persistence

问题 I'm building an AngularJS application that interacts with an API that uses authentication tokens to authenticate users. Everything seems to be working fine, but I'm struggling with a way to properly persist the authentication token between requests. At the moment, when a user logs in with correct credentials an authToken is returned, and I'm setting that on $rootScope.authToken . I'm also sending that auth token for future requests, but if I do a hard reload reload the webpage with F5

问题 I am trying to persist some data into the H2 database. but I keep getting the schema not found error message as below. Jan 02, 2014 8:55:51 PM org.apache.catalina.core.AprLifecycleListener init INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: C:\Program Files\Java\jdk1.7.0_45\bin;C:\windows\Sun\Java\bin;C:\windows\system32;C:\windows;M:\app\oracleuser\product\12.1.0\dbhome_1\bin;C:\Program

问题 EDIT: onload() method changed to afterLoad(): Otherwise objects might not be passed properly to the map. I am currently using some domain classes with a lot of dynamic, complex properties, that I need to persist and update regularly. I keep these in a Map structure for each class since this makes it easy for referencing in my controllers etc. However, since Grails does not seem to be able to persist complex property types like List and Map in the DB I am using the following approach to

问题 Having some trouble getting this working. I am creating a site with a Tournament, which users can register for. The Tournament will have a list of registered members. It's not holding User objects, just the user email address, which is the a key for the user table anyway. I want to store the array list in such a way that I will have multiple copies of the tournament id, but only one instance of a username per tournament id. eg T_ID Username 1 Tom 1 Mike 1 John 2 Tom 2 Chris 2 Timmy 3 Timmy 3

问题 I am working on the persistence layer of a project that involves Workspace 's, each of which may contain zero, one, or more Document 's. (I am trying to follow Domain-Driven-Design principles but my questions may not be directly related to this.) Question 1: Should I separate out persistence? I.e., do you design you entity and value classes in such a way that you can Create entities and values in memory, just as you would do without persistence (possibly using a Factory method Workspaces

问题 Currently I am using ViewData or TempData for object persistance in my ASP.NET MVC application. However in a few cases where I am storing objects into ViewData through my base controller class, I am hitting the database on every request (when ViewData["whatever"] == null). It would be good to persist these into something with a longer lifespan, namely session. Similarly in an order processing pipeline, I don't want things like Order to be saved to the database on creation. I would rather

问题 I know that JPA implementors (like Hibernate) monitor the entities attached to the persistence context, and if any field of any entity is changed, then the change is updated to the database. My question is, how does JPA keep track of the changes? The Entities are not intercepted (by proxyies), so for sure it is not throught the interception of the "setters", how is it done? I am interested on the implementation detail of this "dirty checking" feature. 回答1: They do something that is totally

问题 I am in the process of migrating from BinaryFormatter to Protobuf-net (which so far appears to offer HUGE improvements both in terms of storage size and deserialization time). A problem I've encountered however is that double?[] arrays do not deserialize in the same form they were serialized. Any values in the array that are null get removed in their entirety - i.e. if I start with an array with 6 elements of [null, null, 1, 2, 3, null], after deserialization I end up with an array of [1, 2,

问题 If I have the following code: populationList = [] for i in range(0, 2000) populationList.append(myObject). populationList = [] Would all the objects within populationList get cleaned up now the reference to them has been deleated? I understand that this is the case in Java but it it the same for Python? Or should the objects need to be explicitly deleated? 回答1: CPython uses reference counting to automatically clean up objects that are no longer referenced. Each name, list index, dictionary

问题 I am using EntityListeners ( @PreUpdate ) to perform certain actions once my entities change. However I noticed that changes of a collection inside an entity does not fire the JPA entity listener, that makes sense because the table containing the entity was not changed, but a many to many table was. Is there a way to make the entity listener fire in case of a collection change? 回答1: Listeners are fired for versioned entities (see javax.persistence.Version). Found via this answer: https:/