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• How to find an embedded platform?

  - by gmagana

  I am new to the locating hardware side of embedded programming and so after being completely overwhelmed with all the choices out there (pc104, custom boards, a zillion option for each board, volume discounts, devel kits, ahhh!!) I am asking here for some direction. Basically, I must find a new motherboard and (most likely) re-implement the program logic. Rewriting this in C/C++/Java/C#/Pascal/BASIC is not a problem for me. so my real problem is finding the hardware. This motherboard will have several other devices attached to it. Here is a summary of what I need to do: Required: 2 RS232 serial ports (one used all the time for primary UI, the second one not continuous) 1 modem (9600+ baud ok) [Modem will be in simultaneous use with only one of the serial port devices, so interrupt sharing with one serial port is OK, but not both] Minimum permanent/long term storage: Whatever O/S requires + 1 MB (executable) + 512 KB (Data files) RAM: Minimal, whatever the O/S requires plus maybe 1MB for executable. Nice to have: USB port(s) Ethernet network port Wireless network Implementation languages (any O/S I will adapt to): First choice Java/C# (Mono ok) Second choice is C/Pascal Third is BASIC Ok, given all this, I am having a lot of trouble finding hardware that will support this that is low in cost. Every manufacturer site I visit has a lot of options, and it's difficult to see if their offering will even satisfy my must-have requirements (for example they sometimes list 3 "serial ports", but it appears that only one of the three is RS232, for example, and don't mention what the other two are). The #1 constraint is cost, #2 is size. Can anyone help me with this? This little task has left me thinking I should have gone for EE and not CS :-). EDIT: A bit of background: This is a system currently in production, but the original programmer passed away, and the current hardware manufacturer cannot find hardware to run the (currently) DOS system, so I need to reimplement this in a modern platform. I can only change the programming and the motherboard hardware.

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• How do I obtain and use a CVSNT commit ID?

  - by skiphoppy

  I saw a reference on another question to a unique commit id auto-generated by CVSNT that marks each commit. I think most people in my department are using CVSNT or frontends to it. I found commit identifiers described in the CVSNT manual, but there is no explanation about how to determine what the CVSNT commit identifier is for a particular revision of a file. Is there a way to do this? I'd like to find out what commit identifiers are being generated for other people's checkins so I can group together the files involved in their commits.

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• Perfect hash in Scala.

  - by Lukasz Lew

  I have some class C: class C (...) { ... } I want to use it to index an efficient map. The most efficient map is an Array. So I add a "global" "static" counter in companion object to give each object unique id: object C { var id_counter = 0 } In primary constructor of C, with each creation of C I want to remember global counter value and increase it. Question 1: How to do it? Now I can use id in C objects as perfect hash to index array. But array does not preserve type information like map would, that a given array is indexed by C's id. Question 2: Is it possible to have it with type safety?

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• Simulating a belongs_to_many in rails

  - by DavidP6

  I have a situation where in theory I would need to use a belongs_to_many relationship. I have an Example model and a Sentence model. Each example object has one sentence but these sentences are not necessarily unique. So, for example, I could have two example models that each have one sentence that is the same sentence. I'm not sure how to go about doing this in rails. I tried using has_and_belongs_to_many, but ran into problems. It seems that I only need the belongs_to :many part of that relationship. Ideally it would look something like this, but I know there is no belongs_to :many. Example has_one :sentence end Sentence belongs_to_many :examples end

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• declaring a 2D array of pointer objects

  - by Tyler Stennette

  I'm having a tough time figuring out how to instantiate a 2D array of pointer objects. Here is how I'm doing it: Pieces* chessBoard[9][9]; When I want to set it to an actual object pointer, I'm doing the following: chessBoard[1][1] = new Rook(p1Rook); Rook is a class that inherits attributes from the Pieces class and p1Rook is a char variable set to 'R'. This class also implements virtual functions (not pure virtual) from Pieces such as move() or getPiece() that are unique to the particular chess piece. However, when I compile my program, I get the following error: ChessBoard.cpp:69: error: expected type-specifier before ‘Rook’ ChessBoard.cpp:69: error: cannot convert ‘int*’ to ‘Pieces*’ in assignment Can someone please explain what I should change to get rid of this rather annoying persistent error? I would appreciate it.

