node-mysql
An enhancement to the mysql lib to make it a bit easier to use. Based on the existing funtionalities of (npm) mysql, it also
- Handles transactions.
- Provides a simple ORM, which
- Detects table schema automatically.
- Provides handy functions for creating and updating rows.
- Handles optimistic lock through versioning transparently.
- Maintains "date_created" and "last_updated" automatically.
- Provides database row level lock functionality.
Install
npm install node-mysql
Dependencies
"dependencies": {
"better-js-class": "*",
"cps": "*",
"mysql": "*",
"underscore": "*"
}Use
var db = require('node-mysql');
var DB = db.DB;
var BaseRow = db.Row;
var BaseTable = db.Table;APIs
- DB
- Table
- Row
new DB(conf)
Please refer to the the connection pool conf in mysql package for the format of "conf".
Example
var box = new DB({
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone'
});Beyond the configuration fields provided by mysql package, there are two additional configuration fields that can be used in "conf":
- useTransaction
- useCursor
useTransaction
Only if "useTransaction" is provided can "db.transaction" API be called. Otherwise, calls to "db.transaction" will throw an error with the message "transation-not-setup-error". The "useTransaction" field itself is an configuration object that overrides the fields in "conf" to set up a connection pool for transactions. For instance:
Example
var box = new DB({
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone',
connectionLimit: 50,
useTransaction: {
connectionLimit: 1
}
});will allow the db object "box" to use "box.transaction" API, with a connection pool for transactions set up the same way as the normal connection pool except for the connectionLimit field being overridden to 1. So in "box", there are two mysql connection pools, for normal db requests and transactional db requests, repectively. The normal connection pool's configuration is:
{
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone',
connectionLimit: 50
}while the transactional connection pool's configuration is:
{
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone',
connectionLimit: 1
}useCursor
Similarly to "useTransaction", only if "useCursor" is provided can "db.cursor" API be called. Otherwise, calls to "db.cursor" will throw an exception with the error message "cursor-not-setup-error". The field "useCursor" is very similar to the field "useTransaction", with the only difference that it is for setting up the mysql connection pool for cursors rather than transactions. "useCursor" is also an overriding object based upon the connection pool configuration for normal connections. For instance:
Example
var box = new DB({
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone',
connectionLimit: 50,
useCursor: {
connectionLimit: 1
}
});will allow the API "box.cursor" to be called, with a connection pool for cursors set up the same way as the normal connection pool except for the connectionLimit field being overridden to 1. So in "box", there are two mysql connection pools, for normal db requests and cursor db requests, repectively. The normal connection pool's configuration is:
{
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone',
connectionLimit: 50
}while the cursor connection pool's configuration is:
{
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone',
connectionLimit: 1
}Use Both
"useTransaction" and "useCursor" can be used together:
Example
var box = new DB({
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone',
connectionLimit: 50,
useTransaction: {
connectionLimit: 20
},
useCursor: {
connectionLimit: 1
}
});This will allow all of the three APIs, "box.connect", "box.transaction" and "box.cursor" to be called. In this case, box hold three connection pools, for normal connections, transactional connections and cursor connections, respectively. The normal connection pool is configured as:
{
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone',
connectionLimit: 50
}the transactional connection pool is configured as:
{
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone',
connectionLimit: 20
}and the cursor connection pool is configured as:
{
host : 'localhost',
user : 'root',
password : '',
database : 'prod_clone',
connectionLimit: 1
}db.connect(procedure, callback)
The procedure is a function of the type:
function(connection, callback) {
// work with the database connection
}Example
var basicTest = function(cb) {
box.connect(function(conn, cb) {
cps.seq([
function(_, cb) {
conn.query('select * from users limit 1', cb);
},
function(res, cb) {
console.log(res);
cb();
}
], cb);
}, cb);
};db.transaction(db_connection, procedure, callback)
The procedure is a function of the type:
function(connection, callback) {
// work with the database connection
}Note that db.transaction takes one more arguemnt than the db.connect, which is a database connection object. If this connection object is already a transactional, then it will be used directly in the provided procedure. Otherwise, the connection will be "made transactional" and then used in the provided procedure.
Example
var txnTest = function(cb) {
var add2Rows = function(conn, b, cb) {
dw.transaction(
conn/*This is a non-transactional connection.*/,
function(
conn/*A new transactional connection is
created to handle the transactional session.*/,
cb
) {
cps.seq([
function(_, cb) {
Model.Table.create(conn, getSampleDto(), cb);
},
function(_, cb) {
dw.transaction(
conn/*This is already a transactional connection.*/,
function(
conn/*No new transactional connection created.
