Go excel export tool encapsulation

1. Relevant database research

Recently in use go Develop a management side , Need to provide a Excel Export function . So I went to investigate Go Two commonly used Excel library ：

tealeg/xlsx Simple to use , But it has limited functionality , Only string types can be inserted in cells . I went into its warehouse to have a look , It is found that this library is not maintained .

excelize It's more complicated to use , You need to specify excel Of sheet Coordinates to locate cells for reading or inserting data , But it's more powerful . The warehouse is still being maintained , I mentioned before issue, I replied in half a day .

After comparing the two libraries , Decision based on excelize Encapsulate a tool method , You only need to specify the header and data each time .

2. Encapsulates the code

Reference resources excelize The official demo, Find it every time you write excel You need to specify the content in Sheet Coordinates of .Sheet The coordinates of are divided into column coordinates and row coordinates .

• Column coordinates ： A～Z, （ A～Z)( A～Z), （ A～Z)( A～Z)( A～Z) .... 1~26 Column use A～Z Express . exceed 26 Column is less than 676 Column from AA Begin and end at ZZ, Greater than 676 From the AAA Start , And so on .
• Row coordinates ： from 1 Start to 1048576, The excess part needs to be cut to the next Sheet 了

package utils

/**
 * @Description
 * @Author ggr
 * @Date 2021/7/8 21:06
 **/

import (
	"github.com/360EntSecGroup-Skylar/excelize/v2"
	"strconv"
)

// maxCharCount  most 26 Characters A-Z
const maxCharCount = 26

// ExportExcel  export Excel file 
// sheetName  Worksheet name ,  Be careful not to take... Here sheet1 This kind of name , Otherwise, some errors will occur when the file is opened .
// headers  Column name slice ,  Header 
// rows  Data slicing , Is a two-dimensional array 
func ExportExcel(sheetName string, headers []string, rows [][]interface{}) (*excelize.File, error) {
	f := excelize.NewFile()
	sheetIndex := f.NewSheet(sheetName)
	maxColumnRowNameLen := 1 + len(strconv.Itoa(len(rows)))
	columnCount := len(headers)
	if columnCount > maxCharCount {
		maxColumnRowNameLen++
	} else if columnCount > maxCharCount*maxCharCount {
		maxColumnRowNameLen += 2
	}
	columnNames := make([][]byte, 0, columnCount)
	for i, header := range headers {
		columnName := getColumnName(i, maxColumnRowNameLen)
		columnNames = append(columnNames, columnName)
		//  initialization excel Header , there index from 1 Pay attention to 
		curColumnName := getColumnRowName(columnName, 1)
		err := f.SetCellValue(sheetName, curColumnName, header)
		if err != nil {
			return nil, err
		}
	}
	for rowIndex, row := range rows {
		for columnIndex, columnName := range columnNames {
			//  Start with the second line 
			err := f.SetCellValue(sheetName, getColumnRowName(columnName, rowIndex+2), row[columnIndex])
			if err != nil {
				return nil, err
			}
		}
	}
	f.SetActiveSheet(sheetIndex)
	return f, nil
}

// getColumnName  Generate column names 
// Excel The column name rule of is from A-Z Stand back ; exceed Z In the future, it will be indicated by two letters , such as AA,AB,AC; If two letters are not enough, use three letters to indicate , such as AAA,AAB,AAC
//  Here we map numbers to column names ：0 -> A, 1 -> B, 2 -> C
// maxColumnRowNameLen  Indicates the maximum length of the name box , Suppose the data is 10 That's ok ,1000 Column , Then the last name box is J1000( If there is a header , It is J1001), yes 4 position 
//  Here, according to  maxColumnRowNameLen  Generate slice , This slice can be reused later when the name box is generated , Without capacity expansion 
func getColumnName(column, maxColumnRowNameLen int) []byte {
	const A = 'A'
	if column < maxCharCount {
		//  Allocate the slice capacity for the first time 
		slice := make([]byte, 0, maxColumnRowNameLen)
		return append(slice, byte(A+column))
	} else {
		//  Recursive generation is similar to AA,AB,AAA,AAB This form of column name 
		return append(getColumnName(column/maxCharCount-1, maxColumnRowNameLen), byte(A+column%maxCharCount))
	}
}

// getColumnRowName  Generate name box 
// Excel The name box of the is A1,A2,B1,B2 To represent the , Here, you need to pass in the column name slice generated in the previous step , Then add the uplink index directly to generate the name box , There is no need to allocate memory every time 
func getColumnRowName(columnName []byte, rowIndex int) (columnRowName string) {
	l := len(columnName)
	columnName = strconv.AppendInt(columnName, int64(rowIndex), 10)
	columnRowName = string(columnName)
    //  Restore the column name 
	columnName = columnName[:l]
	return
}

3. The test case

func TestExportExcel(t *testing.T) {

	t.Run("", func(t *testing.T) {
		headers := []string{" user name ", " Gender ", " Age "}
		values := [][]interface{}{
			{" test ", "1", " male "},
			{
				"ggr1", "1", " male ",
			},
		}
		f, _ := ExportExcel("sheet1", headers, values)
		err := f.SaveAs("test.xlsx")
		fmt.Sprintln(err)
	})

}

If you want to be in web Use , excelize.File Provides a Write Method , You can write it to http.ResponseWriter object w in , And set the following response header .

//  The file name is in English , Otherwise, the Chinese code will be disordered 
fileName = "test.xlxs"
w.Header().Add("Content-Type", "application/octet-stream")
w.Header().Add("Content-Disposition", "attachment; filename="+fileName)
w.Header().Add("Content-Transfer-Encoding", "binary")

4. Record on pit

I was using excelize yes v2.4.0 Version of , This version of SheetName The parameter is case sensitive and cannot be set to sheet1, Otherwise, some errors will be reported when you open the file . It took a long time to find out .

Specific questions have been submitted issuer Give it to excelize It's official , The official replied in time and informed that it would be updated in the next version , That's great .

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