Search Results

Search found 5516 results on 221 pages for 'scope identity'.

Page 193/221 | < Previous Page | 189 190 191 192 193 194 195 196 197 198 199 200  | Next Page >

  • How do you chain functions dynamically in jQuery?

    - by clarke78
    I want to loop through an object that contains functions which will execute one after another. My most ideal approach would be to have these chain somehow (ie. func2 waits for func1 and func3 waits for func2) but this needs to happen dynamically and the functions will all have different durations. I'm using jQuery so I thought that perhaps "queue()" may help but I haven't worked with it much. A main concern is to not add any scope/callbacks to the functions within the object. I'd rather somehow enclose them within a parent function to execute within the loop in order to create the callback/chaining. Here's an example of what I've got now, but dumbed down. Thanks for any help! var obj = [ {'name':'func1','callback':function(){ alert(1); }}, {'name':'func2','callback':function(){ alert(2); }}, {'name':'func3','callback':function(){ alert(3); }} ]; $.each(obj, function(x, el) { el.callback(); });

    Read the article

  • Two references to the same domain/entity model

    - by Sbossb
    Problem I want to save the attributes of a model that have changed when a user edits them. Here's what I want to do ... Retrieve edited view model Get domain model and map back updated value Call the update method on repository Get the "old" domain model and compare values of the fields Store the changed values (in JSON) into a table However I am having trouble with step number 4. It seems that the Entity Framework doesn't want to hit the database again to get the model with the old values. It just returns the same entity I have. Attempted Solutions I have tried using the Find() and the SingleOrDefault() methods, but they just return the model I currently have. Example Code private string ArchiveChanges(T updatedEntity) { //Here is the problem! //oldEntity is the same as updatedEntity T oldEntity = DbSet.SingleOrDefault(x => x.ID == updatedEntity.ID); Dictionary<string, object> changed = new Dictionary<string, object>(); foreach (var propertyInfo in typeof(T).GetProperties()) { var property = typeof(T).GetProperty(propertyInfo.Name); //Get the old value and the new value from the models var newValue = property.GetValue(updatedEntity, null); var oldValue = property.GetValue(oldEntity, null); //Check to see if the values are equal if (!object.Equals(newValue, oldValue)) { //Values have changed ... log it changed.Add(propertyInfo.Name, newValue); } } var ser = new System.Web.Script.Serialization.JavaScriptSerializer(); return ser.Serialize(changed); } public override void Update(T entityToUpdate) { //Do something with this string json = ArchiveChanges(entityToUpdate); entityToUpdate.AuditInfo.Updated = DateTime.Now; entityToUpdate.AuditInfo.UpdatedBy = Thread.CurrentPrincipal.Identity.Name; base.Update(entityToUpdate); }

    Read the article

  • How find all overlapping circles from radius of central circle?

    - by roza
    How to do an intersection or overlap query in mongo shell - what circles overlap my search region? Within relate only to the center position but doesn't include radius of the other circles in searched scope. Mongo: # My bad conception: var search = [[30, 30], 10] db.places.find({circle : {"$within" : {"$center" : [search]}}}) Now I can obtain only this circles within central point lies in searched area of circle: Ruby: # field :circle, type: Circle # eg. [ [ 30, 30 ], 10 ] field :radius, type: Integer field :location, :type => Array, :spatial => true spatial_index :location Places.within_circle(location: [ [ 30, 30 ], 10 ]) # {"$query"=>{"location"=>{"$within"=>{"$center"=>[[30, 30], 10]}}} I created example data with additional location (special index) and radius instead circle because circle isn't supported by mongodb geo index: { "_id" : 1, "name" : "a", "circle" : [ [ 5, 5 ], 40 ], "latlng" : [ 5, 5 ], "radius" : 40 } { "_id" : 2, "name" : "b", "circle" : [ [ 10, 10 ], 5 ], "latlng" : [ 10, 10 ], "radius" : 5 } { "_id" : 3, "name" : "c", "circle" : [ [ 20, 20 ], 5 ], "latlng" : [ 20, 20 ], "radius" : 5 } { "_id" : 4, "name" : "d", "circle" : [ [ 30, 30 ], 50 ], "latlng" : [ 30, 30 ], "radius" : 50} { "_id" : 5, "name" : "e", "circle" : [ [ 80, 80 ], 30 ], "latlng" : [ 80, 80 ], "radius" : 30} { "_id" : 6, "name" : "f", "circle" : [ [ 80, 80 ], 20 ], "latlng" : [ 80, 80 ], "radius" : 20} Desired query result: { "_id" : 1, "name" : "a", "circle" : [ [ 5, 5 ], 40 ], "latlng" : [ 5, 5 ], "radius" : 40 } { "_id" : 3, "name" : "c", "circle" : [ [ 20, 20 ], 5 ], "latlng" : [ 20, 20 ], "radius" : 5 } { "_id" : 4, "name" : "d", "circle" : [ [ 30, 30 ], 50 ], "latlng" : [ 30, 30 ], "radius" : 50} { "_id" : 5, "name" : "e", "circle" : [ [ 80, 80 ], 30 ], "latlng" : [ 80, 80 ], "radius" : 30} Solution below assumes that I get all rows and then filter on the ruby side my radius but it returns only: { "_id" : 4, "name" : "d", "circle" : [ [ 30, 30 ], 50 ], "latlng" : [ 30, 30 ], "radius" : 50}

