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• What does /dev/null mean in a shell script?

  - by rishiag

  I've started learning bash scripting by using this guide: http://www.tldp.org/LDP/abs/abs-guide.pdf However I got stuck at the first script: cd /var/log cat /dev/null > messages cat /dev/null > wtmp echo "Log files cleaned up." What do lines 2 and 3 do in Ubuntu (I understand cat)? Is it only for other Linux distributions? After running this script as root, the output I get is Log files cleaned up. But /var/log still contains all the files.

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• Why does Linq to Entity Sum return null when the list is empty?

  - by Hannele

  There are quite a few questions on Stack Overflow about the Linq to Entity / Linq to SQL Sum extension method, about how it returns null when the result set is empty: 1, 2, 3, 4, 5, 6, 7, and many more, as well as a blog post discussing the issue here. Now, I could go a flag these as duplicates, but I feel it is still an inconsistency in the Linq implementation. I am assuming at this point that it is not a bug, but is more or less working as designed. I understand that there are workarounds (for example, casting the field to a nullable type, so you can coalesce with ??), and I also understand that for the underlying SQL, a NULL result is expected for an empty list. But because the result of the Sum extension for nullable types is also not nullable, why would the Linq to SQL / Linq to Entity Sum have been designed to behave this way?

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• Why does Linq to Entity Sum return null when the result set is empty?

  - by Hannele

  There are quite a few questions on Stack Overflow about the Linq to Entity / Linq to SQL Sum extension method, about how it returns null when the result set is empty: 1, 2, 3, 4, 5, 6, 7, and many more, as well as a blog post discussing the issue here. I feel it is an inconsistency in the Linq implementation. I am assuming at this point that it is not a bug, but is more or less working as designed. I understand that there are workarounds (for example, casting the field to a nullable type, so you can coalesce with ??), and I also understand that for the underlying SQL, a NULL result is expected for an empty result set. But because the result of the Sum extension for non-nullable types is also non-nullable, why does the Linq to SQL / Linq to Entity Sum behave this way?

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• How to make MySQL utilize available system resources, or find "the real problem"?

  - by anonymous coward

  This is a MySQL 5.0.26 server, running on SuSE Enterprise 10. This may be a Serverfault question. The web user interface that uses these particular queries (below) is showing sometimes 30+, even up to 120+ seconds at the worst, to generate the pages involved. On development, when the queries are run alone, they take up to 20 seconds on the first run (with no query cache enabled) but anywhere from 2 to 7 seconds after that - I assume because the tables and indexes involved have been placed into ram. From what I can tell, the longest load times are caused by Read/Update Locking. These are MyISAM tables. So it looks like a long update comes in, followed by a couple 7 second queries, and they're just adding up. And I'm fine with that explanation. What I'm not fine with is that MySQL doesn't appear to be utilizing the hardware it's on, and while the bottleneck seems to be the database, I can't understand why. I would say "throw more hardware at it", but we did and it doesn't appear to have changed the situation. Viewing a 'top' during the slowest times never shows much cpu or memory utilization by mysqld, as if the server is having no trouble at all - but then, why are the queries taking so long? How can I make MySQL use the crap out of this hardware, or find out what I'm doing wrong? Extra Details: On the "Memory Health" tab in the MySQL Administrator (for Windows), the Key Buffer is less than 1/8th used - so all the indexes should be in RAM. I can provide a screen shot of any graphs that might help. So desperate to fix this issue. Suffice it to say, there is legacy code "generating" these queries, and they're pretty much stuck the way they are. I have tried every combination of Indexes on the tables involved, but any suggestions are welcome. Here's the current Create Table statement from development (the 'experimental' key I have added, seems to help a little, for the example query only): CREATE TABLE `registration_task` ( `id` varchar(36) NOT NULL default '', `date_entered` datetime NOT NULL default '0000-00-00 00:00:00', `date_modified` datetime NOT NULL default '0000-00-00 00:00:00', `assigned_user_id` varchar(36) default NULL, `modified_user_id` varchar(36) default NULL, `created_by` varchar(36) default NULL, `name` varchar(80) NOT NULL default '', `status` varchar(255) default NULL, `date_due` date default NULL, `time_due` time default NULL, `date_start` date default NULL, `time_start` time default NULL, `parent_id` varchar(36) NOT NULL default '', `priority` varchar(255) NOT NULL default '9', `description` text, `order_number` int(11) default '1', `task_number` int(11) default NULL, `depends_on_id` varchar(36) default NULL, `milestone_flag` varchar(255) default NULL, `estimated_effort` int(11) default NULL, `actual_effort` int(11) default NULL, `utilization` int(11) default '100', `percent_complete` int(11) default '0', `deleted` tinyint(1) NOT NULL default '0', `wf_task_id` varchar(36) default '0', `reg_field` varchar(8) default '', `date_offset` int(11) default '0', `date_source` varchar(10) default '', `date_completed` date default '0000-00-00', `completed_id` varchar(36) default NULL, `original_name` varchar(80) default NULL, PRIMARY KEY (`id`), KEY `idx_reg_task_p` (`deleted`,`parent_id`), KEY `By_Assignee` (`assigned_user_id`,`deleted`), KEY `status_assignee` (`status`,`deleted`), KEY `experimental` (`deleted`,`status`,`assigned_user_id`,`parent_id`,`date_due`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 And one of the ridiculous queries in question: SELECT users.user_name assigned_user_name, registration.FIELD001 parent_name, registration_task.status status, registration_task.date_modified date_modified, registration_task.date_due date_due, registration.FIELD240 assigned_wf, if(LENGTH(registration_task.description)>0,1,0) has_description, registration_task.* FROM registration_task LEFT JOIN users ON registration_task.assigned_user_id=users.id LEFT JOIN registration ON registration_task.parent_id=registration.id where (registration_task.status != 'Completed' AND registration.FIELD001 LIKE '%' AND registration_task.name LIKE '%' AND registration.FIELD060 LIKE 'GN001472%') AND registration_task.deleted=0 ORDER BY date_due asc LIMIT 0,20; my.cnf - '[mysqld]' section. [mysqld] port = 3306 socket = /var/lib/mysql/mysql.sock skip-locking key_buffer = 384M max_allowed_packet = 100M table_cache = 2048 sort_buffer_size = 2M net_buffer_length = 100M read_buffer_size = 2M read_rnd_buffer_size = 160M myisam_sort_buffer_size = 128M query_cache_size = 16M query_cache_limit = 1M EXPLAIN above query, without additional index: +----+-------------+-------------------+--------+--------------------------------+----------------+---------+------------------------------------------------+---------+-----------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------------+--------+--------------------------------+----------------+---------+------------------------------------------------+---------+-----------------------------+ | 1 | SIMPLE | registration_task | ref | idx_reg_task_p,status_assignee | idx_reg_task_p | 1 | const | 1067354 | Using where; Using filesort | | 1 | SIMPLE | registration | eq_ref | PRIMARY,gbl | PRIMARY | 8 | sugarcrm401.registration_task.parent_id | 1 | Using where | | 1 | SIMPLE | users | ref | PRIMARY | PRIMARY | 38 | sugarcrm401.registration_task.assigned_user_id | 1 | | +----+-------------+-------------------+--------+--------------------------------+----------------+---------+------------------------------------------------+---------+-----------------------------+ EXPLAIN above query, with 'experimental' index: +----+-------------+-------------------+--------+-----------------------------------------------------------+------------------+---------+------------------------------------------------+--------+-----------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------------+--------+-----------------------------------------------------------+------------------+---------+------------------------------------------------+--------+-----------------------------+ | 1 | SIMPLE | registration_task | range | idx_reg_task_p,status_assignee,NewIndex1,tcg_experimental | tcg_experimental | 259 | NULL | 103345 | Using where; Using filesort | | 1 | SIMPLE | registration | eq_ref | PRIMARY,gbl | PRIMARY | 8 | sugarcrm401.registration_task.parent_id | 1 | Using where | | 1 | SIMPLE | users | ref | PRIMARY | PRIMARY | 38 | sugarcrm401.registration_task.assigned_user_id | 1 | | +----+-------------+-------------------+--------+-----------------------------------------------------------+------------------+---------+------------------------------------------------+--------+-----------------------------+

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• How are delegates in C# better than function pointers in C/C++?

  - by pecker

  The delegates in C# offer similar functionality as function pointers in C. I heard someone saying "C# delegates are actually better than function pointers in C". How come? Please explain with an example.

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• Search SQL Question Between Related Two Tables

  - by mTuran

  Hi, I am writing some kind of search engine for my web application and i have a problem. I have 2 tables first of is projects table: PROJECTS TABLE id int(11) NO PRI NULL auto_increment employer_id int(11) NO MUL NULL project_title varchar(100) NO MUL NULL project_description text NO NULL project_budget int(11) NO NULL project_allowedtime int(11) NO NULL project_deadline datetime NO NULL total_bids int(11) NO NULL average_bid int(11) NO NULL created datetime NO MUL NULL active tinyint(1) NO MUL NULL PROJECTS_SKILLS TABLE project_id int(11) NO MUL NULL skill_id int(11) NO MUL NULL For example: I want ask this query to database: 1-) Skills are 5 and 7. 2-) Order results by created 3-) project title contains "php" word. 4-) Returned rows should contain projects.* columuns. 5-) Projects should be distinct(i don't want same projects in return of query). Please write sql query that ensure these conditions. Thank You.

