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• Should I be learning Linq, Direct SQL Commands (in .net), EF or other?

  - by Wil

  Basically, I have a very good knowledge of plain old SQL coming from Classic ASP programming. Over the past couple of months, I have been learning C# and today was my first full day at MVC 3 (Razor) which I am loving! I need to get back in to Databases and I know that writing SqlCommand everywhere is obviously outdated (although it is nice I can still do it!). I used to go to a great usergroup as an IT Pro and the developer stuff went completely over my head, however I do remember a few things which kept coming up such as LINQ... However, that was some time ago and now the same people on Twitter are saying how out dated it is. I have tried to do research on both and I am clueless as to what direction I should go in, or when to use one over another (if learning both is a good thing). I am more so confused as I thought EF was a part of the .Net Framework, however, reading through the quick start guide, I had to download a component using Nuget. ... Basically I am out of my depth here and just need some honest advice of where to go!

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• Why DbContext object shouldn't be referred in Service Layer?

  - by nazmoonnoor

  I've been looking for some implementations of Service Layer and Controller interaction in blogs and in some open source projects. All of them seem to refer DbContext object in repository classes but avoided to use in service classes. Service classes essentially using a IQueryable<T> references of DbSet<T>. I want to know why this practice is good and why DbContext shouldn't have a reference in Service Layer.

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• Could multiple uses of the same word in image alt tags hurt SEO?

  - by saratogahiker

  Let's say on an e-commerce site that sells unique pens, on a particular pen's product page, the image of the pen has an alt tag of "unique red-striped pen"... and another product has "unique blue-spotted pen", etc. The key words across all products being "unique" and "pen", which would also be helpful when it comes to SEO. However, if the person just goes to the general "unique pens" category page and sees a list of thumbnail images, each with the words "unique" and "pen" in the alt tag, would that potentially have a negative impact with regards to SEO by having the words too many times?

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• Could you give me an example of how to attach an object in Deleted state – I keep getting an exception [migrated]

  - by carewithl

  From MSDN : An object in the Deleted state can only be attached when the ObjectStateManager is already tracking the relationship instance. Could you give me an example of how to attach an object in the Deleted state. I tried the following and got "System.InvalidOperationException: The object being attached is in an added or deleted state. Relationships cannot be created for objects in this state". var contact = context.Contacts.First(); Console.WriteLine(contact.Addresses.Count()); // 2 var address = contact.Addresses.First(); context.Addresses.DeleteObject(address); contact.Addresses.Attach(address); // InvalidOperationException thank you

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• Are elements returned by Linq-to-Entities query streamed from the DB one at the time or are they retrieved all at once?

  - by carewithl

  Are elements returned by Linq-to-Entities query streamed from the database one at the time ( as they are requested ) or are they retrieved all at once: SampleContext context = new SampleContext(); // SampleContext derives from ObjectContext var search = context.Contacts; foreach (var contact in search) { Console.WriteLine(contact.ContactID); // is each Contact retrieved from the DB // only when foreach requests it? } thank you in advance

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• ASP.Net Entity Framework, objectcontext error

  - by Chris Klepeis

  I'm building a 4 layered ASP.Net web application. The layers are: Data Layer Entity Layer Business Layer UI Layer The entity layer has my data model classes and is built from my entity data model (edmx file) in the datalayer using T4 templates (POCO). The entity layer is referenced in all other layers. My data layer has a class called SourceKeyRepository which has a function like so: public IEnumerable<SourceKey> Get(SourceKey sk) { using (dmc = new DataModelContainer()) { var query = from SourceKey in dmc.SourceKeys select SourceKey; if (sk.sourceKey1 != null) { query = from SourceKey in query where SourceKey.sourceKey1 == sk.sourceKey1 select SourceKey; } return query; } } Lazy loading is disabled since I do not want my queries to run in other layers of this application. I'm receiving the following error when attempting to access the information in the UI layer: The ObjectContext instance has been disposed and can no longer be used for operations that require a connection. I'm sure this is because my DataModelContainer "dmc" was disposed. How can I return this IEnumerable object from my data layer so that it does not rely on the ObjectContext, but solely on the DataModel? Is there a way to limit lazy loading to only occur in the data layer?

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• Appengine datastore phantom entity - inconsistent state?

