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  • LINQ to XML contents of child records.

    - by Fossaw
    I have this LINQ to XML enquiry... var Records = from Item in XDoc.Root.Elements("Item") where (string)Item.Element("ItemNumber") == item.ID.ToString select Item; ... where ItemNumber is a reference number used in the XML, (originally written by this program but manually edited by "others"), and item.ID is the database version of the same thing. The query executes, and I can test for the number of entries in the result fine... if (Records.Count() < 1) ... you get the idea. I have established that there is only one record. Each Item has several child fields. I want to test the values of the child fields are reasonable before passing them on to the database update sub-system. The XML is produced by the program, but edited by users, so I need to really check what is coming back. So I tried... if (DB_English.ToString() != Records.Elements("English").ToString()) ... DB_English is from the database, but the XML in Records, does not contain the contents of that field, it contains... System.Xml.Linq.Extensions+<GetElements>d__29`1[System.Xml.Linq.XElement] ... so, how do I get the value of this element in the XML file? I need to check the field in the XML has not been altered, (the manual editors of this data file are not potentially 100% reliable).

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  • Should I remove all inheritance from my model in order to work with ria services?

    - by TimothyP
    I've posted some questions on this before, but it's different. So consider a small portion of our model: Person Customer Employee Spouse Person is the base class which has 3 classes that inherit from it. These 4 are very central in our design and link to many other entities. I could solve all the problems I'm experiencing with ria-services by removing the inheritance but that would really increase the complexety of the model. The first problem I experienced was that I couldn't query for Customers, Employees or Spouses, but someone gave me a solution, which was to add something like this to the DomainService: public IQueryable<Employee> GetEmployees() { return this.ObjectContext.People.OfType<Employee>(); } public IQueryable<Customer> GetCustomers() { return this.ObjectContext.People.OfType<Customer>(); } public IQueryable<Spouse> GetSpouses() { return this.ObjectContext.People.OfType<Spouse>(); } Next I tried something that seemed very normal to me: var employee = new Employee() { //.... left out to reduce the length of this question }; var spouse = new Spouse() { //.... left out to reduce the length of this questions }; employee.Spouse = spouse; context.People.Add(spouse); context.People.Add(employee); context.SubmitChanges(); Then I get the following exception: Cannot retrieve an entity set for the derived entity type 'Spouse'. Use EntityContainer.GetEntitySet(Type) to get the entity set for the base entity type 'Person'. Even when the spouse is already in the database, and I retreive it first I get similar exceptions. Also note that for some reason in some places "Persons" is used instead of "People"... So how do I solve this problem, what am I doing wrong and will I keep running into walls when using ria services with inheritance? I found some references on the web, all saying it works and then some DomainService code in which they suposedly changed something but no details... I'm using VS2010 RC1 + Silveright 4

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  • C++ type-checking at compile-time

    - by Masterofpsi
    Hi, all. I'm pretty new to C++, and I'm writing a small library (mostly for my own projects) in C++. In the process of designing a type hierarchy, I've run into the problem of defining the assignment operator. I've taken the basic approach that was eventually reached in this article, which is that for every class MyClass in a hierarchy derived from a class Base you define two assignment operators like so: class MyClass: public Base { public: MyClass& operator =(MyClass const& rhs); virtual MyClass& operator =(Base const& rhs); }; // automatically gets defined, so we make it call the virtual function below MyClass& MyClass::operator =(MyClass const& rhs); { return (*this = static_cast<Base const&>(rhs)); } MyClass& MyClass::operator =(Base const& rhs); { assert(typeid(rhs) == typeid(*this)); // assigning to different types is a logical error MyClass const& casted_rhs = dynamic_cast<MyClass const&>(rhs); try { // allocate new variables Base::operator =(rhs); } catch(...) { // delete the allocated variables throw; } // assign to member variables } The part I'm concerned with is the assertion for type equality. Since I'm writing a library, where assertions will presumably be compiled out of the final result, this has led me to go with a scheme that looks more like this: class MyClass: public Base { public: operator =(MyClass const& rhs); // etc virtual inline MyClass& operator =(Base const& rhs) { assert(typeid(rhs) == typeid(*this)); return this->set(static_cast<Base const&>(rhs)); } private: MyClass& set(Base const& rhs); // same basic thing }; But I've been wondering if I could check the types at compile-time. I looked into Boost.TypeTraits, and I came close by doing BOOST_MPL_ASSERT((boost::is_same<BOOST_TYPEOF(*this), BOOST_TYPEOF(rhs)>));, but since rhs is declared as a reference to the parent class and not the derived class, it choked. Now that I think about it, my reasoning seems silly -- I was hoping that since the function was inline, it would be able to check the actual parameters themselves, but of course the preprocessor always gets run before the compiler. But I was wondering if anyone knew of any other way I could enforce this kind of check at compile-time.

