ditto::Store Class Reference

Provides access to Collections and a write transaction API. More...

#include <Store.hpp>

Public Member Functions
Collection	collection (std::string name) const
	Returns a Collection with the provided name.
std::vector< std::unique_ptr< WriteTransactionResult > >	write (std::function< void(WriteTransaction &)> fn) const
	Allows you to group multiple operations together that affect multiple documents, potentially across multiple collections.
PendingCollectionsOperation	collections () const
	Returns an object that lets you fetch or observe the collections in the store.
DiskUsage	get_disk_usage () const
	Provides access to the Store's disk usage.
QueryResult	execute (std::string query, nlohmann::json query_args=nullptr)
	Executes a DQL query and returns matching items as a query result.
std::shared_ptr< StoreObserver >	register_observer (std::string query, StoreObservationHandler change_handler)
	Installs and returns a change observer for a query, configuring Ditto to call the provided change handler whenever documents in the local store change such that the result of the matching query changes. The provided query must be a SELECT query.
std::shared_ptr< StoreObserver >	register_observer (std::string query, nlohmann::json query_args, StoreObservationHandler change_handler)
	Installs and returns a change observer for a query, configuring Ditto to call the provided in change handler whenever documents in the local store change such that the result of the matching query changes. The provided query must be a SELECT query.
std::shared_ptr< StoreObserver >	register_observer (std::string query, StoreObservationHandlerWithNextSignal change_handler)
	Installs and returns a change observer for a query, configuring Ditto to call the provided change handler whenever documents in the local store change such that the result of the matching query changes. The provided query must be a SELECT query.
std::shared_ptr< StoreObserver >	register_observer (std::string query, nlohmann::json query_args, StoreObservationHandlerWithNextSignal change_handler)
	Installs and returns a change observer for a query, configuring Ditto to call the provided change handler whenever documents in the local store change such that the result of the matching query changes. The provided query must be a SELECT query.

Public Attributes
std::set< std::shared_ptr< StoreObserver > >	observers

Detailed Description

Provides access to Collections and a write transaction API.

Member Function Documentation

collection()

Collection ditto::Store::collection

(

std::string

name

)

const

Returns a Collection with the provided name.

Parameters

[in]

name

the name of the collection. A name is valid if: its length is less than 100 it does not contain the char '\0' it is not prefixed with "$TS_" it is not empty

Returns

a Collection.

Exceptions

if	name is not a valid Collection name.

collections()

PendingCollectionsOperation ditto::Store::collections

(

)

const

Returns an object that lets you fetch or observe the collections in the store.

Returns

a PendingCollectionsOperation object that you can use to fetch or observe the collections in the store

execute()

QueryResult ditto::Store::execute	(	std::string	query,
		nlohmann::json	query_args = nullptr )

Executes a DQL query and returns matching items as a query result.

Parameters

query	a string containing a valid query expressed in DQL.
query_args	a dictionnary of values keyed by the placeholder name without the leading :.

Limitations:

• Supports SELECT * FROM <collection_name> with optional WHERE <expression>.
• No Query parameters as functions arguments yet.
• No transactions.

get_disk_usage()

DiskUsage ditto::Store::get_disk_usage

(

)

const

Provides access to the Store's disk usage.

Returns

a DiskUsage object.

register_observer() [1/4]

std::shared_ptr< StoreObserver > ditto::Store::register_observer	(	std::string	query,
		nlohmann::json	query_args,
		StoreObservationHandler	change_handler )

Installs and returns a change observer for a query, configuring Ditto to call the provided in change handler whenever documents in the local store change such that the result of the matching query changes. The provided query must be a SELECT query.

Parameters

query	a string containing a valid query expressed in DQL.
arguments	a dictionary of values keyed by the placeholder name without the leading :. Example: {{"mileage", 123}}.

Returns

An active StoreObserver for the provided query and arguments. You'll have to keep it in scope to keep receiving changes.

• Throws: DittoError if the query is not a valid DQL query.

register_observer() [2/4]

std::shared_ptr< StoreObserver > ditto::Store::register_observer	(	std::string	query,
		nlohmann::json	query_args,
		StoreObservationHandlerWithNextSignal	change_handler )

Installs and returns a change observer for a query, configuring Ditto to call the provided change handler whenever documents in the local store change such that the result of the matching query changes. The provided query must be a SELECT query.

Parameters

query	a string containing a valid query expressed in DQL.
query_args	a dictionary of values keyed by the placeholder name without the leading :. Example: {{"mileage", 123}}.

Returns

: An active StoreObserver for the provided query and arguments. You'll have to keep it in scope to receive changes.

register_observer() [3/4]

std::shared_ptr< StoreObserver > ditto::Store::register_observer	(	std::string	query,
		StoreObservationHandler	change_handler )

Installs and returns a change observer for a query, configuring Ditto to call the provided change handler whenever documents in the local store change such that the result of the matching query changes. The provided query must be a SELECT query.

Parameters

query

a string containing a valid query expressed in DQL.

Returns

An active StoreObserver for the provided query. You'll have to keep it in scope to receive changes.

• Throws: DittoError if the query is not a valid DQL query.

register_observer() [4/4]

std::shared_ptr< StoreObserver > ditto::Store::register_observer	(	std::string	query,
		StoreObservationHandlerWithNextSignal	change_handler )

Installs and returns a change observer for a query, configuring Ditto to call the provided change handler whenever documents in the local store change such that the result of the matching query changes. The provided query must be a SELECT query.

Parameters

query

a string containing a valid query expressed in DQL.

Returns

An active StoreObserver for the provided query. You'll have to keep it in scope to keep receiving changes.

write()

std::vector< std::unique_ptr< WriteTransactionResult > > ditto::Store::write

(

std::function< void(WriteTransaction &)>

fn

)

const

Allows you to group multiple operations together that affect multiple documents, potentially across multiple collections.

Parameters

fn	a lambda that provides access to a write transaction object that can be used to perform operations on the store.

Returns

a list of WriteTransactionResults. There is a result for each operation performed as part of the write transaction.