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  • Real life usage of the projective plane theory

    - by Elazar Leibovich
    I'm learning about the theory of the projective plane. Very generally speaking, it is an extension of the plane, which includes additional points which are defined as the intersection points of two parallel lines. In the projective plane, every two lines have an interesection point. Whether they're parallel or not. Every point in the projective plane can be represented by three numbers (you actually need less than that, but nevemind now). Is there any real life application which uses the projective plane? I can think that, for instance, a software which needs to find the intersections of a line, can benefit from always having an intersection point which might lead to simpler code, but is it really used?

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  • Is an ORM redundant with a NoSQL API?

    - by Earlz
    Hello, with MongoDB (and I assume other NoSQL database APIs worth their salt) the ways of querying the database are much more simplistic than SQL. There is no tedious SQL queries to generate and such. For instance take this from mongodb-csharp: using MongoDB.Driver; Mongo db = new Mongo(); db.Connect(); //Connect to localhost on the default port. Document query = new Document(); query["field1"] = 10; Document result = db["tests"]["reads"].FindOne(query); db.Disconnect(); How could an ORM even simplify that? Is an ORM or other "database abstraction device" required on top of a decent NoSQL API?

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  • What is the best way to convince management that virtualization isn't always appropriate in producti

    - by uncle brad
    I work for a small company with a .NET product that was acquired by a medium sized company with "big iron" products. Recently, the medium-sized part of the company acquired another small company with a similar .NET product and management went to have a look at their technology. They make heavy use of virtualization in their production environment and it's been decided that we will too. Our product was not designed to be run in a virtual environment, but some accommodations can be made. For instance; there are times when we're resource bound due to customer initiated processes. This initiation is "bursty" by nature, but the processing can be made asynchronous and throttled. This is something that would need to be done for scalability anyway. But there is other processing that we do that isn't so easily modified because we're resource bound for extended periods of time. How do I convince management that heavy use of virtualization is probably not appropriate for us?

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  • Rails: How to produce 404 or redirect upon undesired url exploitation?

    - by Baby Diego
    I want to hide the urls for editing users and their profiles behind safer and meaningful urls. For instance, I want /user/13/edit to be /settings/account and /user/13/profile/edit to be /settings/profile. I managed to achieve that, but for that I had to load the user information from the current_user bit from the session. Like so: # users_controller def edit @user = current_user end # profiles_controller def edit @user = current_user @profile = @user.profile end But now, since I can't compare @user.id from the params with the current_user in the session, how can I stop the old urls (/user/13/edit and /user/13/profile/edit) from being exploitable? They always load the forms for the current user, so there's no harm done, but I'd be more comfortable if they just produced a 404 error or something. Thanks in advance.

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  • Issue in configuring JPA with Spring 3 in Jboss 4.2.2 server.

    - by KVMKReddy
    Hi, I am facing issues in configuring JPA with Spring 3 in JBoss 4.2.2 server. Please find the below file of persistence.xml. <?xml version="1.0" encoding="UTF-8"?> <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0"> <persistence-unit name="TestPU"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <jta-data-source>java:/TestDS</jta-data-source> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/> <property name="hibernate.show_sql" value="true"/> </properties> </persistence-unit> </persistence> My spring-beans.xml is as below <bean id="MyAdvise" class=".......Aspect"> <property name="persister"> <bean id="dbPersister" class="..............DataBasePersister"> </bean> </property> </bean> <bean id="localContainerEntityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="showSql" value="true"/> <property name="database" value="ORACLE"/> </bean> </property> <property name="jpaProperties"> <props> <prop key="hibernate.transaction.manager_lookup_class">org.hibernate.transaction.JBossTransactionManagerLookup</prop> </props> </property> </bean> <bean id="myTxManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="localContainerEntityManagerFactory"/> </bean> <tx:annotation-driven transaction-manager="myTxManager" /> My persister bean is as follows. public class DataBasePersister implements IPersister { private static Logger log = Logger.getLogger(DataBasePersister.class); // The Entity Manager @PersistenceContext protected EntityManager entityManager; @Transactional(readOnly = false) public void persist(Object data) { log.info("IN persist() call. Is the data can castable to MethodStats -->:"+(data instanceof MethodStats)); log.info("Entity Manager instance -->:"+(entityManager)); ---------------------- ---------------------- ---------------------- } } I am getting the following exception when the spring container creating my persister bean org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is java.lang.IllegalStateException: JTA EntityManager cannot access a transactions at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:382) at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:371) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:309) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:166) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202) at $Proxy147.getTransaction(Unknown Source) at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:335) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:105) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202) at $Proxy141.persist(Unknown Source) at com.adp.sbs.aop.aspectj.SBSMethodStatsCollectorAspect.doAround(SBSMethodStatsCollectorAspect.java:63) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621) at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610) at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:65) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:161) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:621) at com.adp.sbs.aop.test.TestMethodLevelAnnotationStats$$EnhancerByCGLIB$$efbc78a8.MethodWithOneParamsAndReturnTypeAsString(<generated>) at com.adp.sbs.aop.test.SimpleTestServlet.testMethodAnnotations(SimpleTestServlet.java:46) at com.adp.sbs.aop.test.SimpleTestServlet.doPost(SimpleTestServlet.java:40) at com.adp.sbs.aop.test.SimpleTestServlet.doGet(SimpleTestServlet.java:33) at javax.servlet.http.HttpServlet.service(HttpServlet.java:690) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446) at java.lang.Thread.run(Thread.java:595) Caused by: java.lang.IllegalStateException: JTA EntityManager cannot access a transactions at org.hibernate.ejb.AbstractEntityManagerImpl.getTransaction(AbstractEntityManagerImpl.java:316) at org.springframework.orm.jpa.DefaultJpaDialect.beginTransaction(DefaultJpaDialect.java:70) at org.springframework.orm.jpa.vendor.HibernateJpaDialect.beginTransaction(HibernateJpaDialect.java:57) at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:332) Can you somebody please suggest me how to resolve this.