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• T-SQL to PL/SQL (IDENTITY)

  - by folone

  I've got a T-SQL script, that converts field to IDENTITY (in a weird way). How do I convert it to PL/SQL? (and, probably, figure out, if there is a simpler way to do this - without creating a temporary table). The T-SQL script: -- alter table ts_changes add TS_THREADID VARCHAR(100) NULL; -- Change Field TS_ID TS_NOTIFICATIONEVENTS to IDENTITY BEGIN TRANSACTION GO CREATE TABLE dbo.Tmp_TS_NOTIFICATIONEVENTS ( TS_ID int NOT NULL IDENTITY (1, 1), TS_TABLEID int NOT NULL, TS_CASEID int NULL, TS_WORKFLOWID int NULL, TS_NOTIFICATIONID int NULL, TS_PRIORITY int NULL, TS_STARTDATE int NULL, TS_TIME int NULL, TS_WAITSTATUS int NULL, TS_RECIPIENTID int NULL, TS_LASTCHANGEDATE int NULL, TS_ELAPSEDCYCLES int NULL ) ON [PRIMARY] SET IDENTITY_INSERT dbo.Tmp_TS_NOTIFICATIONEVENTS ON GO IF EXISTS(SELECT * FROM dbo.TS_NOTIFICATIONEVENTS) EXEC('INSERT INTO dbo.Tmp_TS_NOTIFICATIONEVENTS (TS_ID, TS_TABLEID, TS_CASEID, TS_WORKFLOWID, TS_NOTIFICATIONID, TS_PRIORITY, TS_STARTDATE, TS_TIME, TS_WAITSTATUS, TS_RECIPIENTID, TS_LASTCHANGEDATE, TS_ELAPSEDCYCLES) SELECT TS_ID, TS_TABLEID, TS_CASEID, TS_WORKFLOWID, TS_NOTIFICATIONID, TS_PRIORITY, TS_STARTDATE, TS_TIME, TS_WAITSTATUS, TS_RECIPIENTID, TS_LASTCHANGEDATE, TS_ELAPSEDCYCLES FROM dbo.TS_NOTIFICATIONEVENTS WITH (HOLDLOCK TABLOCKX)') GO SET IDENTITY_INSERT dbo.Tmp_TS_NOTIFICATIONEVENTS OFF GO DROP TABLE dbo.TS_NOTIFICATIONEVENTS GO EXECUTE sp_rename N'dbo.Tmp_TS_NOTIFICATIONEVENTS', N'TS_NOTIFICATIONEVENTS', 'OBJECT' GO ALTER TABLE dbo.TS_NOTIFICATIONEVENTS ADD CONSTRAINT aaaaaTS_NOTIFICATIONEVENTS_PK PRIMARY KEY NONCLUSTERED ( TS_ID ) WITH( STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO COMMIT

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• Creating a dynamic, extensible C# Expando Object

  - by Rick Strahl

  I love dynamic functionality in a strongly typed language because it offers us the best of both worlds. In C# (or any of the main .NET languages) we now have the dynamic type that provides a host of dynamic features for the static C# language. One place where I've found dynamic to be incredibly useful is in building extensible types or types that expose traditionally non-object data (like dictionaries) in easier to use and more readable syntax. I wrote about a couple of these for accessing old school ADO.NET DataRows and DataReaders more easily for example. These classes are dynamic wrappers that provide easier syntax and auto-type conversions which greatly simplifies code clutter and increases clarity in existing code. ExpandoObject in .NET 4.0 Another great use case for dynamic objects is the ability to create extensible objects - objects that start out with a set of static members and then can add additional properties and even methods dynamically. The .NET 4.0 framework actually includes an ExpandoObject class which provides a very dynamic object that allows you to add properties and methods on the fly and then access them again. For example with ExpandoObject you can do stuff like this:dynamic expand = new ExpandoObject(); expand.Name = "Rick"; expand.HelloWorld = (Func<string, string>) ((string name) => { return "Hello " + name; }); Console.WriteLine(expand.Name); Console.WriteLine(expand.HelloWorld("Dufus")); Internally ExpandoObject uses a Dictionary like structure and interface to store properties and methods and then allows you to add and access properties and methods easily. As cool as ExpandoObject is it has a few shortcomings too: It's a sealed type so you can't use it as a base class It only works off 'properties' in the internal Dictionary - you can't expose existing type data It doesn't serialize to XML or with DataContractSerializer/DataContractJsonSerializer Expando - A truly extensible Object ExpandoObject is nice if you just need a dynamic container for a dictionary like structure. However, if you want to build an extensible object that starts out with a set of strongly typed properties and then allows you to extend it, ExpandoObject does not work because it's a sealed class that can't be inherited. I started thinking about this very scenario for one of my applications I'm building for a customer. In this system we are connecting to various different user stores. Each user store has the same basic requirements for username, password, name etc. But then each store also has a number of extended properties that is available to each application. In the real world scenario the data is loaded from the database in a data reader and the known properties are assigned from the known fields in the database. All unknown fields are then 'added' to the expando object dynamically. In the past I've done this very thing with a separate property - Properties - just like I do for this class. But the property and dictionary syntax is not ideal and tedious to work with. I started thinking about how to represent these extra property structures. One way certainly would be to add a Dictionary, or an ExpandoObject to hold all those extra properties. But wouldn't it be nice if the application could actually extend an existing object that looks something like this as you can with the Expando object:public class User : Westwind.Utilities.Dynamic.Expando { public string Email { get; set; } public string Password { get; set; } public string Name { get; set; } public bool Active { get; set; } public DateTime? ExpiresOn { get; set; } } and then simply start extending the properties of this object dynamically? Using the Expando object I describe later you can now do the following:[TestMethod] public void UserExampleTest() { var user = new User(); // Set strongly typed properties user.Email = "[email protected]"; user.Password = "nonya123"; user.Name = "Rickochet"; user.Active = true; // Now add dynamic properties dynamic duser = user; duser.Entered = DateTime.Now; duser.Accesses = 1; // you can also add dynamic props via indexer user["NickName"] = "AntiSocialX"; duser["WebSite"] = "http://www.west-wind.com/weblog"; // Access strong type through dynamic ref Assert.AreEqual(user.Name,duser.Name); // Access strong type through indexer Assert.AreEqual(user.Password,user["Password"]); // access dyanmically added value through indexer Assert.AreEqual(duser.Entered,user["Entered"]); // access index added value through dynamic Assert.AreEqual(user["NickName"],duser.NickName); // loop through all properties dynamic AND strong type properties (true) foreach (var prop in user.GetProperties(true)) { object val = prop.Value; if (val == null) val = "null"; Console.WriteLine(prop.Key + ": " + val.ToString()); } } As you can see this code somewhat blurs the line between a static and dynamic type. You start with a strongly typed object that has a fixed set of properties. You can then cast the object to dynamic (as I discussed in my last post) and add additional properties to the object. You can also use an indexer to add dynamic properties to the object. To access the strongly typed properties you can use either the strongly typed instance, the indexer or the dynamic cast of the object. Personally I think it's kinda cool to have an easy way to access strongly typed properties by string which can make some data scenarios much easier. To access the 'dynamically added' properties you can use either the indexer on the strongly typed object, or property syntax on the dynamic cast. Using the dynamic type allows all three modes to work on both strongly typed and dynamic properties. Finally you can iterate over all properties, both dynamic and strongly typed if you chose. Lots of flexibility. Note also that by default the Expando object works against the (this) instance meaning it extends the current object. You can also pass in a separate instance to the constructor in which case that object will be used to iterate over to find properties rather than this. Using this approach provides some really interesting functionality when use the dynamic type. To use this we have to add an explicit constructor to the Expando subclass:public class User : Westwind.Utilities.Dynamic.Expando { public string Email { get; set; } public string Password { get; set; } public string Name { get; set; } public bool Active { get; set; } public DateTime? ExpiresOn { get; set; } public User() : base() { } // only required if you want to mix in seperate instance public User(object instance) : base(instance) { } } to allow the instance to be passed. When you do you can now do:[TestMethod] public void ExpandoMixinTest() { // have Expando work on Addresses var user = new User( new Address() ); // cast to dynamicAccessToPropertyTest dynamic duser = user; // Set strongly typed properties duser.Email = "[email protected]"; user.Password = "nonya123"; // Set properties on address object duser.Address = "32 Kaiea"; //duser.Phone = "808-123-2131"; // set dynamic properties duser.NonExistantProperty = "This works too"; // shows default value Address.Phone value Console.WriteLine(duser.Phone); } Using the dynamic cast in this case allows you to access *three* different 'objects': The strong type properties, the dynamically added properties in the dictionary and the properties of the instance passed in! Effectively this gives you a way to simulate multiple inheritance (which is scary - so be very careful with this, but you can do it). How Expando works Behind the scenes Expando is a DynamicObject subclass as I discussed in my last post. By implementing a few of DynamicObject's methods you can basically create a type that can trap 'property missing' and 'method missing' operations. When you access a non-existant property a known method is fired that our code can intercept and provide a value for. Internally Expando uses a custom dictionary implementation to hold the dynamic properties you might add to your expandable object. Let's look at code first. The code for the Expando type is straight forward and given what it provides relatively short. Here it is.using System; using System.Collections.Generic; using System.Linq; using System.Dynamic; using System.Reflection; namespace Westwind.Utilities.Dynamic { /// <summary> /// Class that provides extensible properties and methods. This /// dynamic object stores 'extra' properties in a dictionary or /// checks the actual properties of the instance. /// /// This means you can subclass this expando and retrieve either /// native properties or properties from values in the dictionary. /// /// This type allows you three ways to access its properties: /// /// Directly: any explicitly declared properties are accessible /// Dynamic: dynamic cast allows access to dictionary and native properties/methods /// Dictionary: Any of the extended properties are accessible via IDictionary interface /// </summary> [Serializable] public class Expando : DynamicObject, IDynamicMetaObjectProvider { /// <summary> /// Instance of object passed in /// </summary> object Instance; /// <summary> /// Cached type of the instance /// </summary> Type InstanceType; PropertyInfo[] InstancePropertyInfo { get { if (_InstancePropertyInfo == null && Instance != null) _InstancePropertyInfo = Instance.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.DeclaredOnly); return _InstancePropertyInfo; } } PropertyInfo[] _InstancePropertyInfo; /// <summary> /// String Dictionary that contains the extra dynamic values /// stored on this object/instance /// </summary> /// <remarks>Using PropertyBag to support XML Serialization of the dictionary</remarks> public PropertyBag Properties = new PropertyBag(); //public Dictionary<string,object> Properties = new Dictionary<string, object>(); /// <summary> /// This constructor just works off the internal dictionary and any /// public properties of this object. /// /// Note you can subclass Expando. /// </summary> public Expando() { Initialize(this); } /// <summary> /// Allows passing in an existing instance variable to 'extend'. /// </summary> /// <remarks> /// You can pass in null here if you don't want to /// check native properties and only check the Dictionary! /// </remarks> /// <param name="instance"></param> public Expando(object instance) { Initialize(instance); } protected virtual void Initialize(object instance) { Instance = instance; if (instance != null) InstanceType = instance.GetType(); } /// <summary> /// Try to retrieve a member by name first from instance properties /// followed by the collection entries. /// </summary> /// <param name="binder"></param> /// <param name="result"></param> /// <returns></returns> public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; // first check the Properties collection for member if (Properties.Keys.Contains(binder.Name)) { result = Properties[binder.Name]; return true; } // Next check for Public properties via Reflection if (Instance != null) { try { return GetProperty(Instance, binder.Name, out result); } catch { } } // failed to retrieve a property result = null; return false; } /// <summary> /// Property setter implementation tries to retrieve value from instance /// first then into this object /// </summary> /// <param name="binder"></param> /// <param name="value"></param> /// <returns></returns> public override bool TrySetMember(SetMemberBinder binder, object value) { // first check to see if there's a native property to set if (Instance != null) { try { bool result = SetProperty(Instance, binder.Name, value); if (result) return true; } catch { } } // no match - set or add to dictionary Properties[binder.Name] = value; return true; } /// <summary> /// Dynamic invocation method. Currently allows only for Reflection based /// operation (no ability to add methods dynamically). /// </summary> /// <param name="binder"></param> /// <param name="args"></param> /// <param name="result"></param> /// <returns></returns> public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { if (Instance != null) { try { // check instance passed in for methods to invoke if (InvokeMethod(Instance, binder.Name, args, out result)) return true; } catch { } } result = null; return false; } /// <summary> /// Reflection Helper method to retrieve a property /// </summary> /// <param name="instance"></param> /// <param name="name"></param> /// <param name="result"></param> /// <returns></returns> protected bool GetProperty(object instance, string name, out object result) { if (instance == null) instance = this; var miArray = InstanceType.GetMember(name, BindingFlags.Public | BindingFlags.GetProperty | BindingFlags.Instance); if (miArray != null && miArray.Length > 0) { var mi = miArray[0]; if (mi.MemberType == MemberTypes.Property) { result = ((PropertyInfo)mi).GetValue(instance,null); return true; } } result = null; return false; } /// <summary> /// Reflection helper method to set a property value /// </summary> /// <param name="instance"></param> /// <param name="name"></param> /// <param name="value"></param> /// <returns></returns> protected bool SetProperty(object instance, string name, object value) { if (instance == null) instance = this; var miArray = InstanceType.GetMember(name, BindingFlags.Public | BindingFlags.SetProperty | BindingFlags.Instance); if (miArray != null && miArray.Length > 0) { var mi = miArray[0]; if (mi.MemberType == MemberTypes.Property) { ((PropertyInfo)mi).SetValue(Instance, value, null); return true; } } return false; } /// <summary> /// Reflection helper method to invoke a method /// </summary> /// <param name="instance"></param> /// <param name="name"></param> /// <param name="args"></param> /// <param name="result"></param> /// <returns></returns> protected bool InvokeMethod(object instance, string name, object[] args, out object result) { if (instance == null) instance = this; // Look at the instanceType var miArray = InstanceType.GetMember(name, BindingFlags.InvokeMethod | BindingFlags.Public | BindingFlags.Instance); if (miArray != null && miArray.Length > 0) { var mi = miArray[0] as MethodInfo; result = mi.Invoke(Instance, args); return true; } result = null; return false; } /// <summary> /// Convenience method that provides a string Indexer /// to the Properties collection AND the strongly typed /// properties of the object by name. /// /// // dynamic /// exp["Address"] = "112 nowhere lane"; /// // strong /// var name = exp["StronglyTypedProperty"] as string; /// </summary> /// <remarks> /// The getter checks the Properties dictionary first /// then looks in PropertyInfo for properties. /// The setter checks the instance properties before /// checking the Properties dictionary. /// </remarks> /// <param name="key"></param> /// /// <returns></returns> public object this[string key] { get { try { // try to get from properties collection first return Properties[key]; } catch (KeyNotFoundException ex) { // try reflection on instanceType object result = null; if (GetProperty(Instance, key, out result)) return result; // nope doesn't exist throw; } } set { if (Properties.ContainsKey(key)) { Properties[key] = value; return; } // check instance for existance of type first var miArray = InstanceType.GetMember(key, BindingFlags.Public | BindingFlags.GetProperty); if (miArray != null && miArray.Length > 0) SetProperty(Instance, key, value); else Properties[key] = value; } } /// <summary> /// Returns and the properties of /// </summary> /// <param name="includeProperties"></param> /// <returns></returns> public IEnumerable<KeyValuePair<string,object>> GetProperties(bool includeInstanceProperties = false) { if (includeInstanceProperties && Instance != null) { foreach (var prop in this.InstancePropertyInfo) yield return new KeyValuePair<string, object>(prop.Name, prop.GetValue(Instance, null)); } foreach (var key in this.Properties.Keys) yield return new KeyValuePair<string, object>(key, this.Properties[key]); } /// <summary> /// Checks whether a property exists in the Property collection /// or as a property on the instance /// </summary> /// <param name="item"></param> /// <returns></returns> public bool Contains(KeyValuePair<string, object> item, bool includeInstanceProperties = false) { bool res = Properties.ContainsKey(item.Key); if (res) return true; if (includeInstanceProperties && Instance != null) { foreach (var prop in this.InstancePropertyInfo) { if (prop.Name == item.Key) return true; } } return false; } } } Although the Expando class supports an indexer, it doesn't actually implement IDictionary or even IEnumerable. It only provides the indexer and Contains() and GetProperties() methods, that work against the Properties dictionary AND the internal instance. The reason for not implementing IDictionary is that a) it doesn't add much value since you can access the Properties dictionary directly and that b) I wanted to keep the interface to class very lean so that it can serve as an entity type if desired. Implementing these IDictionary (or even IEnumerable) causes LINQ extension methods to pop up on the type which obscures the property interface and would only confuse the purpose of the type. IDictionary and IEnumerable are also problematic for XML and JSON Serialization - the XML Serializer doesn't serialize IDictionary<string,object>, nor does the DataContractSerializer. The JavaScriptSerializer does serialize, but it treats the entire object like a dictionary and doesn't serialize the strongly typed properties of the type, only the dictionary values which is also not desirable. Hence the decision to stick with only implementing the indexer to support the user["CustomProperty"] functionality and leaving iteration functions to the publicly exposed Properties dictionary. Note that the Dictionary used here is a custom PropertyBag class I created to allow for serialization to work. One important aspect for my apps is that whatever custom properties get added they have to be accessible to AJAX clients since the particular app I'm working on is a SIngle Page Web app where most of the Web access is through JSON AJAX calls. PropertyBag can serialize to XML and one way serialize to JSON using the JavaScript serializer (not the DCS serializers though). The key components that make Expando work in this code are the Properties Dictionary and the TryGetMember() and TrySetMember() methods. The Properties collection is public so if you choose you can explicitly access the collection to get better performance or to manipulate the members in internal code (like loading up dynamic values form a database). Notice that TryGetMember() and TrySetMember() both work against the dictionary AND the internal instance to retrieve and set properties. This means that user["Name"] works against native properties of the object as does user["Name"] = "RogaDugDog". What's your Use Case? This is still an early prototype but I've plugged it into one of my customer's applications and so far it's working very well. The key features for me were the ability to easily extend the type with values coming from a database and exposing those values in a nice and easy to use manner. I'm also finding that using this type of object for ViewModels works very well to add custom properties to view models. I suspect there will be lots of uses for this - I've been using the extra dictionary approach to extensibility for years - using a dynamic type to make the syntax cleaner is just a bonus here. What can you think of to use this for? Resources Source Code and Tests (GitHub) Also integrated in Westwind.Utilities of the West Wind Web Toolkit West Wind Utilities NuGet© Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp  .NET  Dynamic Types   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Event Logging in LINQ C# .NET

