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  • How to optimize a postgreSQL server for a "write once, read many"-type infrastructure ?

    - by mhu
    Greetings, I am working on a piece of software that logs entries (and related tagging) in a PostgreSQL database for storage and retrieval. We never update any data once it has been inserted; we might remove it when the entry gets too old, but this is done at most once a day. Stored entries can be retrieved by users. The insertion of new entries can happen rather fast and regularly, thus the database will commonly hold several millions elements. The tables used are pretty simple : one table for ids, raw content and insertion date; and one table storing tags and their values associated to an id. User search mostly concern tags values, so SELECTs usually consist of JOIN queries on ids on the two tables. To sum it up : 2 tables Lots of INSERT no UPDATE some DELETE, once a day at most some user-generated SELECT with JOIN huge data set What would an optimal server configuration (software and hardware, I assume for example that RAID10 could help) be for my PostgreSQL server, given these requirements ? By optimal, I mean one that allows SELECT queries taking a reasonably little amount of time. I can provide more information about the current setup (like tables, indexes ...) if needed.

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  • how to sort the items in listbox alphabetically?

    - by user2745378
    i need to sort the items alphabetically in listbox when sort button is clicked. (I have sort button in appbar). But I dunno how to achieve this. here is XAML. All help will be much appreciated. <phone:PhoneApplicationPage.Resources> <DataTemplate x:Key="ProjectTemplate"> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="400" /> </Grid.ColumnDefinitions> <TextBlock Grid.Column="1" Text="{Binding Name}" Style="{StaticResource PhoneTextLargeStyle}" /> </Grid> </DataTemplate> </phone:PhoneApplicationPage.Resources> <Grid x:Name="ContentPanel" Grid.Row="1" Margin="0,0,12,0"> <ListBox x:Name="projectList" ItemsSource="{Binding Items}" SelectionChanged="ListBox_SelectionChanged" ItemTemplate="{StaticResource ProjectTemplate}" /> </Grid> Here's my ViewModel namespace PhoneApp.ViewModels { public class ProjectsViewModel: ItemsViewModelBase<Project> { public ProjectsViewModel(TaskDataContext taskDB) : base(taskDB) { } public override void LoadData() { base.LoadData(); var projectsInDB = _taskDB.Projects.ToList(); Items = new ObservableCollection<Project>(projectsInDB); } public override void AddItem(Project item) { _taskDB.Projects.InsertOnSubmit(item); _taskDB.SubmitChanges(); Items.Add(item); } public override void RemoveItem(int id) { var projects = from p in Items where p.Id == id select p; var item = projects.FirstOrDefault(); if (item != null) { var tasks = (from t in App.TasksViewModel.Items where t.ProjectId == item.Id select t).ToList(); foreach (var task in tasks) App.TasksViewModel.RemoveItem(task.Id); Items.Remove(item); _taskDB.Projects.DeleteOnSubmit(item); _taskDB.SubmitChanges(); } } } } I have added the ViewModel C# Code herewith

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  • Gridview column right click issue

    - by peter
    I have grid named 'GridView1' and displaying columns like this <asp:GridView ID="GridView1" OnRowCommand="ScheduleGridView_RowCommand" runat="server" AutoGenerateColumns="False" Height="60px" Style="text-align: center" Width="869px" EnableViewState="False"> <Columns> <asp:BoundField HeaderText="Topic" DataField="Topic" /> <asp:BoundField DataField="Moderator" HeaderText="Moderator" /> <asp:BoundField DataField="Expert" HeaderText="Expert" /> <asp:BoundField DataField="StartTime" HeaderText="Start" > <HeaderStyle Width="175px" /> </asp:BoundField> <asp:BoundField DataField="EndTime" HeaderText="End" > <HeaderStyle Width="175px" /> </asp:BoundField> <asp:TemplateField HeaderText="Join" ShowHeader="False"> <ItemTemplate> <asp:Button ID="JoinBT" runat="server" CommandArgument="<%# Container.DataItemIndex %>" CommandName="Join" Text="Join" Width="52px" /> </ItemTemplate> <HeaderStyle Height="15px" /> </asp:TemplateField> </Columns> </asp:GridView> Here what is my requirement is whenever we right click on each row in gridview ,it should display three option join meeting(if we click it will go to meeting.aspx),,view details(will go to detail.aspx),,Subscribe(subscribe.aspx) just like when we click right any where we can see view,sortby,refresh like that..Do we need to implement javascript here