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• Error Downloading Metadata from ASMX Service

  - by michael.lukatchik

  It should be possible (and it looks like it is), but assume I have the following functions in my ASMX web service: [WebMethod(MessageName = "CreateExternalRpt1")] public bool CreateExternalRpt(int iProductId, int iOrderProductId, DateTime dtReportTime, string strReportTitle, string strReportCategory, string strReportPrintType, out string strSnapshot, string strApplicantFirst, string strApplicantLast, string strApplicantMiddle, string strOwnerLast, string strOwnerMiddle, string strOwnerFirst, bool blnCurrentReport, int iOrderId, bool blnFlag, string strCustomerId, string strUserId) { … } [WebMethod(MessageName = "CreateExternalRpt2")] public bool CreateExternalRpt(int iProductId, int iOrderProductId, DateTime dtReportTime, string strReportTitle, string strReportCategory, string strReportPrintType, string strReportSnapshot, string strApplicantFirst, string strApplicantLast, string strApplicantMiddle, string strOwnerLast, string strOwnerMiddle, string strOwnerFirst, bool blnCurrentReport, int iOrderId, bool blnFlag) { … } With both of these functions defined in my web service, my .NET client app can’t download the metadata and instead throws a generic error message “There was an error downloading…”. With one of the above methods removed, the .NET client app can successfully download the metadata. I’ve read that by decorating the WebMethod with a unique name, both functions should be exposed in the service metadata. This isn’t working. What am I missing?

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• Hibernate not using schema and catalog name in id generation with strategy increment

  - by Ben

  Hi, I am using the hibernate increment strategy to create my IDs on my entities. @GenericGenerator(name="increment-strategy", strategy="increment") @Id @GeneratedValue(generator="increment=strategy") @Column(name="HDR_ID", unique=true, nullable=false) public int getHdrId(){ return this.hdrId; } The entity has the following table annotation @Table(name = "PORDER.PUB.PO_HEADER", schema = "UVOSi", catalog = "VIRT_UVOS") Please note I have two datasources. When I try to insert an entity Hibernate creates the following SQL statement: select max(hdr_id) from PORDER.PUB.PO_HEADER which causes the following error: Group specified is ambiguous, resubmit the query by fully qualifying group name. When I create a query by hand with entityManager.createQuery() hibernate uses the fully qualified name select XXX from VIRT_UVOS.UVOSi.PORDER.PUB.PO_HEADER and that works fine. So how do I get Hibernate to use the fully qualified name in the Id autogeneration? Btw. I am using Hibernate 3.2 and Seam 2.2 running on JBoss 4.2.3 Regards Immo

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• Hibernate @Index on @Enumerated field doesn't work

  - by mlaverd

  I am using Hibernate to talk to my DB. I have one field that is an enumeration and it is going to be used in a slow query. So I'd like to index it. I've put the following annotations on the field: @Column(name="RIGHT_TYPE", unique=false, nullable=false, length=10) @Enumerated(EnumType.STRING) @Index(name = "ABC_INDEX") protected RightType rightType; However, I don't see any index on that field created. But I can create one manually if I wish so. Why is that? Is there any way to force Hibernate to make it happen?

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• foreign key constraints on primary key columns - issues ?

  - by zzzeek

  What are the pros/cons from a performance/indexing/data management perspective of creating a one-to-one relationship between tables using the primary key on the child as foreign key, versus a pure surrogate primary key on the child? The first approach seems to reduce redundancy and nicely constrains the one-to-one implicitly, while the second approach seems to be favored by DBAs, even though it creates a second index: create table parent ( id integer primary key, data varchar(50) ) create table child ( id integer primary key references parent(id), data varchar(50) ) pure surrogate key: create table parent ( id integer primary key, data varchar(50) ) create table child ( id integer primary key, parent_id integer unique references parent(id), data varchar(50) ) the platforms of interest here are Postgresql, Microsoft SQL Server.

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• Why does this regular expression fail?

  - by Stephen

  I have a password validation script in PHP that checks a few different regular expressions, and throws a unique error message depending on which one fails. Here is an array of the regular expressions and the error messages that are thrown if the match fails: array( 'rule1' => array( '/^.*[\d].*$/i', 'Password must contain at least one number.' ), 'rule2' => array( '/^.*[a-z].*$/i', 'Password must contain at least one lowercase letter' ), 'rule3' => array( '/^.*[A-Z].*$/i', 'Password must contain at least one uppercase letter' ), 'rule4' => array( '/^.*[~!@#$%^&*()_+=].*$/i', 'Password must contain at least one special character [~!@#$%^&*()_+=]' ) ); For some reason, no matter what I pass through the validation, the "Special Characters" rule fails. I'm guessing it's a problem with the expression. If there's a better (or correct) way to write these expressions, I'm all ears!

