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Posted to dev@groovy.apache.org by "K Adithyan (tech)" <ad...@gmail.com> on 2018/05/10 19:33:25 UTC

Java object conversion using ConfigSlurper

Team,

ConfigSlurper can be used to parse groovy-styled configurations and get
them as *ConfigObject. *As an additional feature, either ConfigSlurper can
be enhanced or a new class can be written to return java object itself from
the configuration. Example below

*config.groovy*

myownconfig {
      name = 'Threadpool'
     displayLabel = "Thread Pool"
     threadCount = 12
}
----------------------------------------------

*MyConfig.java*

public class MyConfig
{
     String name;
     String displayLabel
     int threadCount
}
-----------------------------------------------
Usage:

MyConfig myConfig = new ConfigClassConver().object('myownconfig',
MyConfig.class)
println myConfig.name
println ...
-----------------------------------------------


I have implemented this functionality for one of my project needs. If the
team feels, it can be added groovy itself, then the discussion can proceed
in what could be the class name, what features, etc.

What I have given is a sample only. There are couple of other features,
like ConfigSlurper.merge(), parsing multiple files in one directory
(optionally, recursive too), etc.

I feel this will be a good addition to groovy itself.

Pls comment

Regards,

K Adithyan
India

Re: Java object conversion using ConfigSlurper

Posted by Jesper Steen Møller <je...@selskabet.org>.
Hi Adithyank

> On 16 May 2018, at 12.52, adithyank <ad...@gmail.com> wrote:
> 
> Hi Mario Garcia,
> 
> Groovy already has Map coercion feature with which the methods of any class
> can be delegated to the closures in Map. This uses `as` keyword.
> 

> If we implement `asType(Class)` in `ConfigObject` (ConfigObject already
> implements Map), some of the functionalities of existing coercion may be
> affected. I am not sure !

Using "as <classname>" already works, so there's already a pretty simple way to do what you're suggesting:

ConfigObject co = new ConfigSlurper().parse("""
myownconfig {
    name = 'Threadpool'
    displayLabel = "Thread Pool"
    threadCount = 12
}""")

public class MyConfig
{
     String name
     String displayLabel
     int threadCount
}

def myConfig = co.myownconfig as MyConfig

println "${myConfig.displayLabel} - ${myConfig.threadCount}"

(try it in Groovy Console)

-Jesper

Re: Java object conversion using ConfigSlurper

Posted by mg <mg...@arscreat.com>.
Non-PMC +1 on using getAs, because I feel the semantics are sufficiently different, and trying to retrofit this might lead to unexpected edge cases now and/or headaches in the future. What do others think ?
-------- Ursprüngliche Nachricht --------Von: adithyank <ad...@gmail.com> Datum: 16.05.18  16:00  (GMT+01:00) An: dev@groovy.incubator.apache.org Betreff: Re: Java object conversion using ConfigSlurper 
Yes Jesper,

It works. But, If that `MyConfig` class has fields of `List` or `Map` types,
then it does not work. I am looking this feature as a way of converting
`ConfigObject` (inturn Map<String, Map&lt;Stirng, Map&lt;String,
Map&lt;String>>>>....) of any levels to its respective java object with
nested `List<anyclass>`, `Map<anyclass>`, `Other classes`.

Now, what decision can we take? Below are the options

1. I will look on the existing coercion codes to some how fit this use case
of creating nested objects recursively
or
2. `T ConfigObject.getAs(Class<T>)` can be implemented without affecting the
existing semantics of `Map as SomeClass`

Pls advice



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Re: Java object conversion using ConfigSlurper

Posted by Jesper Steen Møller <je...@selskabet.org>.
> On 16 May 2018, at 16.00, adithyank <ad...@gmail.com> wrote:
> 
> It works. But, If that `MyConfig` class has fields of `List` or `Map` types,
> then it does not work.

Actually it does work, too:

ConfigObject co = new ConfigSlurper().parse("""
myownconfig {
    name = 'Threadpool'
    displayLabel = "Thread Pool"
    threadCount = 12
    bleh {
        y = "not"
    }
    fleep = [ 'a', 'b' ]
    nested {
        threadCount = 12
    }
}
""")

public class MyConfig
{
     String name
     String displayLabel
     int threadCount
     Map bleh
     List fleep
     MyConfig nested
}

> I am looking this feature as a way of converting
> `ConfigObject` (inturn Map<String, Map&lt;Stirng, Map&lt;String,
> Map&lt;String>>>>....) of any levels to its respective java object with
> nested `List<anyclass>`, `Map<anyclass>`, `Other classes`.
> 

Anyway, I'm sure you can find examples which aren't covered now.