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  • Managing Many to Many relationships in asp.net Wizard Control

    - by Luis
    Say I have this entity with a lot of attributes. In the input form I have decided to implement a wizard control so I can collect information about this entity in several steps. The problem is that I need to collect information that has been modeled has many to many relationships. I am planning to use a telerik gridview to manage this (add/edit/delete), the problem is where do I store that data since the entity in a insert form is not created on the database yet. OK so I can store all that info in temporary lists residing in the viewstate, waiting for the final submit where I dump all that in the DB, but one of the steps I am collecting files...now storing files in the viewstate is out of the question, same as as storing them in the session... I have been thinking of implementing in a way that the user has to submit some info first (say first 3 steps), commit the data to the database creating the parent entity and then start inserting all the childs entities...but this will get weird as it's confusing since on the first steps you not saving the data to the DB and on the next ones you are commiting directly... Anyone has any thoughts on this? Thanks

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  • compare two text files using linq?

    - by bala3569
    I have 4 text files in one folder and a pattern.txt to compare these text files..In pattern.txt i have insert update delete drop I need to compare this text file with those four text files and if these patterns matches any line in that text files i have to write those lines in another log file...i had read those files using linq..i need to compare those files and write in a text file with line number..here is my code var foldercontent = Directory.GetFiles(pathA) .Select(filename => File.ReadAllText(filename)) .Aggregate(new StringBuilder(), (sb, s) => sb.Append(s).Append(Environment.NewLine), sb => sb.ToString()); var pattern = File.ReadAllLines(pathB).Aggregate(new StringBuilder(), (sb, s) => sb.Append(s).Append(Environment.NewLine), sb => sb.ToString()); using (var dest = File.AppendText(Path.Combine(_logFolderPath, "log.txt"))) { //dest.WriteLine("LineNo : " + counter.ToString() + " : " + "" + line); } EDIT I have already used c# to compare two text files but i need this in linq while ((line = file.ReadLine()) != null) { if (line.IndexOf(line2, StringComparison.CurrentCultureIgnoreCase) != -1) { dest.WriteLine("LineNo : " + counter.ToString() + " : " + " " + line.TrimStart()); } counter++; } file.BaseStream.Seek(0, SeekOrigin.Begin); counter = 1;

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  • File.Replace throwing IOException

    - by WebDevHobo
    I have an app that can make modify images. In some cases, this makes the filesize smaller, in some cases bigger. The program doesn't have an option to "not replace the file if result has a bigger filesize". So I wrote a little C# app to try and solve this. Instead of overwriting the files, I make the app write the result to a folder under the current one and name that folder Test. The C# app I wrote compares grabs the contents of both folders and puts the full path to the file(s) in two List objects. I then compare and replace. The replacing isn't working however. I get the following IOException: Unable to remove the file to be replaced The location is on an external hard-drive, on which I have full rights. Now, I know I can just do File.Delete and File.Move in that order, but this exception has gotten me interested in why this particular setup wont work. Here's the source code: http://pastebin.com/4Vq82Umu And yes, the file specified as last argument of the Replace function does exist.

