Problem with MySQL

New to Julia
1

Dearests,

I have a connect problem with MySQL.jl. I’m writing a module that do some custom queries to a local mysql database. It looks like:

module PfamDatabaseTools

global connection = MySQL.connect("127.0.0.1","myname","mypasswd")

include("file1.jl")
...
include("fileN.jl")

println(connection)
end #end module

Now I activate the package (]activate . ) and after precompilation I see correctly printed on screen
a regular connection

Host: 127.0.0.1
Port: 3306
User: myname
DB:

Now the problem is that if I now try to see what happens to my connection I get a

julia> PfamDatabaseTools.connection
Null MySQL Connection

I tryed to change global into const, but same result. Note that if I do the same outside the module by squeezing all file*jl into a single file, and opening the connection at the beginning of the file, everything works perfectly.

Shooting in the dark, I also tried to GC.@preserve the connection variable, with no success either. It’s like if at the end of the module precompilation, the connection disappears.

Any ideas?

2

Precompilation is done only once, if you want to connect to MySQL every time module is loaded, try putting the connection code into the special __init__() method. Even better approach would be to create connection only when you need it to be able to handle disconnections and similar things.

3

Thank @dfdx ! I added in the main module file a

function __init__()
    global connection = MySQL.connect("127.0.0.1","myname","mypasswd")
    nothing
end

And everything works like a charm. I see that this solution is brittle as it is not able to deal with random disconnection. I’m thinking about your “even better approach”. Marking as solved!