persist | 易学教程

hibernate does not add entity to persistencecontext after persist

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问题 I have a managedbean that has a list of entity objects of current page. after I create a new object and persist it to db using persist() in a transaction; in another transaction when I call merge(because the entity is in detached state due to previous transaction commit); entitymanager cannot find the object in persistence context and throw a select query to database. Am I missing something or is that normal behavior? Update: The above problem exists when I use mysql database and

redis出现的问题

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【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 1. redis快照被强制关闭了 MISCONF Redis is configured to save RDB snapshots, but it is currently not able to persist on disk. Commands that may modify the data set are disabled, because this instance is configured to report errors during writes if RDB snapshotting fails (stop-writes-on-bgsave-error option) redis快照被强制关闭了导致不能持久化的问题，可通过stop-writes-on-bgsave-error值设置为no即可避免这种问题来源： oschina 链接： https://my.oschina.net/u/3631797/blog/3152117

persist new entity onFlush

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问题 I try to user the onFlush Event in Doctrine to persist a new entity, but it leads to an infinite loop when trying to persist. Here is what I do in the Listener: $countusers = $em->getRepository('DankeForumBundle:NotificationUser')->countNotificationsByDeal($entity); if ($countusers > 0) { $notification = new NotificationAction(); $notification->setDeal($entity); $notification->setDatepost(new \DateTime()); $notification->setNotificationtype(NotificationAction::TYPE_TOP_DEAL); // $em is set to

Persisting DropDownList Value in PageIndexChanged of GridView

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问题 Protected Sub grdView_PageIndexChanging(sender As Object, e As GridViewPageEventArgs) Handles grdView.PageIndexChanging grdView.SelectedIndex = -1 grdView.PageIndex = e.NewPageIndex ' To persist DDL values at paging using datatable Dim Data As New DataTable Data.Columns.Add("RowIndex", Type.GetType("System.Int32")) Data.Columns.Add("SelectedValue", Type.GetType("System.String")) For Each Row As GridViewRow In grdView.Rows Dim ddl As DropDownList = DirectCast(Row.FindControl("ddlSample"),

sparkCore-RDD详解

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【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 1.1 什么是RDD 1.1.1 产生背景当初设计RDD主要是为了解决三个问题： Fast :Spark之前的Hadoop用的是MapReduce的编程模型，没有很好的利用分布式内存系统，中间结果都需要保存到external disk，运行效率很低。RDD模型是in-memory computing的，中间结果不需要被物化（materialized），它的 persistence 机制，可以保存中间结果重复使用，对需要迭代运算的机器学习应用和交互式数据挖掘应用，加速显著。Spark快还有一个原因是开头提到过的 Delay Scheduling 机制，它得益于RDD的Dependency设计。 General: MapReduce 编程模型只能提供有限的运算种类（Map和Reduce），RDD希望支持更广泛更多样的operators（map，flatMap，filter等等），然后用户可以任意地组合他们。 The ability of RDDs to accommodate computing needs that were previously met only by introducing new frameworks is, we believe, the most credible evidence

JDO Persist an existing entity creats new entry in DB

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问题 This is my too first exemple using JDO I have the class Account : public class Compte { @PrimaryKey @Persistent(valueStrategy=IdGeneratorStrategy.INCREMENT) private int idCompte; // other attributes private Regle regle; // .... } I have entities saved in the table regle, and when i want to create a new Compte i retreive one of those Regle and i add it to the new Compte and i make Compte persisted. I do that : Compte compte = new Compte(); Regle regle = retreiveRegleByName(name); compte

detached entity passed to persist: entities.Event

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问题 I am having an issue with a hibernate mapper while trying to store items within the database I am trying to persist a Booking object I am trying to store an element with a many to one relationship with an element that already has a many to one relationship with another Booking class has a many to one relationship with the Event class but the Event Class already has a many to one relationship with the Users Class Which I am also trying to save again within the same table Booking{ //many to one

doctrine persist php class which inherit doctrine entity

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问题 Is it possible to have a php class which extends a doctrine entity and to persist it ? example: /** * @Entity */ class A { /** * @ORM\ManyToMany(targetEntity="C", mappedBy="parents") */ protected $children; } class B extends A { ... } class C { /** * @ORM\ManyToMany(targetEntity="A", inversedBy="children") */ protected $parents; } $b = new B(); $em->persist($b); 回答1: Yes it's possible, this is called inheritance mapping, but the child class has to be explicitly declared as @Entity and its

How to persist a new entity containing multiple identical instances of another unpersisted entity with spring-boot and JPA?

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问题 Overview: I'm building a spring-boot application which, in part, retrieves some entities from an external REST service and compares it to previous versions of the entity held locally in a database. I'm injecting EntityManager with @PersistenceContext , and using that to work with the database, as there are many entity types, and the type is initially unknown to the module. I could get a JpaRepository from a factory, but the number of different entity types is liable to grow, and I'd rather

redis 运维异常文件解决

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【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 问题1 2019-12-17 11:26:04.482 [http-nio-8183-exec-10] ERROR o.l.litemall.core.config.GlobalExceptionHandler -able to persist on disk. Commands that may modify the data set are disabled, because this instance is ctes-on-bgsave-error option). Please check the Redis logs for details about the RDB error. redis.clients.jedis.exceptions.JedisDataException: MISCONF Redis is configured to save RDB snapshots, b data set are disabled, because this instance is configured to report errors during writes if RDB snapsogs for details about the RDB error. at redis.clients