  - by aloo

  Getting a weird error on java appengine code that used to work fine (nothing has changed but the data in the datastore). I'm trying to iterate over the results of a query and change a few properties of the entities. The query does return a set of results, however, when I try to access the first result in the list, it throws an exception when trying to access any of its properties (but its key). Here's the exception: org.datanucleus.state.JDOStateManagerImpl isLoaded: Exception thrown by StateManager.isLoaded Could not retrieve entity of kind OnTheCan with key OnTheCan(3204258) org.datanucleus.exceptions.NucleusObjectNotFoundException: Could not retrieve entity of kind OnTheCan with key OnTheCan(3204258) at org.datanucleus.store.appengine.DatastoreExceptionTranslator.wrapEntityNotFoundException(DatastoreExceptionTranslator.java:60) And here is my code: PersistenceManager pm = PMF.get().getPersistenceManager(); Query query = null; List<OnTheCan> cans; query = pm.newQuery("SELECT this FROM " + OnTheCan.class.getName() + " WHERE open == true ORDER BY onTheCanId ASC"); query.setRange(0, num); cans = (List<OnTheCan>) query.execute(); for (OnTheCan c : cans) { System.err.println(c.getOnTheCanId()); // this works fine! getting the key works c.setOpen(false); // failure here with the above exception c.setAutoClosed(true); c.setEndTime(new Date(c.getStartTime().getTime() + 600000/*10*60*1000*/)); } pm.close(); The code throws the exception when trying to execute c.setOpen(false) - thats the first time I'm accessing or setting a property that isnt the key. So it seems there is a phantom entity in my datastore with key 3204258. THis entity doesn't really exist (queried the datastore from admin console) but for some reason its being returned by the query. Could my data store be in an inconsistent state? I've managed the following workaround by placing it as the first line in my for loop. Clearly an ugly hack: if (c.getOnTheCanId() == 3204258) { continue; } Any ideas?

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• SQLAlchemy DetachedInstanceError with regular attribute (not a relation)

  - by haridsv

  I just started using SQLAlchemy and get a DetachedInstanceError and can't find much information on this anywhere. I am using the instance outside a session, so it is natural that SQLAlchemy is unable to load any relations if they are not already loaded, however, the attribute I am accessing is not a relation, in fact this object has no relations at all. I found solutions such as eager loading, but I can't apply to this because this is not a relation. I even tried "touching" this attribute before closing the session, but it still doesn't prevent the exception. What could be causing this exception for a non-relational property even after it has been successfully accessed once before? Any help in debugging this issue is appreciated. I will meanwhile try to get a reproducible stand-alone scenario and update here. Update: This is the actual exception message with a few stacks: File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/attributes.py", line 159, in __get__ return self.impl.get(instance_state(instance), instance_dict(instance)) File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/attributes.py", line 377, in get value = callable_(passive=passive) File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/state.py", line 280, in __call__ self.manager.deferred_scalar_loader(self, toload) File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/mapper.py", line 2323, in _load_scalar_attributes (state_str(state))) DetachedInstanceError: Instance <ReportingJob at 0xa41cd8c> is not bound to a Session; attribute refresh operation cannot proceed The partial model looks like this: metadata = MetaData() ModelBase = declarative_base(metadata=metadata) class ReportingJob(ModelBase): __tablename__ = 'reporting_job' job_id = Column(BigInteger, Sequence('job_id_sequence'), primary_key=True) client_id = Column(BigInteger, nullable=True) And the field client_id is what is causing this exception with a usage like the below: Query: jobs = session \ .query(ReportingJob) \ .filter(ReportingJob.job_id == job_id) \ .all() if jobs: # FIXME(Hari): Workaround for the attribute getting lazy-loaded. jobs[0].client_id return jobs[0] This is what triggers the exception later out of the session scope: msg = msg + ", client_id: %s" % job.client_id

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• JPA - Performance with using multiple entity manager

  - by Nguyen Tuan Linh

  My situation is: The code is not mine I have two kinds of database: one is Dad, one is Son. In Dad, I have a table to store JNDI name. I will look up Dad using JNDI, create entity manager, and retrieve this table. From these retrieved JNDI names, I will create multiple entity managers using multiple Son databases. The problem is: Son have thousands of entities. It takes each Son database around 10 minutes to load all entities. If there is 4 Son databases, it will be 40 minutes. My question: Is there any way to load all entities and use them for all entity manager? Please look at the code below For each Son JNDI: Map<String, String> puSonProperties = new HashMap<String, String>(); puSonProperties.put("javax.persistence.jtaDataSource", sonJndi); EntityManagerFactory emf = Persistence.createEntityManagerFactory("PUSon", puSonProperties); PUSon - All of them use the same persistence unit log.info("Verify entity manager for son: {0} - {1}", sonCode, emSon.find(Son_configuration.class, 0) != null ? "ok" : "failed!"); This is the actual code where the loading of all entities begins. 10 mins.

