Search Results

Search found 1489 results on 60 pages for 'iterate'.

Page 52/60 | < Previous Page | 48 49 50 51 52 53 54 55 56 57 58 59  | Next Page >

• Best way to store a large amount of game objects and update the ones onscreen

  - by user3002473

  Good afternoon guys! I'm a young beginner game developer working on my first large scale game project and I've run into a situation where I'm not quite sure what the best solution may be (if there is a lone solution). The question may be vague (if anyone can think of a better title after having read the question, please edit it) or broad but I'm not quite sure what to do and I thought it would help just to discuss the problem with people more educated in the field. Before we get started, here are some of the questions I've looked at for help in the past: Best way to keep track of game objects Elegant way to simulate large amounts of entities within a game world What is the most efficient container to store dynamic game objects in? I've also read articles about different data structures commonly used in games to store game objects such as this one about slot maps, but none of them are really what I'm looking for. Also, if it helps at all I'm using Python 3 to design the game. It has to be Python 3, if I could I would use C++ or Unityscript or something else, but I'm restricted to having to use Python 3. My game will be a form of side scroller shooter game. In said game the player will traverse large rooms with large amounts of enemies and other game objects to update (think some of the larger areas in Cave Story or Iji). The player obviously can't see the entire room all at once, so there is a viewport that follows the player around and renders only a selection of the room and the game objects that it contains. This is not a foreign concept. The part that's getting me confused has to do with how certain game objects are updated. Some of them are to be updated constantly, regardless of whether or not they can be seen. Other objects however are only to be updated when they are onscreen (for example, an enemy would only be updated to react to the player when it is onscreen or when it is in a certain range of the screen). Another problem is that game objects have to be easily referable by other game objects; something that happens in the player's update() method may affect another object in the world. Collision detection in games is always a serious problem. I need a way of containing the game objects such that it minimizes the number of cases when testing for collisions against one another. The final problem is that of creating and destroying game objects. I think this problem is pretty self explanatory. To store the game objects then I've considered a number of different methods. The original method I had was to simply store all the objects in a hash table by an id. This method was simple, and decently fast as it allows all the objects to be looked up in O(1) complexity, and also allows them to be deleted fairly easily. Hash collisions would not be a major problem; I wasn't originally planning on using computer generated ids to store the game objects I was going to rely on them all using ids given to them by the game designer (such names would be strings like 'Player' or 'EnemyWeapon4'), and even if I did use computer generated ids, if I used a decent hashing algorithm then the chances of collisions would be around 1 in 4 billion. The problem with using a hash table however is that it is inefficient in checking to see what objects are in range of the viewport. Considering the fact that certain game objects move (as well as the viewport itself), the only solution I could think of in order to only update objects that are in the viewport would be to iterate through every object in the hash table and check if it is in the viewport or not, updating only the ones that are in the valid area. This would be incredibly slow in scenarios where the amount of game objects exceeds 500, or even 200. The second solution was to store everything in a 2-d list. The world is partitioned up into cells (a tilemap essentially), where each cell or tile is the same size and is square. Each cell would contain a list of the game objects that are currently occupying it (each game object would be inserted into a cell depending on the center of the object's collision mask). A 2-d list would allow me to take the top-left and bottom-right corners of the viewport and easily grab a rectangular area of the grid containing only the cells containing entities that are in valid range to be updated. This method also solves the problem of collision detection; when I take an entity I can find the cell that it is currently in, then check only against entities in it's cell and the 8 cells around it. One problem with this system however is that it prohibits easy lookup of game objects. One solution I had would be to simultaneously keep a hash table that would contain all the positions of the objects in the 2-d list indexed by the id of said object. The major problem with a 2-d list is that it would need to be rebuilt every single game frame (along with the hash table of object positions), which may be a serious detriment to game speed. Both systems have ups and downs and seem to solve some of each other's problems, however using them both together doesn't seem like the best solution either. If anyone has any thoughts, ideas, suggestions, comments, opinions or solutions on new data structures or better implementations of the existing data structures I have in mind, please post, any and all criticism and help is welcome. Thanks in advance! EDIT: Please don't close the question because it has a bad title, I'm just bad with names!

  Read the article

• SQL ADO.NET shortcut extensions (old school!)

  - by Jeff

  As much as I love me some ORM's (I've used LINQ to SQL quite a bit, and for the MSDN/TechNet Profile and Forums we're using NHibernate more and more), there are times when it's appropriate, and in some ways more simple, to just throw up so old school ADO.NET connections, commands, readers and such. It still feels like a pain though to new up all the stuff, make sure it's closed, blah blah blah. It's pretty much the least favorite task of writing data access code. To minimize the pain, I have a set of extension methods that I like to use that drastically reduce the code you have to write. Here they are... public static void Using(this SqlConnection connection, Action<SqlConnection> action) {     connection.Open();     action(connection);     connection.Close(); } public static SqlCommand Command(this SqlConnection connection, string sql){    var command = new SqlCommand(sql, connection);    return command;}public static SqlCommand AddParameter(this SqlCommand command, string parameterName, object value){    command.Parameters.AddWithValue(parameterName, value);    return command;}public static object ExecuteAndReturnIdentity(this SqlCommand command){    if (command.Connection == null)        throw new Exception("SqlCommand has no connection.");    command.ExecuteNonQuery();    command.Parameters.Clear();    command.CommandText = "SELECT @@IDENTITY";    var result = command.ExecuteScalar();    return result;}public static SqlDataReader ReadOne(this SqlDataReader reader, Action<SqlDataReader> action){    if (reader.Read())        action(reader);    reader.Close();    return reader;}public static SqlDataReader ReadAll(this SqlDataReader reader, Action<SqlDataReader> action){    while (reader.Read())        action(reader);    reader.Close();    return reader;} It has been awhile since I've really revisited these, so you will likely find opportunity for further optimization. The bottom line here is that you can chain together a bunch of these methods to make a much more concise database call, in terms of the code on your screen, anyway. Here are some examples: public Dictionary<string, string> Get(){    var dictionary = new Dictionary<string, string>();    _sqlHelper.GetConnection().Using(connection =>        connection.Command("SELECT Setting, [Value] FROM Settings")            .ExecuteReader()            .ReadAll(r => dictionary.Add(r.GetString(0), r.GetString(1))));    return dictionary;} or... public void ChangeName(User user, string newName){    _sqlHelper.GetConnection().Using(connection =>         connection.Command("UPDATE Users SET Name = @Name WHERE UserID = @UserID")            .AddParameter("@Name", newName)            .AddParameter("@UserID", user.UserID)            .ExecuteNonQuery());} The _sqlHelper.GetConnection() is just some other code that gets a connection object for you. You might have an even cleaner way to take that step out entirely. This looks more fluent, and the real magic sauce for me is the reader bits where you can put any kind of arbitrary method in there to iterate over the results.

  Read the article

• yield – Just yet another sexy c# keyword?

