Unmarshaling JSON top level array into map of string to string

There is no way to do it directly with the json package; you have to do the conversion yourself. This is simple:

package main

import (
    "encoding/json"
    "fmt"
)

func main() {
    data := []byte(`
        [
        {"abc's": "n;05881364"},
        {"abcoulomb": "n;13658345"},
        {"abcs": "n;05881364"}
        ]
    `)

    var mapSlice []map[string]string
    if err := json.Unmarshal(data, &mapSlice); err != nil {
        panic(err)
    }
    resultingMap := map[string]string{}
    for _, m := range mapSlice {
        for k, v := range m {
            resultingMap[k] = v
        }
    }
    fmt.Println(resultingMap)
}

Output

map[abc's:n;05881364 abcoulomb:n;13658345 abcs:n;05881364]

An alternative (though very similar) to Alex's answer is to define your own type along with an UnmarshalJSON function.

package main

import (
    "encoding/json"
    "fmt"
)

type myMapping map[string]string

func (mm myMapping) UnmarshalJSON(b []byte) error {
    var temp []map[string]string
    if err := json.Unmarshal(b, &temp); err != nil {
        return err
    }
    for _, m := range temp {
        for k, v := range m {
            mm[k] = v
        }
    }
    return nil
}

func main() {
    data := []byte(`
            [
                {"abc's": "n;05881364"},
                {"abcoulomb": "n;13658345"},
                {"abcs": "n;05881364"}
            ]`)

    resultingMap := myMapping{}
    if err := json.Unmarshal(data, &resultingMap); err != nil {
        panic(err)
    }
    fmt.Println(resultingMap)
}

Playground