  The first thing you'll want to do before using this code is to create a table in your database called TableHistory: CREATE TABLE [dbo].[TableHistory] (     [TableHistoryID] [int] IDENTITY NOT NULL ,     [TableName] [varchar] (50) NOT NULL ,     [Key1] [varchar] (50) NOT NULL ,     [Key2] [varchar] (50) NULL ,     [Key3] [varchar] (50) NULL ,     [Key4] [varchar] (50) NULL ,     [Key5] [varchar] (50) NULL ,     [Key6] [varchar] (50)NULL ,     [ActionType] [varchar] (50) NULL ,     [Property] [varchar] (50) NULL ,     [OldValue] [varchar] (8000) NULL ,     [NewValue] [varchar] (8000) NULL ,     [ActionUserName] [varchar] (50) NOT NULL ,     [ActionDateTime] [datetime] NOT NULL ) Once you have created the table, you'll need to add it to your custom LINQ class (which I will refer to as DboDataContext), thus creating the TableHistory class. Then, you'll need to add the History.cs file to your project. You'll also want to add the following code to your project to get the system date: public partial class DboDataContext{ [Function(Name = "GetDate", IsComposable = true)] public DateTime GetSystemDate() { MethodInfo mi = MethodBase.GetCurrentMethod() as MethodInfo; return (DateTime)this.ExecuteMethodCall(this, mi, new object[] { }).ReturnValue; }}private static Dictionary<type,> _cachedIL = new Dictionary<type,>();public static T CloneObjectWithIL<t>(T myObject){ Delegate myExec = null; if (!_cachedIL.TryGetValue(typeof(T), out myExec)) { // Create ILGenerator DynamicMethod dymMethod = new DynamicMethod("DoClone", typeof(T), new Type[] { typeof(T) }, true); ConstructorInfo cInfo = myObject.GetType().GetConstructor(new Type[] { }); ILGenerator generator = dymMethod.GetILGenerator(); LocalBuilder lbf = generator.DeclareLocal(typeof(T)); //lbf.SetLocalSymInfo("_temp"); generator.Emit(OpCodes.Newobj, cInfo); generator.Emit(OpCodes.Stloc_0); foreach (FieldInfo field in myObject.GetType().GetFields( System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.NonPublic)) { // Load the new object on the eval stack... (currently 1 item on eval stack) generator.Emit(OpCodes.Ldloc_0); // Load initial object (parameter) (currently 2 items on eval stack) generator.Emit(OpCodes.Ldarg_0); // Replace value by field value (still currently 2 items on eval stack) generator.Emit(OpCodes.Ldfld, field); // Store the value of the top on the eval stack into // the object underneath that value on the value stack. // (0 items on eval stack) generator.Emit(OpCodes.Stfld, field); } // Load new constructed obj on eval stack -> 1 item on stack generator.Emit(OpCodes.Ldloc_0); // Return constructed object. --> 0 items on stack generator.Emit(OpCodes.Ret); myExec = dymMethod.CreateDelegate(typeof(Func<t,>)); _cachedIL.Add(typeof(T), myExec); } return ((Func<t,>)myExec)(myObject);}I got both of the above methods off of the net somewhere (maybe even from CodeProject), but it's been long enough that I can't recall where I got them.Explanation of the History ClassThe History class records changes by creating a TableHistory record, inserting the values for the primary key for the table being modified into the Key1, Key2, ..., Key6 columns (if you have more than 6 values that make up a primary key on any table, you'll want to modify this), setting the type of change being made in the ActionType column (INSERT, UPDATE, or DELETE), old value and new value if it happens to be an update action, and the date and Windows identity of the user who made the change.Let's examine what happens when a call is made to the RecordLinqInsert method:public static void RecordLinqInsert(DboDataContext dbo, IIdentity user, object obj){ TableHistory hist = NewHistoryRecord(obj); hist.ActionType = "INSERT"; hist.ActionUserName = user.Name; hist.ActionDateTime = dbo.GetSystemDate(); dbo.TableHistories.InsertOnSubmit(hist);}private static TableHistory NewHistoryRecord(object obj){ TableHistory hist = new TableHistory(); Type type = obj.GetType(); PropertyInfo[] keys; if (historyRecordExceptions.ContainsKey(type)) { keys = historyRecordExceptions[type].ToArray(); } else { keys = type.GetProperties().Where(o => AttrIsPrimaryKey(o)).ToArray(); } if (keys.Length > KeyMax) throw new HistoryException("object has more than " + KeyMax.ToString() + " keys."); for (int i = 1; i <= keys.Length; i++) { typeof(TableHistory) .GetProperty("Key" + i.ToString()) .SetValue(hist, keys[i - 1].GetValue(obj, null).ToString(), null); } hist.TableName = type.Name; return hist;}protected static bool AttrIsPrimaryKey(PropertyInfo pi){ var attrs = from attr in pi.GetCustomAttributes(typeof(ColumnAttribute), true) where ((ColumnAttribute)attr).IsPrimaryKey select attr; if (attrs != null && attrs.Count() > 0) return true; else return false;}RecordLinqInsert takes as input a data context which it will use to write to the database, the user, and the LINQ object to be recorded (a single object, for instance, a Customer or Order object if you're using AdventureWorks). It then calls the NewHistoryRecord method, which uses LINQ to Objects in conjunction with the AttrIsPrimaryKey method to pull all the primary key properties, set the Key1-KeyN properties of the TableHistory object, and return the new TableHistory object. The code would be called in an application, like so: Continue span.fullpost {display:none;}

