code update

main.go

@@ -3,28 +3,98 @@ package main
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"log"
+	"os"
 
 	"github.com/iancoleman/orderedmap"
+	"github.com/xuri/excelize/v2"
 )
 
 // Initial concept from https://stackoverflow.com/q/68621039
 
 func main() {
+	jsonFile := "test.json"
 	parentNode := "input"
-	s, err := ioutil.ReadFile("test.json")
-	if err != nil {
-		panic(err)
+	sheetName := "Sheet2"
+	outputFilename := "test.xlsx"
+
+	var xlsx *excelize.File
+	var s []byte
+
+	var sheetIndex int
+	var err error
+
+	var cell string
+	var row, column int
+
+	// TODO - truncate sheetName to the maximum 31 characters
+
+	// Check if xlsx file exists already, and if it does then open and append data
+	if fileExists(outputFilename) {
+		fmt.Printf("Output spreadsheet '%s' already exists.\n", outputFilename)
+		xlsx, err = excelize.OpenFile(outputFilename)
+		if err != nil {
+			fmt.Println(err)
+			return
+		}
+
+		// Since we have an existing workbook, check if the sheet we want to write to already exists
+		sheetFound := false
+		for index, name := range xlsx.GetSheetMap() {
+			if name == sheetName {
+				fmt.Printf("Found worksheet '%s' at index '%d'\n", sheetName, index)
+				sheetFound = true
+			}
+		}
+		if !sheetFound {
+			// Create the sheet
+			fmt.Printf("Creating worksheet '%s'\n", sheetName)
+			sheetIndex, err = xlsx.NewSheet(sheetName)
+			if err != nil {
+				fmt.Printf("Error creating worksheet '%s' : %s\n", sheetName, err)
+			}
+			// Set active worksheet
+			fmt.Printf("Setting active sheet to index %d", sheetIndex)
+			xlsx.SetActiveSheet(sheetIndex)
+		}
+
+	} else {
+		fmt.Printf("Creating output spreadsheet '%s'\n", outputFilename)
+		// Create the file
+		xlsx = excelize.NewFile()
+
+		// Rename the default Sheet1 to this worksheet name
+		if sheetName != "Sheet1" {
+			fmt.Printf("Renaming default worksheet to '%s'\n", sheetName)
+			err = xlsx.SetSheetName("Sheet1", sheetName)
+			if err != nil {
+				fmt.Printf("Error setting sheet name to '%s': %s\n", sheetName, err)
+			}
+		}
 	}
 
-	//TestUnmarshalJSON()
+	// Read the json input file
+	if fileExists(jsonFile) {
+		s, err = os.ReadFile(jsonFile)
+		if err != nil {
+			panic(err)
+		}
+	} else {
+		fmt.Printf("Input JSON file '%s' does not exist.\n", jsonFile)
+	}
 
+	// Read the json into an orderedmap to preserve the ordering of json structure
 	o := orderedmap.New()
 	err = json.Unmarshal([]byte(s), &o)
 	if err != nil {
-		fmt.Printf("JSON Unmarshal error", err)
+		fmt.Printf("JSON Unmarshal error %s\n", err)
 	}
 
+	// Assume that our content is within the first top-level key
+	topLevel := o.Keys()
+	fmt.Printf("topLevel: %v\n", topLevel)
+	parentNode = topLevel[0]
+
 	// Get a reference to the top level node we specified earlier
 	// TODO - validate this key exists
 	vislice, ok := o.Get(parentNode)
@@ -38,22 +108,63 @@ func main() {
 	columnNames := columnMap.Keys()
 	fmt.Printf("Creating excel workbook with following headings : '%v'\n", columnNames)
 