    Read the article

  • Has inheritance become bad?

    - by mafutrct
    Personally, I think inheritance is a great tool, that, when applied reasonably, can greatly simplify code. However, I seems to me that many modern tools dislike inheritance. Let's take a simple example: Serialize a class to XML. As soon as inheritance is involved, this can easily turn into a mess. Especially if you're trying to serialize a derived class using the base class serializer. Sure, we can work around that. Something like a KnownType attribute and stuff. Besides being an itch in your code that you have to remember to update every time you add a derived class, that fails, too, if you receive a class from outside your scope that was not known at compile time. (Okay, in some cases you can still work around that, for instance using the NetDataContract serializer in .NET. Surely a certain advancement.) In any case, the basic principle still exists: Serialization and inheritance don't mix well. Considering the huge list of programming strategies that became possible and even common in the past decade, I feel tempted to say that inheritance should be avoided in areas that relate to serialization (in particular remoting and databases). Does that make sense? Or am messing things up? How do you handle inheritance and serialization?

    Read the article

  • Mechanize form submit not going to the correct response page, no errors as to why. Something I'm doing?

    - by Zack Shapiro
    I threw this all in one controller for testing purposes. My code fills out the form correctly for adding a new address to your Amazon account. There are two buttons that submit this form, one takes you to add a new address which is what I don't want, and the other is just a Save & Continue input/image. When I submit the form via that button, as I do below, the form is still on the page, filled out as I have with my code. Inspecting the page titles, they're the same. There are no discernible errors that Mechanize or Amazon spit back. Any ideas? class AmazonCrawler def initialize @agent = Mechanize.new do |agent| agent.user_agent_alias = 'Mac Safari' agent.follow_meta_refresh = true agent.redirect_ok = true end end def login # login_url = "https://www.amazon.com/ap/signin?_encoding=UTF8&openid.assoc_handle=usflex&openid.claimed_id=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.identity=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.mode=checkid_setup&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.ns.pape=http%3A%2F%2Fspecs.openid.net%2Fextensions%2Fpape%2F1.0&openid.pape.max_auth_age=0&openid.return_to=https%3A%2F%2Fwww.amazon.com%2Fgp%2Fcss%2Fhomepage.html%3Fie%3DUTF8%26ref_%3Dgno_yam_ya" login_url = "https://www.amazon.com/gp/css/account/address/view.html?ie=UTF8&ref_=ya_add_address&viewID=newAddress" @agent.get(login_url) form = @agent.page.forms.first form.email = "[email protected]" form.radiobuttons.first.value = "0" form.radiobuttons.last.check form.password = "my_password" dashboard = @agent.submit(form) end end class UsersController < ApplicationController def index response = AmazonCrawler.new.login form = response.forms[1] # fill out form form.enterAddressFullName == "Your Name" form.enterAddressAddressLine1 = "123 Main Street" form.enterAddressAddressLine2 = "Apartment 34" form.enterAddressCity = "San Francisco" form.enterAddressStateOrRegion = "CA" form.enterAddressPostalCode = "94101" form.enterAddressPhoneNumber = "415-555-1212" form.AddressType = "RES" new_response = form.submit( form.button_with(value: /Save.*Continue/) ) end end