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  • i read that for RESTful websites. it is not good to use $_SESSION. Why is it not good? how then do i

    - by keisimone
    I read that it is not good to use $_SESSION. http://www.recessframework.org/page/towards-restful-php-5-basic-tips I am creating a WEBSITE, not web service in PHP. and i am trying to make it more RESTful. at least in spirit. right now i am rewriting all the action to use Form tags POST and add in a hidden value called _method which would be "delete" for deleting action and "put" for updating action. however, i am not sure why it is recommended NOT to use $_SESSION. i would like to know why and what can i do to improve. To allow easy authorization checking, what i did was to after logging in the user, the username is stored in the $_SESSION. Everytime the user navigates to a page, the page would check if the username is stored inside $_SESSION and then based on the $_SESSION retrieves all the info including privileges from the database and then evaluates the authorization to access the page based on the info retrieved. Is the way I am implementing bad? not RESTful? how do i improve performance and security? Thank you.

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  • NHibernate: What are child sessions and why and when should I use them?

    - by stefando
    In the comments for the ayende's blog about the auditing in NHibernate there is a mention about the need to use a child session:session.GetSession(EntityMode.Poco). As far as I understand it, it has something to do with the order of the SQL operation which session.Flush will emit. (For example: If I wanted to perform some delete operation in the pre-insert event but the session was already done with deleting operations, I would need some way to inject them in.) However I did not find documentation about this feature and behavior. Questions: Is my understanding of child sessions correct? How and in which scenarios should I use them? Are they documented somewhere? Could they be used for session "scoping"? (For example: I open the master session which will hold some data and then I create 2 child-sessions from the master one. I'd expect that the two child-scopes will be separated but the will share objects from the master session cache. Is this the case?) Are they first class citizens in NHibernate or are they just hack to support some edge-case scenarios? Thanks in advance for any info.

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  • Is there any function in Matlab for changing the form of matrix?

    - by niko
    Hi, I have to get the unknown matrix by changing the form of known matrix considering the following rules: H = [-P'|I] G = [I|P] where H is known matrix G is unknown matrix which has to be calculated I is identity matrix So for example if we had a matrix H = [1 1 1 1 0 0; 0 0 1 1 0 1; 1 0 0 1 1 0] its form has to be changed to H = [1 1 1 1 0 0; 0 1 1 0 1 0; 1 1 0 0 0 1] so -P' = [1 1 1; 0 1 0; 1 1 0] and in case of binary matrices -P = P therefore G = [1 0 0 1 1 1; 0 1 0 0 1 0; 0 0 1 1 1 0] I know how to solve it on the paper by performing basic row operations but don't know how if there is any function already written in Matlab to calculate G from H or H from G by considering the above rules. I would be very thankful if anyone of you could suggest any method for solving the given problem. Thank you.

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  • Visual Studio 2008 closes unexpectedly

    - by Jose
    I don't know if I can really get an answer to this question, but it really irks me and I would like to know if someone has an idea how to arrive to an answer. I have a pretty large solution in VS 2008 that maybe every week/every other week whenever I click properties to get to the project properties the IDE closes without warning. After that happens it will close EVERY time I try and view the properties. At that point I try and delete the .suo file, I resize the IDE, I close the tabs within the project, I restore default VS Settings(when I'm desperate). Eventually 20-30 minutes later I can actually view the properties. I haven't figured out exactly what fixes it, seems to be different every time. Once it's "fixed" I can't break it again so I can figure out what "fixed" it. This seems to be project specific, because I can view properties of other projects while this project is misbehaving. I guess my first question is, does VS log reasons for closing unexpectedly? Can I find out what the offending reason behind this is? The main frustration is I don't know that cause, nor the cure. Any ideas?

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  • What, if any, printable character did a user type based on the values in a given System.Windows.Form

