Key Points

Gorm is an ORM for RDBs ( specifically MySQL,Postgres, MS SQL, sqlite ) with the ability to create dialects to support other databases
Gorm uses Groovy scripting to define data models and relations
Gorm models can be used in Grails to scaffold Web applications and REST services

References

Reference_description_with_linked_URLs____________________________	Notes_______________________________________________________________


https://objectcomputing.com/files/6415/6694/2515/slide_deck_Groovy_3_and_Beyond_webinar.pdf https://drive.google.com/open?id=1-BgJaeRWcU1Dl5Aa_-LUqNFDWkOUstYN	Groovy 3 and beyond
http://www.groovy-lang.org/closures.html#_groovy_closures_vs_lambda_expressions	Groovy closures vs Lambda expressions
file:///C:/Users/Jim%20Mason/Google%20Drive/_docs/howto/groovy/regex%20-%20Regular%20Expressions%20-%20A%20Gentle%20 User%20Guide%20and%20Tutorial.pdf	Regex rules
Slide_Deck_Groovy_for_Data_Science_Webinar.pdf	Groovy Data Science Tools - Paul King

Groovy 3x changes
http://groovy-lang.org/releasenotes/groovy-3.0.html	Groovy 3x supports Lambda expressions too
https://docs.groovy-lang.org/docs/groovy-3.0.0-rc-1/html/documentation/	Groovy 3x documentation

GORM
https://gorm.grails.org/
https://docs.grails.org/3.0.x/guide/GORM.html
https://gorm.grails.org/
gorm-tips-gr8conf-eu-2018-180601112357.pdf https://www.slideshare.net/alvarosanchezmariscal/6-things- you-need-to-know-about-gorm-6
gorm-data-access-toolkit-gids2017nareshagorm-170427103711.pdf https://www.slideshare.net/nareshak/gorm-the-polyglot-data-access-toolkit
gorm-overview-2012-gormoverviewforsdforumjavasig2009-1231454414107214-1.pdf https://www.slideshare.net/chris.e.richardson/overview-of-grails-object-relational-mapping-gorm-presentation
gorm-basics-2014-grailsgorm-141201080405-conversion-gate02.pdf
gorm-overview-2012-gormoverviewforsdforumjavasig2009-1231454414107214-1.pdf
gorm-data-access-toolkit-gids2017nareshagorm-170427103711.pdf
gorm-tips-gr8conf-eu-2018-180601112357.pdf

gorm-basics-2014-grailsgorm-141201080405-conversion-gate02.pdf https://www.slideshare.net/TedVinke/grails-gorm
gorm-inside-and=out-jeff-scott-brown-2015--141105160207-conversion-gate01.pdf https://www.slideshare.net/SpringCentral/gorm-inside-andout
advanced-gorm-graeme-rocher-141103185142-conversion-gate01.pdf https://www.slideshare.net/SpringCentral/2-gx-2014-advanced-gorm
grails-gorm-2014-141201080405-conversion-gate02.pdf
gorm-inside-and-out-2016-g-rocher-160607123907.pdf https://www.slideshare.net/graemerocher/gr8conf-2016-gorm-inside-and-out
http://daviddawson.me/blog/2017/09/06/groovy-gorm-shell-script.html groovy-gorm-shell-scripting-daviddawson.me-Groovy Gorm Shell Script.pdf	Groovy Gorm Shell Scripting


Groovy DSLs


https://www.slideshare.net/paulk_asert/groovy-dsls-from-beginner-to-expert	Groovy DSLs - Paul King, Guillaume LaForge - detailed
https://www.slideshare.net/glaforge/practical-groovy-dsl	Groovy DSLs in Practice - Guillaume LaForge - good
https://www.slideshare.net/NexThoughts/groovy-dsl-62615687	DSL in Groovy - short
https://www.slideshare.net/paulbowler/dsls-with-groovy	DSLs with Groovy - Paul Bowler

Groovy Frameworks
https://examples.javacodegeeks.com/core-java/spock-tutorial-beginners/	Groovy Spock Tutorial for use case tests: given, when, then, so
https://gebish.org/	Geb - web automation w WebDriver, JQuery, Objects
Gradle
https://docs.gradle.org/current/userguide/getting_started.html	Gradle Getting Started
https://gradle.org/guides/	Gradle basics
https://docs.gradle.org/current/userguide/declaring_repositories.html	Gradle for builds
https://circleci.com/docs/2.0/language-java/	CircleCi gradle builds
Libraries
	Mavencentral for libraries
	Github for libraries
	JCenter for Java libs

Key Concepts

Groovy 3 Key Features

http://groovy-lang.org/releasenotes/groovy-3.0.html

supports JDK 11, JDK 9 and JDK 8 at runtime

onlyJDK 11, JDK 9 supported at build time

Java-style Lambda syntax

The Java syntax for lambda expressions is now supported.