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• Inserting records in Mysql with INSERT IGNORE and NULL values

  - by Homer1980ar

  I have a partitioned table InnoDB with several fields. I'm trying to avoid duplicates on insert. Let's say: Field1 int null Field2 int null Field3 int null Field4 int null Field5 int null I have created a UNIQUE index on those fields. I try to insert some records with NULL values and then try to reinsert them with IGNORE feature on MySql. Unfortunately it seems to replicated the records when using NULL values. If I try with zeros instead of NULL cases everything works, but I do need the nulls there. Any idea? Thanks, Leonardo

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• Problem with auto increment primary key (MySQL).

  - by mathon12

  I have 2 tables each using other's primary key as a foreign key. The primary keys for both are set to auto_increment. The problem is, when I try to create and entry into one of the tables, I have no idea what the primary key of the entry is and can't figure out what to put in the other table as a foreign key. What should I do? Do I drop auto_increment altogether and cook up a unique identifier for each entry so I can use it to address the created entries? I'm using PHP, if that's relevant. Thanks.

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• Why is TRest in Tuple<T1... TRest> not constrained?

  - by Anthony Pegram

  In a Tuple, if you have more than 7 items, you can provide an 8th item that is another tuple and define up to 7 items, and then another tuple as the 8th and on and on down the line. However, there is no constraint on the 8th item at compile time. For example, this is legal code for the compiler: var tuple = new Tuple<int, int, int, int, int, int, int, double> (1, 1, 1, 1, 1, 1, 1, 1d); Even though the intellisense documentation says that TRest must be a Tuple. You do not get any error when writing or building the code, it does not manifest until runtime in the form of an ArgumentException. You can roughly implement a Tuple in a few minutes, complete with a Tuple-constrained 8th item. I just wonder why it was left off the current implementation? Is it possibly a forward-compatibility issue where they could add more elements with a hypothetical C# 5? Short version of rough implementation interface IMyTuple { } class MyTuple<T1> : IMyTuple { public T1 Item1 { get; private set; } public MyTuple(T1 item1) { Item1 = item1; } } class MyTuple<T1, T2> : MyTuple<T1> { public T2 Item2 { get; private set; } public MyTuple(T1 item1, T2 item2) : base(item1) { Item2 = item2; } } class MyTuple<T1, T2, TRest> : MyTuple<T1, T2> where TRest : IMyTuple { public TRest Rest { get; private set; } public MyTuple(T1 item1, T2 item2, TRest rest) : base(item1, item2) { Rest = rest; } } ... var mytuple = new MyTuple<int, int, MyTuple<int>>(1, 1, new MyTuple<int>(1)); // legal var mytuple2 = new MyTuple<int, int, int>(1, 2, 3); // illegal

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• Efficiently generate a 16-character, alphanumeric string

  - by ensnare

  I'm looking for a very quick way to generate an alphanumeric unique id for a primary key in a table. Would something like this work? def genKey(): hash = hashlib.md5(RANDOM_NUMBER).digest().encode("base64") alnum_hash = re.sub(r'[^a-zA-Z0-9]', "", hash) return alnum_hash[:16] What would be a good way to generate random numbers? If I base it on microtime, I have to account for the possibility of several calls of genKey() at the same time from different instances. Or is there a better way to do all this? Thanks.

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• Should I use integer primary IDs?

  - by arthurprs

  For example, I always generate an auto-increment field for the users table, but I also specify a UNIQUE index on their usernames. There are situations that I first need to get the userId for a given username and then execute the desired query, or use a JOIN in the desired query. It's 2 trips to the database or a JOIN vs. a varchar index. Should I use integer primary IDs? Is there a real performance benefit on INT over small VARCHAR indexes?

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• reversing keys/values - create new instance of HashMap

  - by stck777

  I’ve got an existing instance of HashMap simply called sale (it is Map) I use it to log customers and items history. Is there a way to create a new instance of HashMap, that effectively reverses this usage? i.e will show each item purchased as a unique key and the corresponding value as a String set of the customers that have purchased that product. I suspect there is a simple process using keySet() in some way to iterate over the sales map but I just can’t see how to do this. Any help would be much appreciated.

