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• How to run validator from javascript?

  - by David Shochet

  Here is a part of my code: <asp:ListBox ID="lbRD" runat="server" DataSourceID="RDSqlDataSource" onchange="JSFillDetail();" DataTextField="????????" DataValueField="ID" Width="188px" Height="200px"/> <asp:TextBox ID="txtDescription" runat="server" /> <asp:RequiredFieldValidator ID="txtDescriptionRequiredFieldValidator" runat="server" ErrorMessage="???????? ???????? ???????????? ??? ??????????" ControlToValidate="txtDescription" /> I have a listbox, a textbox and a required field validator on my page. When the user selects something from the listbox, the selected item appears in the textbox using a javascript function. When the page is submitted, the validator reports an error in case the textbox is empty. If after that the user selects something from the listbox, the error message is still displayed, even though the textbox is not empty anymore. How can I make the validator validate the textbox, or even better, to clear the error message from the javascript function that fills the textbox? Thanks, David

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• Calculation Conundrum - how do I influence another textfield?

  - by LawVS

  Hey! Basically I have a problem in that when certain parameters are used in my calculator app - it makes the result incorrect. The issue is that I have separate text fields for hours and minutes and say for example I have as the start time "13" in one text field and "30" in the other with the finish time "24" and "00" in their respective text fields. The answer should be 10 hours 30 minutes, but the answer I get is 11 hours 30 minutes. The code for this is the following. -(IBAction)done:(id)sender { int result = [finishHours.text intValue] - [startHours.text intValue]; totalHours.text = [NSString stringWithFormat:@"%d", result]; if (result < 0) { totalHours.text = [NSString stringWithFormat:@"%d", result + 24]; } -(IBAction)done2:(id)sender { int result = [startMinutes.text intValue] - [finishMinutes.text intValue]; totalMinutes.text = [NSString stringWithFormat:@"%d", result]; if (result < 0) { totalMinutes.text = [NSString stringWithFormat:@"%d", result + 60]; } } I want to make it so if certain parameters are met, then the totalHours.text is reduced by 1 hour to reflect the total minutes. How would I go about that calculation in code? Thanks!

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• Is there added overhead to looking up a column in a DataTable by name rather than by index?

  - by Ben McCormack

  In a DataTable object, is there added overhead to looking up a column value by name thisRow("ColumnA") rather than by the column index thisRow(0)? In which scenarios might this be an issue. I work on a team that has lots of experience writing VB6 code and I noticed that didn't do column lookups by name for DataTable objects or data grids. Even in .NET code, we use a set of integer constants to reference column names in these types of objects. I asked our team lead why this was so, and he mentioned that in VB6, there was a lot of overhead in looking up data by column name rather than by index. Is this still true for .NET? Example code (in VB.NET, but same applies to C#): Public Sub TestADOData() Dim dt As New DataTable 'Set up the columns in the DataTable ' dt.Columns.Add(New DataColumn("ID", GetType(Integer))) dt.Columns.Add(New DataColumn("Name", GetType(String))) dt.Columns.Add(New DataColumn("Description", GetType(String))) 'Add some data to the data table ' dt.Rows.Add(1, "Fred", "Pitcher") dt.Rows.Add(3, "Hank", "Center Field") 'Method 1: By Column Name ' For Each r As DataRow In dt.Rows Console.WriteLine( _ "{0,-2} {1,-10} {2,-30}", r("ID"), r("Name"), r("Description")) Next Console.WriteLine() 'Method 2: By Column Name ' For Each r As DataRow In dt.Rows Console.WriteLine("{0,-2} {1,-10} {2,-30}", r(0), r(1), r(2)) Next End Sub Is there an case where method 2 provides a performance advantage over method 1?

