golang 这个 panic 老是整不明白

[zxCoder]

看了教程都是些简单的例子，结果写个程序一出错连哪一行出错都没说，也不知道咋办。。。

runtime error: invalid memory address or nil pointer dereference
/home/keane/app/go/src/runtime/panic.go:199 (0x443fcb)
        panicmem: panic(memoryError)
/home/keane/app/go/src/runtime/signal_unix.go:394 (0x443e08)
        sigpanic: panicmem()
/home/keane/go/pkg/mod/github.com/jinzhu/gorm@v1.9.16/main.go:853 (0x969875)
        (*DB).clone: dialect:           newDialect(s.dialect.GetName(), s.db),
/home/keane/go/pkg/mod/github.com/jinzhu/gorm@v1.9.16/main.go:204 (0x96291e)
        (*DB).NewScope: dbClone := s.clone()
/home/keane/go/pkg/mod/github.com/jinzhu/gorm@v1.9.16/main.go:354 (0x96503b)
        (*DB).Find: return s.NewScope(out).inlineCondition(where...).callCallbacks(s.parent.callbacks.queries).db
/home/keane/GolandProjects/poblog/services/postService.go:168 (0x99722c)
        (*PostService).List: db.Find(&posts)
/home/keane/GolandProjects/poblog/controllers/postController.go:11 (0x9973ac)
        ListPost: _,_=postService.List()
/home/keane/go/pkg/mod/github.com/gin-gonic/gin@v1.6.3/context.go:161 (0x8f2d1a)
        (*Context).Next: c.handlers[c.index](c)
/home/keane/GolandProjects/poblog/middlewares/corsMiddleware.go:23 (0x99747c)
        Cors.func1: c.Next()
/home/keane/go/pkg/mod/github.com/gin-gonic/gin@v1.6.3/context.go:161 (0x8f2d1a)
        (*Context).Next: c.handlers[c.index](c)
/home/keane/go/pkg/mod/github.com/gin-gonic/gin@v1.6.3/recovery.go:83 (0x906b43)
        RecoveryWithWriter.func1: c.Next()
/home/keane/go/pkg/mod/github.com/gin-gonic/gin@v1.6.3/context.go:161 (0x8f2d1a)
        (*Context).Next: c.handlers[c.index](c)
/home/keane/go/pkg/mod/github.com/gin-gonic/gin@v1.6.3/logger.go:241 (0x905c70)
        LoggerWithConfig.func1: c.Next()
/home/keane/go/pkg/mod/github.com/gin-gonic/gin@v1.6.3/context.go:161 (0x8f2d1a)
        (*Context).Next: c.handlers[c.index](c)
/home/keane/go/pkg/mod/github.com/gin-gonic/gin@v1.6.3/gin.go:409 (0x8fcf8c)
        (*Engine).handleHTTPRequest: c.Next()
/home/keane/go/pkg/mod/github.com/gin-gonic/gin@v1.6.3/gin.go:367 (0x8fc68d)
        (*Engine).ServeHTTP: engine.handleHTTPRequest(c)
/home/keane/app/go/src/net/http/server.go:2802 (0x6cb8a3)
        serverHandler.ServeHTTP: handler.ServeHTTP(rw, req)
/home/keane/app/go/src/net/http/server.go:1890 (0x6c7144)
        (*conn).serve: serverHandler{c.server}.ServeHTTP(w, w.req)
/home/keane/app/go/src/runtime/asm_amd64.s:1357 (0x45c0c0)
        goexit: BYTE    $0x90   // NOP

[linxl]

```
/home/keane/GolandProjects/poblog/services/postService.go:168 (0x99722c)
(*PostService).List: db.Find(&posts)
/home/keane/GolandProjects/poblog/controllers/postController.go:11 (0x9973ac)
ListPost: _,_=postService.List()
/home/keane/go/pkg/mod/github.com/gin-gonic/gin@v1.6.3/context.go:161 (0x8f2d1a)
(*Context).Next: c.handlers[c.index](c)
/home/keane/GolandProjects/poblog/middlewares/corsMiddleware.go:23 (0x99747c)
Cors.func1: c.Next()
```
这里面其中一行？

[BoarBoar]

你这是 gorm 抛的错误吧，调用栈里没有业务代码当然不会报行数
这种情况问题多半在 init 函数里，又是空指针，多半是 gorm 那个 DB 什么的全局变量没初始化
最后提醒一句，慎用 init，必须用的时候越简单越好

[labulaka521]

那你倒是把代码贴出来 这样咋看

[xkeyideal]

s.NewScope(out).inlineCondition(where...).callCallbacks(s.parent.callbacks.queries).db
/home/keane/GolandProjects/poblog/services/postService.go:168 (0x99722c)
(*PostService).List: db.Find(&posts
已经很清楚的告诉你了，db 这个变量是空指针

水平有待提高啊