feat(NODE-4871): Add support for int64 deserialization to BigInt

README.md

@@ -304,12 +304,13 @@ Serialize a Javascript object using a predefined Buffer and index into the buffe
 | buffer | <code>Buffer</code> |  | the buffer containing the serialized set of BSON documents. |
 | [options.evalFunctions] | <code>Object</code> | <code>false</code> | evaluate functions in the BSON document scoped to the object deserialized. |
 | [options.cacheFunctions] | <code>Object</code> | <code>false</code> | cache evaluated functions for reuse. |
+| [options.useBigInt64] | <code>Object</code> | <code>false</code> | when deserializing a Long will return a BigInt. |
 | [options.promoteLongs] | <code>Object</code> | <code>true</code> | when deserializing a Long will fit it into a Number if it's smaller than 53 bits |
 | [options.promoteBuffers] | <code>Object</code> | <code>false</code> | when deserializing a Binary will return it as a node.js Buffer instance. |
 | [options.promoteValues] | <code>Object</code> | <code>false</code> | when deserializing will promote BSON values to their Node.js closest equivalent types. |
 | [options.fieldsAsRaw] | <code>Object</code> | <code></code> | allow to specify if there what fields we wish to return as unserialized raw buffer. |
 | [options.bsonRegExp] | <code>Object</code> | <code>false</code> | return BSON regular expressions as BSONRegExp instances. |
-| [options.allowObjectSmallerThanBufferSize] | <code>boolean</code> | <code>false</code> | allows the buffer to be larger than the parsed BSON object |
+| [options.allowObjectSmallerThanBufferSize] | <code>boolean</code> | <code>false</code> | allows the buffer to be larger than the parsed BSON object. |
 
 Deserialize data as BSON.
 

src/parser/deserializer.ts

@@ -14,12 +14,14 @@ import { ObjectId } from '../objectid';
 import { BSONRegExp } from '../regexp';
 import { BSONSymbol } from '../symbol';
 import { Timestamp } from '../timestamp';
-import { ByteUtils } from '../utils/byte_utils';
+import { BSONDataView, ByteUtils } from '../utils/byte_utils';
 import { validateUtf8 } from '../validate_utf8';
 
 /** @public */
 export interface DeserializeOptions {
-  /** when deserializing a Long will fit it into a Number if it's smaller than 53 bits */
+  /** when deserializing a Long will return as a BigInt. */
+  useBigInt64?: boolean;
+  /** when deserializing a Long will fit it into a Number if it's smaller than 53 bits. */
   promoteLongs?: boolean;
   /** when deserializing a Binary will return it as a node.js Buffer instance. */
   promoteBuffers?: boolean;
@@ -29,7 +31,7 @@ export interface DeserializeOptions {
   fieldsAsRaw?: Document;
   /** return BSON regular expressions as BSONRegExp instances. */
   bsonRegExp?: boolean;
-  /** allows the buffer to be larger than the parsed BSON object */
+  /** allows the buffer to be larger than the parsed BSON object. */
   allowObjectSmallerThanBufferSize?: boolean;
   /** Offset into buffer to begin reading document from */
   index?: number;
@@ -96,7 +98,7 @@ export function deserialize(
     );
   }
 
-  // Start deserializtion
+  // Start deserialization
   return deserializeObject(buffer, index, options, isArray);
 }
 
@@ -117,9 +119,18 @@ function deserializeObject(
   const bsonRegExp = typeof options['bsonRegExp'] === 'boolean' ? options['bsonRegExp'] : false;
 
   // Controls the promotion of values vs wrapper classes
-  const promoteBuffers = options['promoteBuffers'] == null ? false : options['promoteBuffers'];
-  const promoteLongs = options['promoteLongs'] == null ? true : options['promoteLongs'];
-  const promoteValues = options['promoteValues'] == null ? true : options['promoteValues'];
+  const promoteBuffers = options.promoteBuffers ?? false;
+  const promoteLongs = options.promoteLongs ?? true;
+  const promoteValues = options.promoteValues ?? true;
+  const useBigInt64 = options.useBigInt64 ?? false;
+
+  if (useBigInt64 && !promoteValues) {
+    throw new BSONError('Must either request bigint or Long for int64 deserialization');
+  }
+
+  if (useBigInt64 && !promoteLongs) {
+    throw new BSONError('Must either request bigint or Long for int64 deserialization');
+  }
 
