MySQL Bugs: #81351: switching session type from classic to JS fails

Bug #81351	switching session type from classic to JS fails
Submitted:	9 May 2016 9:26	Modified:	1 Jun 2016 11:57
Reporter:	Giuseppe Maxia (OCA)	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: Document Store: MySQL Shell	Severity:	S1 (Critical)
Version:	1.0.3	OS:	Any
Assigned to:	Juan Rene Ramirez Monarrez	CPU Architecture:	Any

Description:
When you start mysqlsh in JS mode and try to switch to SQL, you get an error, with an helpful message advising you to connect using the C/S protocol.

Instead, when you start in classic mode and want to switch to JS, there is no failure and no message, but you get errors only when trying to access JS classes:

$ mysqlsh --user=msandbox --sqlc --password=msandbox --port=5712 test
mysqlx: [Warning] Using a password on the command line interface can be insecure.
Creating a Classic Session to msandbox@localhost:5712/test
Default schema `test` accessible through db.

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Currently in SQL mode. Use \js or \py to switch the shell to a scripting language.
mysql-sql> \js
Switching to JavaScript mode...
mysql-js> db.tables
{
    "t1": <ClassicTable:t1>
}
mysql-js> t1=db.getTable('t1')
<ClassicTable:t1>
mysql-js> t1.select()
AttributeError: Invalid object member select at (shell):1:2
in t1.select()
     ^

How to repeat:
Start the shell in classic mode.
Change to JS mode
Try accessing a database object

Suggested fix:
The shell should either connect to the X-protocol port or refuse to switch to JS/Py.

Hello Giuseppe,

Thank you for the report.
Verified as described.

Thanks,
Umesh

Posted by devloper:

This is not a bug, what happens is that you are connecting using a classic
session, the API is very very limited when you do that.
 
 
 
CRUD operations are only available when you use a session through the
XProtocol (XSession or NodeSession)
 
 
 
Here you can see the error is caused because you are trying to use a function
that does not exist on a Classic Table
 
 
 
http://dev.mysql.com/doc/dev/mysqlsh-devapi/classmysh_1_1mysql_1_1_classic_table.html

Thanks for your explanation, but I don't think you got my point. 
The issue is that switching to JS from a classic session should generate a meaningful error, while now the user is kept wondering why. 
If a proper connection in JS mode is impossible, the switch command should not work at all.

session.getTable() should indeed just return an error. The way to use JS in a classic session is through session.runSql()