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• recursive delete trigger and ON DELETE CASCADE contraints are not deleting everything

  - by bitbonk

  I have a very simple datamodel that represents a tree structure: The RootEntity is the root of such a tree, it can contain children of type ContainerEntity and of type AtomEntity. The type ContainerEntity again can contain children of type ContainerEntity and of type AtomEntity but can not contain children of type RootEntity. Children are referenced in a well known order. The DB model for this is below. My problem now is that when I delete a RootEntity I want all children to be deleted recursively. I have create foreign key with CASCADE DELETE and two delete triggers for this. But it is not deleting everything, it always leaves some items in the ContainerEntity, AtomEntity, ContainerEntity_Children and AtomEntity_Children tables. Seemling beginning with the recursionlevel of 3. CREATE TABLE RootEntity ( Id UNIQUEIDENTIFIER NOT NULL, Name VARCHAR(500) NOT NULL, CONSTRAINT PK_RootEntity PRIMARY KEY NONCLUSTERED (Id), ); CREATE TABLE ContainerEntity ( Id UNIQUEIDENTIFIER NOT NULL, Name VARCHAR(500) NOT NULL, CONSTRAINT PK_ContainerEntity PRIMARY KEY NONCLUSTERED (Id), ); CREATE TABLE AtomEntity ( Id UNIQUEIDENTIFIER NOT NULL, Name VARCHAR(500) NOT NULL, CONSTRAINT PK_AtomEntity PRIMARY KEY NONCLUSTERED (Id), ); CREATE TABLE RootEntity_Children ( ParentId UNIQUEIDENTIFIER NOT NULL, OrderIndex INT NOT NULL, ChildContainerEntityId UNIQUEIDENTIFIER NULL, ChildAtomEntityId UNIQUEIDENTIFIER NULL, ChildIsContainerEntity BIT NOT NULL, CONSTRAINT PK_RootEntity_Children PRIMARY KEY NONCLUSTERED (ParentId, OrderIndex), -- foreign key to parent RootEntity CONSTRAINT FK_RootEntiry_Children__RootEntity FOREIGN KEY (ParentId) REFERENCES RootEntity (Id) ON DELETE CASCADE, -- foreign key to referenced (child) ContainerEntity CONSTRAINT FK_RootEntiry_Children__ContainerEntity FOREIGN KEY (ChildContainerEntityId) REFERENCES ContainerEntity (Id) ON DELETE CASCADE, -- foreign key to referenced (child) AtomEntity CONSTRAINT FK_RootEntiry_Children__AtomEntity FOREIGN KEY (ChildAtomEntityId) REFERENCES AtomEntity (Id) ON DELETE CASCADE, ); CREATE TABLE ContainerEntity_Children ( ParentId UNIQUEIDENTIFIER NOT NULL, OrderIndex INT NOT NULL, ChildContainerEntityId UNIQUEIDENTIFIER NULL, ChildAtomEntityId UNIQUEIDENTIFIER NULL, ChildIsContainerEntity BIT NOT NULL, CONSTRAINT PK_ContainerEntity_Children PRIMARY KEY NONCLUSTERED (ParentId, OrderIndex), -- foreign key to parent ContainerEntity CONSTRAINT FK_ContainerEntity_Children__RootEntity FOREIGN KEY (ParentId) REFERENCES ContainerEntity (Id) ON DELETE CASCADE, -- foreign key to referenced (child) ContainerEntity CONSTRAINT FK_ContainerEntity_Children__ContainerEntity FOREIGN KEY (ChildContainerEntityId) REFERENCES ContainerEntity (Id) ON DELETE CASCADE, -- foreign key to referenced (child) AtomEntity CONSTRAINT FK_ContainerEntity_Children__AtomEntity FOREIGN KEY (ChildAtomEntityId) REFERENCES AtomEntity (Id) ON DELETE CASCADE, ); CREATE TRIGGER Delete_RootEntity_Children ON RootEntity_Children FOR DELETE AS DELETE FROM ContainerEntity WHERE Id IN (SELECT ChildContainerEntityId FROM deleted) DELETE FROM AtomEntity WHERE Id IN (SELECT ChildAtomEntityId FROM deleted) GO CREATE TRIGGER Delete_ContainerEntiy_Children ON ContainerEntity_Children FOR DELETE AS DELETE FROM ContainerEntity WHERE Id IN (SELECT ChildContainerEntityId FROM deleted) DELETE FROM AtomEntity WHERE Id IN (SELECT ChildAtomEntityId FROM deleted) GO

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• How can I suppress /etc/issue without losing error messages?

  - by Andy

  Is it possible to tell the ssh client to not print the connects of /etc/issue to stdout when connecting to a remote host, but to print out any other diagnostic (e.g. error) messages? Either using ssh -q or having LogLevel quiet in ~/.ssh/config suppresses the /etc/issue printing, but also turn off error messages. I've tried touching ~/.hushlogin as well - that stops /etc/motd being printed, but doesn't affect /etc/issue. The most obvious solution is just to remove /etc/issue, but company policy dictates the file be there with dire warnings about unauthorised access. This is non-negotiable. Unfortunately, I've got a bunch of scripts that run across quite a few hosts via ssh, and the log files are a) very large and b) full of legalese. Since quite a lot of stuff runs unattended, I don't want to lose any error messages that are printed.

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• What is causing Null Pointer Exception in the following code in java? [migrated]

  - by Joe

  When I run the following code I get Null Pointer Exception. I cannot figure out why that is happening. Need Help. public class LinkedList<T> { private Link head = null; private int length = 0; public T get(int index) { return find(index).item; } public void set(int index, T item) { find(index).item = item; } public int length() { return length; } public void add(T item) { Link<T> ptr = head; if (ptr == null) { // empty list so append to head head = new Link<T>(item); } else { // non-empty list, so locate last link while (ptr.next != null) { ptr = ptr.next; } ptr.next = new Link<T>(item); } length++; // update length cache } // traverse list looking for link at index private Link<T> find(int index) { Link<T> ptr = head; int i = 0; while (i++ != index) { if(ptr!=null) { ptr = ptr.next; } } return ptr; } private static class Link<S> { public S item; public Link<S> next; public Link(S item) { this.item = item; } } public static void main(String[] args) { new LinkedList<String>().get(1); } }

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• Inserting "null" (literally) in to a stored procedure parameter.

  - by Nazadus

  I'm trying to insert the word "Null" (literally) in to a parameter for a stored procedure. For some reason SqlServer seems to think I mean NULL and not "Null". If I do a check for IF @LastName IS NULL // Test: Do stuff Then it bypasses that because the parameter isn't null. But when I do: INSERT INTO Person (<params>) VALUES (<stuff here>, @LastName, <more stuff here>); // LastName is 'Null' It bombs out saying that LastName doesn't accept nulls. I would seriously hate to have this last name, but someone does... and it's bombing the application. We're using SubSonic 2.0 (yeah, it's fairly old but upgrading is painful) as our DAL and stepping through it, I see it does create the parameters properly (for what I can tell). I've tried creating a temp table to see if I could replicate it manually but it seems to work just fine. Here is the example I create: DECLARE @myval VARCHAR(50) SET @myval = 'Null' CREATE TABLE #mytable( name VARCHAR(50)) INSERT INTO #mytable VALUES (@myval) SELECT * FROM #mytable DROP table #mytable Any thoughts on how I can fix this?

