feat: ability to trim trailing zeroes in decimal number string

lib/connection_config.js

@@ -64,7 +64,8 @@ const validOptions = {
   idleTimeout: 1,
   Promise: 1,
   queueLimit: 1,
-  waitForConnections: 1
+  waitForConnections: 1,
+  decimalStringTrimTrailingZero: 1,
 };
 
 class ConnectionConfig {
@@ -117,6 +118,7 @@ class ConnectionConfig {
     this.stringifyObjects = options.stringifyObjects || false;
     this.enableKeepAlive = options.enableKeepAlive !== false;
     this.keepAliveInitialDelay = options.keepAliveInitialDelay || 0;
+    this.decimalStringTrimTrailingZero = options.decimalStringTrimTrailingZero || false;
     if (
       options.timezone &&
       !/^(?:local|Z|[ +-]\d\d:\d\d)$/.test(options.timezone)

lib/packets/packet.js

@@ -377,7 +377,7 @@ class Packet {
     );
   }
 
-  readLengthCodedString(encoding) {
+  readLengthCodedString(encoding, trimTrailingZero = false) {
     const len = this.readLengthCodedNumber();
     // TODO: check manually first byte here to avoid polymorphic return type?
     if (len === null) {
@@ -390,7 +390,10 @@ class Packet {
       this.buffer,
       encoding,
       this.offset - len,
-      this.offset
+      this.offset,
+      {
+        trimTrailingZero
+      }
     );
   }
 
@@ -425,7 +428,7 @@ class Packet {
     return StringParser.decode(
       this.buffer,
       encoding,
-      this.offset - len, 
+      this.offset - len,
       this.offset
     );
   }

lib/parsers/string.js

@@ -4,6 +4,18 @@ const Iconv = require('iconv-lite');
 
 exports.decode = function(buffer, encoding, start, end, options) {
   if (Buffer.isEncoding(encoding)) {
+    if(options?.trimTrailingZero) {
+      for(let i = end - 1; i >= start; i--) {
+        if(buffer[i] === 48) {
+          end--;
+        } else if(buffer[i] === 46) {
+          end--;
+          break;
+        } else {
+          break;
+        }
+      }
+    }
     return buffer.toString(encoding, start, end);
   }
 

lib/parsers/text_parser.js

@@ -17,6 +17,8 @@ function readCodeFor(type, charset, encodingExpr, config, options) {
   const bigNumberStrings = options.bigNumberStrings || config.bigNumberStrings;
   const timezone = options.timezone || config.timezone;
   const dateStrings = options.dateStrings || config.dateStrings;
+  const decimalStringTrimTrailingZero =
+    options.decimalStringTrimTrailingZero || config.decimalStringTrimTrailingZero;
 
   switch (type) {
     case Types.TINY:
@@ -40,7 +42,10 @@ function readCodeFor(type, charset, encodingExpr, config, options) {
       if (config.decimalNumbers) {
         return 'packet.parseLengthCodedFloat()';
       }
-      return 'packet.readLengthCodedString("ascii")';
+      if(decimalStringTrimTrailingZero) {
+        return 'packet.readLengthCodedString("ascii", true)';
+      }
+      return 'packet.readLengthCodedString("ascii", false)';
     case Types.DATE:
       if (helpers.typeMatch(type, dateStrings, Types)) {
         return 'packet.readLengthCodedString("ascii")';

test/common.js

@@ -85,6 +85,7 @@ exports.createConnection = function(args) {
     namedPlaceholders: args && args.namedPlaceholders,
     connectTimeout: args && args.connectTimeout,
     ssl: (args && args.ssl) ?? config.ssl,
+    decimalStringTrimTrailingZero: (args && args.decimalStringTrimTrailingZero) ?? config.decimalStringTrimTrailingZero,
   };
 
   const conn = driver.createConnection(params);

test/unit/connection/test-connection_config.js

@@ -49,3 +49,11 @@ assert.strictEqual(
   ).password,
   'pass!%40$%%5E&*()%5Cword%3A'
 );
+
+assert.doesNotThrow(
+  () =>
+    new ConnectionConfig({
+      decimalStringTrimTrailingZero: true
+    }),
+  'Error, the constructor accepts an object but throws an exception'
+);

test/unit/parsers/test-decimal-parser.js

@@ -0,0 +1,44 @@
+'use strict';
+
+const assert = require('assert');
+const common = require('../../common');
+
+const connection = common.createConnection({decimalStringTrimTrailingZero: true});
+connection.query('CREATE TEMPORARY TABLE t (a decimal(38,16), b varchar(39))');
+connection.query('INSERT INTO t values(\'1.00\', \'1.00\')');
+connection.query('INSERT INTO t values(\'1.01\', \'1.01\')');
+connection.query('INSERT INTO t values(\'1.10\', \'1.10\')');
+connection.query('INSERT INTO t values(\'1.010\', \'1.010\')');
+connection.query('INSERT INTO t values(\'0.00\', \'0.00\')');
+connection.query('INSERT INTO t values(\'100000.0000100000000000\', \'100000.0000100000000000\')');
+connection.query('INSERT INTO t values(\'100000.0000000000000000\', \'100000.0000000000000000\')');
+
+
+// JSON without encoding options - should result in unexpected behaviors
+connection.query({
+  sql: 'SELECT * FROM t',
+}, (err, rows) => {
+  assert.ifError(err);
+  assert.equal(rows[0].a, "1");
+  assert.equal(rows[0].b, "1.00");
+
+  assert.equal(rows[1].a, "1.01");
+  assert.equal(rows[1].b, "1.01");
+
+  assert.equal(rows[2].a, "1.1");
+  assert.equal(rows[2].b, "1.10");
+
+  assert.equal(rows[3].a, "1.01");
+  assert.equal(rows[3].b, "1.010");
+
+  assert.equal(rows[4].a, "0");
+  assert.equal(rows[4].b, "0.00");
+
+  assert.equal(rows[5].a, "100000.00001");
+  assert.equal(rows[5].b, "100000.0000100000000000");
+
+  assert.equal(rows[6].a, "100000");
+  assert.equal(rows[6].b, "100000.0000000000000000");
+});
+
+connection.end();

typings/mysql/lib/Connection.d.ts

@@ -291,6 +291,8 @@ export interface ConnectionOptions {
   authPlugins?: {
     [key: string]: AuthPlugin;
   };
+
+  decimalStringTrimTrailingZero?: boolean;
 }
 
 declare class Connection extends QueryableBase(ExecutableBase(EventEmitter)) {