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• Hibernate bit array to entity mapping

  - by teabot

  I am trying to map a normalized Java model to a legacy database schema using Hibernate 3.5. One particular table encodes a foreign keys in a one-to-many relationship as a bit array column. Consider tables 'person' and 'clubs' that describes people's affiliations to clubs: person .----.------. club: .----.---------.---------------------------. | id | name | | id | name | members | binary(members) | |----+------| |----+---------|---------+-----------------| | 1 | Bob | | 10 | Cricket | 0 | 000 | | 2 | Joe | | 11 | Tennis | 5 | 101 | | 3 | Sue | | 12 | Cooking | 7 | 111 | '----'------' | 13 | Golf | 3 | 100 | '----'---------'---------'-----------------' So hopefully it is clear that person.id is used as the bit index in the bit array club.members. In this example the members column tells us that: no one is a member of Cricket, Bob/Sue - Tennis, Bob/Sue/Joe - Cooking and Sue - Golf. In my Java domain I'd like to declare this with entities like so: class Person { private int id; private String name; ... } class Club { private Set<Person> members; private int id; private String name; ... } I am assuming that I must use a UserType implementation but have been unable to find any examples where the items described by the user type are references to entities - not literal field values - or composites thereof. Additionally I am aware that I'll have to consider how the person entities are fetched when a club instance is loaded. Can anyone tell me how I can tame this legacy schema with Hibernate?

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• How to make CFileDialog synchronize the displayed filename with the selected extension?

  - by RobH

  We have a class that derives from CFileDialog that overrides the OnTypeChange() method to allow it to change the filename to keep it in synch with the selected extension whenever the user selects a new extension from the filter combobox. (Our filters are set to contain only one extension per filter entry.) Unfortunately, the way we are doing this seems to have been broken by the Vista style dialogue. (We were using SetControlText() to set the filename edit box to the filename with the newly selected extension, but the control ID seems to be different for the Vista style dialogue, and the one that I found using Spy++ works just as well as the old ID (i.e., it doesn't)..) Is there a better way to tell the CFileDialog object to update the filename field to use the new extension when the user selects a new filter? It has to work with the old XP style dialogue as well. Failing that, how to I force the use of the XP style dialogue so that I get my functionality back without the dialogue crashing on me? (I'd rather not go that route if at all possible.) I've found a way to get it to fall back to the XP style. I still want to get the new style dialogue to do what I want though.

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• CSRF Protection in AJAX Requests using MVC2

  - by mnemosyn

  The page I'm building depends heavily on AJAX. Basically, there is just one "page" and every data transfer is handled via AJAX. Since overoptimistic caching on the browser side leads to strange problems (data not reloaded), I have to perform all requests (also reads) using POST - that forces a reload. Now I want to prevent the page against CSRF. With form submission, using Html.AntiForgeryToken() works neatly, but in AJAX-request, I guess I will have to append the token manually? Is there anything out-of-the box available? My current attempt looks like this: I'd love to reuse the existing magic. However, HtmlHelper.GetAntiForgeryTokenAndSetCookie is private and I don't want to hack around in MVC. The other option is to write an extension like public static string PlainAntiForgeryToken(this HtmlHelper helper) { // extract the actual field value from the hidden input return helper.AntiForgeryToken().DoSomeHackyStringActions(); } which is somewhat hacky and leaves the bigger problem unsolved: How to verify that token? The default verification implementation is internal and hard-coded against using form fields. I tried to write a slightly modified ValidateAntiForgeryTokenAttribute, but it uses an AntiForgeryDataSerializer which is private and I really didn't want to copy that, too. At this point it seems to be easier to come up with a homegrown solution, but that is really duplicate code. Any suggestions how to do this the smart way? Am I missing something completely obvious?

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• Google Chrome Extension - Help needed

  - by Jim-Y

  Im new on Google Chrome Extensions coding, and i have some basic questions. I want to make a Chrome Extension, and the scheme is the following: -a popup window, containing buttons and result fields (popup.html) -when a button is clicked, i want to trigger an event, this event should connect to a webserver (i make the servlet too), and gather information from the server. (XMLHttpRequest()) -after that, i want my extension to load the gathered information into one of the result fields. Simple, isn't it? But i have several problems, right at the beginning:( I started developing with reading tutorials, but i have fog on the main structure of an extension. Now, i started an app, containing a popup.html, manifest.json ... In popup.html theres a result field, and a button <div id="extension_container"> <div id="header"> <p id="intro">Result here</p> <button type="button" id="button">Click Me!</button> </div> <!-- END header --> <div id="content"> </div> <!-- END content --> When button is clicked, i trigger an event, handeled with jquery, code here: <script> $(document).ready(function(){ $("#button").click(function(){ $("#intro").text("Hello, im added"); alert("Clicked"); }); }); </script> And here comes the problem, in popup.html this doesnt work, if i load it to Chrome, nothing happens. Otherwise, if i open popup.html in browser, not as an extension, everything works fine. So, i think i have basic misunderstandings on extension structures, starting with background pages, background javascript and so on.. :( Could anyone help me?