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  • A Digg-like rotating homepage of popular content, how to include date as a factor?

    - by Ferdy
    I am building an advanced image sharing web application. As you may expect, users can upload images and others can comments on it, vote on it, and favorite it. These events will determine the popularity of the image, which I capture in a "karma" field. Now I want to create a Digg-like homepage system, showing the most popular images. It's easy, since I already have the weighted Karma score. I just sort on that descendingly to show the 20 most valued images. The part that is missing is time. I do not want extremely popular images to always be on the homepage. I guess an easy solution is to restrict the result set to the last 24 hours. However, I'm also thinking that in order to keep the image rotation occur throughout the day, time can be some kind of variable where its offset has an influence on the image's sorting. Specific questions: Would you recommend the easy scenario (just sort for best images within 24 hours) or the more sophisticated one (use datetime offset as part of the sorting)? If you advise the latter, any help on the mathematical solution to this? Would it be best to run a scheduled service to mark images for the homepage, or would you advise a direct query (I'm using MySQL) As an extra note, the homepage should support paging and on a quiet day should include entries of days before in order to make sure it is always "filled" I'm not asking the community to build this algorithm, just looking for some advise :)

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  • Convert a nested array into a flat array with PHP

    - by Ben Fransen
    Hello all, I'm trying to create a generic database mapping class with PHP. Collecting the data through my functions is going well, but as expected I'm retrieving a nested set. A print_r of my received array looks like: Array ( [table] => Session [columns] => Array ( [0] => `Session`.`ID` AS `Session_ID` [1] => `Session`.`User` AS `Session_User` [2] => `Session`.`SessionID` AS `Session_SessionID` [3] => `Session`.`ExpiresAt` AS `Session_ExpiresAt` [4] => `Session`.`CreatedAt` AS `Session_CreatedAt` [5] => `Session`.`LastActivity` AS `Session_LastActivity` [6] => `Session`.`ClientIP` AS `Session_ClientIP` ) [0] => Array ( [table] => User [columns] => Array ( [0] => `User`.`ID` AS `User_ID` [1] => `User`.`UserName` AS `User_UserName` [2] => `User`.`Password` AS `User_Password` [3] => `User`.`FullName` AS `User_FullName` [4] => `User`.`Address` AS `User_Address` ) [0] => Array ( [table] => Address [columns] => Array ( [0] => `Address`.`ID` AS `Address_ID` [1] => `Address`.`UserID` AS `Address_UserID` [2] => `Address`.`Street` AS `Address_Street` [3] => `Address`.`City` AS `Address_City` ) ) ) ) To simplify things I want to recreate this nested array to a flat array so I can easily loop through it and use the 'columns' key to create my SELECT query. I'm kinda struggling with this for a while now and figures, maybe some users at SO can help me out here. I've tried multiple things with recursion, all without luck so far... Any help is much appriciated! Thanks in advance, Ben Fransen

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  • JDO difficulties in retrieving persistent vector

    - by Michael Omer
    I know there are already some posts regarding this subject, but although I tried using them as a reference, I am still stuck. I have a persistent class as follows: @PersistenceCapable(identityType = IdentityType.APPLICATION) public class GameObject implements IMySerializable{ @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) protected Key m_databaseKey; @NotPersistent private final static int END_GAME_VAR = -1000; @Persistent(defaultFetchGroup = "true") protected GameObjectSet m_set; @Persistent protected int m_databaseType = IDatabaseAccess.TYPE_NONE; where GameObjectSet is: @PersistenceCapable(identityType = IdentityType.APPLICATION) @FetchGroup(name = "mySet", members = {@Persistent(name = "m_set")}) public class GameObjectSet { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key id; @Persistent private Vector<GameObjectSetPair> m_set; and GameObjectSetPair is: @PersistenceCapable(identityType = IdentityType.APPLICATION) public class GameObjectSetPair { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key id; @Persistent private String key; @Persistent(defaultFetchGroup = "true") private GameObjectVar value; When I try to fetch the entire structure by fetching the GameObject, the set doesn't have any elements (they are all null) I tried adding the fetching group to the PM, but to no avail. This is my fetching code Vector<GameObject> ret = new Vector<GameObject>(); PersistenceManager pm = PMF.get().getPersistenceManager(); pm.getFetchPlan().setMaxFetchDepth(-1); pm.getFetchPlan().addGroup("mySet"); Query myQuery = pm.newQuery(GameObject.class); myQuery.setFilter("m_databaseType == objectType"); myQuery.declareParameters("int objectType"); try { List<GameObject> res = (List<GameObject>)myQuery.execute(objectType); ret = new Vector<GameObject>(res); for (int i = 0; i < ret.size(); i++) { ret.elementAt(i).getSet(); ret.elementAt(i).getSet().touchSet(); } } catch (Exception e) { } finally { pm.close(); } Does anyone have any idea? Thanks Mike

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  • How to store a list in a column of a database table.