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• Eclipselink update existing tables

  - by javydreamercsw

  Maybe I got it wrong but i though that JPA was able to update an existing table (model changed adding a column) but is not working in my case. I can see in the logs eclipselink attempting to create it but failing because it already exists. Instead of trying an update to add the column it keeps going. (Had to remove some < so it displays) property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/jwrestling"/ property name="javax.persistence.jdbc.password" value="password"/ property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/ property name="javax.persistence.jdbc.user" value="user"/ property name="eclipselink.ddl-generation" value="create-tables"/ property name="eclipselink.logging.logger" value="org.eclipse.persistence.logging.DefaultSessionLog"/ property name="eclipselink.logging.level" value="INFO"/ And here's the table with the change (online column added) [EL Warning]: 2010-05-31 14:39:06.044--ServerSession(16053322)--Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.1.0.v20100517-r7246): org.eclipse.persistence.exceptions.DatabaseException Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'account' already exists Error Code: 1050 Call: CREATE TABLE account (ID INTEGER NOT NULL, USERNAME VARCHAR(32) NOT NULL, SECURITY_KEY VARCHAR(255) NOT NULL, EMAIL VARCHAR(64) NOT NULL, STATUS VARCHAR(8) NOT NULL, TIMEDATE DATETIME NOT NULL, PASSWORD VARCHAR(255) NOT NULL, ONLINE TINYINT(1) default 0 NOT NULL, PRIMARY KEY (ID)) Query: DataModifyQuery(sql="CREATE TABLE account (ID INTEGER NOT NULL, USERNAME VARCHAR(32) NOT NULL, SECURITY_KEY VARCHAR(255) NOT NULL, EMAIL VARCHAR(64) NOT NULL, STATUS VARCHAR(8) NOT NULL, TIMEDATE DATETIME NOT NULL, PASSWORD VARCHAR(255) NOT NULL, ONLINE TINYINT(1) default 0 NOT NULL, PRIMARY KEY (ID))") [EL Warning]: 2010-05-31 14:39:06.074--ServerSession(16053322)--Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.1.0.v20100517-r7246): org.eclipse.persistence.exceptions.DatabaseException After this it continues with the following. Am I doing something wrong or is a bug?

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• Updating nullability of columns in SQL 2008

  - by Shaul

  I have a very wide table, containing lots and lots of bit fields. These bit fields were originally set up as nullable. Now we've just made a decision that it doesn't make sense to have them nullable; the value is either Yes or No, default No. In other words, the schema should change from: create table MyTable( ID bigint not null, Name varchar(100) not null, BitField1 bit null, BitField2 bit null, ... BitFieldN bit null ) to create table MyTable( ID bigint not null, Name varchar(100) not null, BitField1 bit not null, BitField2 bit not null, ... BitFieldN bit not null ) alter table MyTable add constraint DF_BitField1 default 0 for BitField1 alter table MyTable add constraint DF_BitField2 default 0 for BitField2 alter table MyTable add constraint DF_BitField3 default 0 for BitField3 So I've just gone in through the SQL Management Studio, updating all these fields to non-nullable, default value 0. And guess what - when I try to update it, SQL Mgmt studio internally recreates the table and then tries to reinsert all the data into the new table... including the null values! Which of course generates an error, because it's explicitly trying to insert a null value into a non-nullable column. Aaargh! Obviously I could run N update statements of the form: update MyTable set BitField1 = 0 where BitField1 is null update MyTable set BitField2 = 0 where BitField2 is null but as I said before, there are n fields out there, and what's more, this change has to propagate out to several identical databases. Very painful to implement manually. Is there any way to make the table modification just ignore the null values and allow the default rule to kick in when you attempt to insert a null value?

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• Modeling objects with multiple table relationships in Zend Framework

  - by andybaird

  I'm toying with Zend Framework and trying to use the "QuickStart" guide against a website I'm making just to see how the process would work. Forgive me if this answer is obvious, hopefully someone experienced can shed some light on this. I have three database tables: CREATE TABLE `users` ( `id` int(11) NOT NULL auto_increment, `email` varchar(255) NOT NULL, `username` varchar(255) NOT NULL default '', `first` varchar(128) NOT NULL default '', `last` varchar(128) NOT NULL default '', `gender` enum('M','F') default NULL, `birthyear` year(4) default NULL, `postal` varchar(16) default NULL, `auth_method` enum('Default','OpenID','Facebook','Disabled') NOT NULL default 'Default', PRIMARY KEY (`id`), UNIQUE KEY `email` (`email`), UNIQUE KEY `username` (`username`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 CREATE TABLE `user_password` ( `user_id` int(11) NOT NULL, `password` varchar(16) NOT NULL default '', PRIMARY KEY (`user_id`), UNIQUE KEY `user_id` (`user_id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 CREATE TABLE `user_metadata` ( `user_id` int(11) NOT NULL default '0', `signup_date` datetime default NULL, `signup_ip` varchar(15) default NULL, `last_login_date` datetime default NULL, `last_login_ip` varchar(15) default NULL, PRIMARY KEY (`user_id`), UNIQUE KEY `user_id` (`user_id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 I want to create a User model that uses all three tables in certain situations. E.g., the metadata table is accessed if/when the meta data is needed. The user_password table is accessed only if the 'Default' auth_method is set. I'll likely be adding a profile table later on that I would like to be able to access from the user model. What is the best way to do this with ZF and why?

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• What is the purpose of the s==NULL case for mbrtowc?

  - by R..

  mbrtowc is specified to handle a NULL pointer for the s (multibyte character pointer) argument as follows: If s is a null pointer, the mbrtowc() function shall be equivalent to the call: mbrtowc(NULL, "", 1, ps) In this case, the values of the arguments pwc and n are ignored. As far as I can tell, this usage is largely useless. If ps is not storing any partially-converted character, the call will simply return 0 with no side effects. If ps is storing a partially-converted character, then since '\0' is not valid as the next byte in a multibyte sequence ('\0' can only be a string terminator), the call will return (size_t)-1 with errno==EILSEQ. and leave ps in an undefined state. The intended usage seems to have been to reset the state variable, particularly when NULL is passed for ps and the internal state has been used, analogous to mbtowc's behavior with stateful encodings, but this is not specified anywhere as far as I can tell, and it conflicts with the semantics for mbrtowc's storage of partially-converted characters (if mbrtowc were to reset state when encountering a 0 byte after a potentially-valid initial subsequence, it would be unable to detect this dangerous invalid sequence). If mbrtowc were specified to reset the state variable only when s is NULL, but not when it points to a 0 byte, a desirable state-reset behavior would be possible, but such behavior would violate the standard as written. Is this a defect in the standard? As far as I can tell, there is absolutely no way to reset the internal state (used when ps is NULL) once an illegal sequence has been encountered, and thus no correct program can use mbrtowc with ps==NULL.

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• how to monitor the program code execution? (file creation and modification by code lines etc)

  - by infant programmer

  My program is about triggering XSL transformation, Its fact that this code for carrying out the transformation, creates some dll and tmp files and deletes them pretty soon after the transformation is completed. It is almost untraceable for me to monitor the creation and deletion of files manually, so I want to include some chunk of codelines to display "which codeline has created/modified which tmp and dll files" in console window. This is the relevant part of the code: string strXmlQueryTransformPath = @"input.xsl"; string strXmlOutput = string.Empty; StringReader srXmlInput = null; StringWriter swXmlOutput = null; XslCompiledTransform xslTransform = null; XPathDocument xpathXmlOrig = null; XsltSettings xslSettings = null; MemoryStream objMemoryStream = null; objMemoryStream = new MemoryStream(); xslTransform = new XslCompiledTransform(false); xpathXmlOrig = new XPathDocument("input.xml"); xslSettings = new XsltSettings(); xslSettings.EnableScript = true; xslTransform.Load(strXmlQueryTransformPath, xslSettings, new XmlUrlResolver()); xslTransform.Transform(xpathXmlOrig, null, objMemoryStream); objMemoryStream.Position = 0; StreamReader objStreamReader = new StreamReader(objMemoryStream); strXmlOutput = objStreamReader.ReadToEnd(); // make use of Data in string "strXmlOutput" google and msdn search couldn't help me much..

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• How does Haskell do pattern matching without us defining an Eq on our data types?

  - by devoured elysium

  I have defined a binary tree: data Tree = Null | Node Tree Int Tree and have implemented a function that'll yield the sum of the values of all its nodes: sumOfValues :: Tree -> Int sumOfValues Null = 0 sumOfValues (Node Null v Null) = v sumOfValues (Node Null v t2) = v + (sumOfValues t2) sumOfValues (Node t1 v Null) = v + (sumOfValues t1) sumOfValues (Node t1 v t2) = v + (sumOfValues t1) + (sumOfValues t2) It works as expected. I had the idea of also trying to implement it using guards: sumOfValues2 :: Tree -> Int sumOfValues2 Null = 0 sumOfValues2 (Node t1 v t2) | t1 == Null && t2 == Null = v | t1 == Null = v + (sumOfValues2 t2) | t2 == Null = v + (sumOfValues2 t1) | otherwise = v + (sumOfValues2 t1) + (sumOfValues2 t2) but this one doesn't work because I haven't implemented Eq, I believe: No instance for (Eq Tree) arising from a use of `==' at zzz3.hs:13:3-12 Possible fix: add an instance declaration for (Eq Tree) In the first argument of `(&&)', namely `t1 == Null' In the expression: t1 == Null && t2 == Null In a stmt of a pattern guard for the definition of `sumOfValues2': t1 == Null && t2 == Null The question that has to be made, then, is how can Haskell make pattern matching without knowing when a passed argument matches, without resorting to Eq?

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• What is the breakdown of jobs in game development?

  - by Destry Ullrich

  There's a project I'm trying to start for Indie Game Development; specifically, it's going to be a social networking website that lets developers meet through (It's a secret). One of the key components is showing what skills members have. Question: I need to know what MAJOR game development roles are not represented in the following list, keeping in mind that many specialist roles are being condensed into more broad, generalist roles: Art Animator (Characters, creatures, props, etc.) Concept Artist (2D scenes, environments, props, silhouettes, etc.) Technical Artist (UI artists, typefaces, graphic designers, etc.) 3D Artist (Modeling, rigging, texture, lighting, etc.) Audio Composer (Scores, music, etc.) Sound Engineer (SFX, mood setting, audio implementation, etc.) Voice (Dialog, acting, etc.) Design Creative Director (Initial direction, team management, communications, etc.) Gameplay Designer (Systems, mechanics, control mapping, etc.) World Designer (Level design, aesthetics, game progression, events, etc.) Writer (Story, mythos, dialog, flavor text, etc.) Programming Engine Programming (Engine creation, scripting, physics, etc.) Graphics Engineer (Sprites, lighting, GUI, etc.) Network Engineer (LAN, multiplayer, server support, etc.) Technical Director (I don't know what a technical director would even do.) Post Script: I have an art background, so i'm not familiar with what the others behind game creation actually do. What's missing from this list, and if you feel some things should be changed around how so?