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• WPF ValidationRule Validate when the control is loaded

  - by PaN1C_Showt1Me

  Hi ! I have a control with this validation <MyPicker.SelectedItem> <Binding Path="Person.Value" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" NotifyOnValidationError="True"> <Binding.ValidationRules> <rules:MyValidationRule ValidationType="notnull"/> </Binding.ValidationRules> </Binding> </MyPicker.SelectedItem> This is the Validation Class: class MyValidationRule : ValidationRule { private string _validationType; public string ValidationType { get { return _validationType; } set { _validationType = value; } } public override ValidationResult Validate(object value, CultureInfo cultureInfo) { ValidationResult trueResult = new ValidationResult(true, null); switch (_validationType.ToLower()) { case "notnull": return value == null ? new ValidationResult(false, "EMPTY FIELD") : trueResult; default: return trueResult; } } } Question: When the property is changed, then the Validate( ) method is called which is correct. But to call this method at the very beginning when the MyControl is created? I need to prove immediate after initialize if the there's a null value in the control (and display a validation error)

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• Regressing panel data in SAS.

  - by John

  Hey Guys, thanks to your help I succesfully managed all my databases! I am now looking at a panel data set on which I have to regress. Since I only started my Phd this semester together with the econometrics courses I am still new to many statistic applications and regression methods. I want to do a simple regression as in Y = x1 x2 x3 etc, now I already browsed through some literature and found that for panel data it's common to do a fixed effects regression. Also, my Y variable only has positive values so I was thinking in the direction of a Tobit model? I'm doing some research concerning the coverage of analysts in the financial business. My independent variable is the coverage of analysts on a certain firm, so per observation i have 1 analyst and 1 firm, together with different characteristics(market cap and betas etc) of the firm. All this data is monthly. As coverage cannot become negative (only 0) I was thinking of a Tobit model? Do you guys have any ideas what would be a good regression method? Or have some good sources (e books, written books, through university I have access to almost anything concerning my field of work) of information (cause I do have to learn these things for future research)? Thanks!

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• Change Data Capture or Change Tracking - Same as Traditional Audit Trail Table?

  - by HardCode

  Before I delve into the abyss of Microsoft documentation any deeper, I'd like to know if someone experienced with Change Data Capture and Change Tracking know if one or both of these can be used to replace the traditional ... "Audit trail table copy of the 'real table' (all of the fields of the original table, plus date/time, user ID, and DML action field) inserted into by Triggers" ... setup for a database table audit trail, where the trigger populates the audit trail table (which is all manual work). The MSDN overview documentation explains at a high level what Change Data Capture and Change Tracking are, but it isn't clear enough to me, and doesn't state outright, that these tools can be used to replace the traditional audit trail tables we've made so often. Can someone with any experience using Change Data Capture and Change Tracking save me a lot of time, or confirm that I am spending time looking at the right tool? The critical part of our audit trail is capturing all changes to a table's fields (on INSERT, UPDATE, DELETE), when it happened, and who did it. These changes are commonly provided to an end user chronologically via an audit trail report. Which is another question ... Change Data Capture or Change Tracking is the solution, I'd assume that this data can be queried just like data from a normal table? EDIT: I need a permanent audit trail, irregardless of time. I see that Change Data Capture has to do with the transaction logs, so this sounds finite to me.

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• SSIS - How do I use a resultset as input in a SQL task and get data types right?