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• Entity Framework 4 / POCO - Where to start?

  - by Basiclife

  Hi, I've been programming for a while and have used LINQ-To-SQL and LINQ-To-Entities before (although when using entities it has been on a Entity/Table 1-1 relationship - ie not much different than L2SQL) I've been doing a lot of reading about Inversion of Control, Unit of Work, POCO and repository patterns and would like to use this methodology in my new applications. Where I'm struggling is finding a clear, concise beginners guide for EF4 which doesn't assume knowledge of EF1. The specific questions I need answered are: Code first / model first? Pros/cons in regards to EF4 (ie what happens if I do code first, change the code at a later date and need to regenerate my DB model - Does the data get preserved and transformed or dropped?) Assuming I'm going code-first (I'd like to see how EF4 converts that to a DB schema) how do I actually get started? Quite often I've seen articles with entity diagrams stating "So this is my entity model, now I'm going to ..." - Unfortunately, I'm unclear if they're created the model in the designer, saved it to generate code then stopped any further auto-code generation -or- They've coded (POCO)? classes and the somehow imported them into the deisgner view? I suppose what I really need is an understanding of where the "magic" comes from and how to add it myself if I'm not just generating an EF model directly from a DB. I'm aware the question is a little vague but I don't know what I don't know - So any input / correction / clarification appreciated. Needless to say, I don't expect anyone to sit here and teach me EF - I'd just like some good tutorials/forums/blogs/etc. for complete entity newbies Many thanks in advance

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• Going "behind Hibernate's back" to update foreign key values without an associated entity

  - by Alex Cruise

  Updated: I wound up "solving" the problem by doing the opposite! I now have the entity reference field set as read-only (insertable=false updatable=false), and the foreign key field read-write. This means I need to take special care when saving new entities, but on querying, the entity properties get resolved for me. I have a bidirectional one-to-many association in my domain model, where I'm using JPA annotations and Hibernate as the persistence provider. It's pretty much your bog-standard parent/child configuration, with one difference being that I want to expose the parent's foreign key as a separate property of the child alongside the reference to a parent instance, like so: @Entity public class Child { @Id @GeneratedValue Long id; @Column(name="parent_id", insertable=false, updatable=false) private Long parentId; @ManyToOne(cascade=CascadeType.ALL) @JoinColumn(name="parent_id") private Parent parent; private long timestamp; } @Entity public class Parent { @Id @GeneratedValue Long id; @OrderBy("timestamp") @OneToMany(mappedBy="parent", cascade=CascadeType.ALL, fetch=FetchType.LAZY) private List<Child> children; } This works just fine most of the time, but there are many (legacy) cases when I'd like to put an invalid value in the parent_id column without having to create a bogus Parent first. Unfortunately, Hibernate won't save values assigned to the parentId field due to insertable=false, updatable=false, which it requires when the same column is mapped to multiple properties. Is there any nice way to "go behind Hibernate's back" and sneak values into that field without having to drop down to JDBC or implement an interceptor? Thanks!

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• Updating entity fields in app engine development server

  - by Joey

  I recently tried updating a field in one of my entities on the app engine local dev server via the sdk console. It appeared to have updated just fine (a simple float). However, when I followed up with a query on the entity, I received an exception: "Items in the mSomeList list must all be Key instances". mSomeList is just another list field I have in that entity, not the one I modified. Is there any reason manually changing a field would adversely throw something off such that the server gets confused? Is this a known bug? I wrote an http handler to alter the field through server code and it works fine if I take that approach. Update: (adding details) I am using the python google app engine server. Basically if I go into the Google App Engine Launcher and press the SDK Console button, then go into one of my entities and edit a field that is a float (i.e. change it from 0 to 3.5, for instance), I get the "Items in the mMyList list must all be Key instance" suddenly when I query the entity like this: query = DataModels.RegionData.gql("WHERE mRegion = :1", region) entry = query.get() the RegionData entity is what has the mMyList member. As mentioned previously, if I do not manually change the field but rather do so through server code, i.e. query = DataModels.RegionData.gql("WHERE mRegion = :1", region) entry = query.get() entry.mMyFloat = 3.5 entry.put() Then it works.

