Invalid memory address or nil pointer dereference goroutine

[cinematik (Andre)]

I can connect and fetch DB data without using rest api. But when it comes to rest then I get:

2019/03/02 15:25:29 http: panic serving 127.0.0.1:49348: runtime error: invalid memory address or nil pointer dereference
goroutine 4 [running]:
net/http.(*conn).serve.func1(0xc000284000)
C:/Go/src/net/http/server.go:1746 +0xd7
panic(0x6c5180, 0x947770)
C:/Go/src/runtime/panic.go:513 +0x1c7
database/sql.(*DB).conn(0x0, 0x76f940, 0xc00004a080, 0xc0001b7001, 0x2, 0x30000, 0x2)
C:/Go/src/database/sql/sql.go:1081 +0x41
database/sql.(*DB).query(0x0, 0x76f940, 0xc00004a080, 0x721823, 0x13, 0x0, 0x0, 0x0, 0x6ef801, 0x20, …)
C:/Go/src/database/sql/sql.go:1514 +0x6d
database/sql.(*DB).QueryContext(0x0, 0x76f940, 0xc00004a080, 0x721823, 0x13, 0x0, 0x0, 0x0, 0x6addc0, 0x1, …)
C:/Go/src/database/sql/sql.go:1496 +0xda
database/sql.(*DB).Query(0x0, 0x721823, 0x13, 0x0, 0x0, 0x0, 0x40c17f, 0x80, 0x703660)
C:/Go/src/database/sql/sql.go:1510 +0x89
main.getBooks(0x76f780, 0xc0002a8000, 0xc000294200)
C:/Users/User/go/src/books-list - 1/main.go:100 +0xb6
net/http.HandlerFunc.ServeHTTP(0x734af8, 0x76f780, 0xc0002a8000, 0xc000294200)
C:/Go/src/net/http/server.go:1964 +0x4b
github.com/gorilla/mux.(*Router).ServeHTTP(0xc000204300, 0x76f780, 0xc0002a8000, 0xc000294000)
c:/users/user/go/src/github.com/gorilla/mux/mux.go:212 +0xd7
net/http.serverHandler.ServeHTTP(0xc00004f040, 0x76f780, 0xc0002a8000, 0xc000294000)
C:/Go/src/net/http/server.go:2741 +0xb2
net/http.(*conn).serve(0xc000284000, 0x76f900, 0xc00028a040)
C:/Go/src/net/http/server.go:1847 +0x64d
created by net/http.(*Server).Serve
C:/Go/src/net/http/server.go:2851 +0x2fc

In the rest method I do exactly the same as without it (for testing it).
And the most interesting part of the above error is why the program serving 127.0.0.1:49348 while in my code I use http.ListenAndServe("localhost:8000", router) ?

When I stoped the program and started in again then I got slightly similar result with the adress 127.0.0.1:49372. And I suppose that every time the port will be different. Actualy every time I request rest api the port in the error is different.

And it seems that the error hapens in rest method on the following line:

rows, err := db.Query(“select * from books”)

because the next line is

fmt.Println(“attention”)

and I do not get console output.

[Buckler_Co]

Normally when I get this error in a db.Query, its because the books table doesn’t exist or something related to the database itself. I recommend going in to the database management system and checking if the correct database has the table books.

Otherwise, I recommend giving more information about that handler function in the rest API

Are you talking about the read function for your REST API?

[cinematik (Andre)]

Actualy the reason of the issue was nil database object. I would not say the stacktrace is too clear obout it…