  - by George Mamaladze

  yield (see NSDN c# reference) operator came I guess with .NET 2.0 and I my feeling is that it’s not as wide used as it could (or should) be.   I am not going to talk here about necessarity and advantages of using iterator pattern when accessing custom sequences (just google it).   Let’s look at it from the clean code point of view. Let's see if it really helps us to keep our code understandable, reusable and testable.   Let’s say we want to iterate a tree and do something with it’s nodes, for instance calculate a sum of their values. So the most elegant way would be to build a recursive method performing a classic depth traversal returning the sum.           private int CalculateTreeSum(Node top)         {             int sumOfChildNodes = 0;             foreach (Node childNode in top.ChildNodes)             {                 sumOfChildNodes += CalculateTreeSum(childNode);             }             return top.Value + sumOfChildNodes;         }     “Do One Thing” Nevertheless it violates one of the most important rules “Do One Thing”. Our  method CalculateTreeSum does two things at the same time. It travels inside the tree and performs some computation – in this case calculates sum. Doing two things in one method is definitely a bad thing because of several reasons: ·          Understandability: Readability / refactoring ·          Reuseability: when overriding - no chance to override computation without copying iteration code and vice versa. ·          Testability: you are not able to test computation without constructing the tree and you are not able to test correctness of tree iteration.   I want to spend some more words on this last issue. How do you test the method CalculateTreeSum when it contains two in one: computation & iteration? The only chance is to construct a test tree and assert the result of the method call, in our case the sum against our expectation. And if the test fails you do not know wether was the computation algorithm wrong or was that the iteration? At the end to top it all off I tell you: according to Murphy’s Law the iteration will have a bug as well as the calculation. Both bugs in a combination will cause the sum to be accidentally exactly the same you expect and the test will PASS. J   Ok let’s use yield! That’s why it is generally a very good idea not to mix but isolate “things”. Ok let’s use yield!           private int CalculateTreeSumClean(Node top)         {             IEnumerable<Node> treeNodes = GetTreeNodes(top);             return CalculateSum(treeNodes);         }             private int CalculateSum(IEnumerable<Node> nodes)         {             int sumOfNodes = 0;             foreach (Node node in nodes)             {                 sumOfNodes += node.Value;             }             return sumOfNodes;         }           private IEnumerable<Node> GetTreeNodes(Node top)         {             yield return top;             foreach (Node childNode in top.ChildNodes)             {                 foreach (Node currentNode in GetTreeNodes(childNode))                 {                     yield return currentNode;                 }             }         }   Two methods does not know anything about each other. One contains calculation logic another jut the iteration logic. You can relpace the tree iteration algorithm from depth traversal to breath trevaersal or use stack or visitor pattern instead of recursion. This will not influence your calculation logic. And vice versa you can relace the sum with product or do whatever you want with node values, the calculateion algorithm is not aware of beeng working on some tree or graph.  How about not using yield? Now let’s ask the question – what if we do not have yield operator? The brief look at the generated code gives us an answer. The compiler generates a 150 lines long class to implement the iteration logic.       [CompilerGenerated]     private sealed class <GetTreeNodes>d__0 : IEnumerable<Node>, IEnumerable, IEnumerator<Node>, IEnumerator, IDisposable     {         ...        150 Lines of generated code        ...     }   Often we compromise code readability, cleanness, testability, etc. – to reduce number of classes, code lines, keystrokes and mouse clicks. This is the human nature - we are lazy. Knowing and using such a sexy construct like yield, allows us to be lazy, write very few lines of code and at the same time stay clean and do one thing in a method. That's why I generally welcome using staff like that.   Note: The above used recursive depth traversal algorithm is possibly the compact one but not the best one from the performance and memory utilization point of view. It was taken to emphasize on other primary aspects of this post.

  Read the article

• EM CLI, diving in and beyond!

  - by Maureen Byrne

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Doing more in less time… Isn’t that what we all strive to do? With this in mind, I put together two screen watches on Oracle Enterprise Manager 12c command line interface, or EM CLI as it is also known. There is a wealth of information on any topic that you choose to read about, from manual pages to coding documents…might I even say blog posts? In our busy lives it is so nice to just sit back with a short video, watch and learn enough to dive in. Doing more in less time, is the essence of EM CLI. It enables you to script fundamental and complex administrative tasks in an elegant way, thanks to the Jython scripting language. Repetitive tasks can be scripted and reused again and again. Sure, a Graphical User Interface provides a more intuitive step by step approach to tasks, and it provides a way of quickly becoming familiar with a product and its many features, and it is definitely the way to go when viewing performance data and historical trending…but for repetitive and complex tasks, scripting is the way to go! Lets us take the everyday task of creating an administrator. Using EM CLI in interactive mode the command could look like this.. emcli>create_user(name='jan.doe', type='EXTERNAL_USER') This command creates an administrator called jan.doe which is an externally authenticated user, possibly LDAP or SSO, defined by the EXTERNAL_USER tag. The create_user procedure takes many arguments; see the documentation for more information. Now, where EM CLI really shines and shows power is in creating multiple users. Regardless of the number, tens or thousands, the effort is the same. With the use of a standard programming construct, a loop, you can place your create_user() procedure within it. Using a loop allows you to iterate through a previously created list, creating new users until the list is complete. Using EM CLI in Script mode, your Jython loop would look something like this… for user in list_of_users:       create_user(name=user, expire=’true’, password=’welcome123’) This Jython code snippet iterates through a previously defined list of names, list_of_users, and iterates through the list, taking each name, user in this case, and creates an administrator sets the password to welcome123, but forces the user to reset it when they first login. This is only one of over four hundred procedures created to expose Oracle Enterprise Manager 12c functionality in a powerful and programmatic way. It is a few months since we released EM CLI with scripting option. We are seeing many users adapt to this fun and powerful way of using Oracle Enterprise Manager 12c. What are the first steps? Watch these screen watches, and dive in. The first screen watch steps you through where and how to download and install and how to run your first few commands. The Second screen watch steps you through a few scripts. Next time, I am going to show you the basic building blocks to writing a Jython script to perform Oracle Enterprise Manager 12c administrative tasks. Join this growing group of EM CLI users…. Dive in! Normal 0 false false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

  Read the article

• Breaking 1NF to model subset constraints. Does this sound sane?

  - by Chris Travers

  My first question here. Appologize if it is in the wrong forum but this seems pretty conceptual. I am looking at doing something that goes against conventional wisdom and want to get some feedback as to whether this is totally insane or will result in problems, so critique away! I am on PostgreSQL 9.1 but may be moving to 9.2 for this part of this project. To re-iterate: Does it seem sane to break 1NF in this way? I am not looking for debugging code so much as where people see problems that this might lead. The Problem In double entry accounting, financial transactions are journal entries with an arbitrary number of lines. Each line has either a left value (debit) or a right value (credit) which can be modelled as a single value with negatives as debits and positives as credits or vice versa. The sum of all debits and credits must equal zero (so if we go with a single amount field, sum(amount) must equal zero for each financial journal entry). SQL-based databases, pretty much required for this sort of work, have no way to express this sort of constraint natively and so any approach to enforcing it in the database seems rather complex. The Write Model The journal entries are append only. There is a possibility we will add a delete model but it will be subject to a different set of restrictions and so is not applicable here. If and when we allow deletes, we will probably do them using a simple ON DELETE CASCADE designation on the foreign key, and require that deletes go through a dedicated stored procedure which can enforce the other constraints. So inserts and selects have to be accommodated but updates and deletes do not for this task. My Proposed Solution My proposed solution is to break first normal form and model constraints on arrays of tuples, with a trigger that breaks the rows out into another table. CREATE TABLE journal_line ( entry_id bigserial primary key, account_id int not null references account(id), journal_entry_id bigint not null, -- adding references later amount numeric not null ); I would then add "table methods" to extract debits and credits for reporting purposes: CREATE OR REPLACE FUNCTION debits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount < 0 THEN $1.amount * -1 ELSE NULL END; $$; CREATE OR REPLACE FUNCTION credits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount > 0 THEN $1.amount ELSE NULL END; $$; Then the journal entry table (simplified for this example): CREATE TABLE journal_entry ( entry_id bigserial primary key, -- no natural keys :-( journal_id int not null references journal(id), date_posted date not null, reference text not null, description text not null, journal_lines journal_line[] not null ); Then a table method and and check constraints: CREATE OR REPLACE FUNCTION running_total(journal_entry) returns numeric language sql immutable as $$ SELECT sum(amount) FROM unnest($1.journal_lines); $$; ALTER TABLE journal_entry ADD CONSTRAINT CHECK (((journal_entry.running_total) = 0)); ALTER TABLE journal_line ADD FOREIGN KEY journal_entry_id REFERENCES journal_entry(entry_id); And finally we'd have a breakout trigger: CREATE OR REPLACE FUNCTION je_breakout() RETURNS TRIGGER LANGUAGE PLPGSQL AS $$ BEGIN IF TG_OP = 'INSERT' THEN INSERT INTO journal_line (journal_entry_id, account_id, amount) SELECT NEW.id, account_id, amount FROM unnest(NEW.journal_lines); RETURN NEW; ELSE RAISE EXCEPTION 'Operation Not Allowed'; END IF; END; $$; And finally CREATE TRIGGER AFTER INSERT OR UPDATE OR DELETE ON journal_entry FOR EACH ROW EXECUTE_PROCEDURE je_breaout(); Of course the example above is simplified. There will be a status table that will track approval status allowing for separation of duties, etc. However the goal here is to prevent unbalanced transactions. Any feedback? Does this sound entirely insane? Standard Solutions? In getting to this point I have to say I have looked at four different current ERP solutions to this problems: Represent every line item as a debit and a credit against different accounts. Use of foreign keys against the line item table to enforce an eventual running total of 0 Use of constraint triggers in PostgreSQL Forcing all validation here solely through the app logic. My concerns are that #1 is pretty limiting and very hard to audit internally. It's not programmer transparent and so it strikes me as being difficult to work with in the future. The second strikes me as being very complex and required a series of contraints and foreign keys against self to make work, and therefore it strikes me as complex, hard to sort out at least in my mind, and thus hard to work with. The fourth could be done as we force all access through stored procedures anyway and this is the most common solution (have the app total things up and throw an error otherwise). However, I think proof that a constraint is followed is superior to test cases, and so the question becomes whether this in fact generates insert anomilies rather than solving them. If this is a solved problem it isn't the case that everyone agrees on the solution....

