therefore I asked for a FULL class definition for BOOK!
But I got just 1 line.
there can't be help without sufficient information

Now, this gets clear.
With the keyword IDKEY you replaced the default ID naming it RowID.

To store it:

set book=##class(BOOK).%New()
set book.RowId=obj.ID     ;  from JSON obj
set book.Title=obj.Title    ;  from JSON obj
do book.%Save()

to retrieve an existing Rowid:

set book=##class(BOOK).%OpenId(obj.ID)   ;from JSON obj
,;; access or change your book.Title

I'm sorry. it seems you don't understand what I'm talking about.
You just gave me the names. Not the structure and definition. 

Expected example:

Class RestApi.Books Extends %Persistent
{
Property Title As %String;
Property Pages As %Integer; 

Storage Default
{
<Data name="BooksDefaultData">
<Value name="1">
<Value>%%CLASSNAME</Value>
</Value>
<Value name="2">
<Value>Title</Value>
</Value>
<Value name="3">
<Value>Pages</Value>
</Value>
</Data>
<DataLocation>^RestApi.BooksD</DataLocation>
<DefaultData>BooksDefaultData</DefaultData>
<IdLocation>^RestApi.BooksD</IdLocation>
<IndexLocation>^RestApi.BooksI</IndexLocation>
<StreamLocation>^RestApi.BooksS</StreamLocation>
}
}

 Class RestApi.Title Extends %Persistent
{
Property Title As Books;
Property Text As %String; 

Storage Default
{
<Data name="TitleDefaultData">
<Value name="1">
<Value>%%CLASSNAME</Value>
</Value>
<Value name="2">
<Value>Title</Value>
</Value>
<Value name="3">
<Value>Text</Value>
</Value>
</Data>
<DataLocation>^RestApi.TitleD</DataLocation>
<DefaultData>TitleDefaultData</DefaultData>
<IdLocation>^RestApi.TitleD</IdLocation>
<IndexLocation>^RestApi.TitleI</IndexLocation>
<StreamLocation>^RestApi.TitleS</StreamLocation>
}
}

it's midnight now. I finish 

maybe next week.

the story is clear.  Your class definition is not.
once more pls show class definitions for RESTAPI.TITLE   and    ??.BOOK   
(every class has also a package, default is User) 
you may need Studio od VSCode  to see it.

and {"ID":17, "Title":"LEARNING CAHE REST API"} is a
Dynamic JSON object unrelated to any class definition

This returns to what we were talking about yesterday.

You mix classes with JSON objects and RowID might be something different.
so pls add the definition of the classes you talk about (e.g: RESTAPI.TITLE and  TITLE table ??)
it's not obvious what you refer to in "object without ID but having RowID" ???

How did you get the screenshot?

Ah thanks!  That passed me.

To find this quoting in Windows kept me busy for quite a while 2 months ago
as it wasn't part of the README.md  !
 

GRAND MERCI !

Exactly! 
I just was not sure about the abbreviation.  

You depend on the structure of the dynamic object you compose in the 1st line.
if it has a property TitleID  it will work. (using obj.TitleID   lower case!!)

But in your question, it is not clear what Title Class refers to.
I see All.Allbooks and somewhere User.Book and also %request  and no other class around

@Jean Millette 
Just great!  I  was searching for this for quite some time 

Hi @Evgeny Shvarov,

I run my Docker Desktop on WIN10 
And with my setup, I have reviewed more than 300 Docker build sequences
Always focused on how easy it is for the average consumer and how well the description fits reality.
This package forced me to exercise settings that were just not needed before
And (differently from others) there is not the slightest signal in the description of that requirement.
It's some *KIT*  stuff and the official doc doesn't care much about WIN.
it finally moved along. and others should be warned [getting rid of it was another story]
And the result was something that I see multiple times daily in my SMP instances.
Sorry!
Nice screenshots from VSCode.
Just to be clear: I tried but will never use VSCode as long as I have my Studio available.
And I never touched it in any of my reviews or other situations.

GREAT !       without touching the code

You are right.
But it works in a test within a Try-Catch bloxk
   

     try {
         ;;; run your code
         }
     catch e {  
        if $ze["<RESJOB>" while $TLEVEL { tcommit }
        }

@Chris Stewart it was there even earlier see my article  Repairing your Index

the background then, were manually written index globals.
the BIG advantage is to slice it down and run it as slow as you need with practically no extra load