    - by John Berryman
    Howdy! So, per Mehrdad's answer to a related question, I get it that a "proper" database table column doesn't store a list. Rather, you should create another table that effectively holds the elements of said list and then link to it directly or through a junction table. However, the type of list I want to create will be composed of unique items (unlike the linked question's fruit example). Furthermore, the items in my list are explicitly sorted - which means that if I stored the elements in another table, I'd have to sort them every time I accessed them. Finally, the list is basically atomic in that any time I wish to access the list, I will want to access the entire list rather than just a piece of it - so it seems silly to have to issue a database query to gather together pieces of the list. AKX's solution (linked above) is to serialize the list and store it in a binary column. But this also seems inconvenient because it means that I have to worry about serialization and deserialization. Is there any better solution? If there is no better solution, then why? It seems that this problem should come up from time to time. ... just a little more info to let you know where I'm coming from. As soon as I had just begun understanding SQL and databases in general, I was turned on to LINQ to SQL, and so now I'm a little spoiled because I expect to deal with my programming object model without having to think about how the objects are queried or stored in the database. Thanks All! John

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  • Applying for .net jobs as a "self learner"

    - by DeanMc
    Hi All, I have recently started applying for .Net jobs. I currently work in a sales role with a large telco. I found out quite late that I like programming and as such bought my house and made commitments that mean college is not an option. What I would like to know is, is it harder to get a junior job as a self learner? I have gotten a few enquiries regarding my C.V but nothing concrete yet. I try to be involved in projects as I get the chance and tend to put up any worthwhile projects as I develop them. Some examples of my work are: A Xaml lexer and parser: http://www.xlight.mendhak.com A font obfuscation tool: http://www.silverlightforums.com/showthread.php?1516-Font-Obsfucation-Tool-ALPHA A tagger for m4a: http://projectaudiophile.codeplex.com/SourceControl/list/changesets I, of course think that these are great examples of my work but that is my opinion based on self learning. The other query is how much should I actually know? I've never used linked lists but I know that strings are immutable and I understand what that means. I am only touching on T-SQL but I understand things like how properties function in IL (as two standard methods :) ). I suppose I understand a lot of concepts but specific features need some looking up to implement as I may not know the syntax off the top of my head.

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  • How to get height for NSAttributedString at a fixed width

    - by bonaldi
    I want to do some drawing of NSAttributedStrings in fixed-width boxes, but am having trouble calculating the right height they'll take up when drawn. So far, I've tried: Calling - (NSSize) size, but the results are useless (for this purpose), as they'll give whatever width the string desires. Calling - (void)drawWithRect:(NSRect)rect options:(NSStringDrawingOptions)options with a rect shaped to the width I want and NSStringDrawingUsesLineFragmentOrigin in the options, exactly as I'm using in my drawing. The results are ... difficult to understand; certainly not what I'm looking for. (As is pointed out in a number of places, including this Cocoa-Dev thread). Creating a temporary NSTextView and doing: [[tmpView textStorage] setAttributedString:aString]; [tmpView setHorizontallyResizable:NO]; [tmpView sizeToFit]; When I query the frame of tmpView, the width is still as desired, and the height is often correct ... until I get to longer strings, when it's often half the size that's required. (There doesn't seem to be a max size being hit: one frame will be 273.0 high (about 300 too short), the other will be 478.0 (only 60-ish too short)). I'd appreciate any pointers, if anyone else has managed this.