  Read the article

• CPU Usage in Very Large Coherence Clusters

  - by jpurdy

  When sizing Coherence installations, one of the complicating factors is that these installations (by their very nature) tend to be application-specific, with some being large, memory-intensive caches, with others acting as I/O-intensive transaction-processing platforms, and still others performing CPU-intensive calculations across the data grid. Regardless of the primary resource requirements, Coherence sizing calculations are inherently empirical, in that there are so many permutations that a simple spreadsheet approach to sizing is rarely optimal (though it can provide a good starting estimate). So we typically recommend measuring actual resource usage (primarily CPU cycles, network bandwidth and memory) at a given load, and then extrapolating from those measurements. Of course there may be multiple types of load, and these may have varying degrees of correlation -- for example, an increased request rate may drive up the number of objects "pinned" in memory at any point, but the increase may be less than linear if those objects are naturally shared by concurrent requests. But for most reasonably-designed applications, a linear resource model will be reasonably accurate for most levels of scale. However, at extreme scale, sizing becomes a bit more complicated as certain cluster management operations -- while very infrequent -- become increasingly critical. This is because certain operations do not naturally tend to scale out. In a small cluster, sizing is primarily driven by the request rate, required cache size, or other application-driven metrics. In larger clusters (e.g. those with hundreds of cluster members), certain infrastructure tasks become intensive, in particular those related to members joining and leaving the cluster, such as introducing new cluster members to the rest of the cluster, or publishing the location of partitions during rebalancing. These tasks have a strong tendency to require all updates to be routed via a single member for the sake of cluster stability and data integrity. Fortunately that member is dynamically assigned in Coherence, so it is not a single point of failure, but it may still become a single point of bottleneck (until the cluster finishes its reconfiguration, at which point this member will have a similar load to the rest of the members). The most common cause of scaling issues in large clusters is disabling multicast (by configuring well-known addresses, aka WKA). This obviously impacts network usage, but it also has a large impact on CPU usage, primarily since the senior member must directly communicate certain messages with every other cluster member, and this communication requires significant CPU time. In particular, the need to notify the rest of the cluster about membership changes and corresponding partition reassignments adds stress to the senior member. Given that portions of the network stack may tend to be single-threaded (both in Coherence and the underlying OS), this may be even more problematic on servers with poor single-threaded performance. As a result of this, some extremely large clusters may be configured with a smaller number of partitions than ideal. This results in the size of each partition being increased. When a cache server fails, the other servers will use their fractional backups to recover the state of that server (and take over responsibility for their backed-up portion of that state). The finest granularity of this recovery is a single partition, and the single service thread can not accept new requests during this recovery. Ordinarily, recovery is practically instantaneous (it is roughly equivalent to the time required to iterate over a set of backup backing map entries and move them to the primary backing map in the same JVM). But certain factors can increase this duration drastically (to several seconds): large partitions, sufficiently slow single-threaded CPU performance, many or expensive indexes to rebuild, etc. The solution of course is to mitigate each of those factors but in many cases this may be challenging. Larger clusters also lead to the temptation to place more load on the available hardware resources, spreading CPU resources thin. As an example, while we've long been aware of how garbage collection can cause significant pauses, it usually isn't viewed as a major consumer of CPU (in terms of overall system throughput). Typically, the use of a concurrent collector allows greater responsiveness by minimizing pause times, at the cost of reducing system throughput. However, at a recent engagement, we were forced to turn off the concurrent collector and use a traditional parallel "stop the world" collector to reduce CPU usage to an acceptable level. In summary, there are some less obvious factors that may result in excessive CPU consumption in a larger cluster, so it is even more critical to test at full scale, even though allocating sufficient hardware may often be much more difficult for these large clusters.

  Read the article

• QR Code encoding and decoding using zxing

  - by helixed

  Okay, so I'm going to take the off chance that someone here has used zxing before. I'm developing a Java application, and one of the things it needs to do is encode a byte array of data into a QR Code and then decode it at a later time. Here's an example of what my encoder looks like: byte[] b = {0x48, 0x45, 0x4C, 0x4C, 0x4F}; //convert the byte array into a UTF-8 string String data; try { data = new String(b, "UTF8"); } catch (UnsupportedEncodingException e) { //the program shouldn't be able to get here return; } //get a byte matrix for the data ByteMatrix matrix; com.google.zxing.Writer writer = new QRCodeWriter(); try { matrix = writer.encode(data, com.google.zxing.BarcodeFormat.QR_CODE, width, height); } catch (com.google.zxing.WriterException e) { //exit the method return; } //generate an image from the byte matrix int width = matrix.getWidth(); int height = matrix.getHeight(); byte[][] array = matrix.getArray(); //create buffered image to draw to BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); //iterate through the matrix and draw the pixels to the image for (int y = 0; y < height; y++) { for (int x = 0; x < width; x++) { int grayValue = array[y][x] & 0xff; image.setRGB(x, y, (grayValue == 0 ? 0 : 0xFFFFFF)); } } //write the image to the output stream ImageIO.write(image, "png", outputStream); The beginning byte array in this code is just used to test it. The actual byte data will be varied. Here's what my decoder looks like: //get the data from the input stream BufferedImage image = ImageIO.read(inputStream); //convert the image to a binary bitmap source LuminanceSource source = new BufferedImageLuminanceSource(image); BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source)); //decode the barcode QRCodeReader reader = new QRCodeReader(); Result result; try { result = reader.decode(bitmap, hints); } catch (ReaderException e) { //the data is improperly formatted throw new MCCDatabaseMismatchException(); } byte[] b = result.getRawBytes(); System.out.println(ByteHelper.convertUnsignedBytesToHexString(result.getText().getBytes("UTF8"))); System.out.println(ByteHelper.convertUnsignedBytesToHexString(b)); convertUnsignedBytesToHexString(byte) is a method which converts an array of bytes in a string of hexadecimal characters. When I try to run these two blocks of code together, this is the output: 48454c4c4f 202b0b78cc00ec11ec11ec11ec11ec11ec11ec Clearly the text is being encoded, but the actual bytes of data are completely off. Any help would be appreciated here. Thanks, helixed

  Read the article

• How to convert a DataSet object into an ObjectContext (Entity Framework) object on the fly?

