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mod-mysql-postgresql

This Vert.x module uses the https://github.com/mauricio/postgresql-async drivers to support a fully async module for MySQL and PostgreSQL.

Requirements

  • Vert.x 2.1+ (with Scala language module v1.1.0+)
  • A working PostgreSQL or MySQL server
  • For testing PostgreSQL: A testdb database on a local PostgreSQL install and a user called vertx
  • For testing MySQL: A testdb database on a local MySQL install and a user called root

Installation

Depending on your Scala version, you should download the specific version. If you're using Scala 2.10.x:

vertx install io.vertx~mod-mysql-postgresql_2.10~0.3.0

If you're using Scala 2.11.x:

vertx install io.vertx~mod-mysql-postgresql_2.11~0.3.0

If you get a "not found" exception, you might need to edit the repos.txt of your Vert.x installation to use https. See issue 35 (thanks, @dparshin!).

If you get java.lang.ClassNotFoundException: org.vertx.scala.core.VertxAccess$class please update your langs.properties scala entry to:

scala=io.vertx~lang-scala_2.10~1.1.0-M1:org.vertx.scala.platform.impl.ScalaVerticleFactory

If you're using Scala in your own project and want to use Scala 2.11, you can change lang-scala_2.10 to lang-scala_2.11.

Configuration

{
  "address" : <event-bus-addres-to-listen-on>,
  "connection" : <MySQL|PostgreSQL>,
  "host" : <your-host>,
  "port" : <your-port>,
  "maxPoolSize" : <maximum-number-of-open-connections>,
  "username" : <your-username>,
  "password" : <your-password>,
  "database" : <name-of-your-database>
}
  • address - The address this module should register on the event bus. Defaults to campudus.asyncdb
  • connection - The database you want to use. Defaults to PostgreSQL.
  • host - The host of the database. Defaults to localhost.
  • port - The port of the database. Defaults to 5432 for PostgreSQL and 3306 for MySQL.
  • maxPoolSize - The number of connections that may be kept open. Defaults to 10.
  • username - The username to connect to the database. Defaults to postgres for PostgreSQL and root for MySQL.
  • password - The password to connect to the database. Default is not set, i.e. it uses no password.
  • database - The name of the database you want to connect to. Defaults to test.

Usage

All commands are relatively similar. Use JSON with the action field and add the needed parameters for each command.

There are only a few commands available currently, but in theory you should be able to invoke any command on the database with the raw action.

Reply messages

The module will reply to all requests. In the message, there will be either a "status" : "ok" or a "status" : "error". If the request could be processed without problems, it will result in an "ok" status. See an example here:

{
  "status" : "ok",
  "rows" : 2,
  "message" : "SELECT 2",
  "fields" : [ "name", "email", "is_male", "age", "money", "wedding_date" ],
  "results" : [
    ["Mr. Test", "[email protected]", true, 32, 123.45, "2014-04-04"],
    ["Mrs. Test", "[email protected]", false, 16, 543.21, "2022-02-22"]
  ]
}
  • rows gives you the number of rows affected by the statement sent to the server. Bear in mind that PostgreSQL 8.4 only shows a row count on changed rows (DELETE, UPDATE, INSERT statements) whereas PostgreSQL 9.x and MySQL also show the number of SELECTed rows here.
  • message is a status message from the server.
  • fields contains the list of fields of the selected table - Only present if the request resulted in a result set.
  • results contains a list of rows - Only present if the request resulted in a result set.

If the request resulted in an error, a possible reply message looks like this:

{
  "status" : "error",
  "message" : "column \"ager\" does not exist"
}

insert

Use this action to insert new rows into a table. You need to specify a table, the fields to insert and an array of rows to insert. The rows itself are an array of values.

{
  "action" : "insert",
  "table" : "some_test",
  "fields" : ["name", "email", "is_male", "age", "money", "wedding_date"],
  "values" : [
    ["Mr. Test", "[email protected]", true, 32, 123.45, "2014-04-04"],
    ["Mrs. Test", "[email protected]", false, 16, 543.21, "2022-02-22"]
  ]
}

select

The select action creates a SELECT statement to get a projection from a table. You can filter the columns by providing a fields array. If you omit the fields array, it selects every column available in the table.

{
  "action" : "select",
  "table" : "some_test",
  "fields" : ["name", "email", "is_male", "age", "money", "wedding_date"], // Optional
}

prepared

Creates a prepared statement and lets you fill the ? with values.