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• Two entities with @ManyToOne should join 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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• Zip up groups of webpages for viewing in the browser

  - by Arlen Beiler

  I think there should be a standard for saving and viewing bunches of webpages as a website. For instance, say I have a whole bunch of pages, such as I get from the WordPress plugin "Really Static" (which saves the entire site), and I have all the links start with a slash (to make linking to supporting files easier). Now, I can't really use those links if I am reading it from the file system. If there would be a standard where we could zip up files, give them a unique extension (like "hzip" for html zip), and open the file with any browser, which would display it as though the root of that file were the root of the pages. "file://examplefile.hzip/" The links would then all work. This would really help sharing and copying groups of webpages. Is this a good idea? A bad one? What do you think?

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• Java hashcode based on identity

  - by hjfreyer

  The default behavior of Object.hashCode() is to return essentially the "address" of the object so that a.hashCode() == b.hashCode() if and only if a == b. How can I get this behavior in a user-defined class if a superclass already defines hashCode()? For instance: class A { public int hashCode() { return 0; } } class B extends A { public int hashCode() { // Now I want to return a unique hashcode for each object. // In pythonic terms, it'd look something like: return Object.hashCode(this); } } Ideas?

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• Generic ASP.NET MVC Route Conflict

  - by Donn Felker

  I'm working on a Legacy ASP.NET system. I say legacy because there are NO tests around 90% of the system. I'm trying to fix the routes in this project and I'm running into a issue I wish to solve with generic routes. I have the following routes: routes.MapRoute( "DefaultWithPdn", "{controller}/{action}/{pdn}", new { controller = "", action = "Index", pdn = "" }, null ); routes.MapRoute( "DefaultWithClientId", "{controller}/{action}/{clientId}", new { controller = "", action = "index", clientid = "" }, null ); The problem is that the first route is catching all of the traffic for what I need to be routed to the second route. The route is generic (no controller is defined in the constraint in either route definition) because multiple controllers throughout the entire app share this same premise (sometimes we need a "pdn" sometimes we need a "clientId"). How can I map these generic routes so that they go to the proper controller and action, yet not have one be too greedy? Or can I at all? Are these routes too generic (which is what I'm starting to believe is the case). My only option at this point (AFAIK) is one of the following: In the contraints, apply a regex to match the action values like: (foo|bar|biz|bang) and the same for the controller: (home|customer|products) for each controller. However, this has a problem in the fact that I may need to do this: ~/Foo/Home/123 // Should map to "DefaultwithPdn" ~/Foo/Home/abc // Should map to "DefaultWithClientId" Which means that if the Foo Controller has an action that takes a pdn and another action that takes a clientId (which happens all the time in this app), the wrong route is chosen. To hardcode these contstraints into each possible controller/action combo seems like a lot of duplication to me and I have the feeling I've been looking at the problem for too long so I need another pair of eyes to help out. Can I have generic routes to handle this scenario? Or do I need to have custom routes for each controller with constraints applied to the actions on those routes? Thanks

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• Checking instance of non-class constrained type parameter for null in generic method

  - by casperOne

  I currently have a generic method where I want to do some validation on the parameters before working on them. Specifically, if the instance of the type parameter T is a reference type, I want to check to see if it's null and throw an ArgumentNullException if it's null. Something along the lines of: // This can be a method on a generic class, it does not matter. public void DoSomething<T>(T instance) { if (instance == null) throw new ArgumentNullException("instance"); Note, I do not wish to constrain my type parameter using the class constraint. I thought I could use Marc Gravell's answer on "How do I compare a generic type to its default value?", and use the EqualityComparer<T> class like so: static void DoSomething<T>(T instance) { if (EqualityComparer<T>.Default.Equals(instance, null)) throw new ArgumentNullException("instance"); But it gives a very ambiguous error on the call to Equals: Member 'object.Equals(object, object)' cannot be accessed with an instance reference; qualify it with a type name instead How can I check an instance of T against null when T is not constrained on being a value or reference type?