    - by Corey Trager
    As a workaround for a problem, I think I have to handle KeyDown events to get the printable character the user actually typed. KeyDown supplies me with a KeyEventArgs object with the properities KeyCode, KeyData, KeyValue, Modifiers, Alt, Shift, Control. My first attempt was just to consider the KeyCode to be the ascii code, but KeyCode on my keyboard is 46, a period ("."), so I end up printing a period when the user types the delete key. So, I know my logic is inadequate. (For those who are curious, the problem is that I have my own combobox in a DataGridView's control collection and somehow SOME characters I type don't produce the KeyPress and TextChanged ComboBox events. These letters include Q, $, %.... This code will reproduce the problem. Generate a Form App and replace the ctor with this code. Run it, and try typing the letter Q into the two comboxes. public partial class Form1 : Form { ComboBox cmbInGrid; ComboBox cmbNotInGrid; DataGridView grid; public Form1() { InitializeComponent(); grid = new DataGridView(); cmbInGrid = new ComboBox(); cmbNotInGrid = new ComboBox(); cmbInGrid.Items.Add("a"); cmbInGrid.Items.Add("b"); cmbNotInGrid.Items.Add("c"); cmbNotInGrid.Items.Add("d"); this.Controls.Add(cmbNotInGrid); this.Controls.Add(grid); grid.Location = new Point(0, 100); this.grid.Controls.Add(cmbInGrid); }

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  • Getting a table cell to become a different color on mouseover

    - by Andrei Korchagin
    Currently, when I create a table, and I mouseover a cell, that entire row is highlighted. I'm trying to make it so that it is only the immediate cell. Here's all the CSS code that pertains to tables in my stylesheet: table{margin:.5em 0 1em;} table td,table th{text-align:center;border-right:1px solid #fff;padding:.4em .8em;} table th{background-color:#5e5e5e;color:#fff;text-transform:uppercase;font-weight:bold;border- bottom:1px solid #e8e1c8;} table td{background-color:#eee;} table th a{color:#d6f325;} table th a:hover{color:#fff;} table tr.even td{background-color:#ddd;} table tr:hover td{background-color:#fff;} table.nostyle td,table.nostyle th,table.nostyle tr.even td,table.nostyle tr:hover td{border:0;background:none;background-color:transparent;} I know it's probably a simple fix but I can't find where to make it work. Everything I try just kills the mouseover effect entirely rather than making it the way I want it. Thanks in advance!

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  • Conversion failed when converting datetime from character string

    - by salvationishere
    I am developing a C# VS 2008 / SQL Server 2005 Express website application. I have tried some of the fixes for this problem but my call stack differs from others. And these fixes did not fix my problem. What steps can I take to troubleshoot this? Here is my error: System.Data.SqlClient.SqlException was caught Message="Conversion failed when converting datetime from character string." Source=".Net SqlClient Data Provider" ErrorCode=-2146232060 LineNumber=10 Number=241 Procedure="AppendDataCT" Server="\\\\.\\pipe\\772EF469-84F1-43\\tsql\\query" State=1 StackTrace: at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe) at System.Data.SqlClient.SqlCommand.ExecuteNonQuery() at ADONET_namespace.ADONET_methods.AppendDataCT(DataTable dt, Dictionary`2 dic) in c:\Documents and Settings\Admin\My Documents\Visual Studio 2008\WebSites\Jerry\App_Code\ADONET methods.cs:line 102 And here is the related code. When I debugged this code, "dic" only looped through the 3 column names, but did not look into row values which are stored in "dt", the Data Table. public static string AppendDataCT(DataTable dt, Dictionary<string, string> dic) { if (dic.Count != 3) throw new ArgumentOutOfRangeException("dic can only have 3 parameters"); string connString = ConfigurationManager.ConnectionStrings["AW3_string"].ConnectionString; string errorMsg; try { using (SqlConnection conn2 = new SqlConnection(connString)) { using (SqlCommand cmd = conn2.CreateCommand()) { cmd.CommandText = "dbo.AppendDataCT"; cmd.CommandType = CommandType.StoredProcedure; cmd.Connection = conn2; foreach (string s in dic.Keys) { SqlParameter p = cmd.Parameters.AddWithValue(s, dic[s]); p.SqlDbType = SqlDbType.VarChar; } conn2.Open(); cmd.ExecuteNonQuery(); conn2.Close(); errorMsg = "The Person.ContactType table was successfully updated!"; } } }

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  • How to debug memory allocation issues?

