Skip to main content

Spring Data very simple example with Postgres

Hi Folks

Today it's again about server technologies and data persistence, but with spring-data project. This project aims to eliminate boilerplate code required to create the data tier, and not only that,

it also eliminate the code required by ORMs like hibernate to manage session and entity manager and everything we used to do to persist our data. enough talking.

technologies used :
a- spring data
b- spring mvc for simple rest api
c- hibernate as JPA provider
d- gradle for build management
e- ide of your preference, I used intellj in this one.
d- postgres as db

 1- Business as usual we need a simple project structure, I'll keep it simple but scalable :


spring-data-sample (contains gradle root stuff: build, settings)
------ bl : data and business tier, merged together as we don't have any code for data!
------ web : where we expose bl with rest apis

 2- setup the database, and by that you only need to install postgres and prepare the database, I created one called 'cars'. hibernate will fill it for us.

3- Business layer

in build.gradle you need these dependencies :
dependencies { compile '' compile 'org.hibernate:hibernate-entitymanager:4.2.6.Final' compile 'org.postgresql:postgresql:9.4-1200-jdbc4' }
and for the configuration :
annotations :
@EnableJpaRepositories : scans where our repositories are (i'll get to define what a repository is)
@EnableTransactionManagement: allows you to use @Transactional,

a- data source : db connection
b- entity manager factory : for ORM to work, scans entities and defines hibernate properties
responsible for managing sessions and entities and all that ORM stuff.
d- transaction manager
and for our entity, nothing new, just a simple pojo with persistence annotations

now the fun part, all you have to do to get default crud operations is this:

out of the box you will get the following:
1- save (create & update)
2- delete
3- find, findAll, findByColumnXAndColumnY...etc
and to use it we have CarBo as a BL bean :
and the rest is the web part I'll leave it to you to check in the repository. Good Luck !


Popular posts from this blog

Android RecyclerView - Adding Empty View

So RecyclerView was introduced to replace List view and it's optimized to reuse existing views and so it's faster and more efficient as stated in the documentation:

While using it, I faced the issue of missing a useful functionality that is implemented in ListView.
that feature is setting an empty view in case there was no records.

In ListView it was as simple as this

View emptyView = findViewById(;
ListView  myList = ....

but this method doesn't exist for recycler view so we need a work around until android team fixes this.

and here are the screen shots of both list view and recycler view fix

List view :

Recycler view :

here is how I fixed it:

here is the content of empty_view, it can be anything.


Android - Multiple themes for one application

Sometimes you want to have multiple themes for your app
one strong example is having the ability to switch between dark and light themes because during night, a white bright screen can really be annoying for users eyes

Android will do most of the work for you but it may be required to change icons between themes to fit colors
In this blog I'll show a simple app with both dark and light themes and how to change icons without having to do that from code and keep things clean and centralized.
first of all let's create our activity, it will look something like this :

In /rest/values/styles.xml, we inherit Theme.AppCompat
        Base application theme, dependent on API level. This theme is replaced
        by AppBaseTheme from res/values-vXX/styles.xml on newer devices.
    <style name="AppBaseTheme" parent="Theme.AppCompat">
            Theme customizations available in newer API levels can go in

Creating your own OAuth2 server and clients using spring security - part 1

In this series of posts, I'll try to put together a simple working example on how to create your own OAuth2 server.

if you want to know more on OAuth2 and when to use it as authentication and authorization protocol then you can search about it on google and i'll put some URLs later.

Now I assume you are familiar with java web applications using Spring and maven.

to get started we need to create the server side with all dependencies required and i'll list them here, i'll use maven 2 to ease downloading dependencies for us.


1- Create new maven project with arch type webapp:

2- Add the required depenedencies for spring, spring security, spring-oauth2, hibernate & other libraries (required for this tutorial only you can use other libraries if you like)

3- I used hibernate to automate the creation of the schema required by spring OAuth2 to manage tokens (it's required to have schema created in db if you a…