Add option to prepend prefix also to custom name taken from tag

.github/workflows/main.yml

@@ -4,10 +4,10 @@ on: [push, pull_request]
 
 jobs:
   build:
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
-        go: [ '1.12', '1.13', '1.14', '1.15' ]
+        go: [ '1.12', '1.13', '1.14', '1.15', '1.16', '1.17' ]
     name: Test with go ${{ matrix.go }}
     steps:
     - uses: actions/checkout@v2

envconfig.go

@@ -25,6 +25,8 @@ var (
 
 type context struct {
 	name               string
+	prefix             string
+	prefixCustomNames  bool
 	customName         string
 	defaultVal         string
 	usingDefault       bool
@@ -44,6 +46,9 @@ type Options struct {
 	// Prefix allows specifying a prefix for each key.
 	Prefix string
 
+	// PrefixCustomNames enables prefixes for the custom names set via struct tags
+	PrefixCustomNames bool
+
 	// AllOptional determines whether to not throw errors by default for any key
 	// that is not found. AllOptional=true means errors will not be thrown.
 	AllOptional bool
@@ -96,10 +101,12 @@ func InitWithOptions(conf interface{}, opts Options) error {
 	elem := value.Elem()
 
 	ctx := context{
-		name:            opts.Prefix,
-		optional:        opts.AllOptional,
-		leaveNil:        opts.LeaveNil,
-		allowUnexported: opts.AllowUnexported,
+		name:              opts.Prefix,
+		prefix:            opts.Prefix,
+		prefixCustomNames: opts.PrefixCustomNames,
+		optional:          opts.AllOptional,
+		leaveNil:          opts.LeaveNil,
+		allowUnexported:   opts.AllowUnexported,
 	}
 	switch elem.Kind() {
 	case reflect.Ptr:
@@ -175,24 +182,28 @@ func readStruct(value reflect.Value, ctx *context) (nonNil bool, err error) {
 		case field.Kind() == reflect.Struct && !isUnmarshaler(fieldType):
 			var nonNilIn bool
 			nonNilIn, err = readStruct(field, &context{
-				name:            combineName(ctx.name, name),
-				optional:        ctx.optional || tag.optional,
-				defaultVal:      tag.defaultVal,
-				parents:         parents,
-				leaveNil:        ctx.leaveNil,
-				allowUnexported: ctx.allowUnexported,
+				name:              combineName(ctx.name, name),
+				prefix:            ctx.prefix,
+				prefixCustomNames: ctx.prefixCustomNames,
+				optional:          ctx.optional || tag.optional,
+				defaultVal:        tag.defaultVal,
+				parents:           parents,
+				leaveNil:          ctx.leaveNil,
+				allowUnexported:   ctx.allowUnexported,
 			})
 			nonNil = nonNil || nonNilIn
 		default:
 			var ok bool
 			ok, err = setField(field, &context{
-				name:            combineName(ctx.name, name),
-				customName:      tag.customName,
-				optional:        ctx.optional || tag.optional,
-				defaultVal:      tag.defaultVal,
-				parents:         parents,
-				leaveNil:        ctx.leaveNil,
-				allowUnexported: ctx.allowUnexported,
+				name:              combineName(ctx.name, name),
+				prefix:            ctx.prefix,
+				prefixCustomNames: ctx.prefixCustomNames,
+				customName:        tag.customName,
+				optional:          ctx.optional || tag.optional,
+				defaultVal:        tag.defaultVal,
+				parents:           parents,
+				leaveNil:          ctx.leaveNil,
+				allowUnexported:   ctx.allowUnexported,
 			})
 			nonNil = nonNil || ok
 		}
@@ -460,6 +471,9 @@ func readValue(ctx *context) (string, error) {
 
 func makeAllPossibleKeys(ctx *context) (res []string) {
 	if ctx.customName != "" {
+		if ctx.prefixCustomNames {
+			return []string{ctx.prefix + "_" + ctx.customName}
+		}
 		return []string{ctx.customName}
 	}
 

envconfig_test.go

@@ -8,7 +8,9 @@ import (
 	"testing"
 	"time"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
 	"github.com/vrischmann/envconfig"
 )
 
