QueryResult - a general interface for supporting different types of query results. Actual types differ for different queries
type QueryResult interface{}
ResultsIterator - an iterator for query result set
type ResultsIterator interface {
// Next returns the next item in the result set. The `QueryResult` is expected to be nil when
// the iterator gets exhausted
Next() (QueryResult, error)
// Close releases resources occupied by the iterator
Close()
}
State defines interaction with the world state
type State interface {
// GetStateMultipleKeys gets the values for multiple keys in a single call
GetStateMultipleKeys(namespace string, keys []string) ([][]byte, error)
// GetStateRangeScanIterator returns an iterator that contains all the key-values between given key ranges.
// startKey is included in the results and endKey is excluded. An empty startKey refers to the first available key
// and an empty endKey refers to the last available key. For scanning all the keys, both the startKey and the endKey
// can be supplied as empty strings. However, a full scan should be used judiciously for performance reasons.
// The returned ResultsIterator contains results of type *KV which is defined in protos/ledger/queryresult.
GetStateRangeScanIterator(namespace string, startKey string, endKey string) (ResultsIterator, error)
// GetStateMetadata returns the metadata for given namespace and key
GetStateMetadata(namespace, key string) (map[string][]byte, error)
// GetPrivateDataMetadataByHash gets the metadata of a private data item identified by a tuple <namespace, collection, keyhash>
GetPrivateDataMetadataByHash(namespace, collection string, keyhash []byte) (map[string][]byte, error)
// Done releases resources occupied by the State
Done()
}
StateFetcher retrieves an instance of a state
type StateFetcher interface {
validation.Dependency
// FetchState fetches state
FetchState() (State, error)
}