   // Ensures default validation option if none given
   const validation = options.validation == null ? { utf8: true } : options.validation;
@@ -323,6 +334,8 @@ function deserializeObject(
       value = null;
     } else if (elementType === constants.BSON_DATA_LONG) {
       // Unpack the low and high bits
+      const dataview = BSONDataView.fromUint8Array(buffer.subarray(index, index + 8));
+
       const lowBits =
         buffer[index++] |
         (buffer[index++] << 8) |
@@ -334,8 +347,10 @@ function deserializeObject(
         (buffer[index++] << 16) |
         (buffer[index++] << 24);
       const long = new Long(lowBits, highBits);
-      // Promote the long if possible
-      if (promoteLongs && promoteValues === true) {
+      if (useBigInt64) {
+        value = dataview.getBigInt64(0, true);
+      } else if (promoteLongs && promoteValues === true) {
+        // Promote the long if possible
         value =
           long.lessThanOrEqual(JS_INT_MAX_LONG) && long.greaterThanOrEqual(JS_INT_MIN_LONG)
             ? long.toNumber()

test/node/bigint.test.ts

@@ -0,0 +1,102 @@
+import { BSON, BSONError } from '../register-bson';
+import { bufferFromHexArray } from './tools/utils';
+import { expect } from 'chai';
+
+describe('BSON BigInt deserialization support', function () {
+  describe('BSON.deserialize()', function () {
+    type DeserialzationOptions = {
+      useBigInt64: boolean | undefined;
+      promoteValues: boolean | undefined;
+      promoteLongs: boolean | undefined;
+    };
+    type TestTableEntry = {
+      options: DeserialzationOptions;
+      shouldThrow: boolean;
+      expectedResult: BSON.Document;
+      expectedErrorMessage: string;
+    };
+    const testSerializedDoc = bufferFromHexArray(['12', '6100', '2300000000000000']); // key 'a', value 0x23 as int64
+    const useBigInt64Values = [true, false, undefined];
+    const promoteLongsValues = [true, false, undefined];
+    const promoteValuesValues = [true, false, undefined];
+
+    const testTable = useBigInt64Values.flatMap(useBigInt64 => {
+      return promoteLongsValues.flatMap(promoteLongs => {
+        return promoteValuesValues.flatMap(promoteValues => {
+          const useBigInt64Set = useBigInt64 ?? false;
+          const promoteLongsSet = promoteLongs ?? true;
+          const promoteValuesSet = promoteValues ?? true;
+          const shouldThrow = useBigInt64Set && (!promoteValuesSet || !promoteLongsSet);
+          let expectedResult: BSON.Document;
+          if (useBigInt64Set) {
+            expectedResult = { a: 0x23n };
+          } else if (promoteLongsSet && promoteValuesSet) {
+            expectedResult = { a: 0x23 };
+          } else {
+            expectedResult = { a: new BSON.Long(0x23) };
+          }
+          const expectedErrorMessage = shouldThrow
+            ? 'Must either request bigint or Long for int64 deserialization'
+            : '';
+          return [
+            {
+              options: { useBigInt64, promoteValues, promoteLongs },
+              shouldThrow,
+              expectedResult,
+              expectedErrorMessage
+            }
+          ];
+        });
+      });
+    });
+
+    it('meta test: generates 27 tests with exactly 5 error cases and 22 success cases', () => {
+      expect(testTable).to.have.lengthOf(27);
+      expect(testTable.filter(t => t.shouldThrow)).to.have.lengthOf(5);
+      expect(testTable.filter(t => !t.shouldThrow)).to.have.lengthOf(22);
+    });
+
+    function generateTestDescription(entry: TestTableEntry): string {
+      const options = entry.options;
+      const promoteValues = `promoteValues ${
+        options.promoteValues === undefined ? 'is default' : `is ${options.promoteValues}`
+      }`;
+      const promoteLongs = `promoteLongs ${
+        options.promoteLongs === undefined ? 'is default' : `is ${options.promoteLongs}`
+      }`;
+      const useBigInt64 = `useBigInt64 ${
+        options.useBigInt64 === undefined ? 'is default' : `is ${options.useBigInt64}`
+      }`;
+      const flagString = `${useBigInt64}, ${promoteValues}, and ${promoteLongs}`;
+      if (entry.shouldThrow) {
+        return `throws when ${flagString}`;
+      } else {
+        return `deserializes int64 to ${entry.expectedResult.a.constructor.name} when ${flagString}`;
+      }
+    }
+
+    function generateTest(test: TestTableEntry) {
+      const options = test.options;
+      const deserialize = () => {
+        return BSON.deserialize(testSerializedDoc, options);
+      };
+      if (test.shouldThrow) {
+        return () => {
+          expect(deserialize).to.throw(BSONError, test.expectedErrorMessage);
+        };
+      } else {
+        return () => {
+          const deserializedDoc = deserialize();
+          expect(deserializedDoc).to.deep.equal(test.expectedResult);
+        };
+      }
+    }
+
+    for (const tableEntry of testTable) {
+      const test = generateTest(tableEntry);
+      const description = generateTestDescription(tableEntry);
+
+      it(description, test);
+    }
+  });
+});