kotlinlang #server

and giving that a shot. What puzzled me was that the Controller class I created was actually expecting a certain order in the parameter. I'll let you know what the following returns here:

amanda.hinchman-dominguez

06/29/2018, 6:41 PM

Copy code

@Controller
class HtmlController(private val connectionRepository: ConnectionRepository,
                     private val twitter: Twitter) {

    @Autowired
    private val markdownConverter = MarkdownConverter()

robfletcher

06/29/2018, 6:41 PM

Is that controller explicitly constructed in a

@Configuration

class or something?

robfletcher

06/29/2018, 6:41 PM

or (shudder) XML

pavel

06/29/2018, 6:42 PM

this

Copy code

@Autowired
    private val markdownConverter = MarkdownConverter()

shouldn’t work

pavel

06/29/2018, 6:42 PM

autowired here means it will be initialized after creation

robfletcher

06/29/2018, 6:42 PM

it can’t work, and why initialize it if it’s being autowired?

amanda.hinchman-dominguez

06/29/2018, 6:42 PM

I have a @Configuration class directly taken from the springboot docs on the social-media-[stuff]

pavel

06/29/2018, 6:42 PM

val

means it will not

amanda.hinchman-dominguez

06/29/2018, 6:43 PM

@robfletcher OH, good call

pavel

06/29/2018, 6:43 PM

if you want field injection you need

lateinit var

robfletcher

06/29/2018, 6:43 PM

does the

@Configuration

class call the constructor? If so that probably needs to change to accomodate your additional params.

amanda.hinchman-dominguez

06/29/2018, 6:43 PM

@pavel I was wondering about that!

amanda.hinchman-dominguez

06/29/2018, 6:44 PM

Kotlin dictates that would need to happen, but what I worried about is when the initialization would happen then?

robfletcher

06/29/2018, 6:44 PM

but

@Autowired

DOES NOT apply to constructors you call explicitly from

@Configuration

only to components Spring “discovers”

👍 1

robfletcher

06/29/2018, 6:45 PM

if there’s an explicit constructor call you control the wiring there

amanda.hinchman-dominguez

06/29/2018, 6:45 PM

Thanks so much, this really helps. I think some things in the Kotlin rendering like

lateinit

and configurations gave me concerns about how the code will actually pass through the classes

robfletcher

06/29/2018, 6:45 PM

(of course, you may be able to scrap that explicit config, Spring should find the component because of that

@Controller

annotation)

pavel

06/29/2018, 6:45 PM

If it’s

@Autowired

Spring will call the setter right after creating the object

robfletcher

06/29/2018, 6:46 PM

right, but if you use constructor injection you can use

val

and not have to screw around with

lateinit

or mutable properties

pavel

06/29/2018, 6:47 PM

basically kotlin doesn’t know about Spring so when Spring promises you something you need to tell Kotlin about it. Therefore

lateinit var

amanda.hinchman-dominguez

06/29/2018, 6:47 PM

agreed, that's where I want to go. I'm going back into my configuration class to fix those parameters. To be fair, it was very late the other night and I was starting to feel crazy

pavel

06/29/2018, 6:47 PM

but yes, constructor injection is usually better

☝️ 4

👍 3

amanda.hinchman-dominguez

06/29/2018, 6:48 PM

Seriously relieved, I really thought I was going to have to disable the hard data just to figure out what was going on

amanda.hinchman-dominguez

06/29/2018, 6:48 PM

I'll let you know how it goes!

👍 2

06/30/2018, 12:34 AM

hi guys

06/30/2018, 12:34 AM

fairly new to kotlin server side programming

06/30/2018, 12:35 AM

would someone be able to help me understand the use of companion objects?