    Read the article

  • Attribute value nil

    - by mridula
    Can someone tell me why is this happening? I have created a social networking website using Ruby on Rails. This is my first time programming with RoR. I have a model named "Friendship" which contains an attribute "blocked" to indicate whether the user has blocked another user. When I run the following in IRB - friendship = u.friendships.where(:friend_id => 22).first IRB gives me - Friendship Load (0.6ms) SELECT `friendships`.* FROM `friendships` WHERE `friendships`.`user_id` = 17 AND `friendships`.`friend_id` = 22 LIMIT 1 => #<Friendship id: 33, user_id: 17, friend_id: 22, created_at: "2012-04-07 10:29:49", updated_at: "2012-04-07 10:29:49", blocked: 1> As u can see, the "blocked" attribute has value '1'. But when I run the following 1.9.2-p290 :030 > friendship.blocked => nil - it says, the value of blocked is 'nil' and not '1'. Why is this happening? This could be a very silly mistake but I am new to RoR, so kindly help me! I initially didn't include the accessor method for 'blocked'.. I tried that, and still its giving the same result.. Following is the Friendship model.. class Friendship < ActiveRecord::Base belongs_to :friend, :class_name => "User" validates_uniqueness_of :friend_id , :scope => :user_id attr_accessor :blocked attr_accessible :blocked end Here is the schema of the table: 1.9.2-p290 :009 > friendship.class => Friendship(id: integer, user_id: integer, friend_id: integer, created_at: datetime, updated_at: datetime, blocked: integer)

    Read the article

  • Why is function's length information of other shared lib in ELF?

    - by minastaros
    Our project (C++, Linux, gcc, PowerPC) consists of several shared libraries. When releasing a new version of the package, only those libs should change whose source code was actually affected. With "change" I mean absolute binary identity (the checksum over the file is compared. Different checksum - different version according to the policy). (I should mention that the whole project is always built at once, no matter if any code has changed or not per library). Usually this can by achieved by hiding private parts of the included Header files and not changing the public ones. However, there was a case where just a delete was added to the destructor of a class TableManager (in the TableManager.cpp file!) of library libTableManager.so, and yet the binary/checksum of library libB.so (which uses class TableManager ) has changed. TableManager.h: class TableManager { public: TableManager(); ~TableManager(); private: int* myPtr; } TableManager.cpp: TableManager::~TableManager() { doSomeCleanup(); delete myPtr; // this delete has been added } By inspecting libB.so with readelf --all libB.so, looking at the .dynsym section, it turned out that the length of all functions, even the dynamically used ones from other libraries, are stored in libB! It looks like this (length is the 668 in the 3rd column): 527: 00000000 668 FUNC GLOBAL DEFAULT UND _ZN12TableManagerD1Ev So my questions are: Why is the length of a function actually stored in the client lib? Wouldn't a start address be sufficient? Can this be suppressed somehow when compiling/linking of libB.so (kind of "stripping")? We would really like to reduce this degree of dependency...

    Read the article

  • How can I compare the performance of log() and fp division in C++?

    - by Ventzi Zhechev
    Hi, I’m using a log-based class in C++ to store very small floating-point values (as the values otherwise go beyond the scope of double). As I’m performing a large number of multiplications, this has the added benefit of converting the multiplications to sums. However, at a certain point in my algorithm, I need to divide a standard double value by an integer value and than do a *= to a log-based value. I have overloaded the *= operator for my log-based class and the right-hand side value is first converted to a log-based value by running log() and than added to the left-hand side value. Thus the operations actually performed are floating-point division, log() and floating-point summation. My question whether it would be faster to first convert the denominator to a log-based value, which would replace the floating-point division with floating-point subtraction, yielding the following chain of operations: twice log(), floating-point subtraction, floating-point summation. In the end, this boils down to whether floating-point division is faster or slower than log(). I suspect that a common answer would be that this is compiler and architecture dependent, so I’ll say that I use gcc 4.2 from Apple on darwin 10.3.0. Still, I hope to get an answer with a general remark on the speed of these two operators and/or an idea on how to measure the difference myself, as there might be more going on here, e.g. executing the constructors that do the type conversion etc. Cheers!