    - by amitabh
    Hi I am writing an iPhone app that that is trying to create a second a view when the user clicks on an element in UITableView. The code looks like ReplyToViewController *reply = [[ReplyToViewController alloc] initWithNibName:@"ReplyTo" bundle:nil]; reply.delegate = self; Message *message = [resultData objectAtIndex:indexPath.row]; int dbid = [message.bizid intValue]; NSLog(@"dbid=%d",dbid); reply.currentMessage = message; reply.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; [self presentModalViewController:reply animated:YES]; The reply object gets created properly and the view is proper. Last line in above code segment calls some framework code which eventually calls the viewDidLoad method of the ReplyToViewController. Address of the reply object in the above code and the address of the object in viewDidLoad is not same. Any idea where this new object is coming from? How do I debug? I also added init method the following method in ReplyToViewController hoping that it will get called and I can find who is creating this new object. But it does not stop in this method. Any help will be greatly appreciated. - (id) init { /* first initialize the base class */ self = [super init]; return self; } // Following gets called from the 1st code segment. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { // Custom initialization } return self; } - (void)viewDidLoad { [super viewDidLoad]; NSLog(currentMessage.text]; // THIS returns nil and the program fails later in the code. }

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  • How can I introduce a regex action to match the first element in a Catalyst URI ?

    - by RET
    Background: I'm using a CRUD framework in Catalyst that auto-generates forms and lists for all tables in a given database. For example: /admin/list/person or /admin/add/person or /admin/edit/person/3 all dynamically generate pages or forms as appropriate for the table 'person'. (In other words, Admin.pm has actions edit, list, add, delete and so on that expect a table argument and possibly a row-identifying argument.) Question: In the particular application I'm building, the database will be used by multiple customers, so I want to introduce a URI scheme where the first element is the customer's identifier, followed by the administrative action/table etc: /cust1/admin/list/person /cust2/admin/add/person /cust2/admin/edit/person/3 This is for "branding" purposes, and also to ensure that bookmarks or URLs passed from one user to another do the expected thing. But I'm having a lot of trouble getting this to work. I would prefer not to have to modify the subs in the existing framework, so I've been trying variations on the following: sub customer : Regex('^(\w+)/(admin)$') { my ($self, $c, @args) = @_; #validation of captured arg snipped.. my $path = join('/', 'admin', @args); $c->request->path($path); $c->dispatcher->prepare_action($c); $c->forward($c->action, $c->req->args); } But it just will not behave. I've used regex matching actions many times, but putting one in the very first 'barrel' of a URI seems unusually traumatic. Any suggestions gratefully received.

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  • Move SELECT to SQL Server side

    - by noober
    Hello all, I have an SQLCLR trigger. It contains a large and messy SELECT inside, with parts like: (CASE WHEN EXISTS(SELECT * FROM INSERTED I WHERE I.ID = R.ID) THEN '1' ELSE '0' END) AS IsUpdated -- Is selected row just added? as well as JOINs etc. I like to have the result as a single table with all included. Question 1. Can I move this SELECT to SQL Server side? If yes, how to do this? Saying "move", I mean to create a stored procedure or something else that can be executed before reading dataset in while cycle. The 2 following questions make sense only if answer is "yes". Why do I want to move SELECT? First off, I don't like mixing SQL with C# code. At second, I suppose that server-side queries run faster, since the server have more chances to cache them. Question 2. Am I right? Is it some sort of optimizing? Also, the SELECT contains constant strings, but they are localizable. For instance, WHERE R.Status = "Enabled" "Enabled" should be changed for French, German etc. So, I want to write 2 static methods -- OnCreate and OnDestroy -- then mark them as stored procedures. When registering/unregistering my assembly on server side, just call them respectively. In OnCreate format the SELECT string, replacing {0}, {1}... with required values from the assembly resources. Then I can localize resources only, not every script. Question 3. Is it good idea? Is there an existing attribute to mark methods to be executed by SQL Server automatically after (un)registartion an assembly? Regards,

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  • Sharepoint fails to load a C++ dll on windows 2008