{
  "action" : "prepared",
  "statement" : "SELECT * FROM some_test WHERE name=? AND money > ?",
  "values" : ["Mr. Test", 15]
}

raw - Raw commands

Use this action to send arbitrary commands to the database. You should be able to submit any query or insertion with this command.

Here is an example for creating a table in PostgreSQL:

{
  "action" : "raw",
  "command" : "CREATE TABLE some_test (
                 id SERIAL,
                 name VARCHAR(255),
                 email VARCHAR(255),
                 is_male BOOLEAN,
                 age INT,
                 money FLOAT,
                 wedding_date DATE
               );"
}

And if you want to drop it again, you can send the following:

    {
      "action" : "raw",
      "command" : "DROP TABLE some_test;"
    }

Transactions

These commands let you begin a transaction and send an arbitrary number of statements within the started transaction. You can then commit or rollback the transaction. Nested transactions are not possible until now!

Remember to reply to the messages after you send the begin command. Look in the docs how this works (e.g. for Java: http://vertx.io/core_manual_java.html#replying-to-messages). With replying to the messages, the module is able to send all statements within the same transaction. If you don't reply within the timeoutTransaction interval, the transaction will automatically fail and rollback.

transaction begin

This command starts a transaction. You get an Ok message back to which you can then reply with more statements.

{
    "action" : "begin"
}

transaction commit

To commit a transaction you have to send the commit command.

{
    "action" : "commit"
}

transaction rollback

To rollback a transaction you have to send the rollback command.

{
    "action" : "rollback"
}

Example for a transaction

Here is a small example on how a transaction works.

{
    "action" : "begin"
}

This will start the transaction. You get this response:

{
    "status" : "ok"
}

You can then reply to this message with the commands select, prepared, insert and raw. A possible reply could be this:

{
    "action" : "raw",
    "command" : "UPDATE some_test SET email = '[email protected]' WHERE id = 1"
}

You get a reply back depending on the statement you sent. In this case the answer would be:

{
    "status" : "ok",
    "rows" : 1,
    "message" : "UPDATE 1"
}

If you want to make more statements you just have to reply to this message again with the next statement. When you have done all statements you can commit or rollback the transaction.

{
    "action" : "commit"
}

If everything worked, the last answer will be:

{
    "status" : "ok"
}

old transaction command (deprecated, use the new transaction mechanism with begin and commit)

Takes several statements and wraps them into a single transaction for the server to process. Use statement : [...actions...] to create such a transaction. Only select, insert and raw commands are allowed right now.

{
  "action" : "transaction",
  "statements" : [
    {
      "action" : "insert",
      "table" : "account",
      "fields" : ["name", "balance"],
      "values" : ["Mr. Test", "0"]
    },
    {
      "action" : "raw",
      "command" : "UPDATE account SET balance=balance+1 WHERE name='Mr. Test'",
    },
    {
      "action" : "prepared",
      "statement" : "UPDATE account SET balance=balance+? WHERE name=?",
      "values" : [25, 'Mr. Test']
    }
  ]
}

Planned actions

You can always use raw to do anything on the database. If the statement is a query, it will return its results just like a select.

The select and insert commands are just for you to be able to have a cross-database application in the end. If you do not use raw, these commands should create the needed statements for you.

  • update - Updates rows of a table
  • delete - Deletes rows from a table
  • create - Creates a table
  • drop - Drops a table

These actions are currently not available, but they should be implemented in the future. Please see the following examples and send feedback:

{ // UPDATE some_test SET age=age+1 WHERE id=1
  "action" : "update",
  "table" : "some_test",
  "set" : {
    "age" : {$add : 1}
  },
  "conditions" : {
    "$eq" {
      "id" : 1
    }
  }
}

{ // DELETE FROM some_test WHERE id = 5
  "action" : "delete",
  "table" : "some_test",
  "conditions" : {
    "$eq" {
      "id" : 5
    }
  }
}

// SELECT name, email FROM some_test WHERE is_male=? AND money >= ?
{
  "action" : "prepared",
  "statement" : "SELECT name, email FROM some_test WHERE is_male=? AND money >= ?",
  "values" : [true,100]
}

// CREATE TABLE some_test (
//   id SERIAL,
//   name VARCHAR(255),
//   email VARCHAR(255),
//   age INTEGER
// );
{ 
  "action" : "create",
  "table" : "some_test",
  "fields" : ["id PRIMARY KEY", "name VARCHAR(255)", "email VARCHAR(255)", "age INTEGER"]
}

{ // DROP TABLE some_test
  "action" : "drop",
  "table" : "some_test",
}