Repository: go-swagger/go-swagger (go)

Issue:
Optional Headers array parameters generated client code doesn't compile
## Problem statement
When generating code for an API describing a header parameter X of array type, I got a "joinedX declared but not used" compilation error.

## Swagger specification
https://swagger.io/docs/specification/2-0/describing-parameters/#array-and-multi-value-parameters

```yaml
swagger: '2.0'
# ...
paths:
  /example:
    post:
        summary: example
        description: ''
        operationId: examplePost
        parameters:
          - name: Foo
            in: header
            type: array
            required: false
            items:
              type: string
            description: 'a reproducer for this ticket'
```

The corresponding generated code is incorrect functionnally (parameter isn't bound to the request) and doesn't even compile:
```go
// WriteToRequest writes these params to a swagger request
func (o *FooParam) WriteToRequest(r runtime.ClientRequest, reg strfmt.Registry) error {
        // ...
	valuesFoo := o.Foo
	joinedFoo := swag.JoinByFormat(valuesFoo , "")
	// nothing else is done with 'joinedFoo' variable before the return of that function, while I assume it should have been bound to 'r' with 'r.SetHeaderParam(...)'

```

## Steps to reproduce
For convenience I've made a reproducer available at this repository:
https://github.com/xaxa06/goswagger-2471 (follow instructions in README.md there).

Otherwise, call go swagger generator with a YAML similar to above example and try to include the generated code in a main go function -> go compiler will complain about the declared but not used variable.
```sh
> swagger generate client --target pkg/example --name example --spec example.yaml
> go build
# ...
pkg/example/client/operations/example_post_parameters.go:129:2: joinedFoo declared but not used
```

## Environment
swagger version: 0.25.0
go version: 1.15.6
OS:  Linux (Debian 10)


Pull request description:
generate client: added support for array parameter in header
* fixed #2471
* reindented client parameter template for lisibility