  - by Marcel

  Hi all, I have an existing SQL Server database, where I store data from large specific log files (often 100 MB and more), one per database. After some analysis, the database is deleted again. From the database, I have created both a Entity Framework Model and a DataSet Model via the Visual Studio designers. The DataSet is only for bulk importing data with SqlBulkCopy, after a quite complicated parsing process. All queries are then done using the Entity Framework Model, whose CreateQuery Method is exposed via an interface like this public IQueryable<TTarget> GetResults<TTarget>() where TTarget : EntityObject, new() { return this.Context.CreateQuery<TTarget>(typeof(TTarget).Name); } Now, sometimes my files are very small and in such a case I would like to omit the import into the database, but just have a an in-memory representation of the data, accessible as Entities. The idea is to create the DataSet, but instead of bulk importing, to directly transfer it into an ObjectContext which is accessible via the interface. Does this make sense? Now here's what I have done for this conversion so far: I traverse all tables in the DataSet, convert the single rows into entities of the corresponding type and add them to instantiated object of my typed Entity context class, like so MyEntities context = new MyEntities(); //create new in-memory context ///.... //get the item in the navigations table MyDataSet.NavigationResultRow dataRow = ds.NavigationResult.First(); //here, a foreach would be necessary in a true-world scenario NavigationResult entity = new NavigationResult { Direction = dataRow.Direction, ///... NavigationResultID = dataRow.NavigationResultID }; //convert to entities context.AddToNavigationResult(entity); //add to entities ///.... A very tedious work, as I would need to create a converter for each of my entity type and iterate over each table in the DataSet I have. Beware, if I ever change my database model.... Also, I have found out, that I can only instantiate MyEntities, if I provide a valid connection string to a SQL Server database. Since I do not want to actually write to my fully fledged database each time, this hinders my intentions. I intend to have only some in-memory proxy database. Can I do simpler? Is there some automated way of doing such a conversion, like generating an ObjectContext out of a DataSet object? P.S: I have seen a few questions about unit testing that seem somewhat related, but not quite exact.

  Read the article

• SunTlsRsaPremasterSecret KeyGenerator not available

  - by Jill

  Hi, I encountered an error when my application tries to load a RSA Algorithm provider class from JAVA. The exception stack is as follow: javax.jms.JMSException: RSA premaster secret error at org.apache.activemq.util.JMSExceptionSupport.create(JMSExceptionSupport.java:49) at org.apache.activemq.ActiveMQConnection.syncSendPacket(ActiveMQConnection.java:1255) at org.apache.activemq.ActiveMQConnection.ensureConnectionInfoSent(ActiveMQConnection.java:1350) at org.apache.activemq.ActiveMQConnection.setClientID(ActiveMQConnection.java:388) at com.trendmicro.tmsm.TMSMAgent.open(TMSMAgent.java:63) Caused by: javax.net.ssl.SSLKeyException: RSA premaster secret error at com.sun.net.ssl.internal.ssl.RSAClientKeyExchange.<init>(RSAClientKeyExchange.java:97) at com.sun.net.ssl.internal.ssl.ClientHandshaker.serverHelloDone(ClientHandshaker.java:634) at com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:226) at com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Handshaker.java:516) at com.sun.net.ssl.internal.ssl.Handshaker.process_record(Handshaker.java:454) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:884) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1112) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:623) at com.sun.net.ssl.internal.ssl.AppOutputStream.write(AppOutputStream.java:59) at org.apache.activemq.transport.tcp.TcpBufferedOutputStream.flush(TcpBufferedOutputStream.java:115) at java.io.DataOutputStream.flush(DataOutputStream.java:106) at org.apache.activemq.transport.tcp.TcpTransport.oneway(TcpTransport.java:167) at org.apache.activemq.transport.InactivityMonitor.oneway(InactivityMonitor.java:237) at org.apache.activemq.transport.WireFormatNegotiator.sendWireFormat(WireFormatNegotiator.java:168) at org.apache.activemq.transport.WireFormatNegotiator.sendWireFormat(WireFormatNegotiator.java:84) at org.apache.activemq.transport.WireFormatNegotiator.start(WireFormatNegotiator.java:74) at org.apache.activemq.transport.failover.FailoverTransport.doReconnect(FailoverTransport.java:715) at org.apache.activemq.transport.failover.FailoverTransport$2.iterate(FailoverTransport.java:115) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:122) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:43) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:637) Caused by: java.security.NoSuchAlgorithmException: SunTlsRsaPremasterSecret KeyGenerator not available at javax.crypto.KeyGenerator.<init>(DashoA13*..) at javax.crypto.KeyGenerator.getInstance(DashoA13*..) at com.sun.net.ssl.internal.ssl.JsseJce.getKeyGenerator(JsseJce.java:223) at com.sun.net.ssl.internal.ssl.RSAClientKeyExchange.<init>(RSAClientKeyExchange.java:89) ... 22 more I've googled the error message and most of posts says it's because JVM cannot find sunjce_provider.jar. However, I can find the file in /Library/Java/Home/lib/ext folder. The platform is Mac OS X 10.6 and Java version is 1.6.0_17. My questions are: Why JVM does not search /Library/Java/Home/lib/ext for jar files? Can we change CLASSPATH or java.ext.dirs property by modify any config file? Any suggestion to solve this problem? Thanks in advance.

  Read the article

• ASP.NET MVC 2: Updating a Linq-To-Sql Entity with an EntitySet

  - by Simon

  I have a Linq to Sql Entity which has an EntitySet. In my View I display the Entity with it's properties plus an editable list for the child entites. The user can dynamically add and delete those child entities. The DefaultModelBinder works fine so far, it correctly binds the child entites. Now my problem is that I just can't get Linq To Sql to delete the deleted child entities, it will happily add new ones but not delete the deleted ones. I have enabled cascade deleting in the foreign key relationship, and the Linq To Sql designer added the "DeleteOnNull=true" attribute to the foreign key relationships. If I manually delete a child entity like this: myObject.Childs.Remove(child); context.SubmitChanges(); This will delete the child record from the DB. But I can't get it to work for a model binded object. I tried the following: // this does nothing public ActionResult Update(int id, MyObject obj) // obj now has 4 child entities { var obj2 = _repository.GetObj(id); // obj2 has 6 child entities if(TryUpdateModel(obj2)) //it sucessfully updates obj2 and its childs { _repository.SubmitChanges(); // nothing happens, records stay in DB } else ..... return RedirectToAction("List"); } and this throws an InvalidOperationException, I have a german OS so I'm not exactly sure what the error message is in english, but it says something along the lines of that the entity needs a Version (Timestamp row?) or no update check policies. I have set UpdateCheck="Never" to every column except the primary key column. public ActionResult Update(MyObject obj) { _repository.MyObjectTable.Attach(obj, true); _repository.SubmitChanges(); // never gets here, exception at attach } I've read alot about similar "problems" with Linq To Sql, but it seems most of those "problems" are actually by design. So am I right in my assumption that this doesn't work like I expect it to work? Do I really have to manually iterate through the child entities and delete, update and insert them manually? For such a simple object this may work, but I plan to create more complex objects with nested EntitySets and so on. This is just a test to see what works and what not. So far I'm disappointed with Linq To Sql (maybe I just don't get it). Would be the Entity Framework or NHibernate a better choice for this scenario? Or would I run into the same problem?

