[WIP] feat: generate TypeScript from MongoDBJSONSchema or JSON Schemas MONGOSH-2058

src/index.ts

@@ -22,6 +22,7 @@ import { convertInternalToMongodb } from './schema-converters/internalToMongoDB'
 import { convertInternalToStandard } from './schema-converters/internalToStandard';
 import * as schemaStats from './stats';
 import { AnyIterable, StandardJSONSchema, MongoDBJSONSchema, ExpandedJSONSchema } from './types';
+import { toTypescriptTypeDefinition } from './to-typescript';
 
 /**
  * Analyze documents - schema can be retrieved in different formats.
@@ -94,5 +95,6 @@ export {
   getSchemaPaths,
   getSimplifiedSchema,
   SchemaAnalyzer,
-  schemaStats
+  schemaStats,
+  toTypescriptTypeDefinition
 };

src/to-typescript.spec.ts

@@ -0,0 +1,189 @@
+import { analyzeDocuments, StandardJSONSchema, toTypescriptTypeDefinition } from '.';
+
+import assert from 'assert/strict';
+
+import {
+  BSONRegExp,
+  Binary,
+  Code,
+  DBRef,
+  Decimal128,
+  Double,
+  Int32,
+  Long,
+  MaxKey,
+  MinKey,
+  ObjectId,
+  Timestamp,
+  UUID,
+  BSONSymbol
+} from 'bson';
+
+import { inspect } from 'util';
+
+const bsonDocuments = [
+  {
+    _id: new ObjectId('642d766b7300158b1f22e972'),
+    double: new Double(1.2), // Double, 1, double
+    doubleThatIsAlsoAnInteger: new Double(1), // Double, 1, double
+    string: 'Hello, world!', // String, 2, string
+    object: { key: 'value' }, // Object, 3, object
+    array: [1, 2, 3], // Array, 4, array
+    binData: new Binary(Buffer.from([1, 2, 3])), // Binary data, 5, binData
+    // Undefined, 6, undefined (deprecated)
+    objectId: new ObjectId('642d766c7300158b1f22e975'), // ObjectId, 7, objectId
+    boolean: true, // Boolean, 8, boolean
+    date: new Date('2023-04-05T13:25:08.445Z'), // Date, 9, date
+    null: null, // Null, 10, null
+    regex: new BSONRegExp('pattern', 'i'), // Regular Expression, 11, regex
+    // DBPointer, 12, dbPointer (deprecated)
+    javascript: new Code('function() {}'), // JavaScript, 13, javascript
+    symbol: new BSONSymbol('symbol'), // Symbol, 14, symbol (deprecated)
+    javascriptWithScope: new Code('function() {}', { foo: 1, bar: 'a' }), // JavaScript code with scope 15 "javascriptWithScope" Deprecated in MongoDB 4.4.
+    int: new Int32(12345), // 32-bit integer, 16, "int"
+    timestamp: new Timestamp(new Long('7218556297505931265')), // Timestamp, 17, timestamp
+    long: new Long('123456789123456789'), // 64-bit integer, 18, long
+    decimal: new Decimal128(
+      Buffer.from([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16])
+    ), // Decimal128, 19, decimal
+    minKey: new MinKey(), // Min key, -1, minKey
+    maxKey: new MaxKey(), // Max key, 127, maxKey
+
+    binaries: {
+      generic: new Binary(Buffer.from([1, 2, 3]), 0), // 0
+      functionData: new Binary(Buffer.from('//8='), 1), // 1
+      binaryOld: new Binary(Buffer.from('//8='), 2), // 2
+      uuidOld: new Binary(Buffer.from('c//SZESzTGmQ6OfR38A11A=='), 3), // 3
+      uuid: new UUID('AAAAAAAA-AAAA-4AAA-AAAA-AAAAAAAAAAAA'), // 4
+      md5: new Binary(Buffer.from('c//SZESzTGmQ6OfR38A11A=='), 5), // 5
+      encrypted: new Binary(Buffer.from('c//SZESzTGmQ6OfR38A11A=='), 6), // 6
+      compressedTimeSeries: new Binary(
+        Buffer.from(
+          'CQCKW/8XjAEAAIfx//////////H/////////AQAAAAAAAABfAAAAAAAAAAEAAAAAAAAAAgAAAAAAAAAHAAAAAAAAAA4AAAAAAAAAAA==',
