The [`@Transient`](https://docs.spring.io/spring-data/commons/docs/current/api/org/springframework/data/annotation/Transient.html) annotation it is. See http://static.springsource.org/spring-data/data-document/docs/current/reference/html/#mapping-usage-annotations

In case you are looking for the actual package like I was, this one will work:

    import org.springframework.data.annotation.Transient;

Which is from the [Spring framework API][1] documentation.

But this one, which is a [JPA][2] annotation, will not work for MongoDB:

    import javax.persistence.Transient;

Which is part of the [Java Persistence API][3].

  [1]: http://docs.spring.io/spring-data/commons/docs/current/api/org/springframework/data/annotation/Transient.html
  [2]: http://en.wikipedia.org/wiki/Java_Persistence_API
  [3]: http://docs.oracle.com/javaee/5/api/javax/persistence/Transient.html

use `@Transient`
be aware that you use the below package 

    import org.springframework.data.annotation.Transient;

I need to alter one view and I want to introduce 2 temporary table before the SELECT.

Is this possible? And how can I do it?

    ALTER VIEW myView
    AS 
    
    SELECT *
    INTO #temporary1
    
    SELECT *
    INTO #temporary2
    
    SELECT * FROM #temporary1
    UNION ALL 
    SELECT * FROM #temporary1
    
    DROP TABLE #temporary1
    DROP TABLE #temporary2

When I attempt this it complains that ALTER VIEW must be the only statement in the batch.

How can I achieve this?


Is it possible to create a temporary table in a View and drop it after select?

I&#39;m trying to get gedit to auto-indent my code. The auto-indent check-box in preferences doesn&#39;t work. Is there a way to get gedit to auto-indent code?
(By the way, I only really care about C++ indentation. I don&#39;t need indentation for any other language.)

How to get gedit to auto-indent code

I have a standard POJO that has a set of properties in it. The POJO has been annotated as a `@Document`, so as to be persisted in MongoDB as a Document.

How (annotation??) can I ignore/avoid one of the properties in the POJO from being persisted?

Mongo - Ignore property from being persisted

<p>I have a standard POJO that has a set of properties in it. The POJO has been annotated as a <code>@Document</code>, so as to be persisted in MongoDB as a Document.</p>
<p>How (annotation??) can I ignore/avoid one of the properties in the POJO from being persisted?</p>


Given a list

    List&lt;String&gt; l = new ArrayList&lt;String&gt;();
    l.add(&quot;one&quot;);
    l.add(&quot;two&quot;);
    l.add(&quot;three&quot;);
I have a method

    String join(List&lt;String&gt; messages) {
    		if (messages.isEmpty()) return &quot;&quot;;
    		if (messages.size() == 1) return messages.get(0);
    		String message = &quot;&quot;;
    		message = StringUtils.join(messages.subList(0, messages.size() -2), &quot;, &quot;);
    		message = message + (messages.size() &gt; 2 ? &quot;, &quot; : &quot;&quot;) + StringUtils.join(messages.subList(messages.size() -2, messages.size()), &quot;, and &quot;);
    		return message;
    	}
which, for l, produces &quot;one, two, and three&quot;.
My question is, is there a standard (apache-commons) method that does the same?, eg

    WhatEverUtils.join(l, &quot;, &quot;, &quot;, and &quot;);

To clarify. My problem is not getting this method to work. It works just as I want it to, it&#39;s tested and all is well. My problem is that I could not find some apache-commons-like module which implements such functionality. Which surprises me, since I cannot be the first one to need this.

But then maybe everyone else has just done

    StringUtils.join(l, &quot;, &quot;).replaceAll(lastCommaRegex, &quot;, and&quot;);



Joining a List&lt;String&gt; in Java with commas and &quot;and&quot;

Is there a stopwatch in Java?  
On Google I only found code of stopwatches that don&#39;t work - they always return 0 milliseconds.

This code I found doesn&#39;t work and I don&#39;t see why.

    public class StopWatch {
      
      private long startTime = 0;
      private long stopTime = 0;
      private boolean running = false;
      
      
      public void start() {
        this.startTime = System.currentTimeMillis();
        this.running = true;
      }
      
      
      public void stop() {
        this.stopTime = System.currentTimeMillis();
        this.running = false;
      }
      
      
      //elaspsed time in milliseconds
      public long getElapsedTime() {
        long elapsed;
        if (running) {
          elapsed = (System.currentTimeMillis() - startTime);
        } else {
          elapsed = (stopTime - startTime);
        }
        return elapsed;
      }
      
      
      //elaspsed time in seconds
      public long getElapsedTimeSecs() {
        long elapsed;
        if (running) {
          elapsed = ((System.currentTimeMillis() - startTime) / 1000);
        } else {
          elapsed = ((stopTime - startTime) / 1000);
        }
        return elapsed;
      }
    }


Is there a stopwatch in Java?

The Effective Java has the following statement on unit testing singletons

&gt;Making a class a singleton can make it difficult to test its clients, as it’s impossible to substitute a mock implementation for a singleton unless it implements an interface that serves as its type.

