jdbc

0.6.3 • Public • Published 6 months ago

node-jdbc

JDBC API Wrapper for node.js

Latest Version

0.6.2

Installation

Release: npm i --save jdbc
Development: npm i --save jdbc@next (this will install code from the master branch).

Please visit node-jdbc for information on installing with npm.

Status

Supported Java Versions

node-java has experiemental support for 1.8, and if you are brave you can compile it with such. All the tests work out of the box on a 1.8 JVM, but I've only wrapped 1.7 functions.

Note that Java 9 is not currently supported. When node-java supports Java 9, I will look into implementing any new Java 9 API changes (if any).

Major API Refactor

One Instance to Rule Them All (JVM)

node-java spins up one JVM instance only. Due to this fact, any JVM options and classpath setup have to happen before the first java call. I've created a small wrapper (jinst.js) to help out with this. See below for example usage. I usually add this to every file that may be an entry point. The unit tests are setup like this due to the fact that order can't be guaranteed.

var jinst = require('jdbc/lib/jinst');
 
// isJvmCreated will be true after the first java call.  When this happens, the
// options and classpath cannot be adjusted.
if (!jinst.isJvmCreated()) {
  // Add all java options required by your project here.  You get one chance to
  // setup the options before the first java call.
  jinst.addOption("-Xrs");
  // Add all jar files required by your project here.  You get one chance to
  // setup the classpath before the first java call.
  jinst.setupClasspath(['./drivers/hsqldb.jar',
                        './drivers/derby.jar',
                        './drivers/derbyclient.jar',
                        './drivers/derbytools.jar']);
}

Connection Pooling

Everyone gets a pool now. By default with no extra configuration, the pool is created with one connection that can be reserved/released. Currently, the pool is configured with two options: minpoolsize and maxpoolsize. If minpoolsize is set, when the pool is initialized, minpoolsize connections will be created. If maxpoolsize is set (the default value is minpoolsize), and you try and reserve a connection and there aren't any available, the pool will be grown. This can happen until maxpoolsize connections have been reserved. The pool should be initialized after configuration is set with the initialize() function. JDBC connections can then be acquired with the reserve() function and returned to the pool with the release() function. Below is the unit test for the pool that demonstrates this behavior.

var _ = require('lodash');
var nodeunit = require('nodeunit');
var jinst = require('../lib/jinst');
var Pool = require('../lib/pool');
 
if (!jinst.isJvmCreated()) {
  jinst.addOption("-Xrs");
  jinst.setupClasspath(['./drivers/hsqldb.jar',
                        './drivers/derby.jar',
                        './drivers/derbyclient.jar',
                        './drivers/derbytools.jar']);
}
 
var config = {
  url: 'jdbc:hsqldb:hsql://localhost/xdb',
  user : 'SA',
  password: '',
  minpoolsize: 2,
  maxpoolsize: 3
};
 
var testpool = null;
var testconn = null;
 
module.exports = {
  setUp: function(callback) {
    if (testpool === null) {
      testpool = new Pool(config);
    }
    callback();
  },
  testinitialize: function(test) {
    // Initialize the pool (create minpoolsize connections)
    testpool.initialize(function(err) {
      test.expect(1);
      test.equal(null, err);
      test.done();
    });
  },
  testreserve: function(test) {
    // Reserve a connection.
    testpool.reserve(function(err, conn) {
      test.expect(4);
      test.equal(null, err);
      test.ok(conn && typeof conn == 'object');
      test.equal(testpool._pool.length, 1);
      test.equal(testpool._reserved.length, 1);
      testconn = conn;
      test.done();
    });
  },
  testrelease: function(test) {
    // Release a connection.
    testpool.release(testconn, function(err, conn) {
      test.expect(3);
      test.equal(null, err);
      test.equal(testpool._pool.length, 2);
      test.equal(testpool._reserved.length, 0);
      testconn = null;
      test.done();
    });
  },
  testreserverelease: function(test) {
    // Reserve then release a connection.
    testpool.reserve(function(err, conn) {
      if (err) {
        console.log(err);
      } else {
        testpool.release(conn, function(err) {
          test.expect(3);
          test.equal(null, err);
          test.equal(testpool._pool.length, 2);
          test.equal(testpool._reserved.length, 0);
          test.done();
        });
      }
    });
  },
  testreservepastmin: function(test) {
    // Reserve connections past minpoolsize.  This will grow the pool.
    var conns = [];
    for(i = 0; i < 3; i++) {
      testpool.reserve(function(err, conn) {
        conns.push(conn);
        if (i == 3) {
          test.expect(2);
          test.equal(testpool._pool.length, 0);
          test.equal(testpool._reserved.length, 3);
          _.each(conns, function(conn) {
            testpool.release(conn, function(err) {});
          });
          test.done();
        }
      });
    }
  },
  testovermax: function(test) {
    // Reserve connections past maxpoolsize.  This will max out the pool, and
    // throw an error when the last reserve request is made.
    var conns = [];
    for(i = 0; i < 4; i++) {
      testpool.reserve(function(err, conn) {
        if (err) {
          if (i == 3) {
            test.expect(3);
            test.ok(err);
            test.equal(testpool._reserved.length, 3);
            test.equal(testpool._pool.length, 0);
            _.each(conns, function(conn) {
              testpool.release(conn, function(err) {});
            });
            test.done();
          } else {
            console.log(err);
          }
        } else {
          conns.push(conn);
        }
      });
    }
  }
};

