substrate_metadata 1.2.3 substrate_metadata: ^1.2.3 copied to clipboard
Metadata types for Substrate runtimes
substrate_metadata #
substrate_metadata is a flutter and dart library for encoding and decoding chain metadata, constants, extrinsics and events of blocks.
Lets Get Started #
Decode Metadata #
// decoded metadata
final DecodedMetadata decodedMetadata = MetadataDecoder.instance.decode('0x6d657.....790b807d0b');
//
// get raw Map<String, dynamic>
final rawMetadata = decodedMetadata.metadataJson;
//
// get Metadata Object
final metadataObject = decodedMetadata.metadataObject;
Create ChainInfo from Metadata #
// decoded metadata
final DecodedMetadata decodedMetadata = MetadataDecoder.instance.decode('0x6d657.....790b807d0b');
// create ChainInfo from metadata
final ChainInfo chainInfo = ChainInfo.fromMetadata(decodedMetadata);
Decode Extrinsic #
// decode metadata
final DecodedMetadata decodedMetadata = MetadataDecoder.instance.decode('0x6d657.....790b807d0b');
// create ChainInfo from metadata
final ChainInfo chainInfo = ChainInfo.fromMetadata(decodedMetadata);
final String extrinsicHex = '0x990403......a2f9e184';
// Create extrinsics input
final input = Input.fromHex(extrinsicHex);
// decode extrinsic
final dynamic decoded = ExtrinsicsCodec(chainInfo: chainInfo).decode(input);
Encode Extrinsic #
// decode metadata
final DecodedMetadata decodedMetadata = MetadataDecoder.instance.decode('0x6d657.....790b807d0b');
// create ChainInfo from metadata
final ChainInfo chainInfo = ChainInfo.fromMetadata(decodedMetadata);
// Create Output
final output = HexOutput();
final Map<String, dynamic> extrinsicsMap = {'version': 4, 'signature': ....... };
// encode extrinsic
ExtrinsicsCodec(chainInfo: chainInfo).encodeTo(extrinsicsMap, output);
// encoded extrinsics Hex
final extrinsicsHex = output.toString();
Decode Events #
// decode metadata
final DecodedMetadata decodedMetadata = MetadataDecoder.instance.decode('0x6d657.....790b807d0b');
// create ChainInfo from metadata
final ChainInfo chainInfo = ChainInfo.fromMetadata(decodedMetadata);
final String encodedEventsHex = '0x38000dd14c4572......................5ec6e6fcd6184d952d000000';
final input = Input.fromHex(encodedEventsHex);
// list of decoded events
final List<dynamic> decodedEvents = chainInfo.scaleCodec.decode('EventCodec', input);
Encode Events #
// decode metadata
final DecodedMetadata decodedMetadata = MetadataDecoder.instance.decode('0x6d657.....790b807d0b');
// create ChainInfo from metadata
final ChainInfo chainInfo = ChainInfo.fromMetadata(decodedMetadata);
final Map<String, dynamic> events = [{ 'phase': {'ApplyExtrinsic': 0}, 'event': {....} }];
final output = HexOutput();
// encode the events
chainInfo.scaleCodec.encodeTo('EventCodec', events, output);
// events hex
final eventsHex = output.toString();
Decode Constants #
// decode metadata
final DecodedMetadata decodedMetadata = MetadataDecoder.instance.decode('0x6d657.....790b807d0b');
// create ChainInfo from metadata
final ChainInfo chainInfo = ChainInfo.fromMetadata(decodedMetadata);
//
// Look on constants of chain description
for (final palletMapEntry in chainInfo.constants.entries) {
//
// Loop throught all the constants in this given pallet
for (final constantMapEntry in palletMapEntry.value.entries) {
final Constant originalConstant = constantMapEntry.value;
//
// Encoded Constant bytes
final encodedBytes = originalConstant.bytes;
//
// Decoded Constant value
final decoded = originalConstant.value;
}
}
Encode Constants #
// decode metadata
final DecodedMetadata decodedMetadata = MetadataDecoder.instance.decode('0x6d657.....790b807d0b');
// create ChainInfo from metadata
final ChainInfo chainInfo = ChainInfo.fromMetadata(decodedMetadata);
final output = ByteOutput();
final decodedConstantValue = /** Some constant value from originalConstant **/;
originalConstant.type.encodeTo(decodedConstantValue, output);
final encodedConstant = output.toBytes();
Add SpecVersion #
final specJson = {'specName': 'polkadot', 'specVersion':......};
final specVersion = SpecVersion.fromJson(specJson);
// specVersion gets added to support decoding the blocks.