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

Patch:
diff --git a/fixtures/bugs/2471/.gitignore b/fixtures/bugs/2471/.gitignore
new file mode 100644
index 00000000..1e16265b
--- /dev/null
+++ b/fixtures/bugs/2471/.gitignore
@@ -0,0 +1,3 @@
+gen-*
+!gen-fixtures.sh
+*.log
diff --git a/fixtures/bugs/2471/fixture-2471.yaml b/fixtures/bugs/2471/fixture-2471.yaml
new file mode 100644
index 00000000..27d0623f
--- /dev/null
+++ b/fixtures/bugs/2471/fixture-2471.yaml
@@ -0,0 +1,43 @@
+swagger: '2.0'
+basePath: /
+host: localhost
+info:
+  version: 0.1.0
+  title: Reproducer
+  description: |
+    Reproducer for https://github.com/go-swagger/go-swagger/issues/2471
+consumes:
+  - application/json
+produces:
+  - plain/text
+schemes:
+  - http
+paths:
+  /example/{FooPath}:
+    post:
+        summary: example
+        description: ''
+        operationId: examplePost
+        parameters:
+          - name: Foo
+            in: header
+            type: array
+            required: false
+            items:
+              type: string
+            description: 'a reproducer for this ticket'
+          - name: FooQuery
+            in: query
+            type: array
+            required: false
+            items:
+              type: string
+          - name: FooPath
+            in: path
+            type: array
+            required: true
+            items:
+              type: string
+        responses:
+          '201':
+            description: OK
diff --git a/fixtures/bugs/2471/gen-fixtures.sh b/fixtures/bugs/2471/gen-fixtures.sh
new file mode 100755
index 00000000..ded2ce03
--- /dev/null
+++ b/fixtures/bugs/2471/gen-fixtures.sh
@@ -0,0 +1,78 @@
+#! /bin/bash
+if [[ ${1} == "--clean" ]] ; then
+    clean=1
+fi
+continueOnError=
+# A small utility to build fixture servers
+testcases="${testcases} fixture-2471.yaml"
+export SWAGGER_DEBUG=1
+for opts in  "" "--with-flatten=full" "--with-expand" ; do
+for testcase in ${testcases} ; do
+    grep -q discriminator ${testcase}
+    discriminated=$?
+    if [[ ${discriminated} -eq 0 && ${opts} == "--with-expand" ]] ; then
+        echo "Skipped ${testcase} with ${opts}: discriminator not supported with ${opts}"
+        continue
+    fi
+    spec=${testcase}
+    testcase=`basename ${testcase}`
+    if [[ -z ${opts} ]]; then
+        target=./gen-${testcase%.*}-minimal
+    elif [[ ${opts} == "--with-flatten=full" ]] ; then
+        target=./gen-${testcase%.*}-flatten
+    else
+        target=./gen-${testcase%.*}-expand
+    fi
+    serverName="codegensrv"
+    rm -rf ${target}
+    mkdir ${target}
+    echo "Server generation for ${spec} with opts=${opts}"
+    serverName="nrcodegen"
+    swagger generate server --skip-validation ${opts} --spec ${spec} --target ${target} --name=${serverName} 1>${testcase%.*}.log 2>&1
+    #
+    if [[ $? != 0 ]] ; then
+        echo "Generation failed for ${spec}"
+        if [[ ! -z ${continueOnError} ]] ; then
+            failures="${failures} codegen:${spec}"
+            continue
+        else
+            exit 1
+        fi
+    fi
+    echo "${spec}: Generation OK"
+    if [[ ! -d ${target}/models ]] ; then
+        echo "No model in this spec! Continue building server"
+    fi
+    if [[ -d ${target}/cmd/${serverName}"-server" ]] ; then
+        (cd ${target}/cmd/${serverName}"-server"; go build)
+        #(cd ${target}/models; go build)
+        if [[ $? != 0 ]] ; then
+            echo "Build failed for ${spec}"
+            if [[ ! -z ${continueOnError} ]] ; then
+                failures="${failures} build:${spec}"
+                continue
+            else
+                exit 1
+            fi
+        fi
+        echo "${spec}: Build OK"
+        if [[ -n ${clean} ]] ; then
+             rm -rf ${target}
+        fi
+    fi
+
+    swagger generate client --skip-validation ${opts} --spec ${spec} --target ${target} --name=${serverName} 1>${testcase%.*}.log 2>&1
+    (cd ${target}/client; go build)
+    if [[ $? != 0 ]] ; then
+      echo "Client build failed for ${spec}"
+      exit 1
+    fi
+    echo "${spec}: Client build OK"
+done
+done
+if [[ ! -z ${failures} ]] ; then
+    echo ${failures}|tr ' ' '\n'
+else
+    echo "No failures"
+fi
+exit
diff --git a/generator/bindata.go b/generator/bindata.go
index 959496cd..0d372901 100644
--- a/generator/bindata.go
+++ b/generator/bindata.go
@@ -2,7 +2,7 @@
 // sources:
 // templates/client/client.gotmpl (5.125kB)
 // templates/client/facade.gotmpl (3.83kB)
-// templates/client/parameter.gotmpl (12.261kB)
+// templates/client/parameter.gotmpl (12.977kB)
 // templates/client/response.gotmpl (6.363kB)
 // templates/contrib/stratoscale/client/client.gotmpl (3.591kB)
 // templates/contrib/stratoscale/client/facade.gotmpl (2.078kB)
@@ -151,7 +151,7 @@ func templatesClientFacadeGotmpl() (*asset, error) {
 	return a, nil
 }
 
-var _templatesClientParameterGotmpl = 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+var _templatesClientParameterGotmpl = 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
 func templatesClientParameterGotmplBytes() ([]byte, error) {
 	return bindataRead(
@@ -166,8 +166,8 @@ func templatesClientParameterGotmpl() (*asset, error) {
 		return nil, err
 	}
 
-	info := bindataFileInfo{name: "templates/client/parameter.gotmpl", size: 12261, mode: os.FileMode(0644), modTime: time.Unix(1482416923, 0)}
-	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0x90, 0xd8, 0x41, 0xd2, 0x6, 0xe3, 0x24, 0x53, 0x68, 0xa4, 0xc6, 0xcc, 0x6d, 0xa3, 0x61, 0xd3, 0x49, 0x4e, 0xe2, 0x3d, 0xf3, 0x9b, 0x1e, 0x12, 0x19, 0xf, 0xd3, 0xd4, 0x4c, 0x37, 0x6f, 0x72}}
+	info := bindataFileInfo{name: "templates/client/parameter.gotmpl", size: 12977, mode: os.FileMode(0644), modTime: time.Unix(1482416923, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0x2a, 0xb8, 0xaf, 0x1e, 0x8c, 0x32, 0x2b, 0x0, 0x7b, 0x54, 0x83, 0x6, 0x34, 0x78, 0x77, 0x89, 0xf6, 0xc0, 0x64, 0x30, 0x7f, 0xf6, 0x52, 0xea, 0xc5, 0xe0, 0x35, 0x8b, 0xdd, 0xb9, 0x63, 0x84}}
 	return a, nil
 }
 
diff --git a/generator/templates/client/parameter.gotmpl b/generator/templates/client/parameter.gotmpl
index 4ced460d..8e87f138 100644
--- a/generator/templates/client/parameter.gotmpl
+++ b/generator/templates/client/parameter.gotmpl
@@ -150,77 +150,122 @@ func ({{ .ReceiverName }} *{{ pascalize .Name }}Params) WriteToRequest(r runtime
     return err
   }
   var res []error
-  {{range .Params}}
+  {{ range .Params }}
+    {{- if not (or .IsArray .IsMap .IsBodyParam) }}
+      {{- if and .IsNullable (not .AllowEmptyValue) }}
+  if {{ .ValueExpression }} != nil {
+      {{- end}}
+
+      {{- if .IsQueryParam }}
 