Fully Wrapped Connection API

The Java Connection API has almost been completely wrapped. See connection.js for a full list of functions.

conn.setAutoCommit(false, function(err) {
  if (err) {
    callback(err);
  } else {
    callback(null);
  }
});

ResultSet processing separated from statement execution

ResultSet processing has been separated from statement execution to allow for more flexibility. The ResultSet returned from executing a select query can still be processed into an object array using the toObjArray() function on the resultset object.

// Select statement example.
conn.createStatement(function(err, statement) {
  if (err) {
    callback(err);
  } else {
    statement.executeQuery("SELECT * FROM blah;", function(err, resultset) {
      if (err) {
        callback(err)
      } else {
        // Convert the result set to an object array.
        resultset.toObjArray(function(err, results) {
          if (results.length > 0) {
            console.log("ID: " + results[0].ID);
          }
          callback(null, resultset);
        });
      }
    });
  }
});

Automatically Closing Idle Connections

If you pass a maxidle property in the config for a new connection pool, pool.reserve() will close stale connections, and will return a sufficiently fresh connection, or a new connection. maxidle can be number representing the maximum number of milliseconds since a connection was last used, that a connection is still considered alive (without making an extra call to the database to check that the connection is valid). If maxidle is a falsy value or is absent from the config, this feature does not come into effect. This feature is useful, when connections are automatically closed from the server side after a certain period of time, and when it is not appropriate to use the connection keepalive feature.

Usage

Some mininal examples are given below. I've also created a node-example-jdbc project with more thorough examples.

Initialize

var JDBC = require('jdbc');
var jinst = require('jdbc/lib/jinst');
 
if (!jinst.isJvmCreated()) {
  jinst.addOption("-Xrs");
  jinst.setupClasspath(['./drivers/hsqldb.jar',
                        './drivers/derby.jar',
                        './drivers/derbyclient.jar',
                        './drivers/derbytools.jar']);
}
 
var config = {
  // Required
  url: 'jdbc:hsqldb:hsql://localhost/xdb',
 
  // Optional
  drivername: 'my.jdbc.DriverName',
  minpoolsize: 10,
  maxpoolsize: 100,
 
  // Note that if you sepecify the user and password as below, they get
  // converted to properties and submitted to getConnection that way.  That
  // means that if your driver doesn't support the 'user' and 'password'
  // properties this will not work.  You will have to supply the appropriate
  // values in the properties object instead.
  user: 'SA',
  password: '',
  properties: {}
};
 
// or user/password in url
// var config = {
//   // Required
//   url: 'jdbc:hsqldb:hsql://localhost/xdb;user=SA;password=',
//
//   // Optional
//   drivername: 'my.jdbc.DriverName',
//   minpoolsize: 10
//   maxpoolsize: 100,
//   properties: {}
// };
 
// or user/password in properties
// var config = {
//   // Required
//   url: 'jdbc:hsqldb:hsql://localhost/xdb',
//
//   // Optional
//   drivername: 'my.jdbc.DriverName',
//   minpoolsize: 10,
//   maxpoolsize: 100,
//   properties: {
//     user: 'SA',
//     password: ''
//     // Other driver supported properties can be added here as well.
//   }
// };
 
var hsqldb = new JDBC(config);
 
hsqldb.initialize(function(err) {
  if (err) {
    console.log(err);
  }
});