This connection is the same one as
in the calling context*/,
cb
) {
console.log(conn.__transaction__)
Model.Table.create(conn, getSampleDto(), cb);
},
cb
);
},
function(_, cb) {
if (b) {
cb(null, "Commit");
} else {
throw new Error("Roll back");
}
}
], cb);
},
cb
);
};
dw.connect(function(conn, cb) {
/* Uncommenting the following line will merge the two calls
to add2Rows into one transaction. */
// dw.transaction(conn, function(conn, cb) {
cps.seq([
function(_, cb) {
add2Rows(conn, true, cb);
},
function(_, cb) {
add2Rows(conn, true, cb);
}
], cb);
// }, cb);
}, cb);
};db.cursor(query_string, procedure, callback)
This API can be used to cursor thought the (potentially very long list of) results of a query. The procedure parameter is the operation to be applied to each row in the results of the query. Please note the following:
db.cursor will create a separate db connection for cursoring purpose. That is why this API does not take a db_connection in the parameter list, unlike most of the other db related APIs.
If there is an exception thrown out of the row handling procedure, the cursoring will be stopped and the exception will be thrown out to the top level callback (the 3rd parameter to db.cursor). If you intend for the cursor to go over all the results, you need to catch any exceptions in the row handling procedure (using cps.rescue).
Example
// cursor through all the users and update the active status to "1"
var cursorTest = function(cb) {
db.connect(function(conn, cb) {
var q = 'select * from users';
db.cursor(q, function(row, cb) {
cps.rescur({
'try': function() {
cps.seq([
function(_, cb) {
var user = new User.Row(row);
user.update(conn, {active: 1}, cb);
},
function(res, cb) {
console.log(res);
cb();
}
], cb);
},
'catch': function(err, cb) {
console.log(err);
cb();
}
}, cb);
}, cb);
}, cb);
};db.end();
This function destructs the db object.
db.add(config);
This function is used to define a model that belongs to the db object. The model config object is of the following format:
{
"name": {
"type": "String",
"description": "the name of the table"
},
"idFieldName": {
"type": "String",
"optional": true,
"default": "id",
"description": "the name of the primary id column"
},
"versionFieldName": {
"type": "String",
"optional": true,
"default": "version",
"description": "optimistic lock version"
},
"createdFieldName": {
"type": "String",
"optional": true,
"default": "date_created",
"description": "creation time of the row"
},
"updatedFieldName": {
"type": "String",
"optional": true,
"default": "last_updated",
"description": "last update time of the row"
},
"Row": {
"type": "Object",
"optional": true,
"default": "{}",
"description": "the overriding method definition for the Row class of this model"
},
"Table": {
"type": "Object",
"optional": true,
"default": "{}",
"description": "the overriding method definition for the Table class of this model"
}
}Note that db.add returns a Table object, which can be further chained with linking/joining functions such as linksTo, linkedBy and relatesTo.
Example
db.add({
name: 'orders',
idFieldName: 'order_id',
Row: {
getFirstOrderItem: function(conn, cb) {
var me = this;
cps.seq([
function(_, cb) {
me.linkedBy(conn, 'items', cb);
},
function(items, cb) {
cb(null, items[0]);
}
], cb);
}
},
Table: {
createOrderUsingCoupon: function(conn, dto, coupon, cb) {
dto['coupon_id'] = coupon.getId();
this.create(conn, dto, cb);
}
}
})
.linkedBy({
name: 'items',
key: 'order_id',
table: 'order_items'
})
.linksTo({
name: 'user',
key: 'user_id',
table: 'users'
})
.linksTo({
name: 'coupon',
key: 'coupon_id',
table: 'coupons'
})
.linksTo({
name: 'credit_card',
key: 'credit_card_id',
table: 'credit_cards'
})
;
In this example:
- We created a model for the table "orders" in the database.
- We add a method getFirstOrderItem into the Row class of this model.
- We add a method createOrderWithCoupon into the Table class of this model.
- We follow the foreign key relations of the "orders" table to define some link relations.
db.get(table_name)
Once you use db.add to create a model in the db object, you can then use db.get to retrieve it by name. The return value of db.get if a object of the following format:
{
"Row": {
"type": "Row object"
},
"Table": {
"type": "Table object"
}
}Example
var Order = db.get('orders');
var Coupon = db.get('coupons');
db.connect(function(conn, cb) {
cps.seq([
function(_, cb) {
Coupon.Table.findByCode(conn, '10-percent-off', cb);
}
function(coupon, cb) {
var dto = {/*dto data*/};
Order.createOrderWithCoupon(conn, dto, coupon, cb);
},
function(order, cb) {
order.getFirstOrderItem(conn, cb);
},
function(firstItem, cb) {
console.log(firstItem);
cb()
}
], cb);
}, cb);DB.format(query_string, variable_bindings)
This is a wrapper of the query string formatting functionality provided by the mysql package. Note that this is a global static method defined on the class DB. It is NOT an instance method defined a a DB instance db.