    - by Nathan
    I have a sharepoint DLL that does some licensing things and as part of the code it uses an external C++ DLL to get the serial number of the hardisk. When i run this application on windows server 2003 it works fine, but on 2008 the whole site (loaded on load) crashes and resets continually. This is not 2008 R2 and is the same in 64 or 32 bits. If i put a debugger.break before the dll execution then I see the code get to the point of the break then never come back into the dll again. I do get some debug assertion warnings from within the function, again only in 2008, but im not sure this is related. I created a console app that runs the c# dll, which in turn loads the c++ dll, and this works perfectly on 2008 (although does show the assertion errors, but I have suppressed these now). The assertion errors are not in my code but within ICtypes.c and not something I can debug. If i put a breakpoint in the DLL it is never hit and the compiler says : "step in: Stepping over non user code" if i try to debug into the DLL using VS. I have tried wrapping the code used to call the DLL in: SPSecurity.RunWithElevatedPrivileges(delegate() but this also does not help. I have the sourcecode for this DLL so that is not a problem. If i delete the DLL from the directory I get an error about a missing DLL, if i replace it back to no error or warning just a complete failure. If i replace this code with a hardcoded string the whole application works fine. Any advice would be much appreciated, I can't understand why it works as a console app yet not when run by sharepoint, this is with the same user account, on the same machine... This is the code used to call the DLL: [DllImport("idDll.dll", EntryPoint = "GetMachineId", SetLastError = true)] extern static string GetComponentId([MarshalAs(UnmanagedType.LPStr)]String s); public static string GetComponentId() { Debugger.Break(); if (_machine == string.Empty) { string temp = ""; id= ComponentId.GetComponentId(temp); } return id; }

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  • Approach For Syncing One SharePoint List With One or More SharePoint Lists

    - by plattnum
    What would be the best approach or strategy for configuring, customizing or developing in SharePoint a solution that allows me to keep one or more SharePoint lists in sync with a SharePoint list I have designated as a master or parent list. I would like to be able to create a master/parent list of some information that can be extended or used by different parts of the organization without them being able to CRUD any items on the actual columns of the master list. (I have seen some commercial web parts that offer column security on SharePoint lists and although that’s one way of potentially meeting my needs I would like to explore other options.) Scenario: I have a list called FOO: FOO Title Description I would like to create a new list BAR based off of FOO (BAR is managed by sub-organization that doesn't have access to FOO List): BAR FOO.Title (Read-Only) FOO.Description (Read-Only) NewColumn1 NewColumn2 Actions: Create- If a new item is entered in FOO I would like the new item added to BAR. Read - N/A Update - If the title or description is changed in FOO I would like it changed in BAR. Delete- No Deletes in the scenario. (Deletes are handled by the business with status column.) Templates with content extraction offer me this but it’s a one time shot at list creation. Just not sure what the best approach or strategy would be for this in MOSS 2007. Thanks!

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  • Preventing ActiveRecord save() on an instance

    - by Craig Walker
    I have an ActiveRecord model object Foo; it represents a standard database row. I want to be able to display modified versions of instances of this object. I'd like to reuse the class itself, as it already has all the hooks & aspects I'll need. (For example: I already have a view that displays the appropriate attributes). Basically I want to clone the model instance, modify some of its properties, and feed it back to the caller (view, test, etc). I do not want these attribute modifications getting back into the database. However, I do want to include the id attribute in the cloned version, as it makes dealing with the route-helpers much easier. Thus, I plan on calling ActiveRecord::Base.clone(), manually setting the ID of the cloned instance, and then making the appropriate attribute changes to the new instance. This has me worried though; one save() on the modified instance and my original data will get clobbered. So, I'm looking to lock down the new instance so that it won't hurt anything else. I'm already planning on calling freeze() (on the understanding that this prevents further modification to the object, though the documentation isn't terribly clear). However, I don't see any obvious way to prevent a save(). What would be the best approach to achieving this?