-  {{if not (or .IsArray .IsMap .IsBodyParam) }}
-  {{ if and .IsNullable (not .AllowEmptyValue) }}if {{ .ValueExpression }} != nil { {{ end}}
-  {{ if .IsQueryParam }}
   // query param {{ .Name }}
-  {{ if .IsNullable }}var qr{{ pascalize .Name }} {{ .GoType }}
+        {{- if .IsNullable }}
+  var qr{{ pascalize .Name }} {{ .GoType }}
   if {{ .ValueExpression }} != nil {
     qr{{ pascalize .Name }} = *{{ .ValueExpression }}
-  }{{ else }}qr{{ pascalize .Name }} := {{ .ValueExpression }}{{ end}}
-  q{{ pascalize .Name}} := {{ if .Formatter }}{{ .Formatter }}(qr{{ pascalize .Name }}){{ else }}qr{{ pascalize .Name }}{{ if .IsCustomFormatter }}.String(){{end}}{{end}}{{ if not .AllowEmptyValue }}
-  if q{{ pascalize .Name }} != "" { {{ end }}
+  }
+        {{- else }}
+  qr{{ pascalize .Name }} := {{ .ValueExpression }}
+        {{- end}}
+  q{{ pascalize .Name}} := {{ if .Formatter }}{{ .Formatter }}(qr{{ pascalize .Name }}){{ else }}qr{{ pascalize .Name }}{{ if .IsCustomFormatter }}.String(){{end}}{{end}}
+        {{- if not .AllowEmptyValue }}
+  if q{{ pascalize .Name }} != "" {
+        {{- end }}
   if err := r.SetQueryParam({{ printf "%q" .Name }}, q{{ pascalize .Name }}); err != nil {
     return err
   }
-  {{ if not .AllowEmptyValue }}}{{ end }}
-  {{ else if .IsPathParam }}
+        {{- if not .AllowEmptyValue }}
+  }
+        {{- end }}
+
+      {{- else if .IsPathParam }}
+
   // path param {{ .Name }}
   if err := r.SetPathParam({{ printf "%q" .Name }}, {{ if .Formatter }}{{ .Formatter }}({{ if .IsNullable }}*{{end}}{{ .ValueExpression }}){{ else }}{{ if and (not .IsCustomFormatter) .IsNullable }}*{{end}}{{ .ValueExpression }}{{ if .IsCustomFormatter }}.String(){{end}}{{end}}); err != nil {
     return err
   }
-  {{ else if .IsHeaderParam }}
+
+      {{- else if .IsHeaderParam }}
+
   // header param {{ .Name }}
   if err := r.SetHeaderParam({{ printf "%q" .Name }}, {{ if .Formatter }}{{ .Formatter }}({{ if .IsNullable }}*{{end}}{{ .ValueExpression }}){{ else }}{{ if and (not .IsCustomFormatter) .IsNullable }}*{{end}}{{ .ValueExpression }}{{ if .IsCustomFormatter }}.String(){{end}}{{end}}); err != nil {
     return err
   }
-  {{ else if .IsFormParam }}
-  {{ if .IsFileParam }}
-  {{ if .IsNullable}}
+      {{- else if .IsFormParam }}
+        {{- if .IsFileParam }}
+          {{- if .IsNullable }}
   if {{ .ValueExpression }} != nil {
-  {{end}}
+          {{- end }}
     // form file param {{ .Name }}
     if err := r.SetFileParam({{ printf "%q" .Name }}, {{ .ValueExpression }}); err != nil {
       return err
     }
-  {{ if .IsNullable}}
+          {{- if .IsNullable}}
   }
-  {{ end }}
-  {{ else }}
+          {{- end }}
+        {{- else }}
+
   // form param {{ .Name }}
-  {{ if .IsNullable }}var fr{{ pascalize .Name }} {{ .GoType }}
+          {{- if .IsNullable }}
+  var fr{{ pascalize .Name }} {{ .GoType }}
   if {{ .ValueExpression }} != nil {
     fr{{ pascalize .Name }} = *{{ .ValueExpression }}
-  }{{ else }}fr{{ pascalize .Name }} := {{ .ValueExpression }}{{ end}}
-  f{{ pascalize .Name}} := {{ if .Formatter }}{{ .Formatter }}(fr{{ pascalize .Name }}){{ else }}fr{{ pascalize .Name }}{{ if .IsCustomFormatter }}.String(){{end}}{{end}}{{ if not .AllowEmptyValue }}
-  if f{{ pascalize .Name }} != "" { {{ end }}
+  }
+          {{- else }}
+  fr{{ pascalize .Name }} := {{ .ValueExpression }}
