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golang calling mysql function


golang calling mysql function

By : Ku Min
Date : November 17 2020, 04:28 AM
it fixes the issue In order to make a call to MySQL's UUID_SHORT() in your model.User call, it would seem that you'd need to make an additional SQL call to the database before reaching the testutil.DB.Create(&user) line at some point.
It might be nice to find a way to use gorm for the MySQL UUID_SHORT() call itself, but that might end up requiring more work just to map a single row value (user_uuid in this case) for use in your model.User (possibly requiring an additional struct just for UUID_SHORT()).
code :
package model_test

import (
    "database/sql"
    _ "github.com/go-sql-driver/mysql"
    "github.com/jinzhu/gorm"
    "github.com/stretchr/testify/assert"
    "log"
    "testing"
)

type User struct {
    UserUUID uint64 `gorm:"column:user_uuid;primary_key:yes";sql:"notnull;default:uuid_short"`
    UserName string `sql:"notnull"`
}

func (user User) TableName() string {
    return "users"
}

func get_uuid_short() uint64 {
    var uuid_short uint64

    /* connect to db using `sql` package */
    db, err := sql.Open("mysql", "username:password@tcp(127.0.0.1:3306)/uuid_test")
    if err != nil {
        log.Fatal(err)
    }

    /* select UUID_SHORT() */
    rows, err := db.Query("select UUID_SHORT()")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    /* get value of uuid_short */
    for rows.Next() {
        err := rows.Scan(&uuid_short)
        if err != nil {
            log.Fatal(err)
        }
    }

    return uuid_short
}

func TestUserCreate(t *testing.T) {
    user := User{
        UserUUID: get_uuid_short(),    /* get next UUID_SHORT() value */
        UserName: "Go Test",
    }
    db, err := gorm.Open("mysql", "username:password@/uuid_test?charset=utf8&parseTime=True&loc=Local")
    db.Create(&user)
    assert.Nil(t, err)
}
mysql> select * from users;
+-------------------+-----------+
| user_uuid         | user_name |
+-------------------+-----------+
| 24070794506141712 | Go Test   |
| 24070794506141713 | Go Test   |
| 24070794506141714 | Go Test   |
+-------------------+-----------+
3 rows in set (0.00 sec)


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Golang, Go : implicitly calling interface function?

Golang, Go : implicitly calling interface function?


By : Ruben Muradyan
Date : March 29 2020, 07:55 AM
it should still fix some issue fmt.Println and the other functions in pkg/fmt analyze the objects passed to it. If it is an error, the function calls .Error() on the passed object and prints the string returned by Error().
See the source for details. The code says:
code :
switch v := p.field.(type) {
case error:
    // ...
    p.printField(v.Error(), verb, plus, false, depth)
    return
// ...
}
In golang how calling a function with and without trailing brackets works when using net/http

In golang how calling a function with and without trailing brackets works when using net/http


By : Ahmad Siddik Prayogi
Date : March 29 2020, 07:55 AM
I wish this helpful for you You are not "calling" the function from main, you are providing it as a argument to HandleFunc, registering it to be called for the path "/" in the mux.Router. This pattern of providing a function to be called later is typically known as a "callback".
Your ParseSlash function is of the type http.HandlerFunc
code :
type HandlerFunc func(ResponseWriter, *Request)
Calling MySQL function from within a SELECT statement takes significantly more time than calling the function alone from

Calling MySQL function from within a SELECT statement takes significantly more time than calling the function alone from


By : gobi nath
Date : March 29 2020, 07:55 AM
around this issue When you call the get_project_uuid() function from the command line, it only called once thus it runs faster.
When you use this function inside a select statement (i.e., 2nd code section from your question), depending on your statement, this function might be called for each row of the issue table used in the outer select statement. Now if issue table has a lot of rows, it might take longer time to execute.
too many memory references for `mov' when calling a golang function with C by using inline assembly

too many memory references for `mov' when calling a golang function with C by using inline assembly


By : Nitesh Agarwal
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further A "g" constraint allows the compiler to pick memory or register, so obviously you'll end up with mov mem,mem if that happens. mov can have at most 1 memory operand. (Like all x86 instructions, at most one explicit memory operand is possible.)
Use "ri" constraints for the inputs that will be moved to a memory destination, to allow register or immediate but not memory.
code :
int ecx, edx, edi, esi; // dummy outputs as clobbers
register int r8 asm("r8d");  // for all the call-clobbered regs in the calling convention
register int r9 asm("r9d");
register int r10 asm("r10d");
register int r11 asm("r11d");
// These are the regs for x86-64 System V.
//  **I don't know what Go actually clobbers.**

asm("sub  rsp, 0xe0\n\t"    // adjust as necessary to align the stack before a call
    // "push args in reverse order"
    "push  %[fn_len] \n\t"
    "push  %[fn_str] \n\t"
    "call \n\t"
    "add   rsp, 0xe0 + 3*8 \n\t"  // pop red-zone skip space + pushed args

       // real output in RAX, and dummy outputs in call-clobbered regs
    : "=a"(retval), "=c"(ecx), "=d"(edx), "=D"(edi), "=S"(esi), "=r"(r8), "=r"(r9), "=r"(r10), "=r"(r11)
    : [fn_str] "ri" (filename.str), [fn_len] "ri" (filename.len), etc.  // inputs can use the same regs as dummy outputs
    :  "xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7",  // All vector regs are call-clobbered
       "xmm8", "xmm9", "xmm10", "xmm11", "xmm12", "xmm13", "xmm14", "xmm15",
       "memory"  // if you're passing any pointers (even read-only), or the function accesses any globals,
                 // best to make this a compiler memory barrier
    );
Can't open file when calling golang function via Node

Can't open file when calling golang function via Node


By : user2092710
Date : March 29 2020, 07:55 AM
wish help you to fix your issue Remember that strings in Go are like slices. They are composed of a pointer to the backing data and the length. This is why in your code, GoString is defined as:
code :
var GoString = Struct({
    p: "string",  // pointer
    n: "longlong" // length
});
function NewGoString(str) {
    return new GoString({p: str, n: str.length})
}
var simpleRead = ffi.Library("./simpleread.so", {
    ReadSomething: ["void", [GoString]]
});

simpleRead.ReadSomething(NewGoString("/path/to/your/file"))
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