Shorthand method to test whether or not a query pattern has a solution. No information is returned about the possible query solutions, just whether or not a solution exists.
a query with a @where pattern to test
resolves to true if the query's @where pattern matches data in the domain
Shorthand method for deleting a single Subject by its @id. This will also
remove references to the given Subject from other Subjects.
the Subject @id
Handle updates from the domain, from the moment this method is called. All
data changes are signalled, strictly ordered according to the clone's
logical clock. The updates can therefore be correctly used to maintain some
other view of data, for example in a user interface or separate database.
This will include the notification of 'rev-up' updates after a connect to
the domain. To change this behaviour, ignore updates while the clone status
is marked as outdated.
The updates can be received either using the optional handler method, or by async-iterating the returned subscription, e.g.:
for await (let [update] of clone.follow()) {
// Do something with the update
}
This method is equivalent to calling read with a no-op procedure.
a procedure to run for every update
a subscription, allowing the caller to unsubscribe the handler
Shorthand method for retrieving a single Subject and its properties by
its @id, if it exists.
the Subject @id
the properties to retrieve. If no properties are specified, all available properties of the subject will be returned.
a promise resolving to the requested Subject with the requested
properties, or undefined if not found
Returns a stream that processes all quads matching the pattern.
The optional subject.
The optional predicate.
The optional object.
The optional graph.
The resulting quad stream.
Performs some read procedure on the current state, with notifications of subsequent updates.
The updates can be received either using the optional handler method, or by async-iterating the returned subscription, e.g.:
const subs = clone.read(async state => {
// Do something with the initial state
});
for await (let [update] of subs) {
// Do something with the updates that follow the initial state
}
NOTE: if the state procedure throws, it's up to you to handle the rejection; otherwise a global unresolved rejection may occur.
The states passed to the procedure and the handler are immutable and
guaranteed to remain 'live' until the procedure's return Promise resolves
or rejects. If iterating, the iterated states are immutable until next,
return or throw are called on the generator – if a for await loop is
being used, these will be called by Javascript as the loop continues or
terminates.
a procedure to run for the current state
a procedure to run for every update that follows the state in the procedure
a subscription, allowing the caller to unsubscribe the handler
Actively reads data from the domain.
The query executes in response to either subscription to the returned
result, or calling .then.
All results are guaranteed to derive from the current state; however since the results are delivered asynchronously, the current state is not guaranteed to be live in the subscriber. In order to keep this state alive during iteration (for example, to perform a consequential operation), perform the request in the scope of a read procedure instead.
the declarative read description
read subjects
Performs an atomic update to the dataset. The deletes and inserts will be committed in the resolved state, which is expected to also be updatable for further modifications.
Performs some write procedure on the current state.
The state passed to the procedure is immutable and is guaranteed to remain
'live' until its write method is called, or the procedure's return
Promise resolves or rejects.
a procedure to run against the current state. This
procedure is able to modify the given state, incrementally using its
write method
Actively writes data to the domain.
one of the Write types
the declarative write description
the next state of the domain, changed by this write operation only
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A m-ld state machine extends the MeldState API for convenience, but note that the state of a machine is inherently mutable. For example, two consecutive asynchronous reads will not necessarily operate on the same state. To work with immutable state, use the
readandwritemethod overloads taking a procedure.