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• Using nHibernate to map two different data models to one entity model

  - by Dan

  I have two different data models that map to the same Car entity. I needed to create a second entity called ParkedCar, which is identical to Car (and therefore inherits from it) in order to stop nhibernate complaining that two mappings exists for the same entity. public class Car { protected Car() { IsParked = false; } public virtual int Id { get; set; } public bool IsParked { get; internal set; } } public class ParkedCar : Car { public ParkedCar() { IsParked = true; } //no additional properties to car, merely exists to support mapping and signify the car is parked } The only issue is that when I come to retrieve a Car from the database using the Criteria API like so: SessionProvider.OpenSession.Session.CreateCriteria<Car>() .Add(Restrictions.Eq("Id", 123)) .List<Car>(); The query brings back Car Entities that are from the ParkedCar data model. Its as if nhibernate defaults to the specialised entity. And the mappings are defiantly looking in the right place: <class name="Car" xmlns="urn:nhibernate-mapping-2.2" table="tblCar"> <class name="ParkedCar" xmlns="urn:nhibernate-mapping-2.2" table="tblParkedCar" > How do I stop this?

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• Doctrine 2 entity cannot be saved with its many-to-many related entities

  - by user1333185

  I'm writing a project in ZF and have many-to-many related accounts and videos entities and I provide the account with the videos collection. When I try to save the account I receive the following error: A new entity was found through the relationship 'Entities\Account#playlistVideos' that was not configured to cascade persist operations for entity: Entities\Video@000000004d5f02ef00000000196757dc. Explicitly persist the new entity or configure cascading persist operations on the relationship. If you cannot find out which entity causes the problem implement 'Entities\Video#__toString()' to get a clue. I found a suggested solution with cascade={"persist"} which should allow videos to be saved together with the account by only specifying $this-em-persist($account) but then I get the error: Fatal error: method_exists(): The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "Proxies\EntitiesAccountProxy" of the object you are trying to operate on was loaded before unserialize() gets called or provide a __autoload() function to load the class definition in... The same happens when I try to manually persist videos and account. Thank you for the help in advance.

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• Enum.TryParse with Flags attribute

  - by Sunny

  I have written code to TryParse enum either by value or by its name as shown below. How can I extend this code to include parsing enums with Flags attribute? public static bool TryParse<T>(this T enum_type, object value, out T result) where T : struct { return enum_type.TryParse<T>(value, true, out result); } public static bool TryParse<T>(this T enum_type, object value, bool ignoreCase, out T result) where T : struct { result = default(T); var is_converted = false; var is_valid_value_for_conversion = new Func<T, object, bool, bool>[]{ (e, v, i) => e.GetType().IsEnum, (e, v, i) => value != null, (e, v, i) => Enum.GetNames(e.GetType()).Any(n => String.Compare(n, v.ToString(), i) == 0) || Enum.IsDefined(e.GetType(), v) }; if(is_valid_value_for_conversion.All(rule => rule(enum_type, value, ignoreCase))){ result = (T)Enum.Parse(typeof(T), value.ToString(), ignoreCase); is_converted = true; } return is_converted; } Currently this code works for the following enums: enum SomeEnum{ A, B, C } // can parse either by 'A' or 'a' enum SomeEnum1 : int { A = 1, B = 2, C = 3 } // can parse either by 'A' or 'a' or 1 or "1" Does not work for: [Flags] enum SomeEnum2 { A = 1, B = 2, C = 4 } // can parse either by 'A' or 'a' // cannot parse for A|B Thanks!

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• update attribute a element in arraylist on java ?