+          {{- end}}
+  f{{ pascalize .Name}} := {{ if .Formatter }}{{ .Formatter }}(fr{{ pascalize .Name }}){{ else }}fr{{ pascalize .Name }}{{ if .IsCustomFormatter }}.String(){{end}}{{end}}
+          {{- if not .AllowEmptyValue }}
+  if f{{ pascalize .Name }} != "" {
+          {{- end }}
   if err := r.SetFormParam({{ printf "%q" .Name }}, f{{ pascalize .Name }}); err != nil {
     return err
   }
-  {{ if not .AllowEmptyValue }}}{{ end }}
-  {{ end }}
-  {{ end }}
-  {{ if and .IsNullable (not .AllowEmptyValue) }}}{{end}}
-  {{else if .IsArray }}
-  {{ if not .IsBodyParam }}{{ if .Child }}{{ if or .Child.Formatter .Child.IsCustomFormatter }}var values{{ pascalize .Name }} []string
+          {{- if not .AllowEmptyValue }}
+  }
+          {{- end }}
+        {{- end }}
+      {{- end }}
+      {{- if and .IsNullable (not .AllowEmptyValue) }}
+  }
+      {{- end }}
+    {{- else if .IsArray }}
+
+      {{- if not .IsBodyParam }}
+
+        {{- if .Child }}
+          {{- if or .Child.Formatter .Child.IsCustomFormatter }}
+
+  var values{{ pascalize .Name }} []string
   for _, v := range {{ if and (not .IsArray) (not .IsMap) (not .IsStream) (.IsNullable) }}*{{end}}{{ .ValueExpression }} {
     values{{ pascalize .Name }} = append(values{{ pascalize .Name }}, {{ .Child.Formatter }}{{ if .Child.Formatter }}({{ end }}v{{ if .Child.IsCustomFormatter }}.String(){{ end }}{{ if .Child.Formatter }}){{ end }})
   }
-  {{ else }}values{{ pascalize .Name }} := {{ if and (not .IsArray) (not .IsStream) (not .IsMap) (.IsNullable) }}*{{end}}{{ .ValueExpression }}{{ end }}
-  {{ else }}values{{ pascalize .Name }} := {{ if and (not .IsArray) (not .IsStream) (not .IsMap) (.IsNullable) }}*{{end}}{{ .ValueExpression }}{{ end }}
+          {{- else }}
+  values{{ pascalize .Name }} := {{ if and (not .IsArray) (not .IsStream) (not .IsMap) (.IsNullable) }}*{{end}}{{ .ValueExpression }}
+          {{- end }}
+        {{- else }}
+  values{{ pascalize .Name }} := {{ if and (not .IsArray) (not .IsStream) (not .IsMap) (.IsNullable) }}*{{end}}{{ .ValueExpression }}
+        {{- end }}
   joined{{ pascalize .Name}} := swag.JoinByFormat(values{{ pascalize .Name }}, "{{.CollectionFormat}}")
-  {{ if .IsQueryParam }}// query array param {{ .Name }}
+
+        {{- if .IsQueryParam }}
+
+  // query array param {{ .Name }}
   if err := r.SetQueryParam({{ printf "%q" .Name }}, joined{{ pascalize .Name }}...); err != nil {
     return err
   }
-  {{ else if and .IsFormParam }}// form array param {{ .Name }}
+
+        {{- else if and .IsFormParam }}
+
+  // form array param {{ .Name }}
   if err := r.SetFormParam({{ printf "%q" .Name }}, joined{{ pascalize .Name }}...); err != nil {
     return err
   }
-  {{ else if and .IsPathParam }}// path array param {{ .Name }}
-  // SetPathParam does not support variadric arguments, since we used JoinByFormat
+
+        {{- else if and .IsPathParam }}
+
+  // path array param {{ .Name }}
+  // SetPathParam does not support variadic arguments, since we used JoinByFormat
   // we can send the first item in the array as it's all the items of the previous
   // array joined together
   if len(joined{{ pascalize .Name }}) > 0 {
@@ -228,19 +273,32 @@ func ({{ .ReceiverName }} *{{ pascalize .Name }}Params) WriteToRequest(r runtime
       return err
     }
   }
-  {{ end }}{{ end }}
 