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  • Access ASP.NET control using javascript

    - by user3036965
    I have a basic javascript function like this which works as I am able to dynamically change the textbox in a javascript method at runtime. function MyTst(pVal2) { var x = document.getElementById('<%=myImage.ClientID%>'); x.src = "/images/write.gif"; } In the above code I need to be generic. So replace '<%=myImage.ClientID%' with the input param to my method which in this instance is called pVal2 and contains the asp.net server control image id. Can anyone advise on an approach to do this. I've tried lots of things and just cant seem to get it working. Thanks for any advice.

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  • Unit Testing Model Classes that derive from NSManagedObject

    - by Matt Baker
    So...I'm trying to get unit tests set up in my iPhone App but I'm having some issues. I'm trying to test my model classes but they inherit directly from NSManagedObject. I'm sure this is a problem but I don't know how to get around it. Everything is building and running as expected but I get this error when calling any method on the class I'm testing: Unknown.m:0:0 unrecognized selector sent to instance 0xc2b120 If I follow this structure (http://chanson.livejournal.com/115621.html) to create my object in my tests I end up with another error entirely but it still doesn't help me. Basically my question is this: how can I test a class that inherits from NSManagedObject?

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  • C# : What if a static method is called from multiple threads?

    - by Holli
    In my Application I have a static method that is called from multiple threads at the same time. Is there any danger of my data being mixed up? In my first attempt the method was not static and I was creating multiple instance of the class. In that case my data got mixed up somehow. I am not sure how this happens because it only happens sometimes. I am still debugging. But now the method is static on I have no problems so far. Maybe it's just luck. I don't know for sure.

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  • Hiding the console window in a system() call

    - by Justen
    Continuing from this question With each system call, the function constructs a set of parameters and sends them off to another program that is just console-based. Is there a way I can make it so that no console window pops up for each call? I've done a search but the ones that aren't a linker issue just aren't working for me. For instance, I tried the _execl call and System::Diagnostics::Process^ myProcess = gcnew System::Diagnostics::Process; but they aren't working. The _execl will bring a console window up, scroll a bunch of stuff (from the program I called I guess), then close the my app and not even do what it was supposed to do. The System::Diagnostics::Process^ myProcess = gcnew System::Diagnostics::Process; doesn't seem to execute what I want either because the output folder that should contain files, contains nothing. So I'm open for ideas.

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  • Best practices for using Hg with Grails?

    - by leeand00
    What should I check in/not check in? Since many of the files are sometimes auto-generated I'm not entirely sure how to handle this using version control...does it have something to do with tags? For instance in ANT, I know not to check-in my target/bin directories...but Grails adds another level of confusion to this...since some of code is generated and some of it is not. (It may become clearer as I go...but it seems to be that there needs to be some way of being able to tell what was just generated and what was modified by a developer so that it needs to be placed in version control)

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  • why does an event handler never gets called if its added within a loop on an ienumerable

    - by André Carvalho
    For instance: IEnumerable<MyType> list = someCollection.Select(i => new MyType(i)); foreach (var item in list) item.PropertyChanged += item_PropertyChanged; <-- this never gets called Bu if list is assigned like list = someCollection.Select(i => new MyType(i)).ToArray(); the event handler does get called.. Why? (i imagine it has something to do with the fact that a linq query is lazy, but the fact of looping through the result isn't enough??)