  - by tiendv

  I have a class Class TextChunks extends Token { ArrayList<Token> arrt = new ArrayList<Token>(); } extent fron class : class Token { String s; int frequency = 1 ;// Tern frequency in TextChunk } Now in token i have arraylist token , i want to update attribute frequency of token in Texchunks when have more than one tokens same . For clearly a give a example : Texchunks :" in particular in domain and range in some " So have 8 token : in,particular,in,domain,and,range,in,some i want update attribute frequency for token : in this example when i get attribute frequency of token "in" must return 3 it mean when i call : get frequency of Texchunks when dislay : in 3 particular 1 in 3 domain 1 and 1 range 1 in 3 some 1 here my code : public TextChunks updateFrequencyOfTokenInTextChunks (TextChunks tc) throws CloneNotSupportedException { TextChunks result = (TextChunks) tc.clone(); for (int i =0 ; i< result.arrt.size() ; i++ ){ int j=i+1; if (result.arrt.get(i).compareTwoToken(result.arrt.get(j))== true ) { // help here how to update attribute result.arrt.get(i) // and result.arrt.get(J) = ++ and } } return tc; } Thanks in advandce

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• Under what circumstances will an entity be able to lazily load its relationships in JPA

  - by Mowgli

  Assuming a Java EE container is being used with JPA persistence and JTA transaction management where EJB and WAR packages are inside a EAR package. Say an entity with lazy-load relationships has just been returned from a JPQL search, such as the getBoats method below: @Stateless public class BoatFacade implements BoatFacadeRemote, BoatFacadeLocal { @PersistenceContext(unitName = "boats") private EntityManager em; @Override public List<Boat> getBoats(Collection<Integer> boatIDs) { if(boatIDs.isEmpty()) { return Collections.<Boat>emptyList(); } Query query = em.createNamedQuery("getAllBoats"); query.setParameter("boatID", boatIDs); List<Boat> boats = query.getResultList(); return boats; } } The entity: @Entity @NamedQuery( name="getAllBoats", query="Select b from Boat b where b.id in : boatID") public class Boat { @Id private long id; @OneToOne(fetch=FetchType.LAZY) private Gun mainGun; public Gun getMainGun() { return mainGun; } } Where will its lazy-load relationships be loadable (assuming the same stateless request): Same JAR: A method in the same EJB A method in another EJB A method in a POJO in the same EJB JAR Same EAR, but outside EJB JAR: A method in a web tier managed bean. A method in a web tier POJO. Different EAR: A method in a different EAR which receives the entity through RMI. What is it that restricts the scope, for example: the JPA transaction, persistence context or JTA transaction?

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• Find XmlNode where attribute value is contained in string

  - by bflemi3

  I have an xml file... <?xml version="1.0" encoding="UTF-8"?> <items defaultNode="1"> <default contentPlaceholderName="pageContent" template="" genericContentItemName="" /> <item urlSearchPattern="connections-learning" contentPlaceholderName="pageContent" template="Connections Learning Content Page" genericContentItemName="" /> <item urlSearchPattern="online-high-school" contentPlaceholderName="pageContent" template="" genericContentItemName="" /> </items> I am trying to find the first node where the urlSearchPattern attribute is contained in the string urlSearchPattern. Where I'm having trouble is finding the nodes where the attribute is contained in the string value instead of the string value be contained in the attribute. Here's my attempt so far. This will find the firstOrDefault node where the string value is contained in the attribute (I need the opposite)... string urlSearchPattern = Request.QueryString["aspxerrorpath"]; MissingPageSettingsXmlDocument missingPageSettingsXmlDocument = new MissingPageSettingsXmlDocument(); XmlNode missingPageItem = missingPageSettingsXmlDocument.SelectNodes(ITEM_XML_PATH).Cast<XmlNode>().Where(item => item.Attributes["urlSearchPattern"].ToString().ToLower().Contains(urlSearchPattern)).FirstOrDefault();

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• Get & set drop down value using jQuery.

  - by Muhammad Sajid

  If user select an option from dropdown it will shown it a textbox but if he select option having value "Other" then a row will appear to type value for other. my code works fine except when option value is not equal to "Other" <script type="text/javascript"><!-- function setAndReset(box) { if(box.value == 'Other'){ $("#ShowHide").hide(); } document.FormName.hiddenInput.value = box.value; } //--> </script> <body bgcolor="#ffffff"> <form id="FormName" action="" method="get" name="FormName"> <select name="choice1" size="1" onchange="setAndReset(this);"> <option value="one">first</option> <option value="two">second</option> <option value="three">third</option> <option value="other">Other</option> </select> <input type="text" name="hiddenInput" value=""> <tablt><tr id="ShowHide"><td> <input type="text" name="otherInput"> </td></tr></table> <input type="submit" name="submitButtonName"> </form> </body> but it does not show/hide & does not set value in textbox. If it's solve using jquery then i will be thankful to you for you code. Thanks.

