add support {{if}} control struct for output templates (#45)

output.go

@@ -17,6 +17,7 @@ package cobra2snooty
 import (
 	"bytes"
 	"fmt"
+	"regexp"
 	"strings"
 	"text/tabwriter"
 
@@ -26,6 +27,12 @@ import (
 const (
 	outputHeader = `Output
 ------
+`
+	outputDescription = `
+If the command succeeds, the CLI returns output similar to the following sample. Values in brackets represent your values.
+
+.. code-block::
+
 `
 )
 
@@ -36,14 +43,18 @@ const (
 	tabwriterPadChar  = ' '
 )
 
+// regex for one or more characters except right curly bracket '}'.
+const charsExceptRightCurlyBracket = "[^}]+"
+
 // This function can return the output for all commands when the output template is added as an annotation in the command file
 
 func printOutputCreate(buf *bytes.Buffer, cmd *cobra.Command) {
 	if cmd.Annotations["output"] == "" {
 		return
 	}
 
-	output := strings.ReplaceAll(cmd.Annotations["output"], "{{range .Results}}", "")
+	output := removeRange(cmd.Annotations["output"])
+	output = replaceWithValueOrDefault(output)
 	output = strings.ReplaceAll(output, "{{end}}", "")
 	output = strings.ReplaceAll(output, "{{.", "<")
 	output = strings.ReplaceAll(output, "}}", ">")
@@ -54,13 +65,24 @@ func printOutputCreate(buf *bytes.Buffer, cmd *cobra.Command) {
 	w.Init(buf, tabwriterMinWidth, tabwriterWidth, tabwriterPadding, tabwriterPadChar, 0)
 
 	buf.WriteString(outputHeader)
-	buf.WriteString(`
-If the command succeeds, the CLI returns output similar to the following sample. Values in brackets represent your values.
-
-.. code-block::
-
-`)
+	buf.WriteString(outputDescription)
 	fmt.Fprintln(w, "   "+output)
 	w.Flush()
 	buf.WriteString("\n")
 }
+
+func removeRange(text string) string {
+	// remove {{range}} control structure. Examples: {{range .}}, {{range .Results}}
+	re := `{{range ` + charsExceptRightCurlyBracket + `}}`
+	return regexp.MustCompile(re).ReplaceAllString(text, "")
+}
+
+func replaceWithValueOrDefault(text string) string {
+	// replaces {{if .field}}{{.field}}{{else}}defaultValue{{end}} with {{.field}}
+	re := `{{if` + charsExceptRightCurlyBracket + `}}` +
+		`({{` + charsExceptRightCurlyBracket + `}})` +
+		`{{else}}` + charsExceptRightCurlyBracket + `{{end}}`
+
+	// $1 is the first group (surrounded by round brackets in the regex expression)
+	return regexp.MustCompile(re).ReplaceAllString(text, "$1")
+}

output_test.go

@@ -0,0 +1,51 @@
+// Copyright 2023 MongoDB Inc
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cobra2snooty
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/spf13/cobra"
+)
+
+func TestPrintOutputCreate(t *testing.T) {
+	t.Run("replaceWithValueOrDefault", func(t *testing.T) {
+		outputTemplate := `ID	NAME	DATABASE	COLLECTION	TYPE   
+{{range .}}{{.IndexID}}	%s	{{.Database}}	{{.CollectionName}}	{{if .Type }}{{.Type}}{{else}}defaultValue{{end}}
+{{end}}`
+
+		expected := outputHeader + outputDescription +
+			`   ID          NAME     DATABASE     COLLECTION         TYPE
+   <IndexID>   <Name>   <Database>   <CollectionName>   <Type>
+   
+
+`
+
+		cmd := &cobra.Command{
+			Annotations: map[string]string{
+				"output": outputTemplate,
+			},
+		}
+
+		buf := new(bytes.Buffer)
+		printOutputCreate(buf, cmd)
+		result := buf.String()
+
+		if result != expected {
+			t.Errorf("expected:\n[%s]\ngot:\n[%s]\n", expected, result)
+		}
+	})
+}