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  • Do Blob properties on entities affect query performance?

    - by Jaroslav Záruba
    Hello I'm trying to make my mind on whether to store a binary representation of an entity as its Blob property, or whether I better keep the blobs in some separate 'wrapping' class. Possible impact on memory heap and/or a query execution time are my concerns in the first case, complexity votes against the other one. I know Blobs are not indexed, i.e. index size is not what I'm worrying about. Also I assume for blobs Datastore puts defaultFetchGroup to false, but does it mean that blobs don't make a difference in queries? Regards J. Záruba

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  • Entity Framework Update Entity along with child entities (add/update as necessary)

    - by Jorin
    I have a many-to-many relationship between Issues and Scopes in my EF Context. In ASP.NET MVC, I bring up an Edit form that allows the user to edit a particular Issue. At the bottom of the form, is a list of checkboxes that allow them to select which scopes apply to this issue. When editing an issue, it likely will always have some Scopes associated with it already--these boxes will be checked already. However, the user has the opportunity to check more scopes or remove some of the currently checked scopes. My code looked something like this to save just the Issue: using (var edmx = new MayflyEntities()) { Issue issue = new Issue { IssueID = id, TSColumn = formIssue.TSColumn }; edmx.Issues.Attach(issue); UpdateModel(issue); if (ModelState.IsValid) { //if (edmx.SaveChanges() != 1) throw new Exception("Unknown error. Please try again."); edmx.SaveChanges(); TempData["message"] = string.Format("Issue #{0} successfully modified.", id); } } So, when I try to add in the logic to save the associated scopes, I tried several things, but ultimately, this is what made the most sense to me: using (var edmx = new MayflyEntities()) { Issue issue = new Issue { IssueID = id, TSColumn = formIssue.TSColumn }; edmx.Issues.Attach(issue); UpdateModel(issue); foreach (int scopeID in formIssue.ScopeIDs) { var thisScope = new Scope { ID = scopeID }; edmx.Scopes.Attach(thisScope); thisScope.ProjectID = formIssue.ProjectID; if (issue.Scopes.Contains(thisScope)) { issue.Scopes.Attach(thisScope); //the scope already exists } else { issue.Scopes.Add(thisScope); // the scope needs to be added } } if (ModelState.IsValid) { //if (edmx.SaveChanges() != 1) throw new Exception("Unknown error. Please try again."); edmx.SaveChanges(); TempData["message"] = string.Format("Issue #{0} successfully modified.", id); } } But, unfortunately, that just throws the following exception: An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key. What am I doing wrong?

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  • Use of Java constructors in persistent entities

    - by Mr Morgan
    Hello I'm new to JPA and using persistence in Java anyway and I have two questions I can't quite work out: I have generated tags as: @JoinColumn(name = "UserName", referencedColumnName = "UserName") @ManyToOne(optional = false) private User userName; @JoinColumn(name = "DatasetNo", referencedColumnName = "DatasetNo") @ManyToOne(optional = false) private Dataset datasetNo; But in one of the constructors for the class, no reference is made to columns UserName or DatasetNo whereas all other columns in the class are referenced in the constructor. Can anyone tell me why this is? Both columns UserName and DatasetNo are 'foreign keys' on the entity Visualisation which corresponds to a database table of the same name. I can't quite work out the ORM. And when using entity classes, or POJO, is it better to have class variables like: private User userName; Where an instance of a class is specified or simply the key of that class instance like: private String userName; Thanks Mr Morgan.

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  • Testing complex entities

    - by Carlos
    I've got a C# form, with various controls on it. The form controls an ongoing process, and there are many, many aspects that need to be right for the program to run correctly. Each part can be unit tested (for instance, loading some coefficients, drawing some diagnostics) but I often run into problems that are best described with an example: "If I click here, then here, then change this, then re-open the form, then click here, it crashes or produces an error" I've tried my best to use common code organisational ideas (inheritance, DRY, separation of concerns) but there never seems to be a way to test every single path, and inevitably, a form with several controls will have a huge number of ways to execute. What can I read (preferably online) that addresses this kind of issue, and is there a (non-generic) term for it. This isn't a specific problem I'm having, but one that creeps up on me, especially with WinForms.