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• Hi, I have a C hashing routine which is behaving strangely?

  - by aks

  Hi, In this hashing routine: 1.) I am able to add strings. 2.) I am able to view my added strings. 3.) When i try to add a duplicate string, it throws me an error saying already present. 4.) But, when i try to delete the same string which is already present in hash table, then the lookup_routine calls hash function to get an index. At this time, it throws a different hash index to the one it was already added. Hence, my delete routine is failing? I am able to understand the reason why for same string, hash fucntion calculates a different index each time (whereas the same logic works in view hash table routine)? Can someone help me? This is the Output, i am getting: $ ./a Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: 1 Please enter the string :gaura enters in add_string DEBUG purpose in hash function: str passed = gaura Hashval returned in hash func= 1 hashval = 1 enters in lookup_string str in lookup_string = gaura DEBUG purpose in hash function: str passed = gaura Hashval returned in hash func= 1 hashval = 1 DEBUG ERROR :element not found in lookup string DEBUG Purpose NULL Inserting... DEBUG1 : enters here hashval = 1 String added successfully Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: 1 Please enter the string :ayu enters in add_string DEBUG purpose in hash function: str passed = ayu Hashval returned in hash func= 1 hashval = 1 enters in lookup_string str in lookup_string = ayu DEBUG purpose in hash function: str passed = ayu Hashval returned in hash func= 1 hashval = 1 returns NULL in lookup_string DEBUG Purpose NULL Inserting... DEBUG2 : enters here hashval = 1 String added successfully Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: 1 Please enter the string :gaurava enters in add_string DEBUG purpose in hash function: str passed = gaurava Hashval returned in hash func= 7 hashval = 7 enters in lookup_string str in lookup_string = gaurava DEBUG purpose in hash function: str passed = gaurava Hashval returned in hash func= 7 hashval = 7 DEBUG ERROR :element not found in lookup string DEBUG Purpose NULL Inserting... DEBUG1 : enters here hashval = 7 String added successfully Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: 4 Index : i = 1 String = gaura ayu Index : i = 7 String = gaurava Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: 2 Please enter the string you want to delete :gaura String entered = gaura enters in delete_string DEBUG purpose in hash function: str passed = gaura Hashval returned in hash func= 0 hashval = 0 enters in lookup_string str in lookup_string = gaura DEBUG purpose in hash function: str passed = gaura Hashval returned in hash func= 0 hashval = 0 DEBUG ERROR :element not found in lookup string DEBUG Purpose Item not present. So, cannot be deleted Item found in list: Deletion failed Press 1 to add an element to the hashtable Press 2 to delete an element from the hashtable Press 3 to search the hashtable Press 4 to view the hashtable Press 5 to exit Please enter your choice: My routine is pasted below: include include struct list { char *string; struct list *next; }; struct hash_table { int size; /* the size of the table */ struct list *table; / the table elements */ }; struct hash_table * hashtable = NULL; struct hash_table *create_hash_table(int size) { struct hash_table *new_table; int i; if (size<1) return NULL; /* invalid size for table */ /* Attempt to allocate memory for the table structure */ if ((new_table = malloc(sizeof(struct hash_table))) == NULL) { return NULL; } /* Attempt to allocate memory for the table itself */ if ((new_table->table = malloc(sizeof(struct list *) * size)) == NULL) { return NULL; } /* Initialize the elements of the table */ for(i=0; i<size; i++) new_table->table[i] = '\0'; /* Set the table's size */ new_table->size = size; return new_table; } unsigned int hash(struct hash_table *hashtable, char *str) { printf("\n DEBUG purpose in hash function:\n"); printf("\n str passed = %s", str); unsigned int hashval = 0; int i = 0; for(; *str != '\0'; str++) { hashval += str[i]; i++; } hashval = hashval % 10; printf("\n Hashval returned in hash func= %d", hashval); return hashval; } struct list *lookup_string(struct hash_table *hashtable, char *str) { printf("\n enters in lookup_string \n"); printf("\n str in lookup_string = %s",str); struct list * new_list; unsigned int hashval = hash(hashtable, str); printf("\n hashval = %d \n", hashval); if(hashtable->table[hashval] == NULL) { printf("\n DEBUG ERROR :element not found in lookup string \n"); return NULL; } /* Go to the correct list based on the hash value and see if str is * in the list. If it is, return return a pointer to the list element. * If it isn't, the item isn't in the table, so return NULL. */ for(new_list = hashtable->table[hashval]; new_list != NULL;new_list = new_list->next) { if (strcmp(str, new_list->string) == 0) return new_list; } printf("\n returns NULL in lookup_string \n"); return NULL; } int add_string(struct hash_table *hashtable, char *str) { printf("\n enters in add_string \n"); struct list *new_list; struct list *current_list; unsigned int hashval = hash(hashtable, str); printf("\n hashval = %d", hashval); /* Attempt to allocate memory for list */ if ((new_list = malloc(sizeof(struct list))) == NULL) { printf("\n enters here \n"); return 1; } /* Does item already exist? */ current_list = lookup_string(hashtable, str); if (current_list == NULL) { printf("\n DEBUG Purpose \n"); printf("\n NULL \n"); } /* item already exists, don't insert it again. */ if (current_list != NULL) { printf("\n Item already present...\n"); return 2; } /* Insert into list */ printf("\n Inserting...\n"); new_list->string = strdup(str); new_list->next = NULL; //new_list->next = hashtable->table[hashval]; if(hashtable->table[hashval] == NULL) { printf("\n DEBUG1 : enters here \n"); printf("\n hashval = %d", hashval); hashtable->table[hashval] = new_list; } else { printf("\n DEBUG2 : enters here \n"); printf("\n hashval = %d", hashval); struct list * temp_list = hashtable->table[hashval]; while(temp_list->next!=NULL) temp_list = temp_list->next; temp_list->next = new_list; // hashtable->table[hashval] = new_list; } return 0; } int delete_string(struct hash_table *hashtable, char *str) { printf("\n enters in delete_string \n"); struct list *new_list; struct list *current_list; unsigned int hashval = hash(hashtable, str); printf("\n hashval = %d", hashval); /* Does item already exist? */ current_list = lookup_string(hashtable, str); if (current_list == NULL) { printf("\n DEBUG Purpose \n"); printf("\n Item not present. So, cannot be deleted \n"); return 1; } /* item exists, delete it. */ if (current_list != NULL) { struct list * temp = hashtable->table[hashval]; if(strcmp(temp->string,str) == 0) { if(temp->next == NULL) { hashtable->table[hashval] = NULL; free(temp); } else { hashtable->table[hashval] = temp->next; free(temp); } } else { struct list * temp1; while(temp->next != NULL) { temp1 = temp; if(strcmp(temp->string, str) == 0) { break; } else { temp = temp->next; } } if(temp->next == NULL) { temp1->next = NULL; free(temp); } else { temp1->next = temp->next; free(temp); } } } return 0; } void free_table(struct hash_table *hashtable) { int i; struct list *new_list, *temp_list; if (hashtable==NULL) return; /* Free the memory for every item in the table, including the * strings themselves. */ for(i=0; i<hashtable->size; i++) { new_list = hashtable->table[i]; while(new_list!=NULL) { temp_list = new_list; new_list = new_list->next; free(temp_list->string); free(temp_list); } } /* Free the table itself */ free(hashtable->table); free(hashtable); } void view_hashtable(struct hash_table * hashtable) { int i = 0; if(hashtable == NULL) return; for(i =0; i < hashtable->size; i++) { if((hashtable->table[i] == 0) || (strcmp(hashtable->table[i]->string, "*") == 0)) { continue; } printf(" Index : i = %d\t String = %s",i, hashtable->table[i]->string); struct list * temp = hashtable->table[i]->next; while(temp != NULL) { printf("\t %s",temp->string); temp = temp->next; } printf("\n"); } } int main() { hashtable = create_hash_table(10); if(hashtable == NULL) { printf("\n Memory allocation failure during creation of hash table \n"); return 0; } int flag = 1; while(flag) { int choice; printf("\n Press 1 to add an element to the hashtable\n"); printf("\n Press 2 to delete an element from the hashtable\n"); printf("\n Press 3 to search the hashtable\n"); printf("\n Press 4 to view the hashtable\n"); printf("\n Press 5 to exit \n"); printf("\n Please enter your choice: "); scanf("%d",&choice); if(choice == 5) flag = 0; else if(choice == 1) { char str[20]; printf("\n Please enter the string :"); scanf("%s",&str); int i; i = add_string(hashtable,str); if(i == 1) { printf("\n Memory allocation failure:Choice 1 \n"); return 0; } else if(i == 2) { printf("\n String already prsent in hash table : Couldnot add it again\n"); return 0; } else { printf("\n String added successfully \n"); } } else if(choice == 2) { int i; struct list * temp_list; char str[20]; printf("\n Please enter the string you want to delete :"); scanf("%s",&str); printf("\n String entered = %s", str); i = delete_string(hashtable,str); if(i == 0) { printf("\n Item found in list: Deletion success \n"); } else printf("\n Item found in list: Deletion failed \n"); } else if(choice == 3) { struct list * temp_list; char str[20]; printf("\n Please enter the string :"); scanf("%s",&str); temp_list = lookup_string(hashtable,str); if(!temp_list) { printf("\n Item not found in list: Deletion failed \n"); return 0; } printf("\n Item found: Present in Hash Table \n"); } else if(choice == 4) { view_hashtable(hashtable); } else if(choice == 5) { printf("\n Exiting ...."); return 0; } else printf("\n Invalid choice:"); }; free_table(hashtable); return 0; }

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• DropDownList Value not changing with UpdatePanel and ModalPopupExtender