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  • Access 2003 VBA: Return only the index of the last item selected in a ListBox

    - by Eric D. Johnson
    I will preface this with saying, this is my first time using listboxes and earlier posts were criticized for lacking detail. So, all help is greatly appreciated and I hope this is enough information without being overkill. Currently, I have a listbox updating a junction table with an on click event (iterates through selected items and if they are not in the table it adds them). The list box is also updated by an option group (based on the option group value a query populates the list with the appropriate items and they are selected/highlighted based on the junction table). Also, when items are a "sub-category" the "category" is also selected. This functions perfectly until I ask it to do more... Problem 1: I need to differentiate "categories" of items from each other. So, I have included a blank item to the list box to add a space between categories. When the blank items are present the listbox does not update the junction table properly and vice versa. Problem 2: My users want to be able to deselect the "category" under certain circumstances. This is fine, just de-select the "category" after the "sub-category" is selected. However, the "category" is re-selected whenever the listbox is clicked again because it iterates through all entries. Perceived solution for both problems: Return only the index of the item (de)selected and manipulate accordingly. Is this possible? If so, how? OR: Should I take a different approach?

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  • How to nest joins with CakePHP?

    - by Daren Thomas
    I'm trying to behave. So, instead of using following SQL syntax: select * from tableA INNER JOIN tableB on tableA.id = tableB.tableA_id LEFT OUTER JOIN ( tableC INNER JOIN tableD on tableC.tableD_id = tableD.id) on tableC.tableA_id = tableA.id I'd like to use the CakePHP model->find(). This will let me use the Paginator too, since that will not work with custom SQL queries as far as I understand (unless you hardcode one single pagination query to the model which seems a little inflexible to me). What I've tried so far: /* inside tableA_controller.php, inside an action, e.g. "view" */ $this->paginate['recursive'] = -1; # suppress model associations for now $this->paginate['joins'] = array( array( 'table' => 'tableB', 'alias' => 'TableB', 'type' => 'inner', 'conditions' => 'TableB.tableA_id = TableA.id', ), array( 'table' => 'tableC', 'alias' => 'TableC', 'type' => 'left', 'conditions' => 'TableC.tableA_id = TableA.id', 'joins' = array( # this would be the obvious way to do it, but doesn't work array( 'table' => 'tableD', 'alias' => 'TableD', 'type' => 'inner', 'conditions' => 'TableC.tableD_id = TableD.id' ) ) ) ) That is, nesting the joins into the structure. But that doesn't work (CakePHP just ignores the nested 'joins' element which was kind of what I expected, but sad. I have seen hints in comments on how to do subqueries (in the where clause) using a statement builder. Can a similar trick be used here?

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  • NHibernate CreateSqlQuery and object graph

    - by magellings
    Hello I'm a newbie to NHibernate. I'd like to make one sql query to the database using joins to my three tables. I have an Application with many Roles with many Users. I'm trying to get NHibernate to properly form the object graph starting with the Application object. For example, if I have 10 application records, I want 10 application objects and then those objects have their roles which have their users. What I'm getting however resembles a Cartesian product in which I have as many Application objects as total User records. I've looked into this quite a bit and am not sure if it is possible to form the application hierarchy correctly. I can only get the flattened objects to come back. It seems "maybe" possible as in my research I've read about "grouped joins" and "hierarchical output" with an upcoming LINQ to NHibernate release. Again though I'm a newbie. [Update Based on Frans comment in Ayende's post here I'm guessing what I want to do is not possible http://ayende.com/Blog/archive/2008/12/01/solving-the-select-n1-problem.aspx ] Thanks for you time in advance. Session.CreateSQLQuery(@"SELECT a.ID, a.InternalName, r.ID, r.ApplicationID, r.Name, u.UserID, u.RoleID FROM dbo.[Application] a JOIN dbo.[Roles] r ON a.ID = r.ApplicationID JOIN dbo.[UserRoleXRef] u ON u.RoleID = r.ID") .AddEntity("app", typeof(RightsBasedSecurityApplication)) .AddJoin("role", "app.Roles") .AddJoin("user", "role.RightsUsers") .List<RightsBasedSecurityApplication>().AsQueryable();

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  • Creating a REST client API using Reactive Extensions (Rx)

    - by Jonas Follesø
    I'm trying to get my head around the right use cases for Reactive Extensions (Rx). The examples that keeps coming up are UI events (drag and drop, drawing), and suggestions that Rx is suitable for asynchronous applications/operations such as web service calls. I'm working on an application where I need to write a tiny client API for a REST service. I need to call four REST end-points, three to get some reference data (Airports, Airlines, and Statuses), and the fourth is the main service that will give you flight times for a given airport. I have created classes exposing the three reference data services, and the methods look something like this: public Observable<Airport> GetAirports() public Observable<Airline> GetAirlines() public Observable<Status> GetStatuses() public Observable<Flights> GetFlights(string airport) In my GetFlights method I want each Flight to hold a reference the Airport it's departing from, and the Airline operating the flight. To do that I need the data from GetAirports and GetAirlines to be available. My initial thinking was something like this: Write a Rx Query that will Subscribe on the three reference services (Airports, Airlines and Statuses) Add results into a Dictionary (airline code and Airline object) When all three GetAirports, GetAirlines and GetStatuses are complete, then return the GetFlights IObservable. Is this a reasonable scenario for Rx? I'm developing on the Windows Phone 7, so I'm not sure if there are major differences in the Rx implementations across the different platforms.