  Read the article

• Unable to retrieve information form HP-UX pst_status object

  - by bogertron

  I am attempting to get process information by using the HP-UX C/C++ library. After scouring the internet, I have discovered that HP-UX has the pstat.h header file which allows programmers to retrieve the process information. After attempting to understand code from the internet hp website, I attempted to create a little test sample to comprehend what the code does. I attempted to use example 3, however, I ran into several issues. The first issue came when I attempted to execute the following line of code: (void)printf("pid is %d, command is %s\n", pst[i].pst_pid, pst[i].pst_ucomm); When I attempted to print the string, I hit a memory fault. So I decided to attempt to see what the string is and came up with the following: #include <sys/param.h> #include <sys/pstat.h> #include <sys/unistd.h> #include <string.h> int main(int argc, char** argv) { #define BURST ((size_t)10) struct pst_status pst[BURST]; int i, count; int idx = 0; /* index within the context */ int index = 0; /* loop until count == 0, will occur all have been returned */ while ((count=pstat_getproc(pst, sizeof(pst[0]),BURST,idx))>0) { index = 0; printf("index: %d", index); /* got count (max of BURST) this time. process them */ while (pst[i].pst_ucomm[index] != '\0') { printf("%c", pst[i].pst_ucomm[index]); index++; } printf("\n"); for (i = 0; i < count; i++) { printf("pid is %d, command is \n", pst[i].pst_pid); } /* * now go back and do it again, using the next index after * the current 'burst' */ idx = pst[count-1].pst_idx + 1; } if (count == -1) perror("pstat_getproc()"); #undef BURST } Unfortunately, what happens is that I get the first process printed, then pid is 2, command is pid is 2, command is pid is 2, command is... I know that I must be doing something foolish since my C/C++ skills are not that great, but I cannot figure out what the issue is since the code is largely copied from the hp website. So here's the question(s) for clarity: 1. Why can't printf("%s", pst[i].pst_ucomm); handle strings? 2. Why can't I iterate over the processes in the system? Any help is greatly appreciated.

  Read the article

• Asp.Net MVC - Rob Conery's LazyList - Count() or Count

  - by Adam

  I'm trying to create an html table for order logs for customers. A customer is defined as (I've left out a lot of stuff): public class Customer { public LazyList<Order> Orders { get; set; } } The LazyList is set when fetching a Customer: public Customer GetCustomer(int custID) { Customer c = ... c.Orders = new LazyList<Order>(_repository.GetOrders().ByOrderID(custID)); return c; } The order log model: public class OrderLogTableModel { public OrderLogTableModel(LazyList<Order> orders) { Orders = orders; Page = 0; PageSize = 25; } public LazyList<Order> Orders { get; set; } public int Page { get; set; } public int PageSize { get; set; } } and I pass in the customer.Orders after loading a customer. Now the log i'm trying to make, looks something like: <table> <tbody> <% int rowCount = ViewData.Model.Orders.Count(); int innerRows = rowCount - (ViewData.Model.Page * ViewData.Model.PageSize); foreach (Order order in ViewData.Model.Orders.OrderByDescending(x => x.StartDateTime) .Take(innerRows).OrderBy(x => x.StartDateTime) .Take(ViewData.Model.PageSize)) { %> <tr> <td> <%= order.ID %> </td> </tr> <% } %> </tbody> </table> Which works fine. But the problem is evaluating ViewData.Model.Orders.Count() literally takes about 10 minutes. I've tried with the ViewData.Model.Orders.Count property instead, and the results are the same - takes forever. I've also tried calling _repository.GetOrders().ByCustomerID(custID).Count() directly from the view and that executes perfectly within a few ms. Can anybody see any reason why using the LazyList to get a simple count would take so long? It seems like its trying to iterate through the list when getting a simple count.

  Read the article

• availability of Win32_MountPoint and Win32_Volume on Windows XP?

  - by SteveC

  From the MSDN articles I've found -- http://msdn.microsoft.com/en-us/library/aa394515(v=VS.85).aspx -- Win32_Volume and Win32_MountPoint aren't available on Windows XP. However, I'm developing a C# app on Windows XP (64bit), and I can get to those WMI classes just fine. Users of my app will be on Windows XP sp2 with .Net 3.5 sp1. Googling around, I can't determine whether I can count on this or not. Am I successful on my system because of one or more of the following: - windows xp service pack 2? - visual studio 2008 sp1 was installed? - .Net 3.5 sp1? Should I use something other than WMI to get at the volume/mountpoint info? Below is sample code that's working... public static Dictionary<string, NameValueCollection> GetAllVolumeDeviceIDs() { Dictionary<string, NameValueCollection> ret = new Dictionary<string, NameValueCollection>(); // retrieve information from Win32_Volume try { using (ManagementClass volClass = new ManagementClass("Win32_Volume")) { using (ManagementObjectCollection mocVols = volClass.GetInstances()) { // iterate over every volume foreach (ManagementObject moVol in mocVols) { // get the volume's device ID (will be key into our dictionary) string devId = moVol.GetPropertyValue("DeviceID").ToString(); ret.Add(devId, new NameValueCollection()); //Console.WriteLine("Vol: {0}", devId); // for each non-null property on the Volume, add it to our NameValueCollection foreach (PropertyData p in moVol.Properties) { if (p.Value == null) continue; ret[devId].Add(p.Name, p.Value.ToString()); //Console.WriteLine("\t{0}: {1}", p.Name, p.Value); } // find the mountpoints of this volume using (ManagementObjectCollection mocMPs = moVol.GetRelationships("Win32_MountPoint")) { foreach (ManagementObject moMP in mocMPs) { // only care about adding directory // Directory prop will be something like "Win32_Directory.Name=\"C:\\\\\"" string dir = moMP["Directory"].ToString(); // find opening/closing quotes in order to get the substring we want int first = dir.IndexOf('"') + 1; int last = dir.LastIndexOf('"'); string dirSubstr = dir.Substring(first , last - first); // use GetFullPath to normalize/unescape any extra backslashes string fullpath = Path.GetFullPath(dirSubstr); ret[devId].Add(MOUNTPOINT_DIRS_KEY, fullpath); } } } } } } catch (Exception ex) { Console.WriteLine("Problem retrieving Volume information from WMI. {0} - \n{1}",ex.Message,ex.StackTrace); return ret; } return ret; }

  Read the article

• Does .NET have a built in IEnumerable for multiple collections?

  - by Bryce Wagner

  I need an easy way to iterate over multiple collections without actually merging them, and I couldn't find anything built into .NET that looks like it does that. It feels like this should be a somewhat common situation. I don't want to reinvent the wheel. Is there anything built in that does something like this: public class MultiCollectionEnumerable<T> : IEnumerable<T> { private MultiCollectionEnumerator<T> enumerator; public MultiCollectionEnumerable(params IEnumerable<T>[] collections) { enumerator = new MultiCollectionEnumerator<T>(collections); } public IEnumerator<T> GetEnumerator() { enumerator.Reset(); return enumerator; } IEnumerator IEnumerable.GetEnumerator() { enumerator.Reset(); return enumerator; } private class MultiCollectionEnumerator<T> : IEnumerator<T> { private IEnumerable<T>[] collections; private int currentIndex; private IEnumerator<T> currentEnumerator; public MultiCollectionEnumerator(IEnumerable<T>[] collections) { this.collections = collections; this.currentIndex = -1; } public T Current { get { if (currentEnumerator != null) return currentEnumerator.Current; else return default(T); } } public void Dispose() { if (currentEnumerator != null) currentEnumerator.Dispose(); } object IEnumerator.Current { get { return Current; } } public bool MoveNext() { if (currentIndex >= collections.Length) return false; if (currentIndex < 0) { currentIndex = 0; if (collections.Length > 0) currentEnumerator = collections[0].GetEnumerator(); else return false; } while (!currentEnumerator.MoveNext()) { currentEnumerator.Dispose(); currentEnumerator = null; currentIndex++; if (currentIndex >= collections.Length) return false; currentEnumerator = collections[currentIndex].GetEnumerator(); } return true; } public void Reset() { if (currentEnumerator != null) { currentEnumerator.Dispose(); currentEnumerator = null; } this.currentIndex = -1; } } }

