, work is delivered to customers through a series of sprints in which project work is time boxed to a fixed number of days or weeks, usually 30 days. In lean software development, the goal is to deliver as soon as possible, permitting early feedback for the next iteration. Both techniques stress the importance of workflow in which software work product does not accumulate in development awaiting release at some future date. Both permit new or refined requirements and feedback from QA and customers to be acted on with as little delay as possible based on priority. A few years ago I heard a lecture where the speaker talked briefly about a family of concepts from industrial engineering called theory of constraints. In the factory, they use an operations model based on three components: drum, buffer, and rope. The drum synchronizes work product as it flows through the system. Buffers that protect the system by holding output from one stage as it waits to be consumed by the next. The rope pulls product from one work station to the next. Historically, are these ideas part of the heritage of Scrum and Lean, or are they on a separate track? It we wanted to think about Scrum and Lean in terms of drum-buffer-rope, what are the parts? Drum = {daily scrum meeting, monthly release)? Buffer = {burn down list, source control system)? Rope = { daily meeting, constant integration server, monthly releases}? Industrial engineers define work flow in terms of different kinds of factories. I-Factories: straight pipeline. One input, one output. A-Factories: many inputs and one output. V-Factories: one input, many output products. T-Plants: many inputs, many outputs. If it applies, what kind of factory is most like Scrum or Lean and why?

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  • Trouble move-capturing std::unique_ptr in a lambda using std::bind

    - by user2478832
    I'd like to capture a variable of type std::vector<std::unique_ptr<MyClass>> in a lambda expression (in other words, "capture by move"). I found a solution which uses std::bind to capture unique_ptr (http://stackoverflow.com/a/12744730/2478832) and decided to use it as a starting point. However, the most simplified version of the proposed code I could get doesn't compile (lots of template mistakes, it seems to try to call unique_ptr's copy constructor). #include <functional> #include <memory> std::function<void ()> a(std::unique_ptr<int>&& param) { return std::bind( [] (int* p) {}, std::move(param)); } int main() { a(std::unique_ptr<int>(new int())); } Can anybody point out what is wrong with this code? EDIT: tried changing the lambda to take a reference to unique_ptr, it still doesn't compile. #include <functional> #include <memory> std::function<void ()> a(std::unique_ptr<int>&& param) { return std::bind( [] (std::unique_ptr<int>& p) {}, // also as a const reference std::move(param)); } int main() { a(std::unique_ptr<int>(new int())); }

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  • MS SQL Return 1 Row Per Boat

    - by Tyler
    Basically, what I want to do is join 4 tables together and return 1 row for each boat. Table Layouts [Boats] id, date, section, raft [Photos] id, boatid, pthurl, purl [River_Company] id, sort, company, company_short [River_Section] id, section Its very simple as far as structure, however, I've having the time of my life trying to get it to return only 1 row. No boat will ever be on the same day, the only thing that's messing this up is the photo table. If you know a better way for it to return the record table for all the boats boats and only 1 photo from the photo table, please, please post it!!

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  • php array_unique

    - by dotty
    HAy, i have an array Array( [0] => Array ( [0] => 33 [user_id] => 33 [1] => 3 [frame_id] => 3 ) [1] => Array ( [0] => 33 [user_id] => 33 [1] => 3 [frame_id] => 3 ) [2] => Array ( [0] => 33 [user_id] => 33 [1] => 8 [frame_id] => 8 ) [3] => Array ( [0] => 33 [user_id] => 33 [1] => 3 [frame_id] => 3 ) [4] => Array ( [0] => 33 [user_id] => 33 [1] => 3 [frame_id] => 3 ) ) As you can see key 0 is the same as 1,3 and 4. And key 2 is different from them all. When running the array_unique function on them, the only left is Array ( [0] => Array ( [0] => 33 [user_id] => 33 [1] => 3 [frame_id] => 3 ) ) any ideas why array_unique isn't working as expected?

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  • How to user Hibernate @Valid constraint with Spring 3.x?