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  • Getting "[Microsoft][ODBC SQL Server Driver][SQL Server]Incorrect syntax near 'Microsoft.'

    - by brohjoe
    Hi Experts, I'm getting an error, "[Microsoft][ODBC SQL Server Driver][SQL Server]Incorrect syntax near 'Microsoft.' Here is the code: Dim conn As ADODB.Connection Dim rst As ADODB.Recordset Dim stSQL As String Public Sub loadData() 'This was set up using Microsoft ActiveX Data Components version 6.0. 'Create ADODB connection object, open connection and construct the connection string object which is the DSN name. Set conn = New ADODB.Connection conn.ConnectionString = "sql_server" conn.Open 'conn.Execute (strSQL) On Error GoTo ErrorHandler 'Open Excel and run query to export data to SQL Server. strSQL = "SELECT * INTO SalesOrders FROM OPENDATASOURCE(Microsoft.ACE.OLEDB.12.0;" & _ "Data Source=C:\Workbook.xlsx;" & _ "Extended Properties=Excel 12.0; [Sales Orders])" conn.Execute (strSQL) 'Error handling. ErrorExit: 'Reclaim memory from the cntection objects Set rst = Nothing Set conn = Nothing Exit Sub ErrorHandler: MsgBox Err.Description, vbCritical Resume ErrorExit 'clean up and reclaim memory resources. conn.Close If CBool(cnt.State And adStateOpen) Then Set rst = Nothing Set conn = Nothing End If End Sub

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  • What to Return? Error String, Bool with Error String Out, or Void with Exception

    - by Ranger Pretzel
    I spend most of my time in C# and am trying to figure out which is the best practice for handling an exception and cleanly return an error message from a called method back to the calling method. For example, here is some ActiveDirectory authentication code. Please imagine this Method as part of a Class (and not just a standalone function.) bool IsUserAuthenticated(string domain, string user, string pass, out errStr) { bool authentic = false; try { // Instantiate Directory Entry object DirectoryEntry entry = new DirectoryEntry("LDAP://" + domain, user, pass); // Force connection over network to authenticate object nativeObject = entry.NativeObject; // No exception thrown? We must be good, then. authentic = true; } catch (Exception e) { errStr = e.Message().ToString(); } return authentic; } The advantages of doing it this way are a clear YES or NO that you can embed right in your If-Then-Else statement. The downside is that it also requires the person using the method to supply a string to get the Error back (if any.) I guess I could overload this method with the same parameters minus the "out errStr", but ignoring the error seems like a bad idea since there can be many reasons for such a failure... Alternatively, I could write a method that returns an Error String (instead of using "out errStr") in which a returned empty string means that the user authenticated fine. string AuthenticateUser(string domain, string user, string pass) { string errStr = ""; try { // Instantiate Directory Entry object DirectoryEntry entry = new DirectoryEntry("LDAP://" + domain, user, pass); // Force connection over network to authenticate object nativeObject = entry.NativeObject; } catch (Exception e) { errStr = e.Message().ToString(); } return errStr; } But this seems like a "weak" way of doing things. Or should I just make my method "void" and just not handle the exception so that it gets passed back to the calling function? void AuthenticateUser(string domain, string user, string pass) { // Instantiate Directory Entry object DirectoryEntry entry = new DirectoryEntry("LDAP://" + domain, user, pass); // Force connection over network to authenticate object nativeObject = entry.NativeObject; } This seems the most sane to me (for some reason). Yet at the same time, the only real advantage of wrapping those 2 lines over just typing those 2 lines everywhere I need to authenticate is that I don't need to include the "LDAP://" string. The downside with this way of doing it is that the user has to put this method in a try-catch block. Thoughts? Is there another way of doing this that I'm not thinking of?

