Para was designed as a simple and modular back-end framework for object persistence and retrieval. It enables your application to store objects directly to a data store (NoSQL) or any relational database (RDBMS) and it also automatically indexes those objects and makes them searchable.
This plugin allows Para to store data in virtually any SQL database.
The plugin is on Maven Central. Here's the Maven snippet to include in your pom.xml
:
<dependency>
<groupId>com.erudika</groupId>
<artifactId>para-dao-sql</artifactId>
<version>{see_green_version_badge_above}</version>
</dependency>
Alternatively you can download the JAR from the "Releases" tab above put it in a lib
folder alongside the server
WAR file para-x.y.z.war
. Para will look for plugins inside lib
and pick up the plugin but the plugin itself will
try to load the correct driver and needs to know where to look for it. That's why you have to set the system property
loader.path=./lib
.
Here are all the configuration properties for this plugin (these go inside your application.conf
):
para.sql.driver = "com.mysql.jdbc.Driver"
para.sql.url = "mysql://localhost:3306"
para.sql.user = "user"
para.sql.password = "secret"
Finally, set the DAO config property:
para.dao = "SqlDAO"
This could be a Java system property or part of a application.conf
file on the classpath.
This tells Para to use the SqlDAO Data Access Object (DAO) implementation instead of the default.
The environment variable para.sql.url
is required and provides the URL to connect to the SQL database.
The SQL DAO uses JDBC and will prefix your URL with the JDBC protocol, so you don't need to include the JDBC
protocol in your URL path. For example, to connect to a MySQL server with URL mysql://localhost:3306
,
the SQL DAO will prefix this URL with the JDBC protocol to form the full URL jdbc:mysql://localhost:3306
.
The URL you specify should also include in it's path the database to be used by Para. The SQL DAO will not
automatically create a database for you (though Para does create tables within your database automatically),
so you must use an existing database. For example, you cannot simply specify the URL to your MySQL cluster/server
(mysql://localhost:3306
), but rather you need to specify the path to an existing database
(mysql://localhost:3306/para
). Note that the user name and password you provide with para.sql.user
and
para.sql.password
should correspond to the specific database you specify in the URL, and that user should have
complete permissions within that database.
The SQL DAO uses JDBC to connect to your SQL database, which means a SQL driver (java.sql.Driver) will be needed for
your chosen flavor of SQL (for example, com.mysql.jdbc.Driver
is used for MySQL). You must specify the
fully-qualified class name for your SQL driver. Upon initialization, the SQL DAO will attempt to load this driver
and verify that it exists in the classpath. If the driver cannot be found, the SQL DAO will fail to initiailize and
the DAO cannot be used.
In addition to specifying the driver name, you need to ensure the JAR file containing the SQL driver corresponding to
your database is on your classpath when launching Para Server. The easiest way to do this is to add your SQL driver's
JAR file to the lib/
directory relative to the location of the Para Server WAR file para-x.y.z.war
.
BREAKING CHANGE: The schema has changed in v1.30.0 - columns timestamp
and updated
were removed,
column json_updates
was added. H2DAO
attempts to apply these changes automatically or error, but SqlDAO
does not.
Execute the following statements one after another before switching to the new version:
ALTER TABLE {app_identifier} DROP COLUMN timestamp, updated;
ALTER TABLE {app_identifier} ADD json_updates NVARCHAR;
This is not required for tables created after v1.30.0.
Here's the schema for each table created by Para:
CREATE TABLE {app_identifier} (
id NVARCHAR NOT NULL,
type NVARCHAR,
name NVARCHAR,
parentid NVARCHAR,
creatorid NVARCHAR,
json NVARCHAR,
json_updates NVARCHAR
)