Update Data CRUD APP – Fyne Golang GUI Tutorial 62
Update Data CRUD APP – Fyne Golang GUI Tutorial 62
Source Code
package main
// import fyne
import (
"encoding/json"
"io/ioutil"
"fyne.io/fyne/v2"
"fyne.io/fyne/v2/app"
"fyne.io/fyne/v2/container"
"fyne.io/fyne/v2/widget"
)
func main() {
// student struct, you can use any name
type Student struct {
Name string // name N is capital
Phone string
}
// Now creat a slice/ array to store data
var myStudentData []Student
// welcome again
//lets read data from file and display it in list
data_from_file, _ := ioutil.ReadFile("myFile_name.txt")
// file name with extension .txt or .json
// unmarshall/parse data received from file and save/push in slice
// 2 argument 1. data source, 2. data slice to store data
json.Unmarshal(data_from_file, &myStudentData)
// now we can use this data in our list
// lets create our list
// new app
a := app.New()
// new title and window
w := a.NewWindow("CRUD APP")
// resize window
w.Resize(fyne.NewSize(400, 400))
// New label to dispaly name and phone number details
l_name := widget.NewLabel("...")
l_name.TextStyle = fyne.TextStyle{Bold: true}
// for phone number
l_phone := widget.NewLabel("...")
// entry widget for name
e_name := widget.NewEntry()
e_name.SetPlaceHolder("Enter name here...")
// entry widget for phone
e_phone := widget.NewEntry()
e_phone.SetPlaceHolder("Enter phone here...")
// submit button
submit_btn := widget.NewButton("Submit", func() {
// logic part- store our data in json format
// let create a struct for our data
// Get data from entry widget and push to slice
myData1 := &Student{
Name: e_name.Text, // data from name entry widget
Phone: e_phone.Text,
}
// append / push data to our slice
myStudentData = append(myStudentData, *myData1)
// * star is very important
// convert / parse data to json format
// 3 arguments
// 1st is our slice data
// ignore 2nd
// 3rd is identation, we are using space to indent our data
final_data, _ := json.MarshalIndent(myStudentData, "", " ")
// writing data to file
// it take 3 things
//file name .txt or .json or anything you want to use
// data source, final_data in our case
// writing/reading/execute permission
ioutil.WriteFile("myFile_name.txt", final_data, 0644)
/// we are done :)
// lets test
// empty input field after data insertion
e_name.Text = ""
e_phone.Text = ""
// refresh name & phone entry object
e_name.Refresh()
e_phone.Refresh()
})
/// Delete Button
del_button := widget.NewButton("Del", func() {
// Create a new Temporary slice
var TempData []Student // student is the struct we create yesterday
// now loop through the main slice "myStudentData"
// and push all the data to TempData slice except the select one
// here i is the indexs and "e" is the element of slice
// I don't need index here
// I will push all the data to tempdata slice
for _, e := range myStudentData {
// l_name is the label we create to show details
// important not equal to is used. Don't append if equal to e.Name
if l_name.Text != e.Name {
TempData = append(TempData, e)
}
}
// Now append all the data back to main slice myStudentData
myStudentData = TempData
// conver to json and marshall indent
// 3 element
// our slice is the data source (1st argument)
// 2nd is prefix.. we don't need prefix
// 3rd is the indent. we need a single space
result, _ := json.MarshalIndent(myStudentData, "", " ")
// write data to file
// first argument is file name
// data source which is result here.
// last one is permission
ioutil.WriteFile("myFile_name.txt", result, 0644)
})
// list widget
list := widget.NewList(
// first argument is item count
// len() function to get myStudentData slice len
func() int { return len(myStudentData) },
// 2nd argument is for widget choice. I want to use label
func() fyne.CanvasObject { return widget.NewLabel("") },
// 3rd argument is to update widget with our new data
func(lii widget.ListItemID, co fyne.CanvasObject) {
co.(*widget.Label).SetText(myStudentData[lii].Name)
},
)
// update on clicked/ selected
list.OnSelected = func(id widget.ListItemID) {
l_name.Text = myStudentData[id].Name
l_name.Refresh()
// for phone number
l_phone.Text = myStudentData[id].Phone
l_phone.Refresh()
}
// paste update button code here
// Update Button
update_button := widget.NewButton("Update", func() {
// Temp slice
var TempData