Example
DB.format('select * from users where id = ?' [userId]);new Table(table_config)
The table config schema is defined as follows:
{
"name": {
"type": "String",
"optional": false,
"description": "the name of the database table"
},
"idFieldName": {
"type": "String",
"optional": true,
"default": "id",
"description": "the name of the primary id column"
},
"versionFieldName": {
"type": "String",
"optional": true,
"default": "version",
"description": "optimistic lock version"
},
"createdFieldName": {
"type": "String",
"optional": true,
"default": "date_created",
"description": "creation time of the row"
},
"updatedFieldName": {
"type": "String",
"optional": true,
"default": "last_updated",
"description": "last update time of the row"
},
"rowClass": {
"type": "Row class",
"optional": false,
"description": "the Row class of this table"
},
"db": {
"type": "DB class instance",
"optional": false,
"description": "the DB instance that the table belongs to"
}
}See here for an example of creating a table.
table.create(database_connection, data_object, callback)
The callback here takes a Row object as result.
Example
var createTest = function(cb) {
dw.connect(function(conn, cb) {
cps.seq([
function(_, cb) {
User.Table.create(conn, {
first_name: 'Hannah',
last_name: 'Mckay',
gender: 'female'
// ....
}, cb);
},
function(user, cb) { // user is an object of the class User.Row
console.log(user.get('first_name')); // print out 'Hannah'
cb();
}
], cb);
}, cb);
};In the input data object, please do NOT specify the following fields:
- primary ID
- date_created
- last_udpated
- version
All of the these fields will be filled by the invocation to table.create.
table.clone(database_connection, data_object, callback)
This API is very similar to table.create. The key difference is that it does not mask out any data field carried in data_object. Instead, it literally uses every thing in data_object to create a new row. In other words, it'll honor the values of the following fields in data_object:
- primary ID
- date_created
- last_udpated
- version
This API can be useful when one attempts to clone a row in a table literally to another table (which might be in another database).
table.find(database_connection, query_string, callback)
This function is not too different from doing a query directly on a database connection. The only extra thing it does is to turn the result from a list of simple hash objects to a list of Row objects of the corresponding table's "rowClass".
Example
dw.connect(function(conn, cb) {
var o;
cps.seq([
function(_, cb) {
User.Table.find(conn, 'select * from users', cb);
},
function(users, cb) { // users is a list of user object of the class User.Row
console.log(users[0]); // print the information of the first user
cb();
}
], cb);
}, cb);table.findById(database_connection, row_id, callback)
This is simply a short-hand for:
cps.seq([
function(_, cb) {
table.find(
conn,
DB.format('select * from table_name where primary_id = ?', [row_id]),
cb
);
},
function(res, cb) {
cb(res[0]);
}
], cb);It finds a row in a table by its primary ID and returns a single row object of the table's corresponding rowClass.
table.lockById(database_connection, row_id, callback)
This function does the same thing as findById and additionally, it locks the corresponding row for an atomic update. lockById can ONLY be used in a transaction context. Without a transaction context, it behaves the same as findById. Once a row is locked in one transaction, attempts of locking the same row in other transactions will hang until the current transaction either commits or rolls back, which release the current lock.
Example
var lockTest = function(cb) {
var exclusiveUpdate = function(conn, delay, value, cb) {
dw.transaction(null, function(conn, cb) {
cps.seq([
function(_, cb) {
Model.Table.lockById(conn, 1, cb);
},
function(res, cb) {
setTimeout(function() {
cb(null, res);
}, delay);
},
function(row, cb) {
row.update(conn, {'subscription_status': value}, cb);
},
function(res, cb) {
cb();
}
], cb)
}, cb);
};
var conn;
dw.transaction(conn, function(conn, cb) {
cps.seq([
function(_, cb) {
cps.parallel([
function(cb) {
exclusiveUpdate(conn, 2000, 'foo1', cb);
},
function(cb) {
exclusiveUpdate(conn, 0, 'bar1', cb);
}
], cb);
},
function(res, cb) {
console.log(res);
cb();
}
], cb);
}, cb);
};In this example, two threads are executed in parallel. The thread of setting value "bar1" will be block by the thread of setting value "foo1".
table.findAll(database_connection, callback)
This finds all the rows in a table.
table.baseQuery(query_string, variable_bindings)
This is a short-hand for:
DB.format('select * from table_name' + query_string, variable_bindings);It simply prepend a partial string indicating from which table the query is being performed. This might come handy in many cases.
table.linksTo(config)
The config object has the following schema:
{
"name": {
"type": "String",
"description": "The name of the field to add to the row's data."
},
"key": {
"type": "String",
"description": "The key that belongs to the current table and links to another table."
},
"table": {
"type": "String",
"description": "The name of the table that the current table links to."