  - by Richard

  Greetings, I have an asp.net webpage with an modalpopupextender inside of an updatepanel. When I click Ok on the popup, I can get the textbox values from the popup just fine, but the DropDownLists have the old/default value, not the new value I have selected for them. All the controls on the popup are set to enableviewstate = true, and autopostback = false (I just want to make the trip to the server when I click the ok button, not every time I change the value of the popups). Here is the relevant code. ========================== Client Side <asp:UpdatePanel ID="UpdatePanel1" runat="server"> <ContentTemplate> <asp:Panel ID="EditIssuePanel" runat="server" CssClass="modalPopup" Style="display:block;" > <table style="width:500px;"> <tr style="height:50px;"> <td colspan="2" align="center"> <asp:Label ID="lblEditIssueHeader" runat="server" Text="Edit Issue"></asp:Label> </td> </tr> <tr style="height:30px;"> <td class="labelscolumn"> <asp:Label ID="lblIssueName" runat="server" Text="Name:"></asp:Label> </td> <td class="datacolumn"> <asp:TextBox ID="txtName" runat="server" Width="250px" MaxLength="50"></asp:TextBox> </td> </tr> <tr style="height:30px;"> <td class="labelscolumn"> <asp:Label ID="lblDescription" runat="server" Text="Description:"></asp:Label> </td> <td class="datacolumn"> <asp:TextBox ID="txtDescription" runat="server" Width="250px" MaxLength="1000"></asp:TextBox> </td> </tr> <tr style="height:30px;"> <td class="labelscolumn"> <asp:Label ID="lblType" runat="server" Text="Type:"></asp:Label> </td> <td class="datacolumn"> <asp:DropDownList ID="ddlType" runat="server"> <asp:ListItem Selected="True" Value="B">Bug</asp:ListItem> <asp:ListItem Value="R">Request</asp:ListItem> <asp:ListItem Value="O">Other</asp:ListItem> </asp:DropDownList> </td> </tr> <tr style="height:30px;"> <td class="labelscolumn"> <asp:Label ID="lblStatus" runat="server" Text="Status:"></asp:Label> </td> <td class="datacolumn"> <asp:DropDownList ID="ddlStatus" runat="server"> <asp:ListItem Selected="True" Value="L">Logged</asp:ListItem> <asp:ListItem Value="I">In Process</asp:ListItem> <asp:ListItem Value="C">Complete</asp:ListItem> </asp:DropDownList> &nbsp; </td> </tr> <tr style="height:30px;"> <td class="labelscolumn"> <asp:Label ID="lblPriority" runat="server" Text="Priority:"></asp:Label> </td> <td class="datacolumn"> <asp:DropDownList ID="ddlPriority" runat="server" EnableViewState="true" AutoPostBack="false"> <asp:ListItem Selected="True" Value="L">Low</asp:ListItem> <asp:ListItem Value="M">Medium</asp:ListItem> <asp:ListItem Value="H">High</asp:ListItem> </asp:DropDownList> &nbsp;</td> </tr> <tr style="height:30px"> <td class="labelscolumn">Logger</td> <td class="datacolumn"> <asp:Label ID="lblEnteredByClientUserID" runat="server" Text=""></asp:Label> </td> </tr> <tr style="height:30px;"> <td class="labelscolumn"> <asp:Label ID="lblDateResolutionRequested" runat="server" Text="Requested Complete Date:"></asp:Label> </td> <td class="datacolumn"> <igsch:WebDateChooser ID="wdcRequestCompleteDate" runat="server"> </igsch:WebDateChooser> &nbsp;</td> </tr> <tr style="height:30px"> <td class="labelscolumn">Logged Date</td> <td class="datacolumn"> <asp:Label ID="lblLoggedDate" runat="server" Text=""></asp:Label> </td> </tr> <tr style="height:30px"> <td class="labelscolumn">In Process Date</td> <td class="datacolumn"> <asp:Label ID="lblInProcessDate" runat="server" Text=""></asp:Label> </td> </tr> <tr style="height:30px"> <td class="labelscolumn">Resolved Date</td> <td class="datacolumn"> <asp:Label ID="lblResolvedDate" runat="server" Text=""></asp:Label> </td> </tr> <tr style="height:30px;"> <td class="labelscolumn" valign="top"> <asp:Label ID="lblEmailCCList" runat="server" Text="Email CC:"></asp:Label> </td> <td class="datacolumn"> <asp:TextBox ID="txtEmailCCList" runat="server" MaxLength="2000" Rows="0" TextMode="MultiLine" Height="83px" Width="250px"></asp:TextBox> &nbsp;</td> </tr> <tr> <td> <asp:Label ID="lblIssueID" runat="server" Text="" Visible="false"></asp:Label> <asp:Label ID="lblClientID" runat="server" Text="" Visible="false"></asp:Label> </td> <td align="right"> <asp:Button ID="btnEditOk" runat="server" Text="Ok" onclick="btnEditOk_Click"/>&nbsp;&nbsp; <asp:Button ID="btnEditCancel" runat="server" Text="Cancel" onclick="btnEditCancel_Click" />&nbsp;&nbsp;&nbsp;&nbsp; </td> </tr> </table> </asp:Panel> . . . THEN THERE IS A WEBGRID HERE. . . This modal popupextender here got mangled. I cant get stackoverflow to show it right. It shows the properties here though. " BackgroundCssClass="modalBackground" DropShadow="true" OkControlID="btnEditOk" CancelControlID="btnEditCancel" Animations="" </ContentTemplate> </asp:UpdatePanel> ========================================= Server Side protected void btnEditOk_Click(object sender, EventArgs e) { IssueDAO issueDAO = new IssueDAO(); string client = "Eichleay"; string name = null; string description = null; string type = null; string status = null; DateTime? resolvedDate = null; string enteredByClientUserName = User.Identity.Name.ToString(); DateTime? loggedDate = DateTime.Now; DateTime? inProcessDate = null; DateTime? completeDate = null; DateTime? requestCompleteDate = null; string priority = null; int? prioritySort = null; string emailCCList = null; name = txtName.Text.Substring(txtName.Text.Length > 0 ? 1 : 0, (txtName.Text.Length > 0 ? txtName.Text.Length : 1) - 1); description = txtDescription.Text.Substring(txtDescription.Text.Length > 0 ? 1 : 0, (txtDescription.Text.Length == 0 ? 1 : txtDescription.Text.Length) - 1); type = ddlType.SelectedValue; status = ddlStatus.SelectedValue; resolvedDate = string.IsNullOrEmpty(lblResolvedDate.Text) == true ? null : new Nullable<DateTime>(Convert.ToDateTime(lblResolvedDate.Text)); inProcessDate = string.IsNullOrEmpty(lblInProcessDate.Text) == true ? null : new Nullable<DateTime>(Convert.ToDateTime(lblInProcessDate.Text)); completeDate = string.IsNullOrEmpty(lblResolvedDate.Text) == true ? null : new Nullable<DateTime>(Convert.ToDateTime(lblResolvedDate.Text)); requestCompleteDate = wdcRequestCompleteDate.Value == null ? null : string.IsNullOrEmpty(wdcRequestCompleteDate.Value.ToString()) == true ? null : new Nullable<DateTime>(Convert.ToDateTime(wdcRequestCompleteDate.Value.ToString())); priority = ddlPriority.SelectedValue; emailCCList = txtEmailCCList.Text.Substring(txtEmailCCList.Text.Length > 0 ? 1 : 0, (txtEmailCCList.Text.Length > 0 ? txtEmailCCList.Text.Length : 1) - 1); if (lblEditIssueHeader.Text.Substring(0, 3) == "New") { issueDAO.InsertIssue(client, name, description, type, status, resolvedDate, enteredByClientUserName, loggedDate, inProcessDate, completeDate, requestCompleteDate, priority, prioritySort, emailCCList); } else { Issue issue = new Issue(Convert.ToInt32(lblIssueID.Text), lblClientID.Text, txtName.Text.Substring(txtName.Text.Length > 0 ? 1 : 0, (txtName.Text.Length > 0 ? txtName.Text.Length : 1) - 1), txtDescription.Text.Substring(txtDescription.Text.Length > 0 ? 1 : 0, (txtDescription.Text.Length == 0 ? 1 : txtDescription.Text.Length) - 1), ddlType.SelectedValue, ddlStatus.SelectedValue, string.IsNullOrEmpty(lblResolvedDate.Text) == true ? null : new Nullable<DateTime>(Convert.ToDateTime(lblResolvedDate.Text)), lblEnteredByClientUserID.Text, string.IsNullOrEmpty(lblLoggedDate.Text) == true ? null : new Nullable<DateTime>(Convert.ToDateTime(lblLoggedDate.Text)), string.IsNullOrEmpty(lblInProcessDate.Text) == true ? null : new Nullable<DateTime>(Convert.ToDateTime(lblInProcessDate.Text)), string.IsNullOrEmpty(lblResolvedDate.Text) == true ? null : new Nullable<DateTime>(Convert.ToDateTime(lblResolvedDate.Text)), string.IsNullOrEmpty(wdcRequestCompleteDate.Value.ToString()) == true ? null : new Nullable<DateTime>(Convert.ToDateTime(wdcRequestCompleteDate.Value.ToString())), ddlPriority.SelectedValue, null, txtEmailCCList.Text.Substring(txtEmailCCList.Text.Length > 0 ? 1 : 0, (txtEmailCCList.Text.Length > 0 ? txtEmailCCList.Text.Length : 1) - 1)); issueDAO.UpdateIssue(issue); } // wdgIssues.ClearDataSource(); // UpdatePanel1.Update(); lblIssueID.Text = null; lblClientID.Text = null; txtName.Text = null; txtDescription.Text = null; ddlType.SelectedValue = null; ddlStatus.SelectedValue = null; lblLoggedDate.Text = null; lblInProcessDate.Text = null; lblResolvedDate.Text = null; wdcRequestCompleteDate.Value = null; ddlPriority.SelectedValue = null; txtEmailCCList.Text = null; }

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• Foreign Key Relationships and "belongs to many"

  - by jan

  I have the following model: S belongs to T T has many S A,B,C,D,E (etc) have 1 T each, so the T should belong to each of A,B,C,D,E (etc) At first I set up my foreign keys so that in A, fk_a_t would be the foreign key on A.t to T(id), in B it'd be fk_b_t, etc. Everything looks fine in my UML (using MySQLWorkBench), but generating the yii models results in it thinking that T has many A,B,C,D (etc) which to me is the reverse. It sounds to me like either I need to have A_T, B_T, C_T (etc) tables, but this would be a pain as there are a lot of tables that have this relationship. I've also googled that the better way to do this would be some sort of behavior, such that A,B,C,D (etc) can behave as a T, but I'm not clear on exactly how to do this (I will continue to google more on this) What do you think is the better solution? UML: Here's the DDL (auto generated). Just pretend that there is more than 3 tables referencing T. -- ----------------------------------------------------- -- Table `mydb`.`T` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`T` ( `id` INT NOT NULL AUTO_INCREMENT , PRIMARY KEY (`id`) ) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`S` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`S` ( `id` INT NOT NULL AUTO_INCREMENT , `thing` VARCHAR(45) NULL , `t` INT NOT NULL , PRIMARY KEY (`id`) , INDEX `fk_S_T` (`id` ASC) , CONSTRAINT `fk_S_T` FOREIGN KEY (`id` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`A` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`A` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff` VARCHAR(45) NULL , `bar` VARCHAR(45) NULL , `foo` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`B` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`B` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff2` VARCHAR(45) NULL , `foobar` VARCHAR(45) NULL , `other` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`C` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`C` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff3` VARCHAR(45) NULL , `foobar2` VARCHAR(45) NULL , `other4` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB;