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  • NHibernate & Cancelling Changes to Entities

    - by user129609
    Hi, This seems like it would be a common issue to be but I don't know the best way to solve it. I want to be able to send an Entity to a view, have changes be made to the entity in the view, but then cancel (remove) those changes if the user cancels out of the view. What is the proper way to do this. Here are two options I have but I think there should be others that are better 1) Take an entity, create a clone, send the clone to the view...if changes are accepted, update the original entity with the clone's values 2) Send the entity to the view, if the user cancels, remove the entity from NHibernate's cache and reload it from the database For (2), the issue for me would be that the old entity could still be referenced throughout my project after it has been removed from the cache.

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  • How to eager fetch a child collection while joining child collection entities to an association

    - by ShaneC
    Assuming the following fictional layout Dealership has many Cars has a Manufacturer I want to write a query that says get me a Dealership with a Name of X and also get the Cars collection but use a join against the manufacturer when you do so. I think this would require usage of ICriteria. I'm thinking something like this.. var dealershipQuery = Session.CreateCriteria< Dealership>("d") .Add(Restrictions.InsenstiveLike("d.Name", "Foo")) .CreateAlias("d.Cars", "c") .SetFetchMode("d.Cars", FetchMode.Select) .SetFetchMode("c.Manufacturer", FetchMode.Join) .UniqueResult< Dealership>(); But the resulting query looks nothing like I would have expected. I'm starting to think a DetachedCriteria may be required somewhere but I'm not sure. Thoughts?

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  • Replace HTML entities in a string avoiding <img> tags

    - by Xeos
    I have the following input: Hi! How are you? <script>//NOT EVIL!</script> Wassup? :P LOOOL!!! :D :D :D Which is then run through emoticon library and it become this: Hi! How are you? <script>//NOT EVIL!</script> Wassup? <img class="smiley" alt="" title="tongue, :P" src="ui/emoticons/15.gif"> LOOOL!!! <img class="smiley" alt="" title="big grin, :D" src="ui/emoticons/5.gif"> <img class="smiley" alt="" title="big grin, :P" src="ui/emoticons/5.gif"> <img class="smiley" alt="" title="big grin, :P" src="ui/emoticons/5.gif"> I have a function that escapes HTML entites to prevent XSS. So running it on raw input for the first line would produce: Hi! How are you? &lt;script&gt;//NOT EVIL!&lt;/script&gt; Now I need to escape all the input, but at the same time I need to preserve emoticons in their initial state. So when there is <:-P emoticon, it stays like that and does not become &lt;:-P. I was thinking of running a regex split on the emotified text. Then processing each part on its own and then concatenating the string together, but I am not sure how easily can Regex be bypassed? I know the format will always be this: [<img class="smiley" alt="] [empty string] [" title="] [one of the values from a big list] [, ] [another value from the list (may be matching original emoticon)] [" src="ui/emoticons/] [integer from Y to X] [.gif">] Using the list MAY be slow, since I need to run that regex on text that may have 20-30-40 emoticons. Plus there may be 5-10-15 text messages to process. What could be an elegant solution to this? I am ready to use third-party library or jQuery for this. PHP preprocessing is possible as well.

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  • Common one-to-many table for multiple entities

    - by Ben V
    Suppose I have two tables, Customer and Vendor. I want to have a common address table for customer and vendor addresses. Customers and Vendors can both have one to many addresses. Option 1 Add columns for the AddressID to the Customer and Vendor tables. This just doesn't seem like a clean solution to me. Customer Vendor Address -------- --------- --------- CustomerID VendorID AddressID AddressID1 AddressID1 Street AddressID2 AddressID2 City... Option 2 Move the foreign key to the Address table. For a Customer, Address.CustomerID will be populated. For a Vendor, Address.VendorID will be populated. I don't like this either - I shouldn't need to modify the address table every time I want to use it for another entity. Customer Vendor Address -------- --------- --------- CustomerID VendorID AddressID CustomerID VendorID Option 3 I've also seen this - only 1 foreign key column on the Address table with another column to identify which foreign key table the address belongs to. I don't like this one because it requires all the foreign key tables to have the same type of ID. It also seems messy once you start coding against it. Customer Vendor Address -------- --------- --------- CustomerID VendorID AddressID FKTable FKID So, am I just too picky, or is there something I haven't thought of?