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  • Mapping multiple keys to the same value in a Javascript hash

    - by Bears will eat you
    I use a Javascript hash object to store a set of numerical counters, set up like this [this is greatly simplified]: var myHash = { A: 0, B: 0, C: 0 }; Is there a way to make other keys, ones not explicitly in myHash, map to keys that are? For instance, I'd like [again, this is simplified]: myHash['A_prime']++; // or myHash.A_prime++; to be exactly equivalent to myHash['A']++; // or myHash.A++; e.g. incrementing the value found at the key A, not A_prime.

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  • what's the "best" approach to creating the UI of an audio plugin that will be both audio unit and VST for OS X and Windows?

    - by SaldaVonSchwartz
    I'm working on a couple audio plugins. Right now, they are audio units. And while the "DSP" code won't change for the most part between implementations / ports, I'm not sure how to go about the GUI. For instance, I was looking at the Apple-supplied AUs in Lion. Does anyone know how did they go about the UI? Like, are the knobs and controls just subclasses of Cocoa controls? are they using some separate framework or coding these knobs and such from scratch? And then, the plugs I'm working on are going to be available too as VSTs for Windows. I already have them up and running with generic interfaces. But I'm wondering if I should just get over it and recreate all my interfaces with the vstgui code provided by Steinberg or if there's a more practical approach to making the interfaces cross-platform.

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  • What languages allow cross-platform native executables to be created?

    - by JT
    I'm frustrated to discover that Java lacks an acceptable solution for creating programs that will run via double-click. Other than .NET for Windows, what modern and high-level programming languages can I write code in that can be compiled for various platforms and run as a native/binary in each (Windows, Linux, OSX (optional)) Assuming I wanted to write code in python, for instance, is there a cohesive way that I could distribute my software which wouldn't require users to do anything special to get it to run? I want to write and distribute software for computer-illiterate and Java has turned out to be a real pain in this respect.

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  • hibernate Query by primary key

    - by adisembiring
    Hi ... I wanna create query by primary key. Supposed I have class primary key, PersonKey, the properties is name and id. I have Person class, the property is PersonKey, address, DOB. Now, I wanna search person by primary key. First, I create instance of PersonKey, and set the name become: joe, and id become:007 can I get the person by ID, by pass the key variable ??? person.findByKey(someKey); , but the logic do not criteria

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  • iPhone Push Notification Reliablity

    - by David Beck
    How reliable do you find push notification on the iPhone to be? Does it improve when moving from the sandbox to production server? I am testing (with the sandbox of course) and have found that notifications are often delayed or not received at all. I am not talking about sending multiple messages and only the last one arriving, as the documentation indicates, but any notification never showing up. Also, I noticed that if I send a notification with an alert, and then send one with just a badge number, that the second notification will close the alert even after it's already opened. Does this happen between apps as well? For instance, if I send an alert for my app, and then the Facebook app sends a badge, will the Facebook badge close my alert window?

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  • Service locator for generics

    - by vittore
    Hi everyone, I have say a dozen types T which inherit from EntityObject and IDataObject. I have generic the following interface IDataManager<T> where T : EntityObject, IDataObject ... I have also base class for data managers BaseDataManager<T> : IDataManager<T> where T : EntityObject, IDataObject .... And i have particular classes public class Result : EntityObject, IDataObject .... public class ResultDataManager : BaseDataManager<Result> ... I want to implement service locator, which will return instance of IDataManager<T> for T But I stucked how to implement it in a neat way without a lot of castings. Any ideas?

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  • How can I change or remove HttpRequest input arguments in a HttpModule

    - by Eric Gunn
    Is it possible to change or remove http request form inputs in an httpmodule? My goal is to create a security IHttpmodule that will check the request for reasonable values, such as limits on acceptable input and query parameter length, or use the AntiXSS Sanitizer to remove threats, log potential hack attempts, etc. before a request is passed on to a processor. Because this is a cross cutting concern I'd prefer to find a solution that applies to all requests and affects all ways request values could be accessed, Reqest.Form, Action(model), Action(FormCollection), HttpContext.Current.Request.Form, etc. I'm using MVC and have considered creating custom model binders to clean the data before creating the model instance. But that would be application specific, require remembering to register every model binder and only apply to Action(model).

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  • Python list as *args?

