persistence | 易学教程

Converting from String to custom Object for Spring MVC form Data binding?

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I am using Spring MVC's SimpleFormController in conjunction with Spring MVC's form JTL to create a form to edit a Generic object. On my form I have a drop down where the user can specify a server via a drop down. <form:form commandName="generic"> <form:select path="server"> <form:options items="${servers}" itemValue="id" itemLabel="name"/> </form:select> </form:form> Servers here is propagated by a database call for all available servers. server is a Server ORM pojo, that is a sub-object of another ORM pojo (Generic) that serves as my form backing object. My goal here is to change Generic's

NSCoding VS Core data

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问题 I've been searching for an article that explains NSCoding (NSKeyedArchiver...) advantages and disadvantages over use of CoreData (SQLite....). There's a lot of options, I can implement my own custom binary reader/writer, or use plists/xml/json... or use SQLite or NSCoding. I'm kind of lost right now. Can any body explain what's the difference between the MAIN features? 回答1: It depends which kind of data you want to save and whether you will use it only internally or you have to exchange the

Make persistent changes to init.rc

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问题 I want to change the init.rc file of an android pad. But after I change it and reboot the system, the original init.rc comes back. How can I make the change to the init.rc persistently without rebuild the system (since I don't have the source code of the system)? Or is there any way to work around? 回答1: Unpack the uramdisk using following command in host PC(Linux) mkdir /tmp/initrc cd /tmp/initrd sudo mount /dev/sdb1 /mnt sdb1 is partion where uramdisk/uInitrd resides. dd bs=1 skip=64 if=/mnt

How to persist an enum using NHibernate

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问题 Is there a way to persist an enum to the DB using NHibernate? That is have a table of both the code and the name of each value in the enum. I want to keep the enum without an entity, but still have a foreign key (the int representation of the enum) from all other referencing entities to the enum's table. 回答1: Why are you guys over complicating this? It is really simple. The mapping looks like this: <property name="OrganizationType"></property> The model property looks like this: public

What is Persistence Context?

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问题 I am new to the Java world and JPA. I was studying JPA and came across many new terms like Entity, persistence. While reading, I could not understand the exact definition for Persistence Context . Can anyone explain it in simple laymen terms? What is it to do with the data used in the @Entity ? For example, I find this definition too complicated to understand: A persistence context is a set of entities such that for any persistent identity there is a unique entity instance. 回答1: A persistence

Is there a way in PHP to use persistent data as in Java EE? (sharing objects between PHP threads) without session nor cache/DB

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问题 Is there a way in PHP to use "out of session" variables, which would not be loaded/unloaded at every connexion, like in a Java server ? Please excuse me for the lack of accuracy, I don't figure out how to write it in a proper way. The main idea would be to have something like this : <?php ... // $variablesAlreadyLoaded is kind of "static" and shared between all PHP threads // No need to initialize/load/instantiate it. $myVar = $variablesAlreadyLoaded['aConstantValueForEveryone']; ... ?> I

JPA - difference in the use of the mappedBy property to define the owning entity

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问题 What exactly is the difference in the following two declarations B is the owning side @Entity class A { @Id int id; @OneToOne B b; } @Entity class B { @Id int id; @OneToOne(mappedBy="b") A a; } A is the owning side @Entity class A { @Id int id; @OneToOne(mappedBy="a") B b; } @Entity class B { @Id int id; @OneToOne A a; } Thinking of this in "normal SQL" i think it is the same as having two tables each having the other table's foreign key. What i don't understand though is what is the effect

iOS persistent storage strategy

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问题 I'm developing an app which will save data to the local file system. The data that will be saved will be mostly NSString and NSDate. The data will not be saved that often, perhaps new data will be entered 10 times at a typical usage. The data should also of course be retrievable (CRUD) How should I save this data? First of all is it necessary to model these objects? If not should I use property lists? Or SQLLite3? Else should I archive the class models? Use SQLLite3? EDIT: I accidentally left

Remember (persist) the filter, sort order and current page of jqGrid

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问题 My application users asked if it were possible for pages that contain a jqGrid to remember the filter, sort order and current page of the grid (because when they click a grid item to carry out a task and then go back to it they'd like it to be "as they left it") Cookies seem to be the way forward, but how to get the page to load these and set them in the grid before it makes its first data request is a little beyond me at this stage. Does anyone have any experience with this kind of thing

A RESTful persistence solution usable with backbone.js… in PHP?

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问题 I'll preface this with saying that I'm a crappy programmer, I'm sure that what I want to do could be done in 10 lines of node or Rails or something else, but PHP is what I have available. So, I'm hoping to find a simple PHP library which wraps the database calls in an API that looks similar to the RESTful model. I've had little success trying to find such a thing -- searching for PHP CRUD or PHP REST turns up several zillion pages, and I've no idea how to filter through them. I'm really