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  • MVC 2 - Name Attributes on HTML Input Field when using Parent/Child Entities

    - by Click Ahead
    Hi All, I'm pretty new to MVC 2 using the Entity Framework. I have two tables Company {ID int identity PK,Name nvarchar} and User {ID int identity PK,UserName nvarchar,CompanyID int FK}. A Foreign Key exists between User and Company. I generated my ADO.NET Entity Data Model, a Controller and a view to insert a record. My HTML form has the fields Company and UserName and the idea is when I click save a Company and User is inserted into the database. Sounds straight forward right! My question is as follows: I created a strongly-typed view derived from my 'User' entity. I'm using the the html helper Html.TextBoxFor(model = model.Organisation.Name) but the html name attribute for this input field is 'Organisation.Name'. My problem with this is that the dot throws up all sorts of issues in JQuery, which sees this as a property. If I want to change the name I read that I can use DataAnnotations but because I used the Entity Designer this involves using Buddy Classes. Seems like a bit of overkill just to change the html name attribute on this input field. Am I approaching this the right way or am I missing something here? Thanks for the help !

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  • Nhibernate: mapping two different properties between the same 2 entities

    - by Carlos Decas
    I have a Class A: public class ClassA { public int ID {get; private set;} public string Code {get; private set;} public ClassB B {get; private set;} public IList<ClassB> ListB {get; private set;} } And a ClassB: public class ClassB { public int ID {get; private set;} public string Code {get; private set;} public ClassA A {get; private set;} //some other attributes... } And the Mappings: public ClassAMap() { Table("ClassA"); Id(classA => classA .ID, "ID").GeneratedBy.Identity(); Map(classA => classA.Code, "Code").Unique().Not.Nullable(); //HERE IS THE PROBLEM: -------- References(classA => classA.B,"IDClassB").Cascade.SaveUpdate(); //----- HasMany(classA => classA.ListB).Table("ClassB").KeyColumn("IDClassA").AsBag().Not.LazyLoad().Inverse().Cascade.AllDeleteOrphan(); } ClassB Mappings: public ClassBMap() { Table("ClassB"); Id(classB => classB.ID).GeneratedBy.Identity(); References(classB => classB.A, "IDClassA").ForeignKey("ID").Cascade.SaveUpdate(); } The mappings for ListB in classA worked ok, because at first the was only ListB property and not B, when i had to map B i tried this: References(classA => classA.B,"IDClassB"); The mapping test failed because B wasn't saved, so i did this: References(classA => classA.B,"IDClassB").Cascade.SaveUpdate(); This time B was saved, but by saving B, classA was inserted two times, by A.B and by B.A. How can i solve this problem? Why does it work for the ListB property and not for the B property? Thanks

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  • RegEx to replace html entities

    - by DeltaFox
    Hi, all. I'm looking for a way to replace the bullet character in Greasemonkey. I assume a Regular Expression will do the trick, but I'm not as well-versed in it as many of you. For example, "SampleSite.com • Page Title" becoming "SampleSite.com Page Title". The issue is that the character has already been parsed by the time Greasemonkey has gotten to it, and I don't know how to make it recognize the symbol. I've tried these so far, but they haven't worked: newTitle = document.title.replace(/•/g, ""); newTitle = document.title.replace("•", ""); //just for grins, but didn't work anyway

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  • Core Data: migrating entities with self-referential properties