  - by thursdaysgeek

  I am trying to merge records from an Oracle database table to my local SQL table. I have a variable for the package that is an Object, called OWell. I have a data flow task that gets the Oracle data as a SQL statment (select well_id, well_name from OWell order by Well_ID), and then a conversion task to convert well_id from a DT_STR of length 15 to a DT_WSTR; and convert well_name from a DT_STR of length 15 to DT_WSTR of length 50. That is then stored in the recordset OWell. The reason for the conversions is the table that I want to add records to has an identity field: SSIS shows well_id as a DT_WSTR of length 15, well_name a DT_WSTR of length 50. I then have a SQL task that connects to the local database and attempts to add records that are not there yet. I've tried various things: using the OWell as a result set and referring to it in my SQL statement. Currently, I have the ResultSet set to None, and the following SQL statment: Insert into WELL (WELL_ID, WELL_NAME) Select OWELL_ID, OWELL_NAME from OWell where OWELL_ID not in (select WELL.WELL_ID from WELL) For Parameter Mapping, I have Paramater 0, called OWell_ID, from my variable User::OWell. Parameter 1, called OWell_Name is from the same variable. Both are set to VARCHAR, although I've also tried NVARCHAR. I do not have a Result set. I am getting the following error: Error: 0xC002F210 at Insert records to FLEDG, Execute SQL Task: Executing the query "Insert into WELL (WELL_ID, WELL_NAME) Select OWELL..." failed with the following error: "An error occurred while extracting the result into a variable of type (DBTYPE_STR)". Possible failure reasons: Problems with the query, "ResultSet" property not set correctly, parameters not set correctly, or connection not established correctly. I don't think it's a data type issue, but rather that I somehow am not using the resultset properly. How, exactly, am I supposed to refer to that recordset in my SQL task, so that I can use the two recordset fields and add records that are missing?

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• NSPredicate case-insensitive matching on to-many relationship

  - by Brian Webster

  I am implementing a search field where the user can type in a string to filter the items displayed in a view. Each object being displayed has a keywords to-many relationship, and I would like to be able to filter the objects based on their keywords. Each keyword object has a name property, so I've set up an NSPredicate to do the filtering that looks like this: NSPredicate* predicate = [NSPredicate predicateWithFormat:@"keywords.name CONTAINS %@", self.searchString]; This works, but the problem is that the search is case-sensitive, so if the keyword has a capital letter but the user types in all lowercase, no matches are found. I've tried the following modification: NSPredicate* predicate = [NSPredicate predicateWithFormat:@"keywords.name CONTAINS[c] %@", self.searchString]; But that doesn't make any difference in the case sensitivity of the matching. Is there a way to do this case-insensitive matching using just a plain predicate? Or will I need to implement some sort of custom accessor on the keyword class, e.g. write a lowercaseName method and match against a lowercased version of the search string instead? Addendum: After further exploration, the workaround of adding a custom accessor works OK for manual use of NSPredicate, but does not work at all when using NSFetchRequest with Core Data, which only works when querying attributes defined in the Core Data model.

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• JQuery datepicker not working

  - by IniTech

  I'm completely new to JQuery and MVC. I'm working on a pet project that uses both to learn them and I've hit my first snag. I have a date field and I want to add the JQuery datepicker to the UI. Here is what I have done: Added <script src="../../Scripts/jquery-1.3.2.min.js" type="text/javascript"></script> to the site.master Inside my Create.aspx (View), I have <asp:Content ID="Create" ContentPlaceHolderID="MainContent" runat="server"> <h2> Create a Task</h2> <% Html.RenderPartial("TaskForm"); %> </asp:Content> and inside "TaskForm" (a user control) I have: <label for="dDueDate"> Due Date</label> <%= Html.TextBox("dDueDate",(Model.Task.TaskID > 0 ? string.Format("{0:g}",Model.Task.DueDate) : DateTime.Today.ToString("MM/dd/yyyy"))) %> <script type="text/javascript"> $(document).ready(function() { $("#dDueDate").datepicker(); }); </script> As you can see, the above checks to see if a task has an id 0 (we're not creating a new one) if it does, it uses the date on the task, if not it defaults to today. I would expect the datepicker UI element to show up, but instead I get: "Microsoft JScript runtime error: Object doesn't support this property or method" on the $("#dDueDate").datepicker(); Ideas? It is probably a very simple mistake, so don't over-analyze. As I said, this is the first time I've dealt with MVC or JQuery so I'm lost as to where to start.

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• How to set default date in date_select helper in Rails

  - by brad

  I'm trying to set up a date of birth helper in my Rails app (2.3.5). At present it is like so. <%= f.date_select :date_of_birth, :start_year => Time.now.year - 110, :end_year => Time.now.year %> This generates a perfectly functional set of date fields that work just fine but.... They default to today's date which is not ideal for a date of birth field (I'm not sure what is but unless you're running a neonatal unit today's date seems less than ideal). I want it to read Jan 1 2010 instead (or 2011 or whatever year it happens to be). Using the :default option has proven unsuccessful. I've tried many possibilities including; <%= f.date_select :date_of_birth, :default => {:year => Time.now.year, :month => 'Jan', :day => 1}, :start_year => Time.now.year - 110, :end_year => Time.now.year %> and <%= f.date_select :date_of_birth, :default => Time.local(2010,'Jan',1), :start_year => Time.now.year - 110, :end_year => Time.now.year %> None of this changes the behaviour of the first example. Does the default option actually work as described? It seems that this should be a fairly straightforward thing to do. Ta.