  Read the article

• VBA - Access 03 - Iterating through a list box, with an if statement to evaluate

  - by Justin

  So I have a one list box with values like DeptA, DeptB, DeptC & DeptD. I have a method that causes these to automatically populate in this list box if they are applicable. So in other words, if they populate in this list box, I want the resulting logic to say they are "Yes" in a boolean field in the table. So to accomplish this I am trying to use this example of iteration to cycle through the list box first of all, and it works great: dim i as integer dim myval as string For i = o to me.lstResults.listcount - 1 myVal = lstResults.itemdata(i) Next i if i debug.print myval, i get the list of data items that i want from the list box. so now i am trying to evaluate that list so that I can have an UPDATE SQL statement to update the table as i need it to be done. so, i know this is a mistake, but this is what i tried to do (giving it as an example so that you can see what i am trying to get to here) dim sql as string dim i as integer dim myval as string dim db as database sql = "UPDATE tblMain SET " for i = 0 to me.lstResults.listcount - 1 myval = lstResults.itemdata(i) If MyVal = "DeptA" Then sql = sql & "DeptA = Yes" ElseIF myval = "DeptB" Then sql = sql & "DeptB = Yes" ElseIf MyVal = "DeptC" Then sql = sql & "DeptC = Yes" ElseIf MyVal = "DeptD" Then sql = sql & "DeptD = Yes" End If Next i debug.print (sql) sql = sql & ";" set db= currentdb db.execute(sql) msgbox "Good Luck!" So you can see why this is going to cause problems because the listbox that these values (DeptA, DeptB, etc) automatically populate in are dynamic....there is rarely one value in the listbox, and the list of values changes per OrderID (what the form I am using this on populates information for in the first place; unique instance). I am looking for something that will evaluate this list one at a time (i.e. iterate through the list of values, and look for "DeptA", and if it is found add yes to the SQL string, and if it not add no to the SQL string, then march on to the next iteration). Even though the listbox populates values dynamically, they are set values, meaning i know what could end up in it. Thanks for any help, Justin

  Read the article

• Connecting to MSSQL 2008 from Java

  - by Xinus

  I am trying to connect to MSSQL 2008 server from Java here is a program import java.sql.*; public class connectURL { public static void main(String[] args) { // Create a variable for the connection string. String connectionUrl = "jdbc:sqlserver://localhost/SQLEXPRESS/Databases/HelloWorld:1433;";// + //"databaseName=HelloWorld;integratedSecurity=true;"; // Declare the JDBC objects. Connection con = null; Statement stmt = null; ResultSet rs = null; try { // Establish the connection. Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); con = DriverManager.getConnection(connectionUrl); // Create and execute an SQL statement that returns some data. String SQL = "SELECT TOP 10 * FROM Person.Contact"; stmt = con.createStatement(); rs = stmt.executeQuery(SQL); // Iterate through the data in the result set and display it. while (rs.next()) { System.out.println(rs.getString(4) + " " + rs.getString(6)); } } // Handle any errors that may have occurred. catch (Exception e) { e.printStackTrace(); } finally { if (rs != null) try { rs.close(); } catch(Exception e) {} if (stmt != null) try { stmt.close(); } catch(Exception e) {} if (con != null) try { con.close(); } catch(Exception e) {} } } } But it shows error as com.microsoft.sqlserver.jdbc.SQLServerException: The TCP/IP connection to the host localhost/SQLEXPRESS/Databases/HelloWorld, port 1433 has failed. Error: "null. Verify the connection properties, check that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port, and that no firewall is blocking TCP connections to the port.". at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:170) at com.microsoft.sqlserver.jdbc.SQLServerConnection.connectHelper(SQLServerConnection.java:1049) at com.microsoft.sqlserver.jdbc.SQLServerConnection.login(SQLServerConnection.java:833) at com.microsoft.sqlserver.jdbc.SQLServerConnection.connect(SQLServerConnection.java:716) at com.microsoft.sqlserver.jdbc.SQLServerDriver.connect(SQLServerDriver.java:841) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at connectURL.main(connectURL.java:43) I have given followed all the instructions as given in http://teamtutorials.com/database-tutorials/configuring-and-creating-a-database-in-ms-sql-2008 What can be the problem ?

  Read the article

• How to make ASP.Net MVC checkboxes keep state

  - by myotherme

  I have the following situation: I have a class Product that can have a confirmation from various Stations. So I have a ViewModel that holds the Product information, and a list of stations, and all the ProductStationConfirmations. public class ProductViewModel { public Product Product { get; private set; } public List<Station> Stations { get; private set; } public Dictionary<string, ProductStationConfirmation> ProductStationConfirmations { get; private set; } public ProductViewModel(int productID) { // Loads everything from DB } } In my partial view for inserting/editing I iterate over the stations to make a checkbox for each of them: <div class="editor-label"> <%= Html.LabelFor(model => model.Product.Title)%> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Product.Title)%> <%= Html.ValidationMessageFor(model => model.Product.Title)%> </div> <fieldset> <legend>Station Confirmations</legend> <% foreach (var station in Model.Stations) { %> <div class="nexttoeachother"> <div> <%= Html.Encode(station.Name) %> </div> <div> <%= Html.CheckBox("confirm_"+station.ID.ToString(), Request["confirm_"+station.ID.ToString()] == null ? Model.ProductStationConfirmations.ContainsKey(Entities.ProductStationConfirmation.MakeHash(Model.Product.ID, station.ID)) : Request["confirm_" + station.ID.ToString()].Contains("true") ) %> </div> </div> <% } %> </fieldset> This works and I can process the Request values to store the confirmed Stations, but it is really messy. I made it this way to preserve the state of the checkboxes between round trips if there is a problem with the model (missing title, bad value for decimal, or something that can only be checked server-side like duplicate tile). I would expect that there is a nicer way to do this, I just don't know what it is. I suspect that I need to change the shape of my ViewModel to better accommodate the data, but i don't know how. I am using MVC 2.

  Read the article

• Populate Multiple PDFs

  - by gmcalab

  I am using itextsharp to populate my PDFs. I have no issues with this. Basically what I am doing is getting the PDF and populating the fields in memory then passing back the MemoryStream to be displayed on a webpage. All this is working with a single document PDF. What I am trying to figure out now, is merging multiple PDFs into one MemoryStream. The part I cant figure out is, the documents I am populating are identical. So for example, I have a List<Person> that contains 5 persons. I want to fill out a PDF for each person and merge them all into one, in memory. Bare in mind I am going to fill out the same type of document for each person. The problem I am getting is that when I try to add a second copy of the same PDF to be filled out for the second iteration, it just overwrites the first populated PDF, since it's the same document, therefore not adding a second copy for the second Person at all. So basically if I had the 5 people, I would end up with a single page with the data of the 5th person, instead of a PDF with 5 like pages that contain the data of each person respectively. Here's some code... MemoryStream ms = ms = new MemoryStream(); PdfReader docReader = null; PdfStamper Stamper = null; List<Person> persons = new List<Person>() { new Person("Larry", "David"), new Person("Dustin", "Byfuglien"), new Person("Patrick", "Kane"), new Person("Johnathan", "Toews"), new Person("Marian", "Hossa") }; try { // Iterate thru all persons and populate a PDF for each foreach(var person in persons){ PdfCopyFields Copier = new PdfCopyFields(ms); Copier.AddDocument(GetReader("Person.pdf")); Copier.Close(); docReader = new PdfReader(ms.ToArray()); Stamper = new PdfStamper(docReader, ms); AcroFields Fields = Stamper.AcroFields; Fields.SetField("FirstName", person.FirstName); } }catch(Exception e){ // handle error }finally{ if (Stamper != null) { Stamper.Close(); } if (docReader != null) { docReader.Close(); } }

  Read the article

• ASP.NET MVC2: Can you get ModelMetadata.ContainerType from within a collection?