@@ -628,3 +630,74 @@ func TestSliceOverwrite(t *testing.T) {
 	require.Equal(t, []string{"baz"}, conf.Single)
 	require.Equal(t, []int{3, 4}, conf.More)
 }
+
+func TestInitWithPrefix(t *testing.T) {
+	t.Run("DefaulBehaviour", func(t *testing.T) {
+		type Node1 struct {
+			TestEnvNodeFoo1 string `envconfig:"TEST_ENV_NODE_FOO1"`
+			TestEnvNodeBar1 string
+		}
+
+		type Root1 struct {
+			TestEnvFoo1 string `envconfig:"TEST_ENV_FOO1"`
+			TestEnvBar1 string
+			Node1       Node1
+		}
+
+		expect := Root1{
+			TestEnvFoo1: "A1",
+			TestEnvBar1: "B1",
+			Node1: Node1{
+				TestEnvNodeFoo1: "C1",
+				TestEnvNodeBar1: "D1",
+			},
+		}
+
+		require.NoError(t, os.Setenv("TEST_ENV_FOO1", expect.TestEnvFoo1))
+		require.NoError(t, os.Setenv("TESTPREFIX1_TEST_ENV_BAR1", expect.TestEnvBar1))
+		require.NoError(t, os.Setenv("TEST_ENV_NODE_FOO1", expect.Node1.TestEnvNodeFoo1))
+		require.NoError(t, os.Setenv("TESTPREFIX1_NODE1_TEST_ENV_NODE_BAR1", expect.Node1.TestEnvNodeBar1))
+
+		var conf Root1
+		err := envconfig.InitWithPrefix(&conf, "TESTPREFIX1")
+
+		require.NoError(t, err)
+		assert.Equal(t, expect, conf)
+	})
+
+	t.Run("AdvancedBehaviour", func(t *testing.T) {
+		type Node2 struct {
+			TestEnvNodeFoo2 string `envconfig:"TEST_ENV_NODE_FOO2"`
+			TestEnvNodeBar2 string
+		}
+
+		type Root2 struct {
+			TestEnvFoo2 string `envconfig:"TEST_ENV_FOO2"`
+			TestEnvBar2 string
+			Node2       Node2
+		}
+
+		expect := Root2{
+			TestEnvFoo2: "A2",
+			TestEnvBar2: "B2",
+			Node2: Node2{
+				TestEnvNodeFoo2: "C2",
+				TestEnvNodeBar2: "D2",
+			},
+		}
+
+		require.NoError(t, os.Setenv("TESTPREFIX2_TEST_ENV_FOO2", expect.TestEnvFoo2))
+		require.NoError(t, os.Setenv("TESTPREFIX2_TEST_ENV_BAR2", expect.TestEnvBar2))
+		require.NoError(t, os.Setenv("TESTPREFIX2_TEST_ENV_NODE_FOO2", expect.Node2.TestEnvNodeFoo2))
+		require.NoError(t, os.Setenv("TESTPREFIX2_NODE2_TEST_ENV_NODE_BAR2", expect.Node2.TestEnvNodeBar2))
+
+		var conf Root2
+		err := envconfig.InitWithOptions(&conf, envconfig.Options{
+			Prefix:            "TESTPREFIX2",
+			PrefixCustomNames: true,
+		})
+
+		require.NoError(t, err)
+		assert.Equal(t, expect, conf)
+	})
+}

go.mod

@@ -4,9 +4,9 @@ go 1.12
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/kr/text v0.2.0 // indirect
-	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
+	github.com/kr/pretty v0.3.0 // indirect
+	github.com/rogpeppe/go-internal v1.8.0 // indirect
 	github.com/stretchr/testify v1.6.1
-	gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f // indirect
-	gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776 // indirect
+	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

go.sum

@@ -1,25 +1,29 @@
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
-github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
+github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
+github.com/kr/pretty v0.3.0/go.mod h1:640gp4NfQd8pI5XOwp5fnNeVWj67G7CFk/SaSQn7NBk=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
-github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
-github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
-github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
+github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
+github.com/rogpeppe/go-internal v1.8.0 h1:FCbCCtXNOY3UtUuHUYaghJg4y7Fd14rXifAYUAtL9R8=
+github.com/rogpeppe/go-internal v1.8.0/go.mod h1:WmiCO8CzOY8rg0OYDC4/i/2WRWAB6poM+XZ2dLUbcbE=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f h1:BLraFXnmrev5lT+xlilqcH8XK9/i0At2xKjWk4p6zsU=
-gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
+gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776 h1:tQIYjPdBoyREyB9XMu+nnTclpTYkz2zFM+lzLJFO4gQ=
-gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=