Can anyone explain the why this is so ?

Singleton and unit testing

I have a boolean array in java: 

    boolean[] myArray = new boolean[10];

What&#39;s the most elegant way to check if all the values are true?

What is the most elegant way to check if all values in a boolean array are true?

I need to initialize a constant HashMap and would like to do it in one line statement. Avoiding sth like this:

      hashMap.put(&quot;One&quot;, new Integer(1)); // adding value into HashMap
      hashMap.put(&quot;Two&quot;, new Integer(2));      
      hashMap.put(&quot;Three&quot;, new Integer(3));

similar to this in objective C:

    [NSDictionary dictionaryWithObjectsAndKeys:
    @&quot;w&quot;,[NSNumber numberWithInt:1],
    @&quot;K&quot;,[NSNumber numberWithInt:2],
    @&quot;e&quot;,[NSNumber numberWithInt:4],
    @&quot;z&quot;,[NSNumber numberWithInt:5],
    @&quot;l&quot;,[NSNumber numberWithInt:6],
    nil] 

I have not found any example that shows how to do this having looked at so many.
   


adding multiple entries to a HashMap at once in one statement

I have an array of _ids and I want to get all docs accordingly, what&#39;s the best way to do it ?

Something like ...

       
    // doesn&#39;t work ... of course ...

    model.find({
	    &#39;_id&#39; : [
		    &#39;4ed3ede8844f0f351100000c&#39;,
		    &#39;4ed3f117a844e0471100000d&#39;, 
		    &#39;4ed3f18132f50c491100000e&#39;
	    ]
    }, function(err, docs){
	    console.log(docs);
    });

The array might contain hundreds of _ids.

mongodb/mongoose findMany - find all documents with IDs listed in array

Working with Nodejs and MongoDB through Node MongoDB native driver. Need to retrieve some documents, and make modification, then save them right back. This is an example:

    db.open(function (err, db) {
      db.collection(&#39;foo&#39;, function (err, collection) {
        var cursor = collection.find({});
        cursor.each(function (err, doc) {
          if (doc != null) {
            doc.newkey = &#39;foo&#39;; // Make some changes
            db.save(doc); // Update the document
          } else {
            db.close(); // Closing the connection
          }
        });
      });
    });

With asynchronous nature, if the process of updating the document takes longer, then when cursor reaches the end of documents, database connection is closed. Not all updates are saved to the database.

If the `db.close()` is omitted, all the documents are correctly updated, but the application hangs, never exits.

I saw a post suggesting using a counter to track number of updates, when fall back to zero, then close the db. But am I doing anything wrong here? What is the best way to handle this kind of situation? Does `db.close()` have to be used to free up resource? Or does a new db connection needs to open?

When to close MongoDB database connection in Nodejs

Does MongoDB offer a find or query method to test if an item exists based on any field value? We just want check existence, not return the full contents of the item.

How to query MongoDB to test if an item exists?

I have the following json:

    {
      &quot;a1&quot;: {&quot;a&quot;: &quot;b&quot;},
      &quot;a2&quot;: {&quot;a&quot;: &quot;c&quot;}
    }

How can I request all documents where `a1` and `a2` are not equal in the same document?


Mongodb query with fields in the same documents

i&#39;m running mongo 1.8.2 and trying to see how to cleanly shut it down on Mac.

on our ubuntu servers i can shutdown mongo cleanly from the mongo shell with:

    &gt; use admin
    &gt; db.shutdownServer()

but on my Mac, it does not kill the mongod process.  the output shows that it &#39;should be&#39; shutdown but when i ps -ef | grep mongo it shows me an active process.  also, i can still open a mongo shell and query my dbs like it was never shutdown.

the output from my db.shutdownServer() locally is:

    MongoDB shell version: 1.8.2
    connecting to: test
    &gt; use admin                  
    switched to db admin
    &gt; db.shutdownServer()
    Tue Dec 13 11:44:21 DBClientCursor::init call() failed
    Tue Dec 13 11:44:21 query failed : admin.$cmd { shutdown: 1.0 } to: 127.0.0.1
    server should be down...
    Tue Dec 13 11:44:21 trying reconnect to 127.0.0.1
    Tue Dec 13 11:44:21 reconnect 127.0.0.1 failed couldn&#39;t connect to server 127.0.0.1
    Tue Dec 13 11:44:21 Error: error doing query: unknown shell/collection.js:150

i know i can just kill the process but i&#39;d like to do it more cleanly.

What&#39;s a clean way to stop mongod on Mac OS X?

Here is the code:

    @Repository
    public interface AccountRepository extends JpaRepository&lt;Account, Long&gt; {}

_JpaRepository_ from Spring Data JPA project.