    - by Cap
    I have two Python functions, both of which take variable arguments in their function definitions. To give a simple example: def func1(*args): for arg in args: print arg def func2(*args): return [2 * arg for arg in args] I'd like to compose them -- as in func1(func2(3, 4, 5)) -- but I don't want args in func1 to be ([6, 7, 8],), I want it to be (6, 7, 8), as if it was called as func1(6, 7, 8) rather than func1([6, 7, 8]). Normally, I would just use func1(*func2(3, 4, 5)) or have func1 check to see if args[0] was a list. Unfortunately, I can't use the first solution in this particular instance and to apply the second would require doing such a check in many places (there are a lot of functions in the role of func1). Does anybody have an idea how to do this? I imagine some sort of introspection could be used, but I could be wrong.

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  • Why state cannot be part of Presenter in MVP?

    - by rFactor
    I read http://www.codeproject.com/KB/architecture/MVC_MVP_MVVM_design.aspx and it said: As powerful as they are, both MVC and MVP have their problems. One of them is persistence of the View’s state. For instance, if the Model, being a domain object, does not know anything about the UI, and the View does not implement any business logic, then where would we store the state of the View’s elements such as selected items? Fowler comes up with a solution in the form of a Presentation Model pattern. I wonder why Presenter can't hold View state? It already holds all View logic. As far as I understand, in MVC and MVP the state is kept in View. In PM and MVVM the state is kept in the Presentation Model. Why can't Presenter follow PM in this particular case and contain the state of the view? Here is another article which says Presenter does not hold View state, instead the view does: http://www.codeproject.com/KB/aspnet/ArchitectureComparison.aspx

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  • python class attribute

    - by chnet
    Hi, i have a question about class attribute in python. class base : def __init__ (self): pass derived_val = 1 t1 = base() t2 = base () t2.derived_val +=1 t2.__class__.derived_val +=2 print t2.derived_val # its value is 2 print t2.__class__.derived_val # its value is 3 The results are different. I also use id() function to find t2.derived_val and t2.class.derived_val have different memory address. My problem is derived_val is class attribute. Why it is different in above example? Is it because the instance of class copy its own derived_val beside the class attribute?

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  • Sqlalchemy layout with WSGI application

    - by TheDude
    I'm working on writing a small WSGI application using Bottle and SqlAlchemy and am confused on how the "layout" of my application should be in terms of SqlAlchemy. My confusion is with creating engines and sessions. My understanding is that I should only create one engine with the 'create_engine' method. Should I be creating an engine instance in the global namespace in some sort of singleton pattern and creating sessions based off of it? How have you done this in your projects? Any insight would be appreciated. The examples in the documentation dont seem to make this entirely clear (unless I'm missing something obvious). Any thoughts?

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  • Retrieving datatypes from underlying database

    - by H4mm3rHead
    Hi, Im making an application that displays information about an underlying database. The database can be anything, but is typically either Oracle, MSSQL or MySQL. I am trying to extract the datatype but cannot seem to get this right. I have a DbConnection because i dont know whether I need a OleDbConnection or an OdbcConnection. On this connection I make a GetSchema("Columns", "mytablename") query and gets the result back. It seems though that there are some inconsistencies with my datatypes or the query returns different datatypes for the different databases. For instance, in my MSSQL database I query and get an integer back (which seems to be the OleDbType) which I map to a datatype. My varchars is now of type char - no length - and this confuses me a bit. I guess my main question is something like: Is there any way of making a uniform way of extracting datatypes across providers and having an "accurate" representation of the datatype?

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  • validates_uniqueness_of...limiting scope - How do I restrict someone from creating a certain number

    - by bgadoci
    I have the following code: class Like < ActiveRecord::Base belongs_to :site validates_uniqueness_of :ip_address, :scope => [:site_id] end Which limits a person from "liking" a site more than one time based on a remote ip request. Essentially when someone "likes" a site, a record is created in the Likes table and I use a hidden field to request and pass their ip address to the :ip_address column in the like table. With the above code I am limiting the user to one "like" per their ip address. I would like to limit this to a certain number for instance 10. My initial thought was do something like this: validates_uniqueness_of :ip_address, :scope => [:site_id, :limit => 10] But that doesn't seem to work. Is there a simple syntax here that will allow me to do such a thing?

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  • Get starting and end index of a highlighted fragment in a searched field

    - by Umer
    "My search returns a highlighted fragment from a field. I want to know that in that field of particular searched document, where does that fragment starts and ends ?" for instance. consider i am searching "highlighted fragment" in above lines (consider the above para as single document). I am setting my fragmenter as : SimpleFragmenter fragmenter = new SimpleFragmenter(30); now the output of GetBestFragment is somewhat like : "returns a highlighted fragment from" Is it possible to get the starting and ending index of this fragment in the text above (say starting is 10 and ending is 45)

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