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• message queue full error in blackberry

  - by Rahul Varma

  Hi , I have coded to get the info from the user and send an email of clicking a button. The program is getting executed for a while and then the simulator is crashing showing error "DE427"-Message queue full... Here's the code that i have done... if(field==SendMail) { Message m = new Message(); Address a = null; try { a = new Address("[email protected]", "Rahul"); } catch (AddressException e) { // TODO Auto-generated catch block e.printStackTrace(); } Address[] addresses = {a}; try { m.addRecipients(net.rim.blackberry.api.mail.Message.RecipientType.TO, addresses); m.setContent("Name:"+Name.getText().toString()+"\n"+ "Phone :"+Phone.getText().toString()+ "\n"+ "Date & Time:"+DateShow.getText().toString()+"\n"+"Make:"+Make.getText().toString()+ "\n"+"Model:"+Model.getText().toString()+"\n"+"Miles:"+Miles.getText().toString()+"\n"); m.setSubject("Appointment Request (Via Blackberry app)"); } catch (MessagingException e) { // TODO Auto-generated catch block e.printStackTrace(); } Invoke.invokeApplication(Invoke.APP_TYPE_MESSAGES, new MessageArguments(m)); } Can anyone tell me what the error is and how to rectify the problem....Plz...

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• How to refactor this database to allow sync. with smart clients?

  - by Anton Zvgny

  Howdy, I have inherited the following database: http://i46.tinypic.com/einvjr.png (EDIT: I cannot post images, so here goes the link) This currently runs 100% online thru an Asp.Net web app , but some employees will need to have offline access to this database to either get documents or to insert new documents for later synchronization when back to the office. What changes need to be made to this database scheme to support such scenario (sync smart clients with central web database)? Thanks! ps. I'm not an developer/dba, i'm just an mechanic engineer tasked with changing this app, so, take it easy on me :D ps1. We're using MSSQL Server for the online central database and MSSQL Compact for the smart client. ps2. the ImageGuid field of the images table is used to save the images to the file system. The web app takes the guid and create folders according to the first 3 initial letters to persist the image to the file system. ps3. The users of the smart client not always get server data first and then go modifying to sync later the changes. Most of the time they start working completely offline (with a blank local database) and later sync the data to the server. ps4. All the users of the smart client app have an account at the web app.

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• add new option to dropdownlist after jquery dialog and post

  - by RememberME

  I have a form to enter subcontracts. On this form I have a dropdownlist of all companies in the system. Next to it is a button "Create Company". This button opens a jquery dialog which allows the user to create a new company. Once the dialog closes, the new company needs to be added to the dropdownlist and selected. If I refresh, it's there, but I need to do it without refreshing the form b/c I don't want the user to loose everything that they've entered into the other fields. I'm not sure how to do this b/c I don't have the guid of the new company. My jquery dialog: $('#popupCreateCompany').dialog( { autoOpen: false, modal: true, buttons: { 'Add': function() { var dialog = $(this); var form = dialog.find('input:text, select'); $.post('/company/create', $(form).serialize(), function() { dialog.dialog('close'); }) }, 'Cancel': function() { $(this).dialog('close'); } } }); $("#create-company").click(function() { $('#popupCreateCompany').dialog('open'); }); Company field: <label for="company">Company:</label> <%= Html.DropDownList("company", Model.SelectCompanies, "** Select Company **") %> <%= Html.ValidationMessage("Company", "*") %> <button type="button" id="create-company" >Create Company</button>

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• Dojo DataGrid, programmatic creation