> 
> 1. I will look on the existing coercion codes to some how fit this use case
> of creating nested objects recursively
> or
> 2. `T ConfigObject.getAs(Class<T>)` can be implemented without affecting the
> existing semantics of `Map as SomeClass`
> 

I'd go for option "2" in that case - not that I can vote :-)

-Jesper

Re: Java object conversion using ConfigSlurper

Posted by adithyank <ad...@gmail.com>.
Yes Jesper,

It works. But, If that `MyConfig` class has fields of `List` or `Map` types,
then it does not work. I am looking this feature as a way of converting
`ConfigObject` (inturn Map<String, Map&lt;Stirng, Map&lt;String,
Map&lt;String>>>>....) of any levels to its respective java object with
nested `List<anyclass>`, `Map<anyclass>`, `Other classes`.

Now, what decision can we take? Below are the options

1. I will look on the existing coercion codes to some how fit this use case
of creating nested objects recursively
or
2. `T ConfigObject.getAs(Class<T>)` can be implemented without affecting the
existing semantics of `Map as SomeClass`

Pls advice



--
Sent from: http://groovy.329449.n5.nabble.com/Groovy-Dev-f372993.html

Re: Java object conversion using ConfigSlurper

Posted by mg <mg...@arscreat.com>.
I guess it boils down to whether the semantics/intention of getAs is different from asType or not (no Groovy magic expected ?...)
-------- Ursprüngliche Nachricht --------Von: adithyank <ad...@gmail.com> Datum: 16.05.18  12:52  (GMT+01:00) An: dev@groovy.incubator.apache.org Betreff: Re: Java object conversion using ConfigSlurper 
Hi Mario Garcia,

Groovy already has Map coercion feature with which the methods of any class
can be delegated to the closures in Map. This uses `as` keyword.

If we implement `asType(Class)` in `ConfigObject` (ConfigObject already
implements Map), some of the functionalities of existing coercion may be
affected. I am not sure !

If we implement 'getAs(Class)`, existing coercion will be unaffected. So, I
will prefer `getAs(Class)` first.

Note : Any ways, while testing, I will test these behaviors...

Pls advice



--
Sent from: http://groovy.329449.n5.nabble.com/Groovy-Dev-f372993.html

Re: Java object conversion using ConfigSlurper

Posted by adithyank <ad...@gmail.com>.
Hi Mario Garcia,

Groovy already has Map coercion feature with which the methods of any class
can be delegated to the closures in Map. This uses `as` keyword.

If we implement `asType(Class)` in `ConfigObject` (ConfigObject already
implements Map), some of the functionalities of existing coercion may be
affected. I am not sure !

If we implement 'getAs(Class)`, existing coercion will be unaffected. So, I
will prefer `getAs(Class)` first.

Note : Any ways, while testing, I will test these behaviors...

Pls advice



--
Sent from: http://groovy.329449.n5.nabble.com/Groovy-Dev-f372993.html

Re: Java object conversion using ConfigSlurper

Posted by Mario Garcia <ma...@gmail.com>.
Hi, good work :)

It seems a nice feature, but I'm wondering why having two different methods
doing the same ? asType and getAs.

   - I think is always better to avoid having two methods doing the same,
   specially when asType can be called both directly or via sugar syntax.
   - I also think the use case fits asType perfectly, as it's mentioned in
   its Groovydoc entry: "Converts a given object to a type"

IMHO I would stick only to asType.

Mario

El mar., 15 may. 2018 a las 9:36, Daniel.Sun (<su...@apache.org>) escribió:

> I think it is nice for me :-)
>
> Cheers,
> Daniel.Sun
>
>
>
> --
> Sent from: http://groovy.329449.n5.nabble.com/Groovy-Dev-f372993.html
>

Re: Java object conversion using ConfigSlurper

Posted by "Daniel.Sun" <su...@apache.org>.
I think it is nice for me :-)

Cheers,
Daniel.Sun



--
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Re: Java object conversion using ConfigSlurper

Posted by adithyank <ad...@gmail.com>.
Ok. Thanks Daniel.

I will proceed in the below way.

Pls advice

1. I will write new class `ConfigCustomObjectBuilder` in
   `ConfigSlurper.groovy` to convert given ConfigObject to custom class
instance

2. I will add below new method in ConfigObject

   T getAs(Class<T> dataStructure)
   {
       return ConfigCustomObjectBuilder.build(ConfigObject, Class<T>
dataStructure)
   }

3. So, the callers of the method can do the below steps

   a. ConfigObject co = new ConfigSlurper().parse(...)
   b. Do required co.merge(...)
   c. MyConfig mc = co.getAs(MyConfig)
   d. use mc further

4. Optionally, we can implement `asType(Class)` method in `ConfigObject`
class
   so that callers can use below syntax

   c. MyConfig mc = co as MyConfig

Regards,

K Adithyan
India
--




Daniel.Sun wrote
> I think it is useful especially for Java developers. PR is welcome.
> 
> P.S. it would be better if the Java class is a Java bean(with getters and
> setters)





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Re: Java object conversion using ConfigSlurper

Posted by "Daniel.Sun" <su...@apache.org>.
I think it is useful especially for Java developers. PR is welcome.

P.S. it would be better if the Java class is a Java bean(with getters and
setters)

Cheers,
Daniel.Sun



--
Sent from: http://groovy.329449.n5.nabble.com/Groovy-Dev-f372993.html