db

Go package strongo/db

Database abstraction layer (DAL) in Go language

There are 4 main purposes for the package:

1. To abstract work with data storage so underlying storage engine can be changed.

2. To allow write less code that is more readable.

3. To allow easialy add logging & hooks for tx/insert/get/query/update/delete operations across app. Think about preventing updates made outside of transaction or logging automatically what properties have changed.

4. Allow to write unit tests without dependency on specific implementation. (do no compile AppEngine packages for examples)

The main abstraction is done though interface EntityHolder:

type EntityHolder interface {
	TypeOfID() TypeOfID            // Either `string`, `int`, or `complex`
	Kind() string                  // Defines `table` name of the entity
	NewEntity() interface{}        // Used for `get` operations to create emtity to fill with values.
	Entity() interface{}           // Entity with fields to be stored to DB (without ID)
	SetEntity(entity interface{})  //
	IntID() int64                  // Returns ID for entities identified by integer value
	StrID() string                 // Returns ID for entities identified by string value
	SetIntID(id int64)             // Sets integer ID for entities identified by integer value
	SetStrID(id string)            // Sets string ID for entities identified by string value
}

All methods are working with the EntityHolder.

The Database interface defines an interface to a storage that should be implemented by a specific driver. This repo contains implementation for Google AppEngine Datastore. Contributions for other engines are welcome. If the db driver does not support some of the operations it must return ErrNotSupported.

type Database interface {
	TransactionCoordinator
	Inserter
	Getter
	Updater
	MultiGetter
	MultiUpdater
}

where for example the Getter & MultiGetter interfaces are defined as:

type Getter interface {
	Get(c context.Context, entityHolder EntityHolder) error
}

type MultiGetter interface {
	GetMulti(c context.Context, entityHolders []EntityHolder) error
}

Note that getters are populating entities in place through calling SetEntity(entity interface{}) method.

Originally developed to support work with Google AppEngine Datastore it takes into account its specifics. This should work well for other key-value storages as well.

Used by

This package is used in production by:

• https://debtstracker.io/ - an app and Telegram bot to track your personal debts

Frameworks that utilise this strongo/db package

• strongo/bots-framework - framework to build chat bots in Go language.