    Read the article

  • Holding variables in memory, C++

    - by b-gen-jack-o-neill
    Today something strange came to my mind. When I want to hold some string in C (C++) the old way, without using string header, I just create array and store that string into it. But, I read that any variable definition in C in local scope of function ends up in pushing these values onto the stack. So, the string is actually 2* bigger than needed. Because first, the push instructions are located in memory, but then when they are executed (pushed onto the stack) another "copy" of the string is created. First the push instructions, than the stack space is used for one string. So, why is it this way? Why doesn't compiler just add the string (or other variables) to the program instead of creating them once again when executed? Yes, I know you cannot just have some data inside program block, but it could just be attached to the end of the program, with some jump instruction before. And than, we would just point to these data? Because they are stored in RAM when the program is executed. Thanks.

    Read the article

  • Calling multiple functions simultaneously with jquery.

    - by clarke78
    I want to loop through an object that contains functions which will execute one after another. My most ideal approach would be to have these chain somehow (ie. func2 waits for func1 and func3 waits for func2) but this needs to happen dynamically and the functions will all have different durations. I'm using jQuery so I thought that perhaps "queue()" may help but I haven't worked with it much. A main concern is to not add any scope/callbacks to the functions within the object. I'd rather somehow enclose them within a parent function to execute within the loop in order to create the callback/chaining. Here's an example of what I've got now, but dumbed down. Thanks for any help! var obj = [ {'name':'func1','callback':function(){ alert(1); }}, {'name':'func2','callback':function(){ alert(2); }}, {'name':'func3','callback':function(){ alert(3); }} ]; $.each(obj, function(x, el) { el.callback(); });

    Read the article

  • [^.] causing headache in RewriteRule

    - by Ollie2893
    I am struggling with a very basic regex problem in my .htaccess file that I hope someone may be able to shed some light on. The basic premise is that I would like to teach Apache to switch any .html extension into a .var extension. I had thought that the rule would be positively trivial: RewriteRule ^([^.]+)\.html$ $1.var But the [^.] part simply doesn't work. Bizarrely, it works like so RewriteRule ^([^A-Z]+)\.html$ $1.var I do not understand why this latter rule works. Assume I am looking for a file called "index.html" then $1 should match to "index." and the ".html" bit should actually fail to match. To widen the scope of the question slightly, I am actually racking my brain on how to implement a multi-lingual site. I don't like Apache's MultiView option because it forces upon me a flat directory structure with file extensions that aren't recognizable to many development tools. I could go the .var type-map route but am finding that the default config for Apache doesn't support this all that well either (hence my excursions into regex land). So while I am using mod_rewrite, I am thinking that I might go the whole hog: whenever a request for a name.html file is received and this file does not exist, check whether there exists a XX/name.html file instead, where "XX" is the language code according to the user's preferences. This would give me a neater directory structure, though it does perhaps not perform as well as the .var approach in a situation where the language preference of the user's browser is not supported in by my site (in which situation .var would substitute EN or similar). Any thoughts? Thanks.

    Read the article

  • Are programming languages and methods ineffective? (assembler and C knowledge needed)

    - by b-gen-jack-o-neill
    Hi, for a long time, I am thinking and studying output of C language compiler in asemlber form, as well as CPU architecture. I know this may be silly to you, but it seems to me that something is very ineffective. Please, don´t be angry if I am wrong, and there is some reason I do not see for all these principles. I will be very glad if you tell me why is it designed this way. I actually trully believe I am wrong, I know the genius minds of people which get PCs together knew a reason to do so. What exactly, do you ask? I´ll tell you right away, I use C as a example: 1, Stack local scope memory allocation: So, typical local memory allocation uses stack. Just copy esp to ebp and than allocate all the memory via ebp. OK, I would understand this if you explicitly need allocate RAM by default stack values, but if I do understand it correctly, modern OS use paging as a translation layer between application and physical RAM, when adress you desire is further translated before reaching actuall RAM byte. So why don´t just say 0x00000000 is int a,0x00000004 is int b and so? And access them just by mov 0x00000000,#10? Becouse you wont actually access memory blocks 0x00000000 and 0x00000004 but those your OS set the paging tables to. Actually, since memory allocation by ebp and esp use indirect adressing, "my" way would be even faster. 2, Variable allocation duplicitly: When you run aaplication, Loader load its code into RAM. When you create variable, or string, compiler generates code that pushes these values on the top o stack when created in main. So there is actuall instruction for do so, and that actuall number in memory. So, there are 2 entries of the same value in RAM. One in fomr of instruction, second in form of actuall bytes in the RAM. But why? Why not to just when declaring variable count at which memory block it would be, than when used, just insert this memory location?

