README
¶
README for epos
Introduction
epos is a embeddable persistent object store, written in Go. It is meant to store, retrieve, query and delete Go objects to a local file store. In this respect, it is NoSQL database, but it only works on local files and is embeddable into existing Go programs, so it can be thought of as the SQLite of NoSQL databases.
Here is a very basic overview how to use epos:
// open/create database:
db, err := epos.OpenDatabase("foo.db", epos.STORAGE_AUTO) // also available: STORAGE_DISKV, STORAGE_LEVELDB
// insert item:
id, err = db.Coll("users").Insert(new_user)
// update item:
err = db.Coll("users").Update(id, updated_user)
// index fields:
err = db.Coll("users").AddIndex("login")
// query items:
result, err = db.Coll("users").Query(epos.Expression("(eq username foobar)"))
for result.Next(&id, &data) {
// handle data
}
License
See file LICENSE for details.
API Documentation
You can find the latest API documentation here: http://godoc.org/github.com/akrennmair/epos
Author
Andreas Krennmair ak@synflood.at
Documentation
¶
Overview ¶
epos is a embeddable persistent object store, written in Go. It is meant to store, retrieve, query and delete Go objects to a local file store. In this respect, it is NoSQL database, but it only works on local files and is embeddable into existing Go programs, so it can be thought of as the SQLite of NoSQL databases.
Here is a very basic overview how to use epos:
// open/create database:
db, err := epos.OpenDatabase("foo.db", epos.STORAGE_AUTO) // also available: STORAGE_DISKV, STORAGE_LEVELDB
// insert item:
id, err = db.Coll("users").Insert(new_user)
// update item:
err = db.Coll("users").Update(id, updated_user)
// index fields:
err = db.Coll("users").AddIndex("login")
// query items:
result, err = db.Coll("users").Query(epos.Expression("(eq username foobar)"))
for result.Next(&id, &data) {
// handle data
}
Index ¶
- func RegisterStorageBackend(name string, factoryFunc func(path string) StorageBackend) error
- type And
- type Collection
- func (c *Collection) AddIndex(field string) error
- func (c *Collection) Delete(id Id) error
- func (c *Collection) Insert(value interface{}) (Id, error)
- func (c *Collection) Query(q Condition) (*Result, error)
- func (c *Collection) QueryAll() (*Result, error)
- func (c *Collection) QueryId(id Id) (*Result, error)
- func (c *Collection) Reindex(field string) error
- func (c *Collection) RemoveIndex(field string) error
- func (c *Collection) Update(id Id, value interface{}) error
- func (c *Collection) Vacuum() error
- type Condition
- type Database
- type DiskvStorageBackend
- type Equals
- type Id
- type LevelDBStorageBackend
- type Or
- type Result
- type StorageBackend
- type StorageType
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func RegisterStorageBackend ¶
func RegisterStorageBackend(name string, factoryFunc func(path string) StorageBackend) error
RegisterStorageBackend registers a new custom storage backend under a new name. If the name is already used, an error is returned.
In order to create a new custom storage backend, the programmer must also provide a function that takes the path where the storage backend must write its data (as a single file or within a directory) and that returns an object that satisfies the interface StorageBackend
Types ¶
type Collection ¶
type Collection struct {
// contains filtered or unexported fields
}
func (*Collection) AddIndex ¶
func (c *Collection) AddIndex(field string) error
AddIndex creates an index for a field. Existing records will be indexed, and future insert and update operations will index that field, as well. If an index for that field already exists, the AddIndex() is a no-op.
A field describes a top-level element of a struct or a particular key of a map.
func (*Collection) Delete ¶
func (c *Collection) Delete(id Id) error
Delete deletes an object, identified by its ID, from the collection.
func (*Collection) Insert ¶
func (c *Collection) Insert(value interface{}) (Id, error)
Insert inserts an object into the collection. It returns the object's ID and, if the insert fails, a non-nil error describing the problem.
func (*Collection) Query ¶
func (c *Collection) Query(q Condition) (*Result, error)
Query takes a query in the form of a (possibly nested) Condition, and returns a Result object.
func (*Collection) QueryAll ¶
func (c *Collection) QueryAll() (*Result, error)
QueryAll returns a Result object that will deliver all objects in the object store in no particular order.
func (*Collection) QueryId ¶
func (c *Collection) QueryId(id Id) (*Result, error)
QueryId returns a Result object that will exactly deliver the object with the requested ID.
func (*Collection) Reindex ¶
func (c *Collection) Reindex(field string) error
Reindex deletes and recreates the index for a field.
func (*Collection) RemoveIndex ¶
func (c *Collection) RemoveIndex(field string) error
RemoveIndex removes an existing index for a field. It returns a non-nil error if an error occurs.
func (*Collection) Update ¶
func (c *Collection) Update(id Id, value interface{}) error
Update replaces an existing object with a new object. If an error occurs during that operation, it returns a non-nil error.
func (*Collection) Vacuum ¶
func (c *Collection) Vacuum() error
Vacuum expunges old entries that refer to deleted objects from all indexes of a collection.
type Condition ¶
type Condition interface {
// contains filtered or unexported methods
}
func Expression ¶
Expression converts a S-Expr-based query to a structure of Condition objects. The following symbols are available for queries:
(id 1) query entry with ID 1 (eq field-name value) query all entries where field-name equals value (or expr...) OR all query sub-expressions (and expr...) AND all query sub-expressions
type Database ¶
type Database struct {
// contains filtered or unexported fields
}
func OpenDatabase ¶
func OpenDatabase(path string, typ StorageType) (*Database, error)
OpenDatabase opens and if necessary creates a database identified by the provided path. It returns a database object and a non-nil error if an error occured while opening or creating the database.
func (*Database) Close ¶
Close closes the database and frees the memory associated with all collections.
func (*Database) Coll ¶
func (db *Database) Coll(name string) *Collection
Coll returns the collection of the specified name. If the collection doesn't exist yet, it is opened and/or created on the fly.
func (*Database) Collections ¶
Collections returns a list of collection names that are currently in the database.
type DiskvStorageBackend ¶
type DiskvStorageBackend struct {
// contains filtered or unexported fields
}
func (*DiskvStorageBackend) Erase ¶
func (s *DiskvStorageBackend) Erase(key string) error
func (*DiskvStorageBackend) Keys ¶
func (s *DiskvStorageBackend) Keys() <-chan string
type LevelDBStorageBackend ¶
type LevelDBStorageBackend struct {
// contains filtered or unexported fields
}
func (*LevelDBStorageBackend) Erase ¶
func (s *LevelDBStorageBackend) Erase(key string) error
func (*LevelDBStorageBackend) Keys ¶
func (s *LevelDBStorageBackend) Keys() <-chan string
type StorageBackend ¶
type StorageBackend interface {
Read(key string) ([]byte, error)
Write(key string, value []byte) error
Erase(key string) error
Keys() <-chan string
}
func NewDiskvStorageBackend ¶
func NewDiskvStorageBackend(path string) StorageBackend
func NewLevelDBStorageBackend ¶
func NewLevelDBStorageBackend(path string) StorageBackend
type StorageType ¶
type StorageType string
const ( STORAGE_AUTO StorageType = "auto" STORAGE_DISKV StorageType = "diskv" STORAGE_LEVELDB StorageType = "leveldb" )
Source Files
Directories