  - by CodeSponge

  I'm trying to call DisplayFor and DisplayForModel to iterate an IEnumerable< with various element types from within a view. I have Templates defined for each element/Model type. What I would like to do is check the ViewData.ModelMetadata.ContainerType from within the Template so that Template can determine if it was called as part of a collection. A simple example: Index1.aspx: To render a collection of Foos. <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<IEnumerable<Foo>>" %> <asp:Content ContentPlaceHolderID="MainPlaceHolder" runat="server"> <ul><%:Html.DisplayForModel()%></ul> </asp:Content> Index2.aspx: To render a Foo. <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Foo>" %> <asp:Content ContentPlaceHolderID="MainPlaceHolder" runat="server"> <%:Html.DisplayForModel()%> </asp:Content> Shared\DisplayTemplates\Foo.ascx: A context aware Template for Foo. <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<Foo>" %> <% var tag = typeof(IEnumerable).IsAssignableFrom(ViewData.ModelMetaData.ContainerType) ? "li" : "div"; %> <<%:tag%>><%:Model.Name%></<%:tag%>> The problem with this example is that ViewData.ModelMetaData.ContainerType is null in the Template when resolved though Index1.aspx. From what I've read on Brad Wilson post and others it has to do with the use of IEnumerable and its being an interface. Is there a way to insure that the ContainerType is set? Perhaps by creating a ModelMetadataProviders? I looked into that breifly but it appears the ContainerType value is determined before and then passed to the Provider. Any suggestions would be appreciated.

  Read the article

• Advice on displaying and allowing editing of data using ASP.NET MVC?

  - by Remnant

  I am embarking upon my first ASP.NET MVC project and I would like to get some input on possible ways to display database data and general best practice. In short, the body of my webpage will show data from my database in a table like format, with each table row showing similar data. For example: Name Age Position Date Joined Jon Smith 23 Striker 18th Mar 2005 John Doe 38 Defender 3rd Jan 1988 In terms of functionality, primarily I’d like to give the user the ability to edit the data and, after the edit, commit the edit to the database and refresh the view.The reason I want to refresh the view is because the data is date ordered and I will need to re-sort if the user edits a date field. My main question is what architecture / tools would be best suited to this fulfil my requirements at a high level? From the research I have done so far my initial conclusions were: ADO.NET for data retrieval. This is something I have used before and feel comfortable with. I like the look of LINQ to SQL but don’t want to make the learning curve any steeper for my first outing into MVC land just yet. Partial Views to create a template and then iterate through a datatable that I have pulled back from my database model. jQuery to allow the user to edit data in the table, error check edited data entries etc. Also, my intial view was that caching the data would not be a key requirement here. The only field a user will be able to update is the field and, if they do, I will need to commit that data to the database immediately and then refresh the view (as the data is date sorted). Any thoughts on this? Alternatively, I have seen some jQuery plug-ins that emulate a datagrid and provide associated functionality. My first thoughts are that I do not need all the functionality that comes with these plug-ins (e.g. zebra striping, ability to sort by column using sort glyph in column headers etc .) and I don’t really see any benefit to this over and above the solution I have outlined above. Again, is there reason to reconsider this view? Finally, when a user edits a date , I will need to refresh the view. In order to do this I had been reading about Html.RenderAction and this seemed like it may be a better option than using Partial Views as I can incorporate application logic into the action method. Am I right to consider Html.RenderAction or have I misunderstood its usage? Hope this post is clear and not too long. I did consider separate posts for each topic (e.g. Partial View vs. Html.RenderAction, when to use jQury datagrid plug-in) but it feels like these issues are so intertwined that they need to be dealt with in contect of each other. Thanks

  Read the article

• Rails + AMcharts (with export image php script) - PHP script converted to controller?

  - by Elliot

  Hey Guys, This one might be a little confusing. I'm using AMCharts with rails. Amcharts comes with a PHP script to export images called "export.php" I'm trying to figure out how to take the code in export.php and put it into a controller. Here is the code: <?php // amcharts.com export to image utility // set image type (gif/png/jpeg) $imgtype = 'jpeg'; // set image quality (from 0 to 100, not applicable to gif) $imgquality = 100; // get data from $_POST or $_GET ? $data = &$_POST; // get image dimensions $width = (int) $data['width']; $height = (int) $data['height']; // create image object $img = imagecreatetruecolor($width, $height); // populate image with pixels for ($y = 0; $y < $height; $y++) { // innitialize $x = 0; // get row data $row = explode(',', $data['r'.$y]); // place row pixels $cnt = sizeof($row); for ($r = 0; $r < $cnt; $r++) { // get pixel(s) data $pixel = explode(':', $row[$r]); // get color $pixel[0] = str_pad($pixel[0], 6, '0', STR_PAD_LEFT); $cr = hexdec(substr($pixel[0], 0, 2)); $cg = hexdec(substr($pixel[0], 2, 2)); $cb = hexdec(substr($pixel[0], 4, 2)); // allocate color $color = imagecolorallocate($img, $cr, $cg, $cb); // place repeating pixels $repeat = isset($pixel[1]) ? (int) $pixel[1] : 1; for ($c = 0; $c < $repeat; $c++) { // place pixel imagesetpixel($img, $x, $y, $color); // iterate column $x++; } } } // set proper content type header('Content-type: image/'.$imgtype); header('Content-Disposition: attachment; filename="chart.'.$imgtype.'"'); // stream image $function = 'image'.$imgtype; if ($imgtype == 'gif') { $function($img); } else { $function($img, null, $imgquality); } // destroy imagedestroy($img); ?>

  Read the article

• The most efficient method of drawing multiple quads in OpenGL

  - by CPatton

  I'm not very keen with OpenGL and I was wondering if someone could give me some insight on this. I'm a 'seasoned' programmer, I've read the redbook about VBOs and the like, but I was wondering from a more experienced person about the best/most efficient way of achieving this. I've been producing this 2d tile-based game engine to be used in several projects. I have a class called "ScreenObject" which is mainly composed of a Dictionary<Point, Tile> The Point key is to show where to render the Tile on the screen, and the Tile contains one or more textures to be drawn at that point. This ScreenObject is where the tiles will be modified, deleted, added, etc.. My original method of drawing the tiles in the testing I've done was to iterate through the ScreenObject and draw each quad at each location separately. From what I've read, this is a massive waste of resources. It wasn't horribly slow in the testing, but after I've completed the animation classes and effect classes, I'm sure it would be extremely slow. And one last thing, if you wouldn't mind.. As I said before, the Tile class can contain multiple textures to be drawn at the Point location on the screen. I recognize possibly two options for me here. Either add a quad at that location for each texture to be drawn, or, somehow.. use a multiple texture for the same quad (if it's possible). Even if each tile contained one texture only, that would be 64 quads to be drawn on the screen. Most of the tiles will contain 2-5 textures, so the number of total quads would increase dramatically with this method. Would it be feasible to add a quad for each new texture, or am I ignoring a better way to do this? Just need some help understanding this if you don't mind :) I've tried to be as concise as possible, and I'd greatly appreciate any responses.. and even some criticism. Programming is often a learning process and one who develops seems to never stops learning. Thanks for your time.