+          'base64'
+        ),
+        7
+      ), // 7
+      custom: new Binary(Buffer.from('//8='), 128) // 128
+    },
+
+    dbRef: new DBRef('namespace', new ObjectId('642d76b4b7ebfab15d3c4a78')) // not actually a separate type, just a convention
+
+    // TODO: what about arrays of objects or arrays of arrays or heterogynous types in general
+  }
+];
+
+// from https://json-schema.org/learn/miscellaneous-examples#complex-object-with-nested-properties
+const jsonSchema: StandardJSONSchema = {
+  $id: 'https://example.com/complex-object.schema.json',
+  $schema: 'https://json-schema.org/draft/2020-12/schema',
+  title: 'Complex Object',
+  type: 'object',
+  properties: {
+    name: {
+      type: 'string'
+    },
+    age: {
+      type: 'integer',
+      minimum: 0
+    },
+    address: {
+      type: 'object',
+      properties: {
+        street: {
+          type: 'string'
+        },
+        city: {
+          type: 'string'
+        },
+        state: {
+          type: 'string'
+        },
+        postalCode: {
+          type: 'string',
+          pattern: '\\d{5}'
+        }
+      },
+      required: ['street', 'city', 'state', 'postalCode']
+    },
+    hobbies: {
+      type: 'array',
+      items: {
+        type: 'string'
+      }
+    }
+  },
+  required: ['name', 'age']
+};
+
+describe('toTypescriptTypeDefinition', function() {
+  it('converts a MongoDB JSON schema to TypeScript', async function() {
+    const databaseName = 'myDb';
+    const collectionName = 'myCollection';
+    const analyzedDocuments = await analyzeDocuments(bsonDocuments);
+    const schema = await analyzedDocuments.getMongoDBJsonSchema();
+
+    console.log(inspect(schema, { depth: null }));
+
+    assert.equal(toTypescriptTypeDefinition(databaseName, collectionName, schema), `module myDb {
+  type myCollection = {
+    _id?: bson.ObjectId;
+    array?: bson.Double[];
+    binaries?: {
+      binaryOld?: bson.Binary;
+      compressedTimeSeries?: bson.Binary;
+      custom?: bson.Binary;
+      encrypted?: bson.Binary;
+      functionData?: bson.Binary;
+      generic?: bson.Binary;
+      md5?: bson.Binary;
+      uuid?: bson.Binary;
+      uuidOld?: bson.Binary
+    };
+    binData?: bson.Binary;
+    boolean?: boolean;
+    date?: bson.Date;
+    dbRef?: bson.DBPointer;
+    decimal?: bson.Decimal128;
+    double?: bson.Double;
+    doubleThatIsAlsoAnInteger?: bson.Double;
+    int?: bson.Int32;
+    javascript?: bson.Code;
+    javascriptWithScope?: bson.Code;
+    long?: bson.Long;
+    maxKey?: bson.MaxKey;
+    minKey?: bson.MinKey;
+    null?: null;
+    object?: {
+      key?: string
+    };
+    objectId?: bson.ObjectId;
+    regex?: bson.BSONRegExp;
+    string?: string;
+    symbol?: bson.BSONSymbol;
+    timestamp?: bson.Timestamp
+  };
+};`);
+  });
+
+  it('converts a standard JSON schema to TypeScript', function() {
+    const databaseName = 'myDb';
+    const collectionName = 'myCollection';
+
+    console.log(inspect(jsonSchema, { depth: null }));
+
+    assert.equal(toTypescriptTypeDefinition(databaseName, collectionName, jsonSchema), `module myDb {
+  type myCollection = {
+    name?: string;
+    age?: number;
+    address?: {
+      street?: string;
+      city?: string;
+      state?: string;
+      postalCode?: string
+    };
+    hobbies?: string[]
+  };
+};`);
+  });
+});

