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pezkuwichain
31467f90d4
- @pezkuwi/papi-utils (rebrand of @polkadot-api/utils) - @pezkuwi/bizinikiwi-bindings (rebrand of @polkadot-api/substrate-bindings) - @pezkuwi/metadata-builders (rebrand of @polkadot-api/metadata-builders) - @pezkuwi/merkleize-metadata (rebrand of @polkadot-api/merkleize-metadata) All @polkadot-api references replaced with @pezkuwi equivalents.
122 lines
3.8 KiB
Markdown
122 lines
3.8 KiB
Markdown
# @polkadot-api/metadata-builders
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This package has multiple functions that read a metadata object, denormalizes it, and builds other structures needed for different processes
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## getLookupFn
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```ts
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interface MetadataLookup {
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(id: number): LookupEntry
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metadata: V14 | V15
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}
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function getLookupFn(metadata: Metadata): MetadataLookup
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```
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Given the a metadata, returns a function that will give the `LookupEntry` for an id along. The function also has access to the original metadata, as it's usually needed to work with the actual lookup.
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The `LookupEntry` is a denormalized data structure for one entry in the metadata. It also "shortcuts" type references when those are pointers (composites or tuples of length 1). Essentially, it's a union of each of the different types that can be found in the lookup, mostly equivalent to something like:
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```ts
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type TerminalVar =
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| PrimitiveVar // u8, str, char, i128, etc.
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| CompactVar
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| BitSequenceVar
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| AccountId32
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type ComposedVar =
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| TupleVar
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| StructVar
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| SequenceVar
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| ArrayVar
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| OptionVar
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| ResultVar
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| EnumVar
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type LookupEntry = TerminalVar | ComposedVar
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```
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Where, for instance, a StructVar is of the shape
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```ts
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type StructVar = {
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type: "struct"
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value: Record<string, LookupEntry>
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}
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```
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It's useful to get types referenced by storage calls, etc.
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## getDynamicBuilder
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```ts
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function getDynamicBuilder(metadataLookup: MetadataLookup): {
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buildDefinition: (id: number) => Codec
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buildConstant: (pallet: string, name: string) => Codec
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buildEvent: (pallet: string, name: string) => VariantEntry
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buildError: (pallet: string, name: string) => VariantEntry
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buildCall: (pallet: string, name: string) => VariantEntry
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buildStorage: (pallet: string, entry: string) => StorageEntry
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buildRuntimeCall: (api: string, method: string) => RuntimeEntry
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}
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```
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Generates all the codecs needed to SCALE encode or decode the data for any interaction with the chain.
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`buildDefinition` returns the codec for the type identified by the parameter `id`
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`buildConstant` returns the codec for the requested constant (equivalent as calling `buildDefinition` with the type id of that constant)
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`buildEvent`, `buildError` and `buildCall` return an object with the codec, and the indices of the pallet and entry within the metadata:
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```ts
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interface VariantEntry {
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location: [number, number] // [palletIdx, entryIdx],
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codec: Codec
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}
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```
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`buildStorage` creates all the encoders/decoders needed to encode a storage call and decode its result:
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```ts
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interface StorageEntry {
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// Encodes the arguments of the storage call.
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enc: (...args: any[]) => string
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// Decodes the result from the storage call.
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dec: (value: string) => any
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// Decodes the arguments of the storage call
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keyDecoder: (value: string) => any[]
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// Expected number of arguments
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len: number
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// Decoded fallback value as defined in the metadata entry
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fallback: unknown
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}
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```
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Similarly, `buildRuntimeCall` returns the codecs for both encoding the arguments of the runtime call, and the codec for decoding the result
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```ts
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interface RuntimeEntry {
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args: Codec<any[]>
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value: Codec<any>
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}
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```
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## getChecksumBuilder
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```ts
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function getChecksumBuilder(metadataLookup: MetadataLookup): {
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buildDefinition: (id: number) => string | null
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buildRuntimeCall: (api: string, method: string) => string | null
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buildStorage: (pallet: string, entry: string) => string | null
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buildCall: (pallet: string, name: string) => string | null
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buildEvent: (pallet: string, name: string) => string | null
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buildError: (pallet: string, name: string) => string | null
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buildConstant: (pallet: string, constantName: string) => string | null
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}
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```
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Generates the checksums for the different components defined in the metadata.
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`buildDefinition` builds the checksum of one of the types in the lookup. The rest of the methods build the checksum for each of the interfaces of the chain.
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