}
}Example
Order.Table
.linksTo({
name: 'credit_card',
key: 'credit_card_id'
table: 'credit_cards'
})
.linksTo({
name: 'shipping_address',
key: 'shipping_address_id'
table: 'addresses'
})
;Note that for "linksTo", the (join) key is on the current table. Once a "linksTo" is set up, a row object that corresponds to this table can call the "linksTo" method to pull more (associated) data into the row. See examples here.
table.linkedBy(config)
The config object has the following schema:
{
"name": {
"type": "String",
"description": "The name of the field to add to the row's data."
},
"key": {
"type": "String",
"description": "The key that belongs to the other table and links to the current table."
},
"table": {
"type": "String",
"description": "The name of the table that the current table is linked by."
}
}Example
Order.Table
.linkedBy({
name: 'items',
table: OrderItem.Table,
key: 'order_id'
})
;Once a "linkedBy" is set up on a table, a row object corresponding to this table can call the "linkedBy" method to pull more (associated) data into the row. See examples here.
table.relatesTo(config)
The config object has the following schema:
{
"name": {
"type": "String",
"description": "The name of the field to add to the row's data."
},
"through": {
"type": "String",
"description": "The name of the through table, which joins both the current table and the target table."
},
"leftKey": {
"type": "String",
"description": "The key that belongs to the current table and joins with the through table."
},
"table": {
"type": "String",
"description": "The name of the target table that the current table is joining thourgh the through-table."
},
"rightKey": {
"type": "String",
"description": "The key that belongs to the target table and joins with the through table."
}
}Example
Order.Table
.relatesTo({
name: 'coupons',
leftKey: 'order_id',
through: 'order_coupons',
rightKey: 'coupon_id',
table: 'coupons'
})
;table.relatesTo is designed to represent ORM of a many-to-many relation. Once a "relatesTo" is set up on a table, a row object corresponding to this table can call the "relatesTo" method to pull more (associated) data into the row. See examples here.
new Row(row_data)
After having a concrete Row class, row instances can be created using it. The row_data parameter is an object mapping database table column names to their corresponding values.
Example
new User.Row({
first_name: 'Hannah',
last_name: 'Mckay',
gender: 'female'
//....
});row.update(database_connection, update_object, callback)
This function will set the following column automatically:
- last_updated. This field will be set to the present time stamp.
- version. This field will be increased.
Other than these columns, only columns listed in the update_object will be updated.
Example
var findAndUpdateTest = function(cb) {
dw.connect(function(conn, cb) {
cps.seq([
function(_, cb) {
User.Table.findById(conn, id, cb);
},
function(user, cb) {
var dto = {
'last_name': 'Morgan'
};
user.update(conn, dto, cb);
}
], cb);
}, cb);
};row.updateWithoutOptimisticLock(database_connection, update_object, callback)
This function is the same as row.update with only one difference: it does not care about the optimistic lock version field. It neither looks at this field nor update field. This might be useful ocasionally when optimistic lock functionality needs to be overriden.
row.get(column_name)
Get the value of a certain column from the row object.
row.getId()
Get the primary ID of the row object.
row.linksTo(database_connection, field_name, callback)
Given a "linksTo" setup in the corresponding "Table" object, row.linksTo pulls further relevant data into the row.
Example
var order;
cps.seq([
function(_, cb) {
Order.Table.findById(conn, id, cb);
},
function(res, cb) {
order = res;
order.linksTo(conn, 'credit_card', cb);
},
function(_, cb) {
order.linksTo(conn, 'shipping_address', cb);
},
function(_, cb) {
console.log(order.get('credit_card').getId());
console.log(order.get('shipping_address').getId());
cb();
}
], cb);row.linkedBy(database_connection, field_name, callback)
Given a "linkedBy" setup in the corresponding "Table" object, row.linkedBy pulls further relevant data into the row.
Example
var order;
cps.seq([
function(_, cb) {
Order.Table.findById(conn, id, cb);
},
function(res, cb) {
order = res;
order.linkedBy(conn, 'items', cb);
},
function(items, cb) {
// items will both be bound to the return value and be assigned to the 'items' field.
console.log(items);
console.log(order.get('items'));
cb();
}
], cb);row.relatesTo(database_connection, field_name, callback)
Given a "relatesTo" setup in the corresponding "Table" object, row.relatesTo pulls further relevant data into the row.
Example
var order;
cps.seq([
function(_, cb) {
Order.Table.findById(conn, id, cb);
},
function(res, cb) {
order = res;
order.relatesTo(conn, 'coupons', cb);
},
function(coupons, cb) {
// coupons will both be bound to the return value and be assigned to the 'coupons' field.
console.log(coupons);
console.log(order.get('coupons'));
cb();
}
], cb);