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  • python list/dict property best practice

    - by jterrace
    I have a class object that stores some properties that are lists of other objects. Each of the items in the list has an identifier that can be accessed with the id property. I'd like to be able to read and write from these lists but also be able to access a dictionary keyed by their identifier. Let me illustrate with an example: class Child(object): def __init__(self, id, name): self.id = id self.name = name class Teacher(object): def __init__(self, id, name): self.id = id self.name = name class Classroom(object): def __init__(self, children, teachers): self.children = children self.teachers = teachers classroom = Classroom([Child('389','pete')], [Teacher('829','bob')]) This is a silly example, but it illustrates what I'm trying to do. I'd like to be able to interact with the classroom object like this: #access like a list print classroom.children[0] #append like it's a list classroom.children.append(Child('2344','joe')) #delete from like it's a list classroom.children.pop(0) But I'd also like to be able to access it like it's a dictionary, and the dictionary should be automatically updated when I modify the list: #access like a dict print classroom.childrenById['389'] I realize I could just make it a dict, but I want to avoid code like this: classroom.childrendict[child.id] = child I also might have several of these properties, so I don't want to add functions like addChild, which feels very un-pythonic anyway. Is there a way to somehow subclass dict and/or list and provide all of these functions easily with my class's properties? I'd also like to avoid as much code as possible.

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  • Aggregating a list of dates to start and end date

    - by Joe Mako
    I have a list of dates and IDs, and I would like to roll them up into periods of consucitutive dates, within each ID. For a table with the columns "testid" and "pulldate" in a table called "data": | A79 | 2010-06-02 | | A79 | 2010-06-03 | | A79 | 2010-06-04 | | B72 | 2010-04-22 | | B72 | 2010-06-03 | | B72 | 2010-06-04 | | C94 | 2010-04-09 | | C94 | 2010-04-10 | | C94 | 2010-04-11 | | C94 | 2010-04-12 | | C94 | 2010-04-13 | | C94 | 2010-04-14 | | C94 | 2010-06-02 | | C94 | 2010-06-03 | | C94 | 2010-06-04 | I want to generate a table with the columns "testid", "group", "start_date", "end_date": | A79 | 1 | 2010-06-02 | 2010-06-04 | | B72 | 2 | 2010-04-22 | 2010-04-22 | | B72 | 3 | 2010-06-03 | 2010-06-04 | | C94 | 4 | 2010-04-09 | 2010-04-14 | | C94 | 5 | 2010-06-02 | 2010-06-04 | This is the the code I came up with: SELECT t2.testid, t2.group, MIN(t2.pulldate) AS start_date, MAX(t2.pulldate) AS end_date FROM(SELECT t1.pulldate, t1.testid, SUM(t1.check) OVER (ORDER BY t1.testid,t1.pulldate) AS group FROM(SELECT data.pulldate, data.testid, CASE WHEN data.testid=LAG(data.testid,1) OVER (ORDER BY data.testid,data.pulldate) AND data.pulldate=date (LAG(data.pulldate,1) OVER (PARTITION BY data.testid ORDER BY data.pulldate)) + integer '1' THEN 0 ELSE 1 END AS check FROM data ORDER BY data.testid, data.pulldate) AS t1) AS t2 GROUP BY t2.testid,t2.group ORDER BY t2.group; I use the use the LAG windowing function to compare each row to the previous, putting a 1 if I need to increment to start a new group, I then do a running sum of that column, and then aggregate to the combinations of "group" and "testid". Is there a better way to accomplish my goal, or does this operation have a name? I am using PostgreSQL 8.4

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  • Uncommitted reads in SSIS

    - by OldBoy
    I'm trying to debug some legacy Integration Services code, and really want some confirmation on what I think the problem is: We have a very large data task inside a control flow container. This control flow container is set up with TransactionOption = supported - i.e. it will 'inherit' transactions from parent containers, but none are set up here. Inside the data flow there is a call to a stored proc that writes to a table with pseudo code something like: "If a record doesn't exist that matches these parameters then write it" Now, the issue is that there are three records being passed into this proc all with the same parameters, so logically the first record doesn't find a match and a record is created. The second record (with the same parameters) also doesn't find a match and another record is created. My understanding is that the first 'record' passed to the proc in the dataflow is uncommitted and therefore can't be 'read' by the second call. The upshot being that all three records create a row, when logically only the first should. In this scenario am I right in thinking that it is the uncommitted transaction that stops the second call from seeing the first? Even setting the isolation level on the container doesn't help because it's not being wrapped in a transaction anyway.... Hope that makes sense, and any advice gratefully received. Work-arounds confer god-like status on you.