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  • entity framework - getting null exception using foreign key

    - by Nick
    Having some trouble with what should be a very simple scenario. For example purposes, I have two tables: -Users -Comments There is a one-to-many relationship set up for this; there is a foreign key from Comments.CommentorID to Users.UserID. When I do the LINQ query and try to bind to a DataList, I get a null exception. Here is the code: FKMModel.FKMEntities ctx = new FKMModel.FKMEntities(); IQueryable<Comment> CommentQuery = from x in ctx.Comment where x.SiteID == 101 select x; List<Comment> Comments = CommentQuery.ToList(); dl_MajorComments.DataSource = Comments; dl_MajorComments.DataBind(); In the ASPX page, I have the following as an ItemTemplate (I simplified it and took out the styling, etc, for purposes of posting here since it's irrelevant): <div> <%# ((FKMModel.Comment)Container.DataItem).FKMUser.Username %> <%# ((FKMModel.Comment)Container.DataItem).CommentDate.Value.ToShortDateString() %> <%# ((FKMModel.Comment)Container.DataItem).CommentTime %> </div> The exception occurs on the first binding (FKMUser.Username). Since the foreign key is set up, I should have no problem accessing any properties from the Users table. Intellisense set up the FKMUser navigation property and it knows the properties of that foreign table. What is going on here??? Thanks, Nick

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  • Take Current Snapshot of DB and send it to FTP in same PHP Scripts: Advice Needed

    - by Rachel
    Not sure if I can do it this way. I want to get current snapshot of the database and send it via FTP Server, both of this functionality should be implemented in PHP scripts. Here are the steps I am thinking on right now. In my php scripts(basically am extending an PDO into my Dao class and then preparing the query), $qry = SELECT * FROM MyTablename; $stmt = $this->prepare($qry); $stmt = $this->execute(); Now I will store $stmt in csv file using fputcsv or I will execute the sql command from the script itself and than try to store the result in the $file(csv file) note here that I do not have any csv file with me at this point to basically I will have to create one and let's say its $file, so then $file = fputcsv($stmt); or $file = exec("Select * from MyTablename"); Will this put all records in the file ? If yes, then I will use FTP Functionality to transfer file to the FTP Folder. I am not sure if this approach would work and also have concerns regarding the need of preparing the $qry Any suggestions or different approach advised would be highly appreciated. Thanks !!!

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  • Using MongoDB's map/reduce to "group by" two fields

    - by ibz
    I need something slightly more complex than the examples in the MongoDB docs and I can't seem to be able to wrap my head around it. Say I have a collection of objects of the form {date: "2010-10-10", type: "EVENT_TYPE_1", user_id: 123, ...} Now I want to get something similar to a SQL GROUP BY query, grouping over both date and type. That is, I want the number of events of each type in each day. Also, I'd like to make it unique by user_id, ie. if a user has more events in the same day, count it only once. I'm trying to do this with map/reduce. I do db.logs.mapReduce(function() { emit(this.type, 1); }, function(k, vals) { var total = 0; for (var i = 0; i < vals.length; i++) total += vals[i]; return total; }}) which nicely groups by type, but now, how can I group by date at the same time? Seems the key in emit() can't be an array (I thought about doing emit([this.date, this.type], 1)). Also, how can I ensure the per-user uniqueness? I'm just starting with MongoDB and I'm still having trouble grasping the basic concepts. Also, there is not much documentation available out there. Any help from more experienced users is appreciated. Thanks!

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  • Write a sql for updating data based on time

    - by Lu Lu
    Hello everyone, Because I am new with SQL Server and T-SQL, so I will need your help. I have 2 table: Realtime and EOD. To understand my question, I give example data for 2 tables: ---Realtime table--- Symbol Date Value ABC 1/3/2009 03:05:01 327 // this day is not existed in EOD -> inserting BBC 1/3/2009 03:05:01 458 // this day is not existed in EOD -> inserting ABC 1/2/2009 03:05:01 326 // this day is new -> updating BBC 1/2/2009 03:05:01 454 // this day is new -> updating ABC 1/2/2009 02:05:01 323 BBC 1/2/2009 02:05:01 453 ABC 1/2/2009 01:05:01 313 BBC 1/2/2009 01:05:01 423 ---EOD table--- Symbol Date Value ABC 1/2/2009 02:05:01 323 BBC 1/2/2009 02:05:01 453 I will need to create a store procedure to update value of symbols. If data in day of a symbol is new (compare between Realtime & EOD), it will update value and date for EOD at that day if existing, otherwise inserting. And store will update EOD table with new data: ---EOD table--- Symbol Date Value ABC 1/3/2009 03:05:01 327 BBC 1/3/2009 03:05:01 458 ABC 1/2/2009 03:05:01 326 BBC 1/2/2009 03:05:01 454 P/S: I use SQL Server 2005. And I have a similar answered question at here: http://stackoverflow.com/questions/2726369/help-to-the-way-to-write-a-query-for-the-requirement Please help me. Thanks.

