Using GORM standalone

Few days ago we decided to get rid of Apache iBatis in one of our projects. We couldn’t longer maintain large XML mapping and query descriptors with mix of Java, SQL and XML itself. But we also wanted to avoid switching to another ORM framework with lot of features and DAO layer requirement. We tried to implement some simple Spring JdbcTemplate-based ORM in Groovy, but it (strangely) started to look just like Hibernate… All that aliases in generated SQL’s, need to use javax.presistence annotations etc. The only simple existing solutions were Groovy’s DataSet (which is not working outside Groovy script) and GORM. Googling ‘GORM standalone’ show just few useful, but rather outdated, results. So I was forced to spend couple of hours to write desired 6 lines of code:

ExpandoMetaClass.enableGlobally()
        SessionFactory sessionFactory = ctx.getBean("sessionFactory")
        def grailsApp = new DefaultGrailsApplication([Customer.class] as Class[], null)
        grailsApp.initialise()
        GrailsHibernateUtil.configureHibernateDomainClasses(sessionFactory, grailsApp)
        HibernatePluginSupport.enhanceSessionFactory(sessionFactory, grailsApp, ctx)

And after annotating Customer class:

@Entity
@Table(name = "CUSTOMERS")
class Customer {
    String firstName
    String lastName
}

Now we are able to enjoy DAO-less code in pure Groovy:

Customer.findAll().each{ println it.firstName }         
        Customer.withCriteria { eq('lastName', 'Smith') }.each { Customer c -> println c.firstName }
        Customer.findByFirstNameAndLastName('John', 'Smith')

PS. For unknown reasons, these 6 lines work only with Grails 1.1.x

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Need to make a quick json fixes – JSONPath for rescue

From time to time I have a need to do some fixes in my json data. In a world of flat files I do this with grep/sed/awk tool chain. How to handle it for JSON? Searching for a solution I came across the JSONPath. It quite mature tool (from 2007) but I haven't hear about it so I decided to share my experience with others.

First of all you can try it without pain online: http://jsonpath.curiousconcept.com/. Full syntax is described at http://goessner.net/articles/JsonPath/



But also you can download python binding and run it from command line:
$ sudo apt-get install python-jsonpath-rw
$ sudo apt-get install python-setuptools
$ sudo easy_install -U jsonpath

After that you can use inside python or with simple cli wrapper:
#!/usr/bin/python
import sys, json, jsonpath

path = sys.argv[
1]

result = jsonpath.jsonpath(json.load(sys.stdin), path)
print json.dumps(result, indent=2)

… you can use it in your shell e.g. for json:
{
"store": {
"book": [
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
],
"bicycle": {
"color": "red",
"price": 19.95
}
}
}

You can print only book nodes with price lower than 10 by:
$ jsonpath '$..book[?(@.price 

Result:
[
{
"category": "reference",
"price": 8.95,
"title": "Sayings of the Century",
"author": "Nigel Rees"
},
{
"category": "fiction",
"price": 8.99,
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"author": "Herman Melville"
}
]

Have a nice JSON hacking!From time to time I have a need to do some fixes in my json data. In a world of flat files I do this with grep/sed/awk tool chain. How to handle it for JSON? Searching for a solution I came across the JSONPath. It quite mature tool (from 2007) but I haven't hear about it so I decided to share my experience with others.