+	// Add the header row
+	row = 1
+	column = 1
+	for i := 0; i < len(columnNames); i++ {
+		cell, _ = excelize.CoordinatesToCellName(column, row)
+		fmt.Printf("Setting cell %s to value %s\n", cell, columnNames[i])
+		xlsx.SetCellValue(sheetName, cell, columnNames[i])
+		column++
+	}
+
+	// Set starting row for data
+	row = 2
+
+	fmt.Printf("Adding %d rows of data to spreadsheet.\n", len(vslice))
+
+	// Iterate the whole slice to get the data and add to the worksheet
 	for i, v := range vslice {
 		// Print the contents each slice
 		//fmt.Printf("'%d' : '%v'\n", i, v)
 
-		fmt.Printf("Slice element %d\n", i)
+		//fmt.Printf("Slice element %d\n", i)
+		_ = i
+
+		// Each iteration should start back at column 1
+		column = 1
 
 		// Print each key-value pair contained in this slice
 		vmap := v.(orderedmap.OrderedMap)
 		k := vmap.Keys()
+
 		for j := range k {
+			//a = string(asciiValue)
+			//cell = a + strconv.Itoa(2+i)
+			cell, _ = excelize.CoordinatesToCellName(column, row)
+
 			e, _ := vmap.Get(k[j])
-			fmt.Printf("'%s' : '%v'\n", k[j], e)
+			//fmt.Printf("Setting cell %s to value %v\n", cell, e)
+			xlsx.SetCellValue(sheetName, cell, e)
+
+			// Move to the next column
+			//asciiValue++
+			column++
 		}
 		//fmt.Printf("k: %v\n", k)
+
+		// Move to next row
+		row++
 	}
 
+	// Close off the file
+	if err := xlsx.SaveAs(outputFilename); err != nil {
+		log.Fatal(err)
+		return
+	}
+
+	fmt.Printf("Excel file '%s' generated sucessfully.\n", outputFilename)
+
 	/*
 		//Test https://gitlab.com/c0b/go-ordered-json
 		var om *ordered.OrderedMap = ordered.NewOrderedMap()
@@ -71,50 +182,14 @@ func main() {
 			fmt.Printf("%-12s: %v\n", pair.Key, pair.Value)
 		}
 	*/
+}
 
-	/*
-	   var data interface{}
-	   json.Unmarshal(file, &data) // reading all json data
-	   //fmt.Println(data)
-	   t, ok := data.([]interface{}) // assertion Interface
-	   _ = ok
-	   //fmt.Printf("%[1]v  %[1]T\n", t) //map[string]interface {}
-
-	   myMap := t[0] // aim here to get APP, Company and Category which will be the column name of Excel sheet
-	   fmt.Printf("myMap: %v\n", myMap)
-	   columnData, _ := myMap.(map[string]interface{}) // extract the underlying concrete data from interface
-	   fmt.Printf("columnData: %v\n", columnData)
-	   keys := make([]string, 0, len(columnData)) // creating and initializing slice to store column
-
-	   	for k := range columnData {
-	   		fmt.Printf("%[1]v %[1]T\n", k)
-	   		keys = append(keys, k)
-	   	}
-
-	   return
-
-	   xlsx := excelize.NewFile()
-	   sheetName := "Sheet1"
-	   xlsx.SetSheetName(xlsx.GetSheetName(1), sheetName)
-	   c := 'A'
-	   asciiValue := int(c)
-	   var a string
-
-	   	for i := 0; i < len(keys); i++ {
-	   		a = string(asciiValue)
-	   		xlsx.SetCellValue(sheetName, a+"1", keys[i])
-	   		asciiValue++
-	   	}
-
-	   err = xlsx.SaveAs("./Onkar.xlsx")
-
-	   	if err != nil {
-	   		fmt.Println(err)
-	   		return
-	   	}
-
-	   fmt.Println("Excel file generated sucessfully")
-	*/
+func fileExists(filename string) bool {
+	info, err := os.Stat(filename)
+	if os.IsNotExist(err) {
+		return false
+	}
+	return !info.IsDir()
 }
 
 func TestUnmarshalJSON() {