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  • Hibernate Communications Link Failure in Hibernate Based Java Servlet application powered by MySQL

    - by Vatsala
    Let me describe my question - I have a Java application - Hibernate as the DB interfacing layer over MySQL. I get the communications link failure error in my application. The occurence of this error is a very specific case. I get this error , When I leave mysql server unattended for more than approximately 6 hours (i.e. when there are no queries issued to MySQL for more than approximately 6 hours). I am pasting a top 'exception' level description below, and adding a pastebin link for a detailed stacktrace description. javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: org.hibernate.exception.JDBCConnectionException: Cannot open connection - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure - The last packet successfully received from the server was 1,274,868,181,212 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago. - Caused by: java.net.ConnectException: Connection refused: connect the link to the pastebin for further investigation - http://pastebin.com/4KujAmgD What I understand from these exception statements is that MySQL is refusing to take in any connections after a period of idle/nil activity. I have been reading up a bit about this via google search, and came to know that one of the possible ways to overcome this is to set values for c3p0 properties as c3p0 comes bundled with Hibernate. Specifically, I read from here http://www.mchange.com/projects/c3p0/index.html that setting two properties idleConnectionTestPeriod and preferredTestQuery will solve this for me. But these values dont seem to have had an effect. Is this the correct approach to fixing this? If not, what is the right way to get over this? The following are related Communications Link Failure questions at stackoverflow.com, but I've not found a satisfactory answer in their answers. http://stackoverflow.com/questions/2121829/java-db-communications-link-failure http://stackoverflow.com/questions/298988/how-to-handle-communication-link-failure Note 1 - i dont get this error when I am using my application continuosly. Note 2 - I use JPA with Hibernate and hence my hibernate.dialect,etc hibernate properties reside within the persistence.xml in the META-INF folder (does that prevent the c3p0 properties from working?) edit - Here are the c3p0 parameters I tried out - select 1; 2

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  • How to combine designable components with dependency injection

    - by Wim Coenen
    When creating a designable .NET component, you are required to provide a default constructor. From the IComponent documentation: To be a component, a class must implement the IComponent interface and provide a basic constructor that requires no parameters or a single parameter of type IContainer. This makes it impossible to do dependency injection via constructor arguments. (Extra constructors could be provided, but the designer would ignore them.) Some alternatives we're considering: Service Locator Don't use dependency injection, instead use the service locator pattern to acquire dependencies. This seems to be what IComponent.Site.GetService is for. I guess we could create a reusable ISite implementation (ConfigurableServiceLocator?) which can be configured with the necessary dependencies. But how does this work in a designer context? Dependency Injection via properties Inject dependencies via properties. Provide default instances if they are necessary to show the component in a designer. Document which properties need to be injected. Inject dependencies with an Initialize method This is much like injection via properties but it keeps the list of dependencies that need to be injected in one place. This way the list of required dependencies is documented implicitly, and the compiler will assists you with errors when the list changes. Any idea what the best practice is here? How do you do it? edit: I have removed "(e.g. a WinForms UserControl)" since I intended the question to be about components in general. Components are all about inversion of control (see section 8.3.1 of the UMLv2 specification) so I don't think that "you shouldn't inject any services" is a good answer. edit 2: It took some playing with WPF and the MVVM pattern to finally "get" Mark's answer. I see now that visual controls are indeed a special case. As for using non-visual components on designer surfaces, I think the .NET component model is fundamentally incompatible with dependency injection. It appears to be designed around the service locator pattern instead. Maybe this will start to change with the infrastructure that was added in .NET 4.0 in the System.ComponentModel.Composition namespace.

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  • Generate an ID via COM interop

    - by Erik van Brakel
    At the moment, we've got an unmaintanable ball of code which offers an interface to a third party application. The third party application has a COM assembly which MUST be used to create new entries. This process involves two steps: generate a new object (basically an ID), and update that object with new field values. Because COM interop is so slow, we only use that to generate the ID (and related objects) in the database. The actual update is done using a regular SQL query. What I am trying to figure out if it's possible to use NHibernate to do some of the heavy lifting for us, without bypassing the COM assembly. Here's the code for saving something to the database as I envision it: using(var s = sessionFactory.OpenSession()) using(var t = s.BeginTransaction()) { MyEntity entity = new MyEntity(); s.Save(entity); t.Commit(); } Regular NH code I'd say. Now, this is where it gets tricky. I think I have to supply my own implementation of NHibernate.Id.IIdentifierGenerator which calls the COM assembly in the Generate method. That's not a problem. What IS a problem is that the COM assembly requires initialisation, which does take a bit of time. It also doesn't like multiple instances in the same process, for some reason. What I would like to know is if there's a way to properly access an external service in the generator code. I'm free to use any technique I want, so if it involves something like an IoC container that's no problem. The thing I am looking for is where exactly to hook-up my code so I can access the things I need in my generator, without having to resort to using singletons or other nasty stuff.