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• Reattaching an object graph to an EntityContext: "cannot track multiple objects with the same key"

  - by dkr88

  Can EF really be this bad? Maybe... Let's say I have a fully loaded, disconnected object graph that looks like this: myReport = {Report} {ReportEdit {User: "JohnDoe"}} {ReportEdit {User: "JohnDoe"}} Basically a report with 2 edits that were done by the same user. And then I do this: EntityContext.Attach(myReport); InvalidOperationException: An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key. Why? Because the EF is trying to attach the {User: "JohnDoe"} entity TWICE. This will work: myReport = {Report} {ReportEdit {User: "JohnDoe"}} EntityContext.Attach(myReport); No problems here because the {User: "JohnDoe"} entity only appears in the object graph once. What's more, since you can't control how the EF attaches an entity, there is no way to stop it from attaching the entire object graph. So really if you want to reattach a complex entity that contains more than one reference to the same entity... well, good luck. At least that's how it looks to me. Any comments? UPDATE: Added sample code: // Load the report Report theReport; using (var context1 = new TestEntities()) { context1.Reports.MergeOption = MergeOption.NoTracking; theReport = (from r in context1.Reports.Include("ReportEdits.User") where r.Id == reportId select r).First(); } // theReport looks like this: // {Report[Id=1]} // {ReportEdit[Id=1] {User[Id=1,Name="John Doe"]} // {ReportEdit[Id=2] {User[Id=1,Name="John Doe"]} // Try to re-attach the report object graph using (var context2 = new TestEntities()) { context2.Attach(theReport); // InvalidOperationException }

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• Default value for file path in function gives SyntaxError. Work around?

  - by LtPinback

  for this, import os.path def f(data_file_path=os.path.join(os.getcwd(),'temp'),type): ... return data I get this, SyntaxError: non-default argument follows default argument Is there a way to make this work or do I have to define a variable such as, rawdata_path = os.path.join(os.getcwd(),'temp') and then plug that into the function?

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• How can I get a value out of a jQuery object?

  - by Jannis

  I am returning some data (example below) and saving it to a jQuery object (or is this an array and I am confusing the two?) when I log the variable that is the object it has the values I am looking for but how do I access the data inside this object? code $itemPosition = { 'top': $item.offset().top, 'left':$item.offset().left }, console.log($itemPosition); This would log out (the in this case expected) top: 0 & left: 490. But how can I know work with those values? Also, while this it is probably obvious I am still in the early stages of learning jQuery/Javascript rest assured that reference books are on their way, but so far the SO community has been invaluable to my learning, so thanks for reading! J.

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• Initialize virtual attributes

  - by Horace Loeb

  I have an IncomingEmail model with an attachments virtual attribute: class IncomingEmail < ActiveRecord::Base attr_accessor :attachments end I want the attachments virtual attribute to be initialized to [] rather than nil so that I can do: >> i = IncomingEmail.new => #<IncomingEmail id: nil,...) >> i.attachments << "whatever" Without first setting i.attachments to [] (put another way, I want this virtual attribute to default to an empty array rather than nil)

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• Get variable value from XML to JavaScript. Pure way.

  - by kalininew

  I have XML: <point> ... <longitude>34.123123</longitude> </point> <point> ... <longitude>11.12534534</longitude> </point> <point> ... <longitude>32.567653</longitude> </point> <point> ... <longitude>33.345345</longitude> </point> ... Task: get values of <longitude> in javascript (in variable). Which is purest way? It is possible to do it without XSLT (without making dummy elements)?

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• When does a const return type interfere with template instantiation?

  - by Rimo

  From Herb Sutter's GotW #6 Return-by-value should normally be const for non-builtin return types. ... Note: Lakos (pg. 618) argues against returning const value, and notes that it is redundant for builtins anyway (for example, returning "const int"), which he notes may interfere with template instantiation. While Sutter seems to disagree on whether to return a const value or non-const value when returning an object of a non-built type by value with Lakos, he generally agrees that returning a const value of a built-in type (e.g const int) is not a good idea. While I understand why that is useless because the return value cannot be modified as it is an rvalue, I cannot find an example of how that might interfere with template instantiation. Please give me an example of how having a const qualifier for a return type might interfere with template instantiation.

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