Linq2db: Implement `IndexColumns` schema table population for MySql on our side

[nitz]

I'm able to use linq2db to connect to my database successfully in the create connection dialog using the test button. However, when I go to actually expand the tree view to start using the connect, It throws a SqlNullValueException, with the message "Data is Null. This method or property cannot be called on Null Values". I've attached the MessageBox with the full call stack below.

Connection string: Server=<redacted>.amazonaws.com;Database=<redacted>;Uid=<redacted>;Pwd=<redacted>;

I do have rows with null values in them.

Full error MessageBox:

(via)

[MaceWindu]

Interesting, basically it is a bug in MySql.Data provider's GetSchema implementation (not surprising). Looks like we need to implement it on our side after we can reproduce it as MySqlConnector provider's GetSchema support is even less functional.

[MaceWindu]

moved to main repo as it is linq2db issue

[nitz]

Makes sense! I unfortunately can't provide the database, itself, but if there's other information I can provide, let me know!

[MaceWindu]

Error is on this line: https://github.com/mysql/mysql-connector-net/blob/8.0/MySQL.Data/src/SchemaProvider.cs#L363

and show index documentation clearly says:

 Collation

How the column is sorted in the index. This can have values A (ascending), D (descending), or NULL (not sorted). 

people really need to read their own documentation...

[MaceWindu]

Actually Oracle was informed about it 4+ years ago: https://bugs.mysql.com/bug.php?id=75301
:man_facepalming:

[MaceWindu]

Actually there are some chances it will be fixed in MySql.Data too. Somebody tried to send PR (not the easiest task for that repo) https://github.com/mysql/mysql-connector-net/pull/30

Update: as it often happens to PRs in that repo - it was closed by bot. Bad luck :rofl: , maybe we need to wait another 5 years for fix