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• Django Encoding Issues with MySQL

  - by Jordan Reiter

  Okay, so I have a MySQL database set up. Most of the tables are latin1 and Django handles them fine. But, some of them are UTF-8 and Django does not handle them. Here's a sample table (these tables are all from django-geonames): DROP TABLE IF EXISTS `geoname`; SET @saved_cs_client = @@character_set_client; SET character_set_client = utf8; CREATE TABLE `geoname` ( `id` int(11) NOT NULL, `name` varchar(200) NOT NULL, `ascii_name` varchar(200) NOT NULL, `latitude` decimal(20,17) NOT NULL, `longitude` decimal(20,17) NOT NULL, `point` point default NULL, `fclass` varchar(1) NOT NULL, `fcode` varchar(7) NOT NULL, `country_id` varchar(2) NOT NULL, `cc2` varchar(60) NOT NULL, `admin1_id` int(11) default NULL, `admin2_id` int(11) default NULL, `admin3_id` int(11) default NULL, `admin4_id` int(11) default NULL, `population` int(11) NOT NULL, `elevation` int(11) NOT NULL, `gtopo30` int(11) NOT NULL, `timezone_id` int(11) default NULL, `moddate` date NOT NULL, PRIMARY KEY (`id`), KEY `country_id_refs_iso_alpha2_e2614807` (`country_id`), KEY `admin1_id_refs_id_a28cd057` (`admin1_id`), KEY `admin2_id_refs_id_4f9a0f7e` (`admin2_id`), KEY `admin3_id_refs_id_f8a5e181` (`admin3_id`), KEY `admin4_id_refs_id_9cc00ec8` (`admin4_id`), KEY `fcode_refs_code_977fe2ec` (`fcode`), KEY `timezone_id_refs_id_5b46c585` (`timezone_id`), KEY `geoname_52094d6e` (`name`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; SET character_set_client = @saved_cs_client; Now, if I try to get data from the table directly using MySQLdb and a cursor, I get the text with the proper encoding: >>> import MySQLdb >>> from django.conf import settings >>> >>> conn = MySQLdb.connect (host = "localhost", ... user = settings.DATABASES['default']['USER'], ... passwd = settings.DATABASES['default']['PASSWORD'], ... db = settings.DATABASES['default']['NAME']) >>> cursor = conn.cursor () >>> cursor.execute("select name from geoname where name like 'Uni%Hidalgo'"); 1L >>> g = cursor.fetchone() >>> g[0] 'Uni\xc3\xb3n Hidalgo' >>> print g[0] Unión Hidalgo However, if I try to use the Geoname model (which is actually a django.contrib.gis.db.models.Model), it fails: >>> from geonames.models import Geoname >>> g = Geoname.objects.get(name__istartswith='Uni',name__icontains='Hidalgo') >>> g.name u'Uni\xc3\xb3n Hidalgo' >>> print g.name Unión Hidalgo There's pretty clearly an encoding error here. In both cases the database is returning 'Uni\xc3\xb3n Hidalgo' but Django is (incorrectly?) translating the '\xc3\xb3n' to ó. What can I do to fix this?

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• Reasoner Conversion Problems:

  - by Annalyne

  I have this code right here in Java and I wanted to translate it in C++, but I had some problems going: this is the java code: import java.io.*; import java.util.*; public class ClueReasoner { private int numPlayers; private int playerNum; private int numCards; private SATSolver solver; private String caseFile = "cf"; private String[] players = {"sc", "mu", "wh", "gr", "pe", "pl"}; private String[] suspects = {"mu", "pl", "gr", "pe", "sc", "wh"}; private String[] weapons = {"kn", "ca", "re", "ro", "pi", "wr"}; private String[] rooms = {"ha", "lo", "di", "ki", "ba", "co", "bi", "li", "st"}; private String[] cards; public ClueReasoner() { numPlayers = players.length; // Initialize card info cards = new String[suspects.length + weapons.length + rooms.length]; int i = 0; for (String card : suspects) cards[i++] = card; for (String card : weapons) cards[i++] = card; for (String card : rooms) cards[i++] = card; numCards = i; // Initialize solver solver = new SATSolver(); addInitialClauses(); } private int getPlayerNum(String player) { if (player.equals(caseFile)) return numPlayers; for (int i = 0; i < numPlayers; i++) if (player.equals(players[i])) return i; System.out.println("Illegal player: " + player); return -1; } private int getCardNum(String card) { for (int i = 0; i < numCards; i++) if (card.equals(cards[i])) return i; System.out.println("Illegal card: " + card); return -1; } private int getPairNum(String player, String card) { return getPairNum(getPlayerNum(player), getCardNum(card)); } private int getPairNum(int playerNum, int cardNum) { return playerNum * numCards + cardNum + 1; } public void addInitialClauses() { // TO BE IMPLEMENTED AS AN EXERCISE // Each card is in at least one place (including case file). for (int c = 0; c < numCards; c++) { int[] clause = new int[numPlayers + 1]; for (int p = 0; p <= numPlayers; p++) clause[p] = getPairNum(p, c); solver.addClause(clause); } // If a card is one place, it cannot be in another place. // At least one card of each category is in the case file. // No two cards in each category can both be in the case file. } public void hand(String player, String[] cards) { playerNum = getPlayerNum(player); // TO BE IMPLEMENTED AS AN EXERCISE } public void suggest(String suggester, String card1, String card2, String card3, String refuter, String cardShown) { // TO BE IMPLEMENTED AS AN EXERCISE } public void accuse(String accuser, String card1, String card2, String card3, boolean isCorrect) { // TO BE IMPLEMENTED AS AN EXERCISE } public int query(String player, String card) { return solver.testLiteral(getPairNum(player, card)); } public String queryString(int returnCode) { if (returnCode == SATSolver.TRUE) return "Y"; else if (returnCode == SATSolver.FALSE) return "n"; else return "-"; } public void printNotepad() { PrintStream out = System.out; for (String player : players) out.print("\t" + player); out.println("\t" + caseFile); for (String card : cards) { out.print(card + "\t"); for (String player : players) out.print(queryString(query(player, card)) + "\t"); out.println(queryString(query(caseFile, card))); } } public static void main(String[] args) { ClueReasoner cr = new ClueReasoner(); String[] myCards = {"wh", "li", "st"}; cr.hand("sc", myCards); cr.suggest("sc", "sc", "ro", "lo", "mu", "sc"); cr.suggest("mu", "pe", "pi", "di", "pe", null); cr.suggest("wh", "mu", "re", "ba", "pe", null); cr.suggest("gr", "wh", "kn", "ba", "pl", null); cr.suggest("pe", "gr", "ca", "di", "wh", null); cr.suggest("pl", "wh", "wr", "st", "sc", "wh"); cr.suggest("sc", "pl", "ro", "co", "mu", "pl"); cr.suggest("mu", "pe", "ro", "ba", "wh", null); cr.suggest("wh", "mu", "ca", "st", "gr", null); cr.suggest("gr", "pe", "kn", "di", "pe", null); cr.suggest("pe", "mu", "pi", "di", "pl", null); cr.suggest("pl", "gr", "kn", "co", "wh", null); cr.suggest("sc", "pe", "kn", "lo", "mu", "lo"); cr.suggest("mu", "pe", "kn", "di", "wh", null); cr.suggest("wh", "pe", "wr", "ha", "gr", null); cr.suggest("gr", "wh", "pi", "co", "pl", null); cr.suggest("pe", "sc", "pi", "ha", "mu", null); cr.suggest("pl", "pe", "pi", "ba", null, null); cr.suggest("sc", "wh", "pi", "ha", "pe", "ha"); cr.suggest("wh", "pe", "pi", "ha", "pe", null); cr.suggest("pe", "pe", "pi", "ha", null, null); cr.suggest("sc", "gr", "pi", "st", "wh", "gr"); cr.suggest("mu", "pe", "pi", "ba", "pl", null); cr.suggest("wh", "pe", "pi", "st", "sc", "st"); cr.suggest("gr", "wh", "pi", "st", "sc", "wh"); cr.suggest("pe", "wh", "pi", "st", "sc", "wh"); cr.suggest("pl", "pe", "pi", "ki", "gr", null); cr.printNotepad(); cr.accuse("sc", "pe", "pi", "bi", true); } } how can I convert this? there are too many errors I get. for my C++ code (as a commentor asked for) #include <iostream> #include <cstdlib> #include <string> using namespace std; void Scene_Reasoner() { int numPlayer; int playerNum; int cardNum; string filecase = "Case: "; string players [] = {"sc", "mu", "wh", "gr", "pe", "pl"}; string suspects [] = {"mu", "pl", "gr", "pe", "sc", "wh"}; string weapons [] = {"kn", "ca", "re", "ro", "pi", "wr"}; string rooms[] = {"ha", "lo", "di", "ki", "ba", "co", "bi", "li", "st"}; string cards [0]; }; void Scene_Reason_Base () { numPlayer = players.length; // Initialize card info cards = new String[suspects.length + weapons.length + rooms.length]; int i = 0; for (String card : suspects) cards[i++] = card; for (String card : weapons) cards[i++] = card; for (String card : rooms) cards[i++] = card; cardNum = i; }; private int getCardNum (string card) { for (int i = 0; i < numCards; i++) if (card.equals(cards[i])) return i; cout << "Illegal card: " + card <<endl; return -1; }; private int getPairNum(String player, String card) { return getPairNum(getPlayerNum(player), getCardNum(card)); }; private int getPairNum(int playerNum, int cardNum) { return playerNum * numCards + cardNum + 1; }; int main () { return 0; }

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