What a fuck confusion of database/sql driver's import

[Liigo Zhuang]

When import "github.com/go-sql-driver/mysql", I got compile error:

"imported and not used: github.com/go-sql-driver/mysql"

And after removing this import, I got runtime error:

"sql: unknown driver "mysql" (forgotten import?)"

I do know how to make it happy, I just saying it's confusing and annoying, especially for beginners.

----------------------------------------------------------------------

package main

import "fmt"

import "database/sql"

import "github.com/go-sql-driver/mysql"

func main() {

db, err := sql.Open("mysql", "liigo:zhu...@192.168.1.100");

if err != nil {

fmt.Println("connect fails:", err)

return

}

db.Close()

}

----------------------------------------------------------------------

--
by Liigo, http://blog.csdn.net/liigo/

Google+  https://plus.google.com/105597640837742873343/

[Dave Cheney]

Use a side effect import

import _ "github.com/go-sql-driver/mysql"

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[Kyle Lemons]

Please don't employ vulgar language on this mailing list.

--

[Carlos Castillo]

To be fair, AFAIK nowhere in the database/sql documentation does it say to do this. Although to fling blame the other way, the README.md for github.com/go-sql-driver/mysql actually does say what to do (under Usage).

In the documentation of the image package, it shows in the package comment how to use a side-effect import to register the PNG driver, perhaps database/sql should do the same (unfortunately there are no built-in SQL drivers to use as example).

On Friday, July 12, 2013 7:30:08 PM UTC-7, Dave Cheney wrote:

Use a side effect import

import _ "github.com/go-sql-driver/mysql"

On Sat, Jul 13, 2013 at 12:26 PM, Liigo Zhuang <com....@gmail.com> wrote:
> When import "github.com/go-sql-driver/mysql", I got compile error:
> "imported and not used: github.com/go-sql-driver/mysql"
>
> And after removing this import, I got runtime error:
> "sql: unknown driver "mysql" (forgotten import?)"
>
> I do know how to make it happy, I just saying it's confusing and annoying,
> especially for beginners.
>
> ----------------------------------------------------------------------
> package main
>
> import "fmt"
> import "database/sql"
> import "github.com/go-sql-driver/mysql"
>
> func main() {

> db, err := sql.Open("mysql", "liigo:...@192.168.1.100");

[Julien Schmidt]

For beginners I would recommend this detailed tutorial for the database/sql package: https://github.com/VividCortex/go-database-sql-tutorial

Looking at your code I'm also pretty sure your DSN string is wrong, here are examples how it should look like: https://github.com/go-sql-driver/mysql#examples
The more technical and detailed specification can be found above.

On Saturday, July 13, 2013 4:26:50 AM UTC+2, Liigo Zhuang wrote:

When import "github.com/go-sql-driver/mysql", I got compile error:

"imported and not used: github.com/go-sql-driver/mysql"

And after removing this import, I got runtime error:

"sql: unknown driver "mysql" (forgotten import?)"

I do know how to make it happy, I just saying it's confusing and annoying, especially for beginners.

----------------------------------------------------------------------

package main

import "fmt"

import "database/sql"

import "github.com/go-sql-driver/mysql"

func main() {

db, err := sql.Open("mysql", "liigo:...@192.168.1.100");

[Andrew Gerrand]

On 13 Jul 2013 12:26, "Liigo Zhuang" <com....@gmail.com> wrote:
>
> When import "github.com/go-sql-driver/mysql", I got compile error:
> "imported and not used: github.com/go-sql-driver/mysql"
>
> And after removing this import, I got runtime error:
> "sql: unknown driver "mysql" (forgotten import?)"
>
> I do know how to make it happy, I just saying it's confusing and annoying, especially for beginners.

I submit that it is confusing and annoying *only* for beginners. Side-effect imports are a common Go idiom, and one that every Go programmer should understand.

Another example is the image package and the various image codec packages: by underscore-importing "image/png" you give the "image" package the ability to read PNG files.

Andrew 

[David DENG]

In document of package image, there are clear instructions about side-effect importing. I think package sql needs the same thing.

David

ps: @Liigo, using words like f*** is both rude and stupid, especially on the title.

[Andrew Gerrand]

On 15 July 2013 09:36, David DENG <david...@gmail.com> wrote:

In document of package image, there are clear instructions about side-effect importing. I think package sql needs the same thing.

I agree the docs need improvement. Filed http://golang.org/issue/5886

Andrew

[Hans Stimer]

ps: @Liigo, using words like f*** is both rude and stupid, especially on the title.

The guy is frustrated, and he vented a little bit. No harm in that, as long as it doesn't become disruptive.

In this case, with the poor grammar, I find it endearing. Kind of like "All your base are belong to us", or "pwnd".

"What a fuck confusion" is one of the better ones I've heard lately. However, I haven't had many of those cases with Go, as compared to every other language I've used. I think the top "What a fuck confusion" goes to C++, or more consisely WFC C++. I think the WFC C++ meter hit 11, not to mention the ridiculous compile times, when people started metaprogramming with templates.

[Dan Kortschak]

On Sun, 2013-07-14 at 18:40 -0700, Hans Stimer wrote:
> ps: @Liigo, using words like f*** is both rude and stupid, especially
> on the title.

But it was retained in the response? (not directed at Hans).

> The guy is frustrated, and he vented a little bit. No harm in that, as
> long as it doesn't become disruptive.
>
> In this case, with the poor grammar, I find it endearing. Kind of
> like "All your base are belong to us", or "pwnd".

Yes, it's pretty clear the OP does not have English as his first
language. People often swear beyond what is normally deemed appropriate
when speaking/writing in a foreign language.

