fetching-strategy | 易学教程

Skip child to fetching of parent - JPA

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问题 I am facing an issue where the data is getting fechted recursively. I wanted to avoid the child to fetch the parent data. Which is causing a recursive issue. I have mentioned the code below Pojo Structure class Parent { .. @OneToMany(mappedBy = "parent", fetch = FetchType.LAZY) private List<Child> childs; .. } class Child { .. @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "parentId") private Parent parent; .. } Fetching the data like this ` em = EMF.get().createEntityManager(); Query

Skip child to fetching of parent - JPA

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Python - Flask API service - Loop through API data sources, cache, and give rapid feedback on call

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问题 I'm trying to develop an API service that after collecting data continuously from different sources, elaborate that data, and keep that information ready from being requested from another service. I'm using Flask and it's working on top of a single thread. My problem is about the slowlines accessing the cached data. The gathering process it works pretty well, but sometimes when I ask for the data the server it's busy because in the meantime it's fetching the data from the sources. How should

NHibernate Eager Fetching Over Multiple Levels

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问题 I have a 3-leveled hierarchy of entities: Customer-Order-Line, which I would like to retrieve in entirety for a given customer, using ISession.Get(id). I have the following XML fragments: customer.hbm.xml: <bag name="Orders" cascade="all-delete-orphan" inverse="false" fetch="join"> <key column="CustomerID" /> <one-to-many class="Order" /> </bag> order.hbm.xml: <bag name="Lines" cascade="all-delete-orphan" inverse="false" fetch="join"> <key column="OrderID" /> <one-to-many class="Line" /> <

Join two data tables from different source databases in .NET?

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问题 How do you join two data tables from different source databases in .NET? Ideally, I can craft two queries manually and simply join on a single field. In this case, linked servers and scheduled imports are not an option. I've looked into the data relation object, but (correct me if I'm wrong) that only works for parent-child relationships. 回答1: I had a similar situation where I had 2 datatables and joined them using LINQ. Here is the code from my situation, maybe it'll help you out. var

Nhibernate producing proxy despite HQL fetch

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问题 I have the following HQL statement: select distinct t from TaskEntity as inner join fetch t.Case as c inner join fetch c.Client as client inner join fetch c.Matter as matter However, despite Matter having a FETCH against it, it's still returning as a proxy. My mapping for this object is below References(x => x.Matter).Columns(new[] {"c_client","c_matter" }); I've tried using JOIN on this, but my issue I'm going from 1 to 2 columns, so it wouldn't accept the mapping. Any thoughts? Thanks, 回答1:

Is this the right way of using ThenFetch() to load multiple collections?

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问题 I'm trying to load all the collections eagerly, using NHibernate 3 alpha 1. I'm wondering if this the right way of using ThenFetch()? Properties with plural names are collections. The others are just a single object. IQueryable<T> milestoneInstances = Db.Find<T, IQueryable<T>>(db => from mi in db where mi.RunDate == runDate select mi).Fetch(mi => mi.Milestone) .ThenFetch(m => m.PrimaryOwners) .Fetch(mi => mi.Milestone) .ThenFetch(m => m.SecondaryOwners) .Fetch(mi => mi.Milestone) .ThenFetch(m

Is this the right way of using ThenFetch() to load multiple collections?

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I'm trying to load all the collections eagerly, using NHibernate 3 alpha 1 . I'm wondering if this the right way of using ThenFetch()? Properties with plural names are collections. The others are just a single object. IQueryable<T> milestoneInstances = Db.Find<T, IQueryable<T>>(db => from mi in db where mi.RunDate == runDate select mi).Fetch(mi => mi.Milestone) .ThenFetch(m => m.PrimaryOwners) .Fetch(mi => mi.Milestone) .ThenFetch(m => m.SecondaryOwners) .Fetch(mi => mi.Milestone) .ThenFetch(m => m.Predecessors) .Fetch(mi => mi.Milestone) .ThenFetch(m => m.Function) .Fetch(mi => mi.Milestone)

Hibernate fetching in criteria ignored

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I have some class User which has one to many relation to LoginSession class (I have a collection of LoginSessions in my User class). @Entity(name="T_User") public class User() { .... @OneToMany(fetch=FetchType.LAZY, mappedBy="user", cascade=CascadeType.ALL) @Fetch(FetchMode.SELECT) @JsonIgnore private Set<LoginSession> userLoginSession; .... } Here is the LoginSession class: @Entity(name="T_LoginSession") public class LoginSession extends BasicDTO { @ManyToOne @JoinColumn(name="userId") protected User user; ... And I have this Criteria: Criteria crit = session.createCriteria(User.class); crit

Hibernate fetching in criteria ignored

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问题 I have some class User which has one to many relation to LoginSession class (I have a collection of LoginSessions in my User class). @Entity(name="T_User") public class User() { .... @OneToMany(fetch=FetchType.LAZY, mappedBy="user", cascade=CascadeType.ALL) @Fetch(FetchMode.SELECT) @JsonIgnore private Set<LoginSession> userLoginSession; .... } Here is the LoginSession class: @Entity(name="T_LoginSession") public class LoginSession extends BasicDTO { @ManyToOne @JoinColumn(name="userId")