    Read the article

  • copy rows with special condition

    - by pooria_googooli
    I have a table with a lot of columns. For example I have a table with these columns : ID,Fname,Lname,Tel,Mob,Email,Job,Code,Company,...... ID column is auto number column. I want to copy all rows in this table to this table and change the company column value to 12 in this copied row. I don't want to write name all of the columns because I have a lot of table with a lot of columns. I tried this code but I had this error : declare @c int; declare @i int; select * into CmDet from CmDet; select @C= count(id) from CmDet; while @i < @C begin UPDATE CmDet SET company =12 WHERE company=11 set @i += 1 end error : Msg 2714, Level 16, State 6, Line 3 There is already an object named 'CmDet' in the database. I changed the code to this declare @c int declare @i int insert into CmDet select * from CmDet; select @C= count(id) from CmDet; while @i < @C begin UPDATE CmDet SET company =12 WHERE company=11 set @i += 1 end and I had this error : Msg 8101, Level 16, State 1, Line 3 An explicit value for the identity column in table 'CmDet' can only be specified when a column list is used and IDENTITY_INSERT is ON. What should I do ?

    Read the article

  • NHibernate not dropping foreign key constraints.

    - by Kendrick
    I'm new to NHibernate, so this is probably my mistake, but when I use: schema.Create(true, true); I get: SchemaExport [(null)]- There is already an object named 'XXX' in the database. System.Data.SqlClient.SqlException: There is already an object named 'XXX' in the database. I grabbed the SQL code nHibernate was using, ran it directly from MSSMS, and recieved similar errors. Looking into it, the generated code is not properly dropping the foreign key constraints. The drop looks like this: if exists (select 1 from sysobjects where id = OBJECT_ID(N'dbo[FK22212EAFBFE4C58]') AND parent_obj = OBJECT_ID('YYY')) alter table dbo.YYY drop constraint FK22212EAFBFE4C58 Doing a "select OBJECT_ID(N'dbo[FK22212EAFBFE4C58]')" I get null. If I take out the "dbo" (i.e. "select OBJECT_ID(N'[FK22212EAFBFE4C58]')") then the ID is returned. So, my question is, why is nHibernate adding the dbo, and why does that prevent the object from being returned (since the table owning the constraint is dbo.XXX) One of my mapping files: <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping namespace="CanineApp.Model" assembly="CanineApp.Model" xmlns="urn:nhibernate-mapping-2.2"> <class name="MedicalLog" table="MedicalLog" schema="dbo"> <id name="MedicalLogID" type="Int64"> <generator class="identity" /> </id> <property name="InvoiceAmount" type="Decimal" not-null="true" /> ... <many-to-one name="Canine" class="Canine" column="CanineID" not-null="true" fetch="join" /> <many-to-one name="TreatmentCategory" class="TreatmentCategory" column="TreatmentCategoryID" not-null="true" access="field.camelcase-underscore" /> </class> </hibernate-mapping>

    Read the article

  • sending address of a variable declared on the stack?