  Read the article

• How do I copy all referenced jars of an eclipse project using ant4eclipse?

  - by interstellar

  I've tried like this (link): <taskdef resource="net/sf/antcontrib/antlib.xml" /> <taskdef resource="net/sf/ant4eclipse/antlib.xml" /> <target name="copy_jars"> <getEclipseClasspath workspace="${basedir}/.." projectname="MyProject" property="classpath" relative="false" runtime="true" pathseparator="#" /> <!-- iterate over all classpath entries --> <foreach list="${classpath}" delimiter="#" target="copy_jar_file" param="classpath.entry" /> </target> <target name="copy_jar_file"> <!-- check if current is a .jar-file ... --> <if> <isfileselected file="${classpath.entry}"> <filename name="**/*.jar" /> </isfileselected> <then> <!-- copy the jar file to a destination directory --> <copy file="${classpath.entry}" tofile="${dest.dir}"/> </then> </if> </target> But I get the exception: [getEclipseClasspath] net.sf.ant4eclipse.model.FileParserException: Could not parse plugin project 'E:\...\MyProject' since it contains neither a Bundle-Manifest nor a plugin.xml! [getEclipseClasspath] at net.sf.ant4eclipse.model.pdesupport.plugin.PluginDescriptorParser.parseEclipseProject(Unknown Source) [getEclipseClasspath] at net.sf.ant4eclipse.model.pdesupport.plugin.PluginProjectRoleIdentifier.applyRole(Unknown Source) [getEclipseClasspath] at net.sf.ant4eclipse.model.roles.RoleIdentifierRegistry.applyRoles(Unknown Source) [getEclipseClasspath] at net.sf.ant4eclipse.tools.ProjectFactory.readProjectFromWorkspace(Unknown Source) [getEclipseClasspath] at net.sf.ant4eclipse.tools.resolver.AbstractClasspathResolver.resolveEclipseClasspathEntry(Unknown Source) [getEclipseClasspath] at net.sf.ant4eclipse.tools.resolver.AbstractClasspathResolver.resolveProjectClasspath(Unknown Source) [getEclipseClasspath] at net.sf.ant4eclipse.tools.resolver.ProjectClasspathResolver.resolveProjectClasspath(Unknown Source) [getEclipseClasspath] at net.sf.ant4eclipse.ant.task.project.GetEclipseClassPathTask.resolvePath(Unknown Source) [getEclipseClasspath] at net.sf.ant4eclipse.ant.task.project.AbstractGetProjectPathTask.execute(Unknown Source) [getEclipseClasspath] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288) [getEclipseClasspath] at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source) [getEclipseClasspath] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [getEclipseClasspath] at java.lang.reflect.Method.invoke(Method.java:597) [getEclipseClasspath] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:105) [getEclipseClasspath] at org.apache.tools.ant.Task.perform(Task.java:348) [getEclipseClasspath] at org.apache.tools.ant.Target.execute(Target.java:357) [getEclipseClasspath] at org.apache.tools.ant.Target.performTasks(Target.java:385) [getEclipseClasspath] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1329) [getEclipseClasspath] at org.apache.tools.ant.Project.executeTarget(Project.java:1298) [getEclipseClasspath] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41) [getEclipseClasspath] at org.eclipse.ant.internal.ui.antsupport.EclipseDefaultExecutor.executeTargets(EclipseDefaultExecutor.java:32) [getEclipseClasspath] at org.apache.tools.ant.Project.executeTargets(Project.java:1181) [getEclipseClasspath] at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.run(InternalAntRunner.java:423) [getEclipseClasspath] at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.main(InternalAntRunner.java:137) BUILD FAILED E:\...\build.xml:132: Exception whilst resolving the classpath of project MyProject! Reason: Could not parse plugin project 'E:\...\MyProject' since it contains neither a Bundle-Manifest nor a plugin.xml! I wan't to copy just the jars, not the referenced projects. Is there a way to parametrize the task getEclipseClasspath so it only gets the jars, not the projects?

  Read the article

• Tomcat JNDI Connection Pool docs - Random Connection Closed Exceptions

  - by Andy Faibishenko

  I found this in the Tomcat documentation here What I don't understand is why they close all the JDBC objects twice - once in the try{} block and once in the finally{} block. Why not just close them once in the finally{} clause? This is the relevant docs: Random Connection Closed Exceptions These can occur when one request gets a db connection from the connection pool and closes it twice. When using a connection pool, closing the connection just returns it to the pool for reuse by another request, it doesn't close the connection. And Tomcat uses multiple threads to handle concurrent requests. Here is an example of the sequence of events which could cause this error in Tomcat: Request 1 running in Thread 1 gets a db connection. Request 1 closes the db connection. The JVM switches the running thread to Thread 2 Request 2 running in Thread 2 gets a db connection (the same db connection just closed by Request 1). The JVM switches the running thread back to Thread 1 Request 1 closes the db connection a second time in a finally block. The JVM switches the running thread back to Thread 2 Request 2 Thread 2 tries to use the db connection but fails because Request 1 closed it. Here is an example of properly written code to use a db connection obtained from a connection pool: Connection conn = null; Statement stmt = null; // Or PreparedStatement if needed ResultSet rs = null; try { conn = ... get connection from connection pool ... stmt = conn.createStatement("select ..."); rs = stmt.executeQuery(); ... iterate through the result set ... rs.close(); rs = null; stmt.close(); stmt = null; conn.close(); // Return to connection pool conn = null; // Make sure we don't close it twice } catch (SQLException e) { ... deal with errors ... } finally { // Always make sure result sets and statements are closed, // and the connection is returned to the pool if (rs != null) { try { rs.close(); } catch (SQLException e) { ; } rs = null; } if (stmt != null) { try { stmt.close(); } catch (SQLException e) { ; } stmt = null; } if (conn != null) { try { conn.close(); } catch (SQLException e) { ; } conn = null; } }

  Read the article

• XPathNavigator in Silverlight

  - by vladimir

  I have a code library that makes heavy use of XPathNavigator to parse some specific xml document. The xml document is cross-referenced, meaning that an element can reference another which has not yet been encountered during parsing: <ElementA ...> <DependentElementX id="1234"> </ElementA> <ElementX id="1234" .../> The document doesn't really look like this, but the point is that 1) there is an xml schema that enforces the overall document structure, 2) elements inside the document can reference each other using some IDs, and 3) there is quite a few such cross references between different elements in the document. The document is parsed in two phases. In the first pass I walk through the document XPathDocument doc = ...; XPathNavigator nav = doc.CreateNavigator(); nav.MoveToRoot(); nav.MoveToFirstChild()... and occasionally 'bookmark' the current position (element) in the document using XPathNavigator.Clone() method. This gives me a lightweight instance of an XPathNavigator which I can store somewhere and use later to jump back to a particular place (element) in my document. Once I have enough information collected in the first pass (for example, I have made sure there is indeed an ElementX with an id='1234'), I jump back to saved bookmarks (using those saved XPathNavigators) and complete the parsing. Well, now I'm about to use this library in Silverlight 3.0 and to my horror the XPathNavigator is not in the System.Xml assembly. Questions: 1) Am I missing something obvious (i.e. XPathNavigator does exist in some shape or form, for example in a toolkit or a freeware library)? 2) If I do have to make modifications in the code, what would be the best way to go? Ideally, I would like to make minimal changes, not to rewrite 80% of the code just to be able to use something like XLinq. To resume, in case I have to give up XPathNavigator, all I need is a way to bookmark places in my document and to get back to them so that I can continue to iterate from where I left off. Thanks in advance for any help/ideas.

  Read the article

< Previous Page | 48 49 50 51 52 53 54 55 56 57 58 59  | Next Page >