    - by Dan
    My Core Data model contains an entity, Shape, that has two self-referential relationships, which means four properties. One pair is a one-to-many relationship (Shape.containedBy <- Shape.contains) and the another is a many-to-many relationship (Shape.nextShapes <<- Shape.previousShapes). It all works perfectly in the application, so I don't think self-referencing relationships is a problem in general. However, when it comes to migrating the model to a new version, then Xcode fails to compile the automatically generated mapping model, with this error message: 2009-10-30 17:10:09.387 mapc[18619:607] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unable to parse the format string "FUNCTION($manager ,'destinationInstancesForSourceRelationshipNamed:sourceInstances:' , 'contains' , $source.contains) == 1"' *** Call stack at first throw: ( 0 CoreFoundation 0x00007fff80d735a4 __exceptionPreprocess + 180 1 libobjc.A.dylib 0x00007fff83f0a313 objc_exception_throw + 45 2 Foundation 0x00007fff819bc8d4 _qfqp2_performParsing + 8412 3 Foundation 0x00007fff819ba79d +[NSPredicate predicateWithFormat:arguments:] + 59 4 Foundation 0x00007fff81a482ef +[NSExpression expressionWithFormat:arguments:] + 68 5 Foundation 0x00007fff81a48843 +[NSExpression expressionWithFormat:] + 155 6 XDBase 0x0000000100038e94 -[XDDevRelationshipMapping valueExpressionAsString] + 260 7 XDBase 0x000000010003ae5c -[XDMappingCompilerSupport generateCompileResultForMappingModel:] + 2828 8 XDBase 0x000000010003b135 -[XDMappingCompilerSupport compileSourcePath:options:] + 309 9 mapc 0x0000000100001a1c 0x0 + 4294973980 10 mapc 0x0000000100001794 0x0 + 4294973332 ) terminate called after throwing an instance of 'NSException' Command /Developer/usr/bin/mapc failed with exit code 6 The 'contains' is the name of one of the self-referential properties. Anyway, the really big problem is that I can't even look at this Mapping Property as Xcode crashes as soon as I select the entity mapping when viewing the mapping model. So I'm a bit lost really where to go from here. I really can't remove the self-referential properties, so I'm thinking I've got manually create a mapping model that compiles? Any ideas? Cheers

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  • Spring, Hibernate and Ehcache - Wrong entities

    - by asrijaal
    Hi there, I've got a webapp which uses spring+hibernate for my data layer. I'm using 2nd level caching with ehcache as provider. Everything seems to work so far but sometimes we encounter a problem which I can't really figure out atm. One of my tables is used for labels within the application - every user who logs access this table with his set language. Works for 90% of the time. But sometimes the user gets labels for the wrong language, e.g. instead of german everything turns to italian. After a logout and login all labels are correct. Does anyone of you encountered something like this? I'm not sure where to look at: spring+hibernate+ehcache is a solid package or is it not? Cheers

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  • Detaching all entities of T to get fresh data

    - by Goran
    Lets take an example where there are two type of entites loaded: Product and Category, Product.CategoryId - Category.Id. We have available CRUD operations on products (not Categories). If on another screen Categories are updated (or from another user in the network), we would like to be able to reload the Categories, while preserving the context we currently use, since we could be in the middle of editing data, and we do not want changes to be lost (and we cannot depend on saving, since we have incomplete data). Since there is no easy way to tell EF to get fresh data (added, removed and modified), we thought of twp possible ways: 1) Getting products attached to context, and categories detached from context. This would mean that we loose the ability to access Product.Category.Name, which we do sometimes require, so we would need to manually resolve it (example when printing data). 2) detaching / attaching all Categories from current context. Context.ChangeTracker.Entries().Where(x => x.Entity.GetType() == typeof(T)).ForEach(x => x.State = EntityState.Detached); And then reload the categories, which will get fresh data. Do you find any problem with this second approach? We understand that this will require all constraints to be put on foreign keys, and not navigation properties, since when detaching all Categories, Product.Category navigation properties would be reset to null also. Also, there could be a potential performance problem, which we did not test, since there could be couple of thousand products loaded, and all would need to resolve navigation property when reloading. Which of the two do you prefer, and is there a better way (EF6 + .NET 4.0)?