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• Validations for a has_many/belongs_to relationship

  - by Craig Walker

  I have a Recipe model which has_many Ingredients (which in turn belongs_to Recipe). I want Ingredient to be existent dependent on Recipe; an Ingredient should never exist without a Recipe. I'm trying to enforce the presence of a valid Recipe ID in the Ingredient. I've been doing this with a validates :recipe, :presence => true (Rails 3) statement in Ingredient. This works fine if I save the Recipe before adding an Ingredient to it's ingredients collection. However, if I don't have explicit control over the saving (such as when I'm creating a Recipe and its Ingredients from a nested form) then I get an error: Ingredients recipe can't be blank I can get around this simply by dropping the presence validation on Ingredient.recipe. However, I don't particularly like this, as it means I'm working without a safety net. What is the best way to enforce existence-dependence in Rails? Things I'm considering (please comment on the wisdom of each): Adding a not-null constraint on the ingredients.recipe_id database column, and letting the database do the checking for me. A custom validation that somehow checks whether the Ingredient is in an unsaved recipe's ingredient collection (and thus can't have a recipe_id but is still considered valid).

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• Referencing file on disk from NSManagedObject

  - by Kamchatka

  Hello, What would be the best way to name a file associated to a NSManagedObject. The NSManagedObject will hold the URL to this file. But I need to create a unique filename for my file. Is there some kind of autoincrement id that I could use? Should I use mktemp (but it's not a temporary file) or try to convert the NSManagedObjectId to a filename? but I fear there will be special characters which might cause problem. What would you suggest?

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• SQL Server stored procedure return code oddity

  - by gbn

  Hello The client that calls this code is restricted and can only deal with return codes from stored procs. So, we modified our usual contract to RETURN -1 on error and default to RETURN 0 if no error If the code hits the inner catch block, then the RETURN code default to -4. Where does this come from, does anyone know...? IF OBJECT_ID('dbo.foo') IS NOT NULL DROP TABLE dbo.foo GO CREATE TABLE dbo.foo ( KeyCol char(12) NOT NULL, ValueCol xml NOT NULL, Comment varchar(1000) NULL, CONSTRAINT PK_foo PRIMARY KEY CLUSTERED (KeyCol) ) GO IF OBJECT_ID('dbo.bar') IS NOT NULL DROP PROCEDURE dbo.bar GO CREATE PROCEDURE dbo.bar @Key char(12), @Value xml, @Comment varchar(1000) AS SET NOCOUNT ON DECLARE @StartTranCount tinyint; BEGIN TRY SELECT @StartTranCount = @@TRANCOUNT; IF @StartTranCount = 0 BEGIN TRAN; BEGIN TRY --SELECT @StartTranCount = 'fish' INSERT dbo.foo (KeyCol, ValueCol, Comment) VALUES (@Key, @Value, @Comment); END TRY BEGIN CATCH IF ERROR_NUMBER() = 2627 --PK violation UPDATE dbo.foo SET ValueCol = @Value, Comment = @Comment WHERE KeyCol = @Key; ELSE RAISERROR ('Tits up', 16, 1); END CATCH IF @StartTranCount = 0 COMMIT TRAN; END TRY BEGIN CATCH IF @StartTranCount = 0 AND XACT_STATE() <> 0 ROLLBACK TRAN; RETURN -1 END CATCH --Without this, we'll send -4 if we hit the UPDATE CATCH block above --RETURN 0 GO --Run with RETURN 0 and fish line commented out DECLARE @rtn int EXEC @rtn = dbo.bar 'abcdefghijkl', '<foobar />', 'testing' SELECT @rtn; SELECT * FROM dbo.foo DECLARE @rtn int EXEC @rtn = dbo.bar 'abcdefghijkl', '<foobar2 />', 'testing2' --updated OK but we get @rtn = -4 SELECT @rtn; SELECT * FROM dbo.foo --uncomment fish line DECLARE @rtn int EXEC @rtn = dbo.bar 'abcdefghijkl', '<foobar />', 'testing' --Hit outer CATCH, @rtn = -1 as expected SELECT @rtn; SELECT * FROM dbo.foo

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• How do i serlialize the product using php?

  - by Ibrahim Azhar Armar

  hi, i am building a real estate application where in it will store the properties and search it. the property will have different categories like (residential, commercial, industrial or agricultural). based upon the category i want to serailize each and every property listing . for example the property with id 1 belongs to resedential will have the serial code rs_SOMERANDOMUNIQUENUMBER. and for commercial it can be cm_SOMERANDOMUNIQUENUMBER and so on. for this my database table looks like this. CREATE TABLE IF NOT EXISTS `propSerials` ( `id` bigint(20) NOT NULL auto_increment, `serial` varchar(50) NOT NULL, `property_id` int(10) UNIQUE NOT NULL, PRIMARY KEY  (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; what would be the best possible format to store the serial with the prefix according to category? thank you

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