-  {{ end }}
+        {{- else if .IsHeaderParam }}
+
+  // header array param {{ .Name }}
+  if len(joined{{ pascalize .Name }}) > 0 {
+     if err := r.SetHeaderParam({{ printf "%q" .Name }}, joined{{ pascalize .Name }}[0]); err != nil {
+      return err
+    }
+  }
+        {{- end }}
+      {{- end }}
+    {{- end }}
 
-  {{if .IsBodyParam}}
-  {{ if or .Schema.IsInterface .Schema.IsStream (and .Schema.IsArray .Child) (and .Schema.IsMap .Child) (and .Schema.IsNullable (not .HasDiscriminator)) }} if {{ .ValueExpression }} != nil { {{end}}
+    {{- if .IsBodyParam }}
+      {{- if or .Schema.IsInterface .Schema.IsStream (and .Schema.IsArray .Child) (and .Schema.IsMap .Child) (and .Schema.IsNullable (not .HasDiscriminator)) }}
+  if {{ .ValueExpression }} != nil {
+      {{- end }}
     if err := r.SetBodyParam({{ .ValueExpression }}); err != nil {
       return err
     }
-  {{ if or .Schema.IsInterface .Schema.IsStream (and .Schema.IsArray .Child) (and .Schema.IsMap .Child) (and .Schema.IsNullable (not .HasDiscriminator)) }} } {{end}}
-  {{end}}
+      {{- if or .Schema.IsInterface .Schema.IsStream (and .Schema.IsArray .Child) (and .Schema.IsMap .Child) (and .Schema.IsNullable (not .HasDiscriminator)) }}
+  }
+      {{- end }}
+    {{- end }}
 
-  {{end}}
+  {{- end }}
   if len(res) > 0 {
     return errors.CompositeValidationError(res...)
   }


Test patch:
diff --git a/generator/client_test.go b/generator/client_test.go
index a0327fa4..1e8d26c2 100644
--- a/generator/client_test.go
+++ b/generator/client_test.go
@@ -377,3 +377,51 @@ func TestGenClient_1518(t *testing.T) {
 		}
 	}
 }
+
+func TestGenClient_2471(t *testing.T) {
+	t.Parallel()
+	defer discardOutput()()
+
+	opts := testClientGenOpts()
+	opts.Spec = filepath.Join("..", "fixtures", "bugs", "2471", "fixture-2471.yaml")
+
+	cwd, _ := os.Getwd()
+	tft, _ := ioutil.TempDir(cwd, "generated")
+	opts.Target = tft
+
+	defer func() {
+		_ = os.RemoveAll(tft)
+	}()
+
+	err := GenerateClient("client", []string{}, []string{}, opts)
+	require.NoError(t, err)
+
+	fixtureConfig := map[string][]string{
+		"client/operations/example_post_parameters.go": { // generated file
+			`func (o *ExamplePostParams) WriteToRequest(r runtime.ClientRequest, reg strfmt.Registry) error {`,
+			`	if err := r.SetTimeout(o.timeout); err != nil {`,
+			`	valuesFoo := o.Foo`,
+			`	joinedFoo := swag.JoinByFormat(valuesFoo, "")`,
+			`	if len(joinedFoo) > 0 {`,
+			`		if err := r.SetHeaderParam("Foo", joinedFoo[0]); err != nil {`,
+			`	valuesFooPath := o.FooPath`,
+			`	joinedFooPath := swag.JoinByFormat(valuesFooPath, "")`,
+			`	if len(joinedFooPath) > 0 {`,
+			`		if err := r.SetPathParam("FooPath", joinedFooPath[0]); err != nil {`,
+			`	valuesFooQuery := o.FooQuery`,
+			`	joinedFooQuery := swag.JoinByFormat(valuesFooQuery, "")`,
+			`	if err := r.SetQueryParam("FooQuery", joinedFooQuery...); err != nil {`,
+		},
+	}
+
+	for fileToInspect, expectedCode := range fixtureConfig {
+		code, err := ioutil.ReadFile(filepath.Join(opts.Target, filepath.FromSlash(fileToInspect)))
+		require.NoError(t, err)
+
+		for line, codeLine := range expectedCode {
+			if !assertInCode(t, strings.TrimSpace(codeLine), string(code)) {
+				t.Logf("Code expected did not match in codegenfile %s for expected line %d: %q", fileToInspect, line, expectedCode[line])
+			}
+		}
+	}
+}