  - by djna

  I'm trying to create a DataGrid dynamically. Declarative creation is working fine: A source of data: <span dojoType="dojo.data.ItemFileReadStore" jsId="theStore" url="dataonly001.json"> </span> a simple layout: <script type="text/javascript" > var layout = [ { field: 'custId', name: 'Id', } // more items elided ... ]; </script> The grid: <body class="tundra" id="mainbody"> <div id="grid" dojoType="dojox.grid.DataGrid" store="theStore" structure="layout" autoWidth="true" ></div> </body> And I get the grid displayed nicely. Instead, I want to create the grid dynamically. For the sake of figuring out what's broken I've tried to use exactly the same layout and store, removing just teh grid declaration and adding this script: <script type="text/javascript" djConfig="parseOnLoad: true, debugAtAllCosts: true"> dojo.addOnLoad(function(){ // initialise and lay out home page console.log("Have a store:" + theStore); console.log("Have a structure:" + layout); var grid = new dojox.grid.DataGrid({ id:"grid", store : theStore, clientSort : "true", structure : layout }); grid.startup(); dojo.place(grid.domNode, dojo.body(), "first"); }); </script> The effect that I get is a completely empty rectangle is displayed. Using FireBug I can see that the DataGrid widget is created but that it has no rows or columns. So my guess is that the datastore or layout are not being passed correctly. However, it does appear that at the point of creation the values of theStore and layout are correct. Suggestions please, or indeed a working example of a programmic grid might solve the problem.

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• ASP.NET MVC 2: How to write this Linq SQL as a Dynamic Query (using strings)?

  - by Dr. Zim

  Skip to the "specific question" as needed. Some background: The scenario: I have a set of products with a "drill down" filter (Query Object) populated with DDLs. Each progressive DDL selection will further limit the product list as well as what options are left for the DDLs. For example, selecting a hammer out of tools limits the Product Sizes to only show hammer sizes. Current setup: I created a query object, sent it to a repository, and fed each option to a SQL "table valued function" where null values represent "get all products". I consider this a good effort, but far from DDD acceptable. I want to avoid any "programming" in SQL, hopefully doing everything with a repository. Comments on this topic would be appreciated. Specific question: How would I rewrite this query as a Dynamic Query? A link to something like 101 Linq Examples would be fantastic, but with a Dynamic Query scope. I really want to pass to this method the field in quotes "" for which I want a list of options and how many products have that option. (from p in db.Products group p by p.ProductSize into g select new Category { PropertyType = g.Key, Count = g.Count() }).Distinct(); Each DDL option will have "The selection (21)" where the (21) is the quantity of products that have that attribute. Upon selecting an option, all other remaining DDLs will update with the remaining options and counts.

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• twitter bootstrap typeahead (method 'toLowerCase' of undefined)

  - by mmoscosa

  I am trying to use twitter bootstrap to get the manufacturers from my DB. Because twitter bootstrap typeahead does not support ajax calls I am using this fork: https://gist.github.com/1866577 In that page there is this comment that mentions how to do exactly what I want to do. The problem is when I run my code I keep on getting: Uncaught TypeError: Cannot call method 'toLowerCase' of undefined I googled around and came tried changing my jquery file to both using the minified and non minified as well as the one hosted on google code and I kept getting the same error. My code currently is as follows: $('#manufacturer').typeahead({ source: function(typeahead, query){ $.ajax({ url: window.location.origin+"/bows/get_manufacturers.json", type: "POST", data: "", dataType: "JSON", async: false, success: function(results){ var manufacturers = new Array; $.map(results.data.manufacturers, function(data, item){ var group; group = { manufacturer_id: data.Manufacturer.id, manufacturer: data.Manufacturer.manufacturer }; manufacturers.push(group); }); typeahead.process(manufacturers); } }); }, property: 'name', items:11, onselect: function (obj) { } }); on the url field I added the window.location.origin to avoid any problems as already discussed on another question Also before I was using $.each() and then decided to use $.map() as recomended Tomislav Markovski in a similar question Anyone has any idea why I keep getting this problem?! Thank you

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• Understanding evaluation of expressions containing '++' and '->' operators in C.

  - by Leif Ericson

  Consider this example: struct { int num; } s, *ps; s.num = 0; ps = &s; ++ps->num; printf("%d", s.num); /* Prints 1 */ It prints 1. So I understand that it is because according to operators precedence, -> is higher than ++, so the value ps->num (which is 0) is firstly fetched and then the ++ operator operates on it, so it increments it to 1. struct { int num; } s, *ps; s.num = 0; ps = &s; ps++->num; printf("%d", s.num); /* Prints 0 */ In this example I get 0 and I don't understand why; the explanation of the first example should be the same for this example. But it seems that this expression is evaluated as follows: At first, the operator ++ operates, and it operates on ps, so it increments it to the next struct. Only then -> operates and it does nothing because it just fetches the num field of the next struct and does nothing with it. But it contradicts the precedence of operators, which says that -> have higher precedence than ++. Can someone explain this behavior? Edit: After reading two answers which refer to a C++ precedence tables which indicate that a prefix ++/-- operators have lower precedence than ->, I did some googling and came up with this link that states that this rule applies also to C itself. It fits exactly and fully explains this behavior, but I must add that the table in this link contradicts a table in my own copy of K&R ANSI C. So if you have suggestions as to which source is correct I would like to know. Thanks.