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  • DDD: Enum like entities

    - by Chris
    Hi all, I have the following DB model: **Person table** ID | Name | StateId ------------------------------ 1 Joe 1 2 Peter 1 3 John 2 **State table** ID | Desc ------------------------------ 1 Working 2 Vacation and domain model would be (simplified): public class Person { public int Id { get; } public string Name { get; set; } public State State { get; set; } } public class State { private int id; public string Name { get; set; } } The state might be used in the domain logic e.g.: if(person.State == State.Working) // some logic So from my understanding, the State acts like a value object which is used for domain logic checks. But it also needs to be present in the DB model to represent a clean ERM. So state might be extended to: public class State { private int id; public string Name { get; set; } public static State New {get {return new State([hardCodedIdHere?], [hardCodeNameHere?]);}} } But using this approach the name of the state would be hardcoded into the domain. Do you know what I mean? Is there a standard approach for such a thing? From my point of view what I am trying to do is using an object (which is persisted from the ERM design perspective) as a sort of value object within my domain. What do you think? Question update: Probably my question wasn't clear enough. What I need to know is, how I would use an entity (like the State example) that is stored in a database within my domain logic. To avoid things like: if(person.State.Id == State.Working.Id) // some logic or if(person.State.Id == WORKING_ID) // some logic

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  • How to filter entities by their parents in ManyToOne side in Google App Engine

    - by palto
    I use Google App Engine. When I try to do a JPA query like this: "SELECT p FROM Participant p WHERE p.party.id = :partyKey AND p.name=:participantName" I get the following error Caused by: org.datanucleus.store.appengine.FatalNucleusUserException: SELECT FROM Participant p WHERE p.party.id = :partyKey AND p.name=:participantName: Can only reference properties of a sub-object if the sub-object is embedded. I gave the key of the Party object as a parameter to the "partyKey" named parameter. The model is like this: Party has multiple Participants. I want to query a participant based on the party and the name of the participant. I just can't figure out how to filter using the party. What options do I have?

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  • The best JSF coding pattern for editing JPA entities using @RequestScoped only

    - by AlanObject
    I am in a project where I will write a lot of pages like this, so I want to use the most efficient (to write) coding pattern. Background: In the past I have used CODI's @ViewAccessScoped to preserve state between requests, and more recently I have started using flash scoped objects to save state. I can't use JSF @ViewScoped because I use CDI and they don't play well together. So I want to see if I can do this with only @RequestScoped backing beans. The page is designed like this (the p namespace is Primefaces): <f:metadata> <f:viewParam name="ID" value="#{backing.id}" /> </f:metadata> .... <h1>Edit Object Page</h1> <h:form id="formObj" rendered="#{backing.accessOK}"> <p:panelGrid columns="2"> <h:outputLabel value="Field #1:"/> <p:inputText value="#{backing.record.field1}" /> (more input fields) <h:outputLabel value="Action:" /> <h:panelGroup> <p:commandButton value="Save" action="#{backing.save}" /> <p:commandButton value="Cancel" action="backing.cancel" /> </h:panelGroup> </p:panelGrid> <p:messages showDetail="true" showSummary="true" /> </h:form> If the page is requested, the method accessOK() has the ability to keep the h:form from being rendered. Instead, the p:messages is shown with whatever FacesMessage(s) the accessOK() method cares to set. The pattern for the bean backing looks like this: @Named @RequestScoped public class Backing { private long id; private SomeJPAEntity record; private Boolean accessOK; public long getId() { return id; } public void setId(long value) { id = value; } public boolean accessOK() { if (accessOK != null) return accessOK; if (getRecord() == null) { // add a FacesMessage that explains the record // does not exist return accessOK = false; // note single = } // do any other access checks, such as write permissions return accessOK = true; } public SomeJPAEntity getRecord() { if (record != null) return record; if (getId() > 0) record = // get the record from DB else record = new SomeJPAEntity(); return record; } public String execute() { if (!accessOK()) return null; // bad edit // do other integrity checks here. If fail, set FacesMessages // and return null; if (getId() > 0) // merge the record back into the data base else // persist the record } } Here is what goes wrong with this model. When the Save button is clicked, a new instance of Backing is built, and then there are a lot of calls to the getRecord() getter before the setID() setter is called. So the logic in getRecord() breaks because it cannot rely on the id property being valid when it is called. When this was a @ViewAccessScoped (or ViewScoped) backing bean, then both the id and record properties are already set when the form is processed with the commandButton. Alternatively you can save those properties in flash storage but that has its own problems I want to avoid. So is there a way to make this programming model work within the specification?

