@graphql-tools/module-loader/esm/index.js

A set of utils for faster development of GraphQL tools

import { existsSync, promises as fsPromises } from 'fs';
import { isSchema } from 'graphql';
const { access } = fsPromises;
const InvalidError = new Error(`Imported object was not a string, DocumentNode or GraphQLSchema`);
const createLoadError = (error) => new Error('Unable to load schema from module: ' + `${error.message || /* istanbul ignore next */ error}`);
// module:node/module#export
function extractData(pointer) {
    const parts = pointer.replace(/^module\:/i, '').split('#');
    if (!parts || parts.length > 2) {
        throw new Error('Schema pointer should match "module:path/to/module#export"');
    }
    return {
        modulePath: parts[0],
        exportName: parts[1],
    };
}
/**
 * * This loader loads documents and type definitions from a Node module
 *
 * ```js
 * const schema = await loadSchema('module:someModuleName#someNamedExport', {
 *   loaders: [new ModuleLoader()],
 * })
 * ```
 */
export class ModuleLoader {
    isExpressionValid(pointer) {
        return typeof pointer === 'string' && pointer.toLowerCase().startsWith('module:');
    }
    async canLoad(pointer) {
        if (this.isExpressionValid(pointer)) {
            const { modulePath } = extractData(pointer);
            try {
                const moduleAbsolutePath = require.resolve(modulePath);
                await access(moduleAbsolutePath);
                return true;
            }
            catch (e) {
                return false;
            }
        }
        return false;
    }
    canLoadSync(pointer) {
        if (this.isExpressionValid(pointer)) {
            const { modulePath } = extractData(pointer);
            try {
                const moduleAbsolutePath = require.resolve(modulePath);
                return existsSync(moduleAbsolutePath);
            }
            catch (e) {
                return false;
            }
        }
        return false;
    }
    async load(pointer) {
        try {
            const result = this.parse(pointer, await this.importModule(pointer));
            if (result) {
                return [result];
            }
            throw InvalidError;
        }
        catch (error) {
            throw createLoadError(error);
        }
    }
    loadSync(pointer) {
        try {
            const result = this.parse(pointer, this.importModuleSync(pointer));
            if (result) {
                return [result];
            }
            throw InvalidError;
        }
        catch (error) {
            throw createLoadError(error);
        }
    }
    parse(pointer, importedModule) {
        if (isSchema(importedModule)) {
            return {
                schema: importedModule,
                location: pointer,
            };
        }
        else if (typeof importedModule === 'string') {
            return {
                location: pointer,
                rawSDL: importedModule,
            };
        }
        else if (typeof importedModule === 'object' && importedModule.kind === 'Document') {
            return {
                location: pointer,
                document: importedModule,
            };
        }
    }
    extractFromModule(mod, modulePath, identifier) {
        const thing = identifier ? mod[identifier] : mod;
        if (!thing) {
            throw new Error('Unable to import an object from module: ' + modulePath);
        }
        return thing;
    }
    // Sync and Async
    async importModule(pointer) {
        const { modulePath, exportName } = extractData(pointer);
        const imported = await import(modulePath);
        return this.extractFromModule(imported, modulePath, exportName || 'default');
    }
    importModuleSync(pointer) {
        const { modulePath, exportName } = extractData(pointer);
        // eslint-disable-next-line @typescript-eslint/no-require-imports
        const imported = require(modulePath);
        return this.extractFromModule(imported, modulePath, exportName);
    }
}