Here is the testing code:

    public class JpaAccountRepositoryTest extends JpaRepositoryTest {
        @Inject
        private AccountRepository accountRepository;

        @Inject
        private Account account;
    
        @Test
        @Transactional
        public void createAccount() {
            Account returnedAccount = accountRepository.save(account);

            System.out.printf(&quot;account ID is %d and for returned account ID is %d\n&quot;, account.getId(), returnedAccount.getId());
        }
    }

Here is the result:

    account ID is 0 and for returned account ID is 1

Here is from CrudReporsitory.save() javadoc:

&gt; Saves a given entity. Use the returned instance for further operations as the save operation might have changed the entity instance completely. 

Here is the actual code for SimpleJpaRepository from Spring Data JPA:

     @Transactional
        public T save(T entity) { 
                if (entityInformation.isNew(entity)) {
                        em.persist(entity);
                        return entity;
                } else {
                        return em.merge(entity);
                }
        }

So, the question is why do we need to use the returned instance instead of the original one? (yes, we must do it, otherwise we continue to work with detached instance, but why)

The original EntityManager.persist() method returns void, so our instance is attached to the persistence context. Does some proxy magic happens while passing account to save to repository? Is it the architecture limitation of Spring Data JPA project?

Why use returned instance after save() on Spring Data JPA Repository?

I am trying to incorporate Spring-Data-JPA into my project.
One thing that confuses me is how do I achieve setMaxResults(n) by annotation ?

for example, my code: 

    public interface UserRepository extends CrudRepository&lt;User , Long&gt;
    {
      @Query(value=&quot;From User u where u.otherObj = ?1 &quot;)
      public User findByOtherObj(OtherObj otherObj);
    }

I only need to return `one (and only one)` User from otherObj, but I cannot find a way to annotate the maxResults. Can somebody give me a hint ?

(mysql complains :

    com.mysql.jdbc.JDBC4PreparedStatement@5add5415: select user0_.id as id100_, user0_.created as created100_ from User user0_ where user0_.id=2 limit ** NOT SPECIFIED **
    WARN  util.JDBCExceptionReporter - SQL Error: 0, SQLState: 07001
    ERROR util.JDBCExceptionReporter - No value specified for parameter 2

)

I found a link : https://jira.springsource.org/browse/DATAJPA-147,
I tried but failed. It seems not possible now? 
Why is such an important feature not built into Spring-Data?

If I implement this feature manually:

    public class UserRepositoryImpl implements UserRepository

I have to implement tons of predefined methods in `CrudRepository`, this would be terrible.

environments : spring-3.1 , spring-data-jpa-1.0.3.RELEASE.jar , spring-data-commons-core-1.1.0.RELEASE.jar

setMaxResults for Spring-Data-JPA annotation?

I just started working on a Spring-data, Hibernate, MySQL, JPA project. I  switched to spring-data so that I wouldn&#39;t have to worry about creating queries by hand.

I noticed that the use of `@Transactional` isn&#39;t required when you&#39;re using spring-data since I also tried my queries without the annotation.

Is there a specific reason why I should/shouldn&#39;t be using the `@Transactional` annotation?

Works:

    @Transactional
    public List listStudentsBySchool(long id) {
        return repository.findByClasses_School_Id(id);
    }

Also works:

    public List listStudentsBySchool(long id) {
        return repository.findByClasses_School_Id(id);
    }

Thanks in advance!

How to use @Transactional with Spring Data?

What is the simplest way of declaring a Spring data JPA query that uses properties of an input parameter as query parameters?

For example, suppose I have an entity class:

    public class Person {
        @Id
        private long id;

        @Column
        private String forename;

        @Column
        private String surname;
    }

and another class:

    public class Name {
        private String forename;
        private String surname;

        [constructor and getters]
    }

... then I would like to write a Spring data repository as follows:

    public interface PersonRepository extends CrudRepository&lt;Person, Long&gt; {
        @Query(&quot;select p from Person p where p.forename = ?1.forename and p.surname = ?1.surname&quot;)
        findByName(Name name);
    }

... but Spring data / JPA doesn&#39;t like me specifying property names on the `?1` parameter.

What is the neatest alternative?

Spring data JPA query with parameter properties

I encountered the `@NoRepositoryBean` interface several times whilst reading the Spring Data documentation.

To quote from the documentation:
&gt; If you&#39;re using automatic repository interface detection using the
&gt; Spring namespace using the interface just as is will cause Spring
&gt; trying to create an instance of MyRepository. This is of course not
&gt; desired as it just acts as indermediate between Repository and the
&gt; actual repository interfaces you want to define for each entity. To
&gt; exclude an interface extending Repository from being instantiated as
&gt; repository instance annotate it with `@NoRepositoryBean`.

However, I am still not sure when and where to use it. Can someone please advise and give me a concrete usage example?

Content Type	Original Author	Original Content on Stackoverflow
Question	Saket	View Question on Stackoverflow
Solution 1 - Java	Saket	View Answer on Stackoverflow
Solution 2 - Java	Jeach	View Answer on Stackoverflow
Solution 3 - Java	Pravin Bansal	View Answer on Stackoverflow

Mongo - Ignore property from being persisted

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How to get gedit to auto-indent code

Is it possible to create a temporary table in a View and drop it after select?

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