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• PostgreSQL: BYTEA vs OID+Large Object?

  - by mlaverd

  I started an application with Hibernate 3.2 and PostgreSQL 8.4. I have some byte[] fields that were mapped as @Basic (= PG bytea) and others that got mapped as @Lob (=PG Large Object). Why the inconsistency? Because I was a Hibernate noob. Now, those fields are max 4 Kb (but average is 2-3 kb). The PostgreSQL documentation mentioned that the LOs are good when the fields are big, but I didn't see what 'big' meant. I have upgraded to PostgreSQL 9.0 with Hibernate 3.6 and I was stuck to change the annotation to @Type(type="org.hibernate.type.PrimitiveByteArrayBlobType"). This bug has brought forward a potential compatibility issue, and I eventually found out that Large Objects are a pain to deal with, compared to a normal field. So I am thinking of changing all of it to bytea. But I am concerned that bytea fields are encoded in Hex, so there is some overhead in encoding and decoding, and this would hurt the performance. Are there good benchmarks about the performance of both of these? Anybody has made the switch and saw a difference?

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• Re-Convert timestamp DATE back to original format (when editing) PHP MySQL

  - by Jess

  Ok so I have managed to get the format of the date presented in HTML (upon display) to how I want (dd/mm/yyy)...However, the user also can change the date via a form. So this is how it's setup as present. Firstly, the conversion from YYYY-MM-DD to DD/MM/YYYY and then display in HTML: $timestamp = strtotime($duedate); echo date('d/m/Y', $timestamp); Now when the user selects to update the due date, the value already stored value is drawn up and presented in my text field (using exactly the same code as above).. All good so far. But when my user runs the update script (clicks submit), the new due date is not being stored, and in my DB its seen as '0000-00-00'. I know I need to convert it back to the correct format that MySQL wants to have it in, in order for it to be saved, but I'm not sure on how to do this. This is what I have so far in my update script (for the due date): $duedate = $_POST['duedate']; $timestamp = strtotime($duedate); date('Y/m/d', $timestamp); $query = "UPDATE films SET filmname= '".$filmname."', duedate= '".$duedate; Can somebody please point me in the right direction to have the new date, when processed, converted back to the accepted format by MySQL. I appreciate any help given! Thanks.

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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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• Accessing class member variables inside a BackgroundWorker's DoWork event handler, and other Backgro

  - by Justin

  Question 1 In the DoWork event handler of a BackgroundWorker, is it safe to access (for both reading and writing) member variables of the class that contains the BackgroundWorker? Is it safe to access other variables that are not declared inside the DoWork event handler itself? Obviously DoWork should not be accessing any UI objects of, say, a WinForms application, as the UI should only be updated from the UI thread. But what about accessing other (not UI-related) member variables? The reason why I ask is that I've seen the occasional comment come up while Googling saying that accessing member variables is not allowed. The only example I can find at the moment is a comment on this MSDN page, which says: Note, that the BGW can cause exceptions if it attempts to access or modify class level variables. All data must be passed to it by delegates and events. And also: NEVER. NEVER. Never try to reference variables not declared inside of DoWork. It may seem to work at times, but in reality you are just getting lucky. As far as I know, MSDN itself does not document any restrictions of this kind (although if I'm wrong, I'd appreciate a link). But comments like these do seem to pop up every now and again. (Of course if DoWork does access/modify a member variable that could be accessed/modified by the main thread at the same time, it is necessary to synchronise access to that field, eg by using a locking object. But the above quotes seem to require a blanket ban of accessing member variables, rather than just synchronising access!) Question 2 To make this into a more general question, are there any other (not documented?) restrictions that users of the BackgroundWorker should be aware of, aside from the above? Any "best practices", perhaps?

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