    - by kobac
    I have a doubt concerning declaring variables, their scope, and if their address could be sent to other functions even if they are declared on the stack? class A{ AA a; void f1(){ B b; aa.f2(&b); } }; class AA{ B* mb; f2(B* b){ mb = b; //... } }; Afterwards, I use my AA::mb pointer in the code. So things I would like to know are following. When the program exits A::f1() function, b variable since declared as a local variable and placed on the stack, can't be used anymore afterwards. What happens with the validity of the AA::mb pointer? It contains the address of the local variable which could not be available anymore, so the pointer isn't valid anymore? If B class is a std::<vector>, and AA::mb is not a pointer anymore to that vector, but a vector collection itself for example. I would like to avoid copying all of it's contents in AA::f2() to a member AA::mb in line mb = b. Which solution would you recommend since I can't assign a pointer to it, because it'll be destroyed when the program exits AA::f2()

    Read the article

  • How do I execute a sql statement through a variable (dyname sql) that tries to do an insert into a variable table?

    - by Testifier
    If I do what I wanna do with a TEMPORARY TABLE, it works fine: DECLARE @CTRFR VARCHAR(MAX) SET @CTRFR = 'select blah blah blah' -- <-- very long select statement. this returns a 0 or some greater number. Please note! --> I NEED THIS NUMBER. IF EXISTS ( SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo][#CTRFRResult]') AND type IN ( N'U' ) ) DROP TABLE [dbo].[#CTRFRResult] CREATE TABLE #CTRFRResult ( CTRFRResult VARCHAR(MAX) ) SET @CTRFR = 'insert into #CTRFRResult ' + @CTRFR EXEC(@CTRFR) The above works fine. The problem is that several databases are using the same TEMP table. Therefore I need to use a VARIABLE table (instead of a temporary table). What I have below is not working because it says that the table must be declared. DECLARE @CTRFRResult TABLE ( CTRFRResult VARCHAR(MAX) ) SET @CTRFR = 'insert into @CTRFRResult ' + @CTRFR -- I think the issue is here. EXEC(@CTRFR) Setting @CTRFR to 'insert into...' is not working because I'm assuming the table name is out of scope. How would I go about mimicking the temporary table code using a variable table?

    Read the article

  • recursive wget with hotlinked requisites

    - by dongle
    I often use wget to mirror very large websites. Sites that contain hotlinked content (be it images, video, css, js) pose a problem, as I seem unable to specify that I would like wget to grab page requisites that are on other hosts, without having the crawl also follow hyperlinks to other hosts. For example, let's look at this page https://dl.dropbox.com/u/11471672/wget-all-the-things.html Let's pretend that this is a large site that I would like to completely mirror, including all page requisites – including those that are hotlinked. wget -e robots=off -r -l inf -pk ^^ gets everything but the hotlinked image wget -e robots=off -r -l inf -pk -H ^^ gets everything, including hotlinked image, but goes wildly out of control, proceeding to download the entire web wget -e robots=off -r -l inf -pk -H --ignore-tags=a ^^ gets the first page, including both hotlinked and local image, does not follow the hyperlink to the site outside of scope, but obviously also does not follow the hyperlink to the next page of the site. I know that there are various other tools and methods of accomplishing this (HTTrack and Heritrix allow for the user to make a distinction between hotlinked content on other hosts vs hyperlinks to other hosts) but I'd like to see if this is possible with wget. Ideally this would not be done in post-processing, as I would like the external content, requests, and headers to be included in the WARC file I'm outputting.

    Read the article

  • Sorting nested set by name while keep depth integrity

    - by wb
    I'm using the nested set model that'll later be used to build a sitemap for my web site. This is my table structure. create table departments ( id int identity(0, 1) primary key , lft int , rgt int , name nvarchar(60) ); insert into departments (lft, rgt, name) values (1, 10, 'departments'); insert into departments (lft, rgt, name) values (2, 3, 'd'); insert into departments (lft, rgt, name) values (4, 9, 'a'); insert into departments (lft, rgt, name) values (5, 6, 'b'); insert into departments (lft, rgt, name) values (7, 8, 'c'); How can I sort by depth as well as name? I can do select replicate('----', count(parent.name) - 1) + ' ' + node.name , count(parent.name) - 1 as depth , node.lft from departments node , departments parent where node.lft between parent.lft and parent.rgt group by node.name, node.lft order by depth asc, node.name asc; However, that does not match children with their parent for some reason. department lft rgt --------------------------- departments 0 1 ---- a 1 4 ---- d 1 2 -------- b 2 5 -------- c 2 7 As you can see, department 'd' has department 'a's children! Thank you.