    - by Burak Dede
    I am working on simple form to validate fields like this one. public class Contact { @NotNull @Max(64) @Size(max=64) private String name; @NotNull @Email @Size(min=4) private String mail; @NotNull @Size(max=300) private String text; } I provide getter and setters hibernate dependencies on my classpath also.But i still do not get the how to validate simple form there is actually not so much documentation for spring hibernate combination. @RequestMapping(value = "/contact", method = RequestMethod.POST) public String add(@Valid Contact contact, BindingResult result) { .... } Could you explain it or give some tutorial , except original spring 3.x documentation

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  • How can a not null constraint be dropped?

    - by Tomislav Nakic-Alfirevic
    Let's say there's a table created as follows: create table testTable ( colA int not null ) How would you drop the not null constraint? I'm looking for something along the lines of ALTER TABLE testTable ALTER COLUMN colA DROP NOT NULL; which is what it would look like if I used PostgreSQL. To my amazement, as far as I've been able to find, the MySQL docs, Google and yes, even Stackoverflow (in spite of dozens or hundreds of NULL-related questions) don't seem to lead towards a single simple SQL statement which will do the job.

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  • So can unique_ptr be used safely in stl collections?

    - by DanDan
    I am confused with unique_ptr and rvalue move philosophy. Let's say we have two collections: std::vector<std::auto_ptr<int>> autoCollection; std::vector<std::unique_ptr<int>> uniqueCollection; Now I would expect the following to fail, as there is no telling what the algorithm is doing internally and maybe making internal pivot copies and the like, thus ripping away ownership from the auto_ptr: std::sort(autoCollection.begin(), autoCollection.end()); I get this. And the compiler rightly disallows this happening. But then I do this: std::sort(uniqueCollection.begin(), uniqueCollection.end()); And this compiles. And I do not understand why. I did not think unique_ptrs could be copied. Does this mean a pivot value cannot be taken, so the sort is less efficient? Or is this pivot actually a move, which in fact is as dangerous as the collection of auto_ptrs, and should be disallowed by the compiler? I think I am missing some crucial piece of information, so I eagerly await someone to supply me with the aha! moment.

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  • Is it possible to a db constraint in for this rule?

    - by Pure.Krome
    Hi folks, I wish to make sure that my data has a constraint the following check (constraint?) in place This table can only have one BorderColour per hub/category. (eg. #FFAABB) But it can have multiple nulls. (all the other rows are nulls, for this field) Table Schema ArticleId INT PRIMARY KEY NOT NULL HubId TINYINT NOT NULL CategoryId INT NOT NULL Title NVARCHAR(100) NOT NULL Content NVARCHAR(MAX) NOT NULL BorderColour VARCHAR(7) -- Can be nullable. I'm gussing I would have to make a check constraint? But i'm not sure how, etc. sample data. 1, 1, 1, 'test', 'blah...', '#FFAACC' 1, 1, 1, 'test2', 'sfsd', NULL 1, 1, 2, 'Test3', 'sdfsd dsf s', NULL 1, 1, 2, 'Test4', 'sfsdsss', '#AABBCC' now .. if i add the following line, i should get some sql error.... INSERT INTO tblArticle VALUES (1, 2, 'aaa', 'bbb', '#ABABAB') any ideas?

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  • C# dictionary uniqueness for sibling classes using IEquatable<T>

    - by anthony
    I would like to store insances of two classes in a dictionary structure and use IEquatable to determine uniqueness of these instances. Both of these classes share an (abstract) base class. Consider the following classes: abstract class Foo { ... } class SubFoo1 : Foo { ... } class SubFoo2 : Foo { ... } The dictionary will be delcared: Dictionary<Foo, Bar> Which classes should be declared as IEquatable? And what should the generic type T be for those declarations? Is this even possible?