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  • How do I efficiently write a "toggle database value" function in AJAX?

    - by AmbroseChapel
    Say I have a website which shows the user ten images and asks them to categorise each image by clicking on buttons. A button for "funny", a button for "scary", a button for "pretty" and so on. These buttons aren't exclusive. A picture can be both funny and scary. The user clicks the "funny" button. An AJAX request is sent off to the database to mark that image as funny. The "funny" button lights up, by assigning a class in the DOM to mark it as "on". But the user made a mistake. They meant to hit the next button over. They should click "funny" again to turn it off, right? At this point I'm not sure whats the most efficient way to proceed. The database knows that the "funny" flag is set, but it's inefficient to query the database every time a button is clicked to say, is this flag set or not, then go on with a second database call to toggle it. Should I infer the state of the database flag from the DOM, i.e. if that button has the class "on" then the flag must be set, and branch at that point? Or would it be better to have a data structure in Javascript in the page which duplicates the state of each image in the database, so that every time I set the database flag to true, I also set the value in the Javascript data to true and so on?

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  • Nhibernate join on a table twice

    - by Zuber
    Consider the following Class structure... public class ListViewControl { public int SystemId {get; set;} public List<ControlAction> Actions {get; set;} public List<ControlAction> ListViewActions {get; set;} } public class ControlAction { public string blahBlah {get; set;} } I want to load class ListViewControl eagerly using NHibernate. The mapping using Fluent is as shown below public UIControlMap() { Id(x => x.SystemId); HasMany(x => x.Actions) .KeyColumn("ActionId") .Cascade.AllDeleteOrphan() .AsBag() .Cache.ReadWrite().IncludeAll(); HasMany(x => x.ListViewActions) .KeyColumn("ListViewActionId") .Cascade.AllDeleteOrphan() .AsBag() .Cache.ReadWrite().IncludeAll(); } This is how I am trying to load it eagerly var baseActions = DetachedCriteria.For<ListViewControl>() .CreateCriteria("Actions", JoinType.InnerJoin) .SetFetchMode("BlahBlah", FetchMode.Eager) .SetResultTransformer(new DistinctRootEntityResultTransformer()); var listViewActions = DetachedCriteria.For<ListViewControl>() .CreateCriteria("ListViewActions", JoinType.InnerJoin) .SetFetchMode("BlahBlah", FetchMode.Eager) .SetResultTransformer(new DistinctRootEntityResultTransformer()); var listViews = DetachedCriteria.For<ListViewControl>() .SetFetchMode("Actions", FetchMode.Eager) .SetFetchMode("ListViewActions",FetchMode.Eager) .SetResultTransformer(new DistinctRootEntityResultTransformer()); var result = _session.CreateMultiCriteria() .Add("listViewActions", listViewActions) .Add("baseActions", baseActions) .Add("listViews", listViews) .SetResultTransformer(new DistinctRootEntityResultTransformer()) .GetResult("listViews"); Now, my problem is that the class ListViewControl get the correct records in both Actions and ListViewActions, but there are multiple entries of the same record. The number of records is equal to the number of joins made to the ControlAction table, in this case two. How can I avoid this? If I remove the SetFetchMode from the listViews query, the actions are loaded lazily through a proxy which I don't want.

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  • MySQL database design question

    - by Greelmo
    I'm trying to weigh the pros and cons of a database design, and would like to get some feedback as to the best approach. Here is the situation: I have users of my system that have only a few required items (username, password). They can then supply a lot of optional information. This optional information continues to grow as the system grows, so I want to do it in such a way that adding new optional information is easy. Currently, I have a separate table for each piece of information. For example, there's a table called 'names' that holds 'user_id', 'first_name', and 'last_name'. There's 'address', 'occupation', etc. You get the drift. In most cases, when I talk to my database, I'm looking only for users with one particular qualifier (name, address, etc.). However, there are instances when I want to see what information a user has set. The 'edit account' page, for example, must run queries for each piece of information it wants. Is this wasteful? Is there a way I can structure my queries or my database to make it so I never have to do one query for each piece of information like that without getting my tables to huge? If i want to add 'marital status', how hard will that be if I don't have a one-table-per-attribute system? Thanks in advance.

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