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  • Have parameters in Dao methods to get entities the most efficient way for read-only access

    - by Blankman
    Allot of my use of hibernate, at least for that data that is presented on many parts of the web application, is for read-only purposes. I want to add some parameters to my Dao methods so I can modify the way hibernate pulls the data and how it handles transactions etc. Example usage: Data on the front page of my website is displayed to the users, it is read-only, so I want to avoid any session/entity tracking that hibernate usually does. This is data that is read-only, will not be changed in this transaction, etc. What would be the most performant way to pull the data? (the code below is c#/nhibernate, I'm implementing this in java as I learn it) public IList<Article> GetArticles() { return Session.CreateCriteria(typeof(Article)) // some where cluase }

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  • Magento coupon entities in database

    - by koramaiku
    I'm trying to develop a Magento plugin which involves using coupons. Apparently after looking around I found I found a source that mentions use of a 'salesrule' table for coupons. However when I looked at my database i couldn't find it. However I did find 3 tables that had mention 'coupon' called 'coupon_aggregated', 'coupon_aggregated_order', and 'coupon_aggregated_updated'. I just wanted to know what is the difference between the 3 tables so I can start using them? I am on the latest version of Magento. Thanks guys in advance.

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  • Accessing non-related entities in LinqToSql entity classes

    - by Chris Johnson
    In LinqToSql, if I want to access a non-related entity in an entity partial class, how do I do this without creating a new DataContext? Here's the scenario: I have the tables Client, IssueType and ClientIssueType. A Client may specify a list of IssueTypes if they do not want to use the default IssueTypes. I have the default IssueTypes in the ClientIssueType table with a ClientId of null. In my Client partial I'd like to try to retrieve all IssueTypes, and if none are found, return all default IssueTypes. The only way I can see of accessing the IssueTypes with a null ClientId is by accessing the table through a new DataContext, which is problematic once I want to start assigning them to Issues. Where am I going wrong?

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  • Uniquing with Existing Core Data Entities

    - by warrenm
    I'm using Core Data to store a lot (1000s) of items. A pair of properties on each item are used to determine uniqueness, so when a new item comes in, I compare it against the existing items before inserting it. Since the incoming data is in the form of an RSS feed, there are often many duplicates, and the cost of the uniquing step is O(N^2), which has become significant. Right now, I create a set of existing items before iterating over the list of (possible) new items. My theory is that on the first iteration, all the items will be faulted in, and assuming we aren't pressed for memory, most of those items will remain resident over the course of the iteration. I see my options thusly: Use string comparison for uniquing, iterating over all "new" items and comparing to all existing items (Current approach) Use a predicate to filter the set of existing items against the properties of the "new" items. Use a predicate with Core Data to determine uniqueness of each "new" item (without retrieving the set of existing items). Is option 3 likely to be faster than my current approach? Do you know of a better way?

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  • Second level cache for entities with where clause

    - by bertolami
    I am wondering where the hibernate second level cache works as expected if I put a where clause in the hbm.xml class definition: <hibernate-mapping> <class name="com.clazzes.A" table="TABLE_A" mutable="false" where="xyz=5" > <cache usage="read-only"/> <id name="id" /> ... Will hibernate still put the id as key into the cache, or do I have enable the query cache? E.g. when I then execute a HQL query like from A where id=2 that results in an SQL similar to select * from TABLE_A where id=2 and (xyz=5). If I execute this query twice, will it consider the second level cache, or will it nevertheless execute the SQL twice?

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  • iPhone - Create non-persistent entities in core data

    - by ncohen
    Hi everyone, I would like to use entity objects but not store them... I read that I could create them like this: myElement = (Element *)[NSEntityDescription insertNewObjectForEntityForName:@"Element" inManagedObjectContext:managedObjectContext]; And right after that remove them: [managedObjectContext deleteObject:myElement]; then I can use my elements: myElement.property1 = @"Hello"; This works pretty well even though I think this is probably not the most optimal way to do it... Then I try to use it in my UITableView... the problem is that the object get released after the initialization. My table becomes empty when I move it! Thanks edit: I've also tried to copy the element ([myElement copy]) but I get an error...

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