I'm trying to generate type interfaces using definitions directly from Substrate and ORML libraries. I'm using the polkadotjs package versions 8.1.1.

My type generate file looks like:

import * as ormlDefinitions from '@open-web3/orml-types/interfaces/definitions';

// import fs from 'fs';
import { generateDefaultConsts, generateDefaultQuery, generateDefaultRpc, generateDefaultTx } from '@polkadot/typegen/generate';
import { generateInterfaceTypes } from '@polkadot/typegen/generate/interfaceRegistry';
import { generateTsDef } from '@polkadot/typegen/generate/tsDef';
import * as defaultDefinitions from '@polkadot/types/interfaces/definitions';

// import * as webbDefinitions from '../src/interfaces/definitions.js';
import metadata from '../src/metadata/static-latest.js';

// eslint-disable-next-line @typescript-eslint/no-unused-vars
const { runtime: _runtime, ...ormlModulesDefinitions } = ormlDefinitions;

// eslint-disable-next-line @typescript-eslint/no-unused-vars
const { runtime, ...substrateDefinitions } = defaultDefinitions;

// eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
const definitions = {
  '@open-web3/orml-types/interfaces': ormlModulesDefinitions,
  '@polkadot/types/interfaces': substrateDefinitions
  // '@webb-tools/types/interfaces': webbDefinitions
} as any;

generateTsDef(definitions, 'packages/types/src/interfaces', '@webb-tools/types/interfaces');
generateInterfaceTypes(definitions, 'packages/types/src/interfaces/augment-types.ts');
generateDefaultConsts('packages/types/src/interfaces/augment-api-consts.ts', metadata, definitions, false);

generateDefaultTx('packages/types/src/interfaces/augment-api-tx.ts', metadata, definitions, false);
generateDefaultQuery('packages/types/src/interfaces/augment-api-query.ts', metadata, definitions, false);
generateDefaultRpc('packages/types/src/interfaces/augment-api-rpc.ts', definitions);

Even without our custom types, I'm stuck getting this to execute and generate the type files. The errors are due to some undefined parameters.

TypeError: Cannot convert undefined or null to object
    at Function.entries (<anonymous>)
    at file:///Users/drew/webb/webb.js/node_modules/@polkadot/typegen/generate/tsDef.js:295:12
    at writeFile (file:///Users/drew/webb/webb.js/node_modules/@polkadot/typegen/util/file.js:9:19)
    at generateTsDef (file:///Users/drew/webb/webb.js/node_modules/@polkadot/typegen/generate/tsDef.js:293:3)
    at file:///Users/drew/webb/webb.js/packages/types/scripts/generate.ts:42:1
    at ModuleJob.run (node:internal/modules/esm/module_job:195:25)
    at async Promise.all (index 0)
    at async ESMLoader.import (node:internal/modules/esm/loader:337:24)
    at async loadESM (node:internal/process/esm_loader:88:5)
    at async handleMainPromise (node:internal/modules/run_main:61:12)

Any ideas how to add custom type libraries and generate from metadata? Is there some tutorial available against up-to-date dependencies?

  • More confusing is that the generated type files contain: '@open-web3/orml-types/interfaces/__esModule' as imported packages, and yet this package is pulling types from our runtime and not ORML.
    – Drew Stone
    Apr 17, 2022 at 13:58
  • For this comment above, this is what is generated: import type { Perbill, Permill, WebbProposalsHeaderTypedChainId } from '@open-web3/orml-types/interfaces/__esModule'; My Query/TX auto-generated files look OK but my types are not in the type file. I have updated our metadata but not sure if I should start defining our types directly in the type-definitions?
    – Drew Stone
    Apr 17, 2022 at 14:15

1 Answer 1


There is a tutorial on generating type definitions here:

And some sample code here:


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