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  • Variable field in a constraint annotation

    - by Javi
    Hello, I need to create a custom constraint annotation which can access the value of another field of my bean. I'll use this annotation to validate the field because it depends on the value of the other but the way I define it the compiler says "The value for annotation attribute" of my field "must be a constant expression". I've defined it in this way: @Target(ElementType.FIELD) @Retention(RetentionPolicy.RUNTIME) @Constraint(validatedBy=EqualsFieldValidator.class) @Documented public @interface EqualsField { public String field(); String message() default "{com.myCom.annotations.EqualsField.message}"; Class<?>[] groups() default {}; Class<? extends Payload>[] payload() default {}; } public class EqualsFieldValidator implements ConstraintValidator<EqualsField, String>{ private EqualsField equalsField; @Override public void initialize(EqualsField equalsField) { this.equalsField = equalsField; } @Override public boolean isValid(String thisField, ConstraintValidatorContext arg1) { //my validation } } and in my bean I want something like this: public class MyBean{ private String field1; @EqualsField(field=field1) private String field2; } Is there any way to define the annotation so the field value can be a variable? Thanks

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  • How can I get this code involving unique_ptr to compile?!

    - by Neil G
    #include <vector> #include <memory> using namespace std; class A { public: A(): i(new int) {} A(A const& a) = delete; A(A &&a): i(move(a.i)) {} unique_ptr<int> i; }; class AGroup { public: void AddA(A &&a) { a_.emplace_back(move(a)); } vector<A> a_; }; int main() { AGroup ag; ag.AddA(A()); return 0; } does not compile... (says that unique_ptr's copy constructor is deleted) I tried replacing move with forward. Not sure if I did it right, but it didn't work for me.

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  • Rails: constraint violation on create but not on update

    - by justinbach
    Note: This is a "railsier" (and more succinct) version of this question, which was getting a little long. I'm getting Rails behavior on a production server that I can't replicate on the development server. The codebases are identical save for credentials and caching settings, and both are powered by Oracle 10g databases with identical schema (but different data). My Rails application contains a user model, which has_one registration; registration in turn has_and_belongs_to_many company_ownerships through a registration_ownerships table. Upon registering, users fill out data pertinent to all three models, including a series of checkboxes indicating what registration_ownerships might apply to their account. On the dev server, the registration process is seamless, no matter what data is entered. On production, however, if users check off any of the company ownership fields before submitting their registration, Oracle complains about a constraint violation on the primary key of the company_ownerships table (which is a two-field key based on company_ownership_id and registration_id) and users get the standard Rails 500 error screen. In every case, I've verified that no conflicting record on these two fields exists in the production database, so I don't know why the constraint is getting violated. To further confuse things, if a user registers without listing any ownerships and later goes back and modifies their account to reflect ownership data (which is done through the same interface), the application happily complies with their request and Oracle is well-behaved (this is both on production and dev). I've spent the past couple days trying to figure out what might be causing this problem and am reaching the end of my wits. Any advice would be greatly appreciated!

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  • SQL CHECK constraint to prevent date overlap

    - by Michael
    I have a table that describes which software versions were installed on a machine at various times: machine_id::integer, version::text, datefrom::timestamp, dateto::timestamp I'd like to do a constraint to ensure that no date ranges overlap, i.e. it is not possible to have multiple software versions installed on a machine at the same time. How can this be achieved in SQL? I am using PostgreSQL v8.4.

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  • Validate uniqueness within a recent set

    - by Matchu
    Is there a standard Rails 3 way of detecting uniqueness within a particular scope, or is this custom validation all I can do? class Post < ActiveRecord::Base # [named scope for recent posts] validates do |post| if Post.recent.where('url = ?', post.url).count > 0 errors[:url] = 'has already been posted recently - thanks anyway!' end end end (Haven't yet tried that exact code, so there may be errors, but you get the idea.)

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  • Fastest way to compute a "Visual" checksum of an image

    - by ensnare
    I'm looking to create an ID system for cataloging images. I can't use md5() since that will change if I alter the EXIF tags of the image. I am currently using the SHA1 checksum computed by imagemagick. It works perfectly, but it's really, really slow on larger images (~15 seconds on a quad-core xeon for a 21 megapixel JPG). Are there any other "visual" methods of uniquely identifying an image that would be faster? Thank you.

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