He's got his answer though. So can we leave this.

[Liigo Zhuang]

I just complain, not ask for help.

I do known the way of "import _ xxxxx" BEFORE posting original email. Remember my last words in original email?

"I do know how to make it happy, I just saying it's confusing and annoying, especially for beginners."

2013/7/14 Julien Schmidt <g...@julienschmidt.com>

For beginners I would recommend this detailed tutorial for the database/sql package: https://github.com/VividCortex/go-database-sql-tutorial 

Looking at your code I'm also pretty sure your DSN string is wrong, here are examples how it should look like: https://github.com/go-sql-driver/mysql#examples

The more technical and detailed specification can be found above.

Yes, thanks. the dsn string is wrong. I do found it. It's easy to fix. This is out of topic.

 

On Saturday, July 13, 2013 4:26:50 AM UTC+2, Liigo Zhuang wrote:

When import "github.com/go-sql-driver/mysql", I got compile error:

"imported and not used: github.com/go-sql-driver/mysql"

And after removing this import, I got runtime error:

"sql: unknown driver "mysql" (forgotten import?)"

I do know how to make it happy, I just saying it's confusing and annoying, especially for beginners.

----------------------------------------------------------------------

package main

import "fmt"

import "database/sql"

import "github.com/go-sql-driver/mysql"

func main() {

db, err := sql.Open("mysql", "liigo:...@192.168.1.100");

if err != nil {

fmt.Println("connect fails:", err)

return

}

db.Close()

}

----------------------------------------------------------------------

--
by Liigo, http://blog.csdn.net/liigo/

Google+  https://plus.google.com/105597640837742873343/

--

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[Liigo Zhuang]

2013/7/14 John <johns...@gmail.com>

Also, though you didn't ask about any of this, you can make this much nicer really easy.  Figured since I was looking I would throw in some pointers that

helped me out when I started with Go.

----------------------------------------------------------------------

package main

import (    // This way you dont have to say import, import,import.  You can do this with "var" and "const" too.

    "fmt"

    "database/sql"

    _ "github.com/go-sql-driver/mysql'  // I changed this to the side effect import.

)

func main() {

    db, err := sql.Open("mysql", "liigo:...@192.168.1.100")  // Don't need the ";"

    defer db.Close()  // Defer makes it so when your main exits db.Close() gets called.

You are wrong. If connect fails, db will be nil, and defered db.Close() will panic. I'm using the proper way.

 

    if err != nil {

        fmt.Println("connect fails:", err)  

        return

    }

}
----------------------------------------------------------------------

On Friday, July 12, 2013 7:26:50 PM UTC-7, Liigo Zhuang wrote:

When import "github.com/go-sql-driver/mysql", I got compile error:

"imported and not used: github.com/go-sql-driver/mysql"

And after removing this import, I got runtime error:

"sql: unknown driver "mysql" (forgotten import?)"

I do know how to make it happy, I just saying it's confusing and annoying, especially for beginners.

----------------------------------------------------------------------

package main

import "fmt"

import "database/sql"

import "github.com/go-sql-driver/mysql"

func main() {

db, err := sql.Open("mysql", "liigo:...@192.168.1.100");

if err != nil {

fmt.Println("connect fails:", err)

return

}

db.Close()

}

----------------------------------------------------------------------

--
by Liigo, http://blog.csdn.net/liigo/

Google+  https://plus.google.com/105597640837742873343/

[minux]

On Mon, Jul 15, 2013 at 2:45 PM, Liigo Zhuang <com....@gmail.com> wrote:

2013/7/14 John <johns...@gmail.com>

Also, though you didn't ask about any of this, you can make this much nicer really easy.  Figured since I was looking I would throw in some pointers that

helped me out when I started with Go.

----------------------------------------------------------------------

package main

import (    // This way you dont have to say import, import,import.  You can do this with "var" and "const" too.

    "fmt"

    "database/sql"

    _ "github.com/go-sql-driver/mysql'  // I changed this to the side effect import.

)

func main() {

    db, err := sql.Open("mysql", "liigo:...@192.168.1.100")  // Don't need the ";"

    defer db.Close()  // Defer makes it so when your main exits db.Close() gets called.

You are wrong. If connect fails, db will be nil, and defered db.Close() will panic. I'm using the proper way.

the defer statement won't panic, only when the deferred statement (db.Close() runs) could it

panic. so your code is still incorrect. and the general Go idiom is to compare err with nil

first, if it's not nil, prepare the err and return; after that defer resource.Close(). 

[John]

minux is right, I should have just had it after the error check.  Oversight on my part.

[Aram Hăvărneanu]

> I just complain, not ask for help.

Complain away then.

--
Aram Hăvărneanu

[androi...@gmail.com]

It worked for me...Thank you :)

On Saturday, July 13, 2013 8:00:08 AM UTC+5:30, Dave Cheney wrote:

Use a side effect import

import _ "github.com/go-sql-driver/mysql"

On Sat, Jul 13, 2013 at 12:26 PM, Liigo Zhuang <com....@gmail.com> wrote:
> When import "github.com/go-sql-driver/mysql", I got compile error:
> "imported and not used: github.com/go-sql-driver/mysql"
>
> And after removing this import, I got runtime error:
> "sql: unknown driver "mysql" (forgotten import?)"
>
> I do know how to make it happy, I just saying it's confusing and annoying,
> especially for beginners.
>
> ----------------------------------------------------------------------
> package main
>
> import "fmt"
> import "database/sql"
> import "github.com/go-sql-driver/mysql"
>
> func main() {

> db, err := sql.Open("mysql", "liigo:...@192.168.1.100");