chainObject.addSpecVersion(specVersion);
Create ChainInfo from SpecVersion #
// when using preV14 metadata
final chainDefinitions = LegacyTypesBundle.fromJson(chainJson);
final Chain chain = Chain(chainDefinitions);
// or
// when using V14 metadata, you don't need to provide chainDefinitions
final Chain chain = Chain();
final specJson = {'specName': 'polkadot', 'specVersion':......};
final SpecVersion specVersion = SpecVersion.fromJson(specJson);
final ChainInfo chainInfo = chain.getChainInfoFromSpecVersion(specVersion);
Decode Extrinsic (With Chain) #
// when using preV14 metadata
final chainDefinitions = LegacyTypesBundle.fromJson(chainJson);
final Chain chain = Chain(chainDefinitions);
// or
// when using V14 metadata, you don't need to provide chainDefinitions
final Chain chain = Chain();
// Preferred to provide all the available Spec-Version information.
chain.initSpecVersionFromFile('../chain/versions.json');
final RawBlock rawBlock = RawBlock.fromJson( { blockJson } );
// DecodedBlockExtrinsics
final DecodedBlockExtrinsics decodedExtrinsic = chain.decodeExtrinsics(rawBlock);
Encode Extrinsic (With Chain) #
// when using preV14 metadata
final chainDefinitions = LegacyTypesBundle.fromJson(chainJson);
final Chain chain = Chain(chainDefinitions);
// or
// when using V14 metadata, you don't need to provide chainDefinitions
final Chain chain = Chain();
// Preferred to provide all the available Spec-Version information.
chain.initSpecVersionFromFile('../chain/versions.json');
final RawBlock rawBlock = RawBlock.fromJson( { blockJson } );
// DecodedBlockExtrinsics
final DecodedBlockExtrinsics decodedExtrinsic = chain.decodeExtrinsics(rawBlock);
// encodedRawBlock.hashCode == rawBlock
final RawBlock encodedRawBlock = chain.encodeExtrinsic(decodedExtrinsic);
Decode Events (With Chain) #
// when using preV14 metadata
final chainDefinitions = LegacyTypesBundle.fromJson(chainJson);
final Chain chain = Chain(chainDefinitions);
// or
// when using V14 metadata, you don't need to provide chainDefinitions
final Chain chain = Chain();
// Preferred to provide all the available Spec-Version information.
chain.initSpecVersionFromFile('../chain/versions.json');
final RawBlockEvents rawBlockEvents = RawBlockEvents.fromJson( { blockJson } );
// DecodedBlockEvents
final DecodedBlockEvents decodedEvents = chain.decodeEvents(rawBlockEvents);
Encode Events (With Chain) #
// when using preV14 metadata
final chainDefinitions = LegacyTypesBundle.fromJson(chainJson);
final Chain chain = Chain(chainDefinitions);
// or
// when using V14 metadata, you don't need to provide chainDefinitions
final Chain chain = Chain();
// Preferred to provide all the available Spec-Version information.
chain.initSpecVersionFromFile('../chain/versions.json');
final rawBlockEvents = RawBlockEvents.fromJson( { blockJson } );
// DecodedBlockEvents
final DecodedBlockEvents decodedEvents = chain.decodeEvents(rawBlockEvents);
// encodedBlockEvents.hashCode == rawBlockEvents.hashCode
final RawBlockEvents encodedBlockEvents = chain.encodeEvents(decodedEvents);