src/to-typescript.ts

@@ -0,0 +1,138 @@
+import assert from 'assert';
+import type { MongoDBJSONSchema } from './types';
+
+function getBSONType(property: MongoDBJSONSchema): string | string[] | undefined {
+  return property.bsonType || property.type;
+}
+
+function isBSONObjectProperty(property: MongoDBJSONSchema): boolean {
+  return getBSONType(property) === 'object';
+}
+
+function isBSONArrayProperty(property: MongoDBJSONSchema): boolean {
+  return getBSONType(property) === 'array';
+}
+
+function isBSONPrimitive(property: MongoDBJSONSchema): boolean {
+  return !(isBSONArrayProperty(property) || isBSONObjectProperty(property));
+}
+
+function toTypeName(type: string): string {
+  // JSON Schema types
+  if (type === 'string') {
+    return 'string';
+  }
+  if (type === 'number' || type === 'integer') {
+    return 'number';
+  }
+  if (type === 'boolean') {
+    return 'boolean';
+  }
+  if (type === 'null') {
+    return 'null';
+  }
+
+  // BSON types
+  // see InternalTypeToBsonTypeMap
+  if (type === 'double') {
+    return 'bson.Double';
+  }
+  if (type === 'binData') {
+    return 'bson.Binary';
+  }
+  if (type === 'objectId') {
+    return 'bson.ObjectId';
+  }
+  if (type === 'bool') {
+    return 'boolean';
+  }
+  if (type === 'date') {
+    return 'bson.Date';
+  }
+  if (type === 'regex') {
+    return 'bson.BSONRegExp';
+  }
+  if (type === 'symbol') {
+    return 'bson.BSONSymbol';
+  }
+  if (type === 'javascript' || type === 'javascriptWithScope') {
+    return 'bson.Code';
+  }
+  if (type === 'int') {
+    return 'bson.Int32';
+  }
+  if (type === 'timestamp') {
+    return 'bson.Timestamp';
+  }
+  if (type === 'long') {
+    return 'bson.Long';
+  }
+  if (type === 'decimal') {
+    return 'bson.Decimal128';
+  }
+  if (type === 'minKey') {
+    return 'bson.MinKey';
+  }
+  if (type === 'maxKey') {
+    return 'bson.MaxKey';
+  }
+  if (type === 'dbPointer') {
+    return 'bson.DBPointer';
+  }
+  if (type === 'undefined') {
+    return 'undefined';
+  }
+
+  return 'any';
+}
+
+function uniqueTypes(property: MongoDBJSONSchema): Set<string> {
+  const type = getBSONType(property);
+  return new Set(Array.isArray(type) ? type.map((t) => toTypeName(t)) : [toTypeName(type ?? 'any')]);
+}
+
+function indentSpaces(indent: number) {
+  const spaces = [];
+  for (let i = 0; i < indent; i++) {
+    spaces.push('  ');
+  }
+  return spaces.join('');
+}
+
+function arrayType(types: string[]) {
+  assert(types.length, 'expected types');
+
+  if (types.length === 1) {
+    return `${types[0]}[]`;
+  }
+  return `${types.join(' | ')})[]`;
+}
+
+function toTypescriptType(properties: Record<string, MongoDBJSONSchema>, indent: number): string {
+  const eachFieldDefinition = Object.entries(properties).map(([propertyName, schema]) => {
+    if (isBSONPrimitive(schema)) {
+      return `${indentSpaces(indent)}${propertyName}?: ${[...uniqueTypes(schema)].join(' | ')}`;
+    }
+
+    if (isBSONArrayProperty(schema)) {
+      assert(schema.items, 'expected schema.items');
+      return `${indentSpaces(indent)}${propertyName}?: ${arrayType([...uniqueTypes(schema.items)])}`;
+    }
+
+    if (isBSONObjectProperty(schema)) {
+      assert(schema.properties, 'expected schema.properties');
+      return `${indentSpaces(indent)}${propertyName}?: ${toTypescriptType(schema.properties, indent + 1)}`;
+    }
+
+    assert(false, 'this should not be possible');
+  });
+
+  return `{\n${eachFieldDefinition.join(';\n')}\n${indentSpaces(indent - 1)}}`;
+}
+export function toTypescriptTypeDefinition(databaseName: string, collectionName: string, schema: MongoDBJSONSchema): string {
+  assert(schema.properties, 'expected schama.properties');
+
+  return `module ${databaseName} {
+  type ${collectionName} = ${toTypescriptType(schema.properties, 2)};
+};`;
+}

src/types.ts

@@ -3,7 +3,7 @@ import { InternalSchema } from '.';
 
 export type StandardJSONSchema = JSONSchema4;
 
-export type MongoDBJSONSchema = Pick<StandardJSONSchema, 'title' | 'required' | 'description'> & {
+export type MongoDBJSONSchema = Partial<StandardJSONSchema> & Pick<StandardJSONSchema, 'title' | 'required' | 'description'> & {
   bsonType?: string | string[];
   properties?: Record<string, MongoDBJSONSchema>;
   items?: MongoDBJSONSchema | MongoDBJSONSchema[];