    Read the article

  • Is inheritance bad nowadays?

    - by mafutrct
    Personally, I think inheritance is a great tool, that, when applied reasonably, can greatly simplify code. However, I seems to me that many modern tools dislike inheritance. Let's take a simple example: Serialize a class to XML. As soon as inheritance is involved, this can easily turn into a mess. Especially if you're trying to serialize a derived class using the base class serializer. Sure, we can work around that. Something like a KnownType attribute and stuff. Besides being an itch in your code that you have to remember to update every time you add a derived class, that fails, too, if you receive a class from outside your scope that was not known at compile time. (Okay, in some cases you can still work around that, for instance using the NetDataContract serializer in .NET. Surely a certain advancement.) In any case, the basic principle still exists: Serialization and inheritance don't mix well. Considering the huge list of programming strategies that became possible and even common in the past decade, I feel tempted to say that inheritance should be avoided in areas that relate to serialization (in particular remoting and databases). Does that make sense? Or am messing things up? How do you handle inheritance and serialization?

    Read the article

  • How to enforce jsf to create new instance of bean instead of throwing NullPointerException?

    - by Roman
    I'm almost sure that I do something wrong and thus the question's title is a bit incorrect. I have a form with several fields for creating a new User-objects (fields like login, password, birthday etc). And I have 2 buttons - Cancel and Create. I didn't finish Create yet :) , but when I press Cancel I see NullPointerException. Here is simplified code: <f:view> <h:form> <h:panelGroup layout="block"> <h:inputText id="add_login" value="#{userSupport.user.login}"/> <h:inputSecret id="add_password" value="#{userSupport.user.password}"/> <h:inputText id="add_name" value="#{userSupport.user.name}"/> <h:inputText id="add_surname" value="#{userSupport.user.surname}"/> <h:commandButton value="Cancel" action="cancel"/> </h:panelGroup> </h:form> </f:view> UserSupport class has field user with getter and setter and some other methods. It's a Spring bean with Session scope. When I press cancel, I see NPE because jsf tries to save values from inputs in user-object, but user-object is null. What is the correct way of doing this?

    Read the article

  • JPA Problems mapping relationships

    - by Rosen Martev
    Hello. I have a problem when I try to persist my model. An exception is thrown when creating the EntityManagerFactory: Blockquote javax.persistence.PersistenceException: [PersistenceUnit: NIF] Unable to build EntityManagerFactory at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:677) at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:126) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:52) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:34) at project.serealization.util.PersistentManager.createSession(PersistentManager.java:24) at project.serealization.SerializationTest.testProject(SerializationTest.java:25) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at junit.framework.TestCase.runTest(TestCase.java:168) at junit.framework.TestCase.runBare(TestCase.java:134) at junit.framework.TestResult$1.protect(TestResult.java:110) at junit.framework.TestResult.runProtected(TestResult.java:128) at junit.framework.TestResult.run(TestResult.java:113) at junit.framework.TestCase.run(TestCase.java:124) at junit.framework.TestSuite.runTest(TestSuite.java:232) at junit.framework.TestSuite.run(TestSuite.java:227) at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:79) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) Caused by: org.hibernate.HibernateException: Wrong column type in nif.action_element for column FLOW_ID. Found: double, expected: bigint at org.hibernate.mapping.Table.validateColumns(Table.java:284) at org.hibernate.cfg.Configuration.validateSchema(Configuration.java:1116) at org.hibernate.tool.hbm2ddl.SchemaValidator.validate(SchemaValidator.java:139) at org.hibernate.impl.SessionFactoryImpl.(SessionFactoryImpl.java:349) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1327) at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:867) at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:669) ... 24 more The code for SimpleActionElement and SimpleFlow is as follows: @Entity public class SimpleActionElement { @OneToOne(cascade = CascadeType.ALL, targetEntity = SimpleFlow.class) @JoinColumn(name = "FLOW_ID") private SimpleFlow<T> flow; ... } @Entity public class SimpleFlow<T> { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "ELEMENT_ID") private Long element_id; ... }

    Read the article

  • Can it be done?