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  • Issue with GCD and too many threads

    - by dariaa
    I have an image loader class which provided with NSURL loads and image from the web and executes completion block. Code is actually quite simple - (void)downloadImageWithURL:(NSString *)URLString completion:(BELoadImageCompletionBlock)completion { dispatch_async(_queue, ^{ // dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{ UIImage *image = nil; NSURL *URL = [NSURL URLWithString:URLString]; if (URL) { image = [UIImage imageWithData:[NSData dataWithContentsOfURL:URL]]; } dispatch_async(dispatch_get_main_queue(), ^{ completion(image, URLString); }); }); } When I replace dispatch_async(_queue, ^{ with commented out dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{ Images are loading much faster, wich is quite logical (before that images would be loaded one at a time, now a bunch of them are loading simultaneously). My issue is that I have perhaps 50 images and I call downloadImageWithURL:completion: method for all of them and when I use global queue instead of _queue my app eventually crashes and I see there are 85+ threads. Can the problem be that my calling dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0) 50 times in a row makes GCD create too many threads? I thought that gcd handles all the treading and makes sure the number of threads is not huge, but if it's not the case is there any way I can influence number of threads?

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  • Nhibernate Fluent domain Object with Id(x => x.id).GeneratedBy.Assigned not saveable

    - by urpcor
    Hi there, I am using for some legacy db the corresponding domainclasses with mappings. Now the Ids of the entities are calculated by some stored Procedure in the DB which gives back the Id for the new row.(Its legacy, I cant change this) Now I create the new entity , set the Id and Call Save. But nothing happens. no exeption. Even NH Profiler does not say a bit. its as the Save call does nothing. I expect that NH thinks that the record is already in the db because its got an Id already. But I am using Id(x = x.id).GeneratedBy.Assigned() and intetionally the Session.Save(object) method. I am confused. I saw so many samples there it worked. does any body have any ideas about it? public class Appendix { public virtual int id { get; set; } public virtual AppendixHierarchy AppendixHierachy { get; set; } public virtual byte[] appendix { get; set; } } public class AppendixMap : ClassMap<Appendix> { public AppendixMap () { WithTable("appendix"); Id(x => x.id).GeneratedBy.Assigned(); References(x => x.AppendixHierachy).ColumnName("appendixHierarchyId"); Map(x => x.appendix); } }

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  • Advanced All In One .NET Framework (should i go for a software factory ?)

    - by alfredo dobrekk
    Hi, i m starting a new project that would basically take input from user and save them to database among about 30 screens, and i would like to find a framework that will allow the maximum number of these features out of the box : .net c#. windows form. unit testing continuous integration logging screens with lists, combo boxes, text boxes, add, delete, save, cancel that are easy to update when you add a property to your classes or a field to your database. auto completion on controls to help user find its way use of an orm like nhibernate easy multithreading and display of wait screens for user easy undo redo tabbed child windows search forms ability to grant access to some functionnalities according to user profiles mvp/mvvm or whatever design patterns either some code generation from database to c# classe or generation of database schema from c# classes some kind of database versioning / upgrade to easily update database when i release patches to application once in production automatic control resizing code metrics analysis some code generator i can use against my entities that would generate some rough form i can rearrange after code documentation generator ... At this point i have 3 options : Build from scratch on top of clr :( Find functionnalities among several open source framework and use them as a stack for infrastucture Find a "software factory" I know its lot but i really would like to use existing code to build upon so i can focus on business rules. What open source tools would u use to achieve these ?

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