Examples:

(1..10).forEach(e -> { println e })

assert (1..10).stream()
                .filter(e -> e % 2 == 0)
                .map(e -> e * 2)
                .toList() == [4, 8, 12, 16, 20]

The normal variants are supported and Groovy adds additional features such as default parameter values:

// general form
def add = (int x, int y) -> { def z = y; return x + z }
assert add(3, 4) == 7

// curly braces are optional for a single expression
def sub = (int x, int y) -> x - y
assert sub(4, 3) == 1

// parameter types are optional
def mult = (x, y) -> x * y
assert mult(3, 4) == 12

// no parentheses required for a single parameter with no type
def isEven = n -> n % 2 == 0
assert isEven(6)
assert !isEven(7)

// no arguments case
def theAnswer = () -> 42
assert theAnswer() == 42

// any statement requires braces
def checkMath = () -> { assert 1 + 1 == 2 }
checkMath()

// example showing default parameter values (no Java equivalent)
def addWithDefault = (int x, int y = 100) -> x + y
assert addWithDefault(1, 200) == 201
assert addWithDefault(1) == 101

Potential Value Opportunities

Potential Challenges

Bug> Groovyconsole can't open groovy file from menu or cli

bug> can't open a file from groovyconsole using the file menu

workaround> use CTL + O

open groovyconsole normally
use CTL + O to open file selector window
select a groovy file
press Enter
<< file opens normally in groovy console

Candidate Solutions

Step-by-step guide for Example

GORM Shell Scripting needs transaction context

http://daviddawson.me/blog/2017/09/06/groovy-gorm-shell-script.html

Set a transaction context for a data source in GORM

Gorm has come along well and is pretty isolated from the surrounding Grails infrastructure now. All you need to do is to create a HibernateDatastore (or other) and pass in a config and your domain classes for initialisation. Then, you can start to use them as you do in Grails.

One rub is that there is no natural place to wrap a transactional Session around. This appears as a hiernate exception related to no session being present. This is something often not noticed in a grails app, as its all created automatically by Grails, and is also created by a full fat standalone Gorm app when you’re using services with any form of transactional annotation. Yet, you need a session to use hibernate, which the RDBMS version of Gorm uses.

The solution is to use the .withTransaction method added onto all grails domain classes. This creates a session and puts it into the thread context.

I did a light bit of syntax sugaring to hide that stuff and make things more readable, and its good to go!

GORM hibernate script


#!/usr/bin/env groovy

@Grapes([
        @Grab("org.grails:grails-datastore-gorm-hibernate5:6.1.4.RELEASE"),
        @Grab("com.h2database:h2:1.4.192"),
        @Grab("org.apache.tomcat:tomcat-jdbc:8.5.0"),
        @Grab("org.apache.tomcat.embed:tomcat-embed-logging-log4j:8.5.0"),
        @Grab("org.slf4j:slf4j-api:1.7.10")
])
import grails.gorm.annotation.Entity
import org.grails.datastore.gorm.GormEntity
import org.grails.orm.hibernate.HibernateDatastore

// Create the domain classes you want
@Entity
class Person implements GormEntity<Person> {

    String firstName
    String lastName

    static mapping = {
        firstName blank: false
        lastName blank: false
    }
}

//Guts of the script, do your db stuff here with the power of Gorm
gormScript {
    new Person(firstName: 'Dave', lastName: 'Ronald').save()
    new Person(firstName: 'Jeff', lastName: 'Happy').save()
    new Person(firstName: 'Sergio', lastName: 'del Amo').save()
    new Person(firstName: 'Monica', lastName: 'Crazy').save()

    println "People = ${Person.count()}"

    def sergio = Person.findByFirstName("Sergio")

    println "Got ${sergio.firstName} ${sergio.lastName}"
}


def gormScript(Closure exec) {
    Map configuration = [
            'hibernate.hbm2ddl.auto':'create-drop',
            'dataSource.url':'jdbc:h2:mem:myDB'
    ]
    HibernateDatastore datastore = new HibernateDatastore( configuration, Person)

    Person.withTransaction {
        exec()
    }
}

sample code block

sample code block

Recommended Next Steps

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