    - by bzarah
    We are in design phase of a project whose goal is replatforming an ASP classic application to ASP.Net 4.0. The system needs to be entirely web based. There are several new requirements for the new system that make this a challenging project: The system needs to be database independent. It must, at version 1.0, support MS SQL Server, Oracle, MySQL, Postgres and DB2. The system must be able to allow easy reporting from the database by third party reporting packages. The system must allow an administrative end user to create their own tables in the database through the web based interface. The system must allow an administrative end user to design/configure a user interface (web based) where they can select tables and fields in the system (either our system's core tables or their own custom tables created in #3) The system must allow an administrative end user to create and maintain relationships between these custom created tables, and also between these tables and our system's core tables. The system must allow an administrative end user to create business rules that will enforce validation, show/hide UI elements, block certain actions based on the identity of specific users, specific user groups or privileges. Essentially it's a system that has some core ticket tracking functionality, but allows the end user to extend the interface, business rules and the database. Is this possible to build in a .Net, Web based environment? If so, what do you think the level of effort would be to get this done? We are currently a 6 person shop, with 2.5 full time developers.

    Read the article

  • What is causing this template-related compile error? (c++)

    - by Setien
    When I try to compile this: #include <map> #include <string> template <class T> class ZUniquePool { typedef std::map< int, T* > ZObjectMap; ZObjectMap m_objects; public: T * Get( int id ) { ZObjectMap::const_iterator it = m_objects.find( id ); if( it == m_objects.end() ) { T * p = new T; m_objects[ id ] = p; return p; } return m_objects[ id ]; } }; int main( int argc, char * args ) { ZUniquePool< std::string > pool; return 0; } I get this: main.cpp: In member function ‘T* ZUniquePool<T>::Get(int)’: main.cpp:12: error: expected `;' before ‘it’ main.cpp:13: error: ‘it’ was not declared in this scope I'm using GCC 4.2.1 on Mac OS X. It works in VS2008. I'm wondering whether it might be a variation of this problem: http://stackoverflow.com/questions/1364837/why-doesnt-this-c-template-code-compile But as my error output is only partially similar, and my code works in VS2008, I am not sure. Can anyone shed some light on what I am doing wrong?

    Read the article

  • scala 2.8 CanBuildFrom

    - by oxbow_lakes
    Following on from another question I asked, I wanted to understand a bit more about the Scala method TraversableLike[A].map whose signature is as follows: def map[B, That](f: A => B)(implicit bf: CanBuildFrom[Repr, B, That]): That Notice a few things about this method: it takes a function turning each A in the traversable into a B it returns That and takes an implicit argument of type CanBuildFrom[Repr, B, That] I can call this as follows: > val s: Set[Int] = List("Paris", "London").map(_.length) s: Set[Int] Set(5,6) What I cannot quite grasp is how the fact that That is bound to B (i.e. it is some collection of B's) is being enforced by the compiler. The type parameters look to be independent in both the signature above and in the signature of the trait CanBuildFrom itself: trait CanBuildFrom[-From, -Elem, +To] How is the scala compiler ensuring that That cannot be forced into something which does not make sense? > val s: Set[String] = List("Paris", "London").map(_.length) //will not compile EDIT - this question of course boils down to: How does the compiler decide what implicit CanBuildFrom objects are in scope for the call?

    Read the article

  • How to persist in order

    - by parhs
    I have two entities: EXAM and EXAM_NORMAL. EXAM @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private Long id; private String name; private String codeName; @Enumerated(EnumType.STRING) private ExamType examType; @ManyToOne private Category category; @OneToMany(mappedBy="id",cascade=CascadeType.PERSIST) @OrderBy("id") private List<Exam_Normal> exam_Normal; EXAM_NORMAL @Id private Long item; @Id @ManyToOne private Exam id; @Enumerated(EnumType.STRING) private Gender gender; private Integer age_month_from; private Integer age_month_to; The problem is that if I put a list of EXAM_NORMAL at an EXAM class if I try to persist(EXAM) I get an error because it tries to persist EXAM_NORMAL first but it cant because the primary key of EXAM is missing because it isn't persisted... Is there any way to define the order? Or should I set null the list, persist and then set the list again? thanks:)

    Read the article

< Previous Page | 189 190 191 192 193 194 195 196 197 198 199 200  | Next Page >