sails-mysql-transaction is a Sails ORM Adapter for MySQL with transaction and replication cluster support.
This adapter essentially wraps around the popular sails-mysql adapter and provides additional API to perform
operations that ties around a database transaction. It also provides to read from a cluster of read-replicas in a
load-balanced fashion.
-
Add
sails-mysql-transactionsto your application’spackage.json. Do not run install directly ifsailsis not already installed in your package. -
If you already have
sails-mysqlinstalled, it might interfere with operations of this module. Remove it from yourpackage.jsonand uninstall the same usingnpm remove sails-mysql. -
This package installs successfully only when sails is already installed in the package. If the package is already installed, then simply run
npm install sails-mysql-transactions --save, otherwise runnpm installand it will take care of rest.
If npm install seems erratic to install dependencies in order, you could add the following in your package.json as
a postinstall script of npm. This would ensure that this module is installed after
sails has been completely installed. Note that in this method, you would not need to add sails-mysql-transactions as a
dependency in your package.json
{
"scripts": {
"postinstall": "npm install sails-mysql-transactions"
}
}
This package overwrites the waterline module inside Sails with a fork of Waterline maintained by Postman. As such,
if you ever re-install or update sails, ensure you re-install this adapter right after it.
Do check SailsJS compatibility list before upgrading your Sails version while already using this adapter.
The integration test Sails App located in tests/integration/app directory of this repository has a fully functional
installation. Simply run npm install within test/integration/app directory.
module.exports = {
/* your other config stay as is */
connections: {
mySQLT: {
adapter: 'sails-mysql-transactions',
host: '{{your-db-host}}',
user: '{{your-db-username}}',
password: '{{your-db-password}}',
database: '{{your-db-tablename}}',
transactionConnectionLimit: 10,
rollbackTransactionOnError: true,
queryCaseSensitive: false,
/* this section is needed only if replication feature is required */
replication: {
enabled: true,
inheritMaster: true,
canRetry: true,
removeNodeErrorCount: 5,
restoreNodeTimeout: 1000 * 60 * 5,
defaultSelector: 'RR', // 'RANDOM' or 'ORDER'
sources: {
readonly: {
enabled: true,
host: '{{replica-1-host}}',
user: '{{replica-1-user}}',
password: '{{replica-1-password}}'
}
}
}
}
},
models: {
connection: 'mySQLT'
}
}var Transaction = require('sails-mysql-transactions').Transaction;
module.exports = {
create: function (req, res) {
// start a new transaction
Transaction.start(function (err, transaction) {
if (err) {
// the first error might even fail to return a transaction object, so double-check.
transaction && transaction.rollback();
return res.serverError(err);
}
OneModel.transact(transaction).create(req.params.all(), function (err, modelInstance) {
if (err) {
transaction.rollback();
return res.serverError(err);
}
// using transaction to update another model and using the promises architecture
AnotherModel.transact(transaction).findOne(req.param('id')).exec(function (err, anotherInstance) {
if (err) {
transaction.rollback();
return res.serverError(err);
}
// using update and association changes
modelInstance.someAssociatedModel.remove(req.param('remove_id'));
// standard .save() works when in transaction
modelInstance.save(function (err, savedModel) {
if (err) {
transaction.rollback();
return res.serverError(err);
}
// finally commit the transaction before sending response
transaction.commit();
return res.json({
one: savedModel,
another: anotherInstance
});
});
});
});
});
}
};route = function (req, res) {
Transaction.start(function (err, transaction) {
OneModel.transact(transaction).create(/* ... */);
OneModel.transact(transaction).update(/* ... */);
OneModel.transact(transaction).find(/* ... */);
OneModel.transact(transaction).findOrCreate(/* ... */);
OneModel.transact(transaction).findOne(/* ... */);
OneModel.transact(transaction).destroy(/* ... */);
OneModel.transact(transaction).count(/* ... */);
});
};Other than those, update, save and association operations on instance methods work within transaction provided they
were either stemmed from the same transaction or wrapped (transaction.wrap(instance)) by a transaction.
In cases where you are performing model instance opertaions such as save, destroy, etc on instances that has been
stemmed from a .populate, transaction might fail. In such scenarios, performing a transaction.wrap(instance); before
doing instance operations should fix such errors.
If you want to selectively intercept errors from this module, compare using instanceof Transaction.AdapterError.
Note that this adapter adds an additional auto column called transactionId. If you do not want to use transaction on
a particular model, you can turn off creation of this column by setting autoTK: false in your model.
When one or more read replica sources are provded, the following API can be used to access data from one of the defined replication source databases. This distributes your database workloads across multiple systems.
Readonly still works without read replica using the normal non-transactional connection set.
action = function (req, res) {
OneModel.readonly().find();
OneModel.readonly().findOne();
OneModel.readonly().count();
};Since sails-mysql makes a SELECT query before every update; it makes sense that the query results can be utilised to
return the changeset when a model is updated. The third parameter of .update returns an array having objects that
contain only the fields that have changed and that too with their original values.
-
queryCaseSensitivewhen set to true, disables the feature where waterline performs case insensitive queries. (Note that it iseswlNextoptions for waterline-sequel.) -
The bundled waterline adds additional feature to do the following
Model.<function:operate>().populateSome(Object<association:criteria>);allows you to populate multiple associations in one call. It also accepts array of associations as argument.populateon Models acceptsselect: []as part of criteria parameter.- Model deletion does not fetch full model data during deletion.
- An additional asynchronous function
fromObject()which creates a model instance based on the model attributes.
- This function accepts the attributes object and the callback function as the parameter.
- The callback function will receive the error object and the Model Instance object
OneModel.fromObject(attributesObject, function (err, instance) {
if (err) { return Error; }
// instance is the required object
});Contribution is accepted in form of Pull Requests that passes Travis CI tests. You should install this repository using
npm install -d and run npm test locally before sending Pull Request.
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