Reserve Connection, Execute Queries, Release Connection

// This assumes initialization as above.
// For series execution.
var asyncjs = require('async');
 
hsqldb.reserve(function(err, connObj) {
  // The connection returned from the pool is an object with two fields
  // {uuid: <uuid>, conn: <Connection>}
  if (connObj) {
    console.log("Using connection: " + connObj.uuid);
    // Grab the Connection for use.
    var conn = connObj.conn;
 
    // Adjust some connection options.  See connection.js for a full set of
    // supported methods.
    asyncjs.series([
      function(callback) {
        conn.setAutoCommit(false, function(err) {
          if (err) {
            callback(err);
          } else {
            callback(null);
          }
        });
      },
      function(callback) {
        conn.setSchema("test", function(err) {
          if (err) {
            callback(err);
          } else {
            callback(null);
          }
        });
      }
    ], function(err, results) {
      // Check for errors if need be.
      // results is an array.
    });
 
    // Query the database.
    asyncjs.series([
      function(callback) {
        // CREATE SQL.
        conn.createStatement(function(err, statement) {
          if (err) {
            callback(err);
          } else {
            statement.executeUpdate("CREATE TABLE blah "
                                  + "(id int, name varchar(10), date DATE, "
                                  + " time TIME, timestamp TIMESTAMP);",
                                  function(err, count) {
              if (err) {
                callback(err);
              } else {
                callback(null, count);
              }
            });
          }
        });
      },
      function(callback) {
        conn.createStatement(function(err, statement) {
          if (err) {
            callback(err);
          } else {
            statement.executeUpdate("INSERT INTO blah "
                                  + "VALUES (1, 'Jason', CURRENT_DATE, "
                                  + "CURRENT_TIME, CURRENT_TIMESTAMP);",
                                  function(err, count) {
              if (err) {
                callback(err);
              } else {
                callback(null, count);
              }
            });
          }
        });
      },
      function(callback) {
        // Update statement.
        conn.createStatement(function(err, statement) {
          if (err) {
            callback(err);
          } else {
            statement.executeUpdate("UPDATE blah "
                                  + "SET id = 2 "
                                  + "WHERE name = 'Jason';",
                                  function(err, count) {
              if (err) {
                callback(err);
              } else {
                callback(null, count);
              }
            });
          }
        });
      },
      function(callback) {
        // Select statement example.
        conn.createStatement(function(err, statement) {
          if (err) {
            callback(err);
          } else {
            // Adjust some statement options before use.  See statement.js for
            // a full listing of supported options.
            statement.setFetchSize(100, function(err) {
              if (err) {
                callback(err);
              } else {
                statement.executeQuery("SELECT * FROM blah;",
                                       function(err, resultset) {
                  if (err) {
                    callback(err)
                  } else {
                    resultset.toObjArray(function(err, results) {
                      if (results.length > 0) {
                        console.log("ID: " + results[0].ID);
                      }
                      callback(null, resultset);
                    });
                  }
                });
              }
            });
          }
        });
      },
      function(callback) {
        conn.createStatement(function(err, statement) {
          if (err) {
            callback(err);
          } else {
            statement.executeUpdate("DELETE FROM blah "
                                  + "WHERE id = 2;", function(err, count) {
              if (err) {
                callback(err);
              } else {
                callback(null, count);
              }
            });
          }
        });
      },
      function(callback) {
        conn.createStatement(function(err, statement) {
          if (err) {
            callback(err);
          } else {
            statement.executeUpdate("DROP TABLE blah;", function(err, count) {
              if (err) {
                callback(err);
              } else {
                callback(null, count);
              }
            });
          }
        });
      }
    ], function(err, results) {
      // Results can also be processed here.
      // Release the connection back to the pool.
      hsqldb.release(connObj, function(err) {
        if (err) {
          console.log(err.message);
        }
      });
    });
  }
});

Keywords

install

npm i jdbc

weekly downloads

2,056

version

0.6.3

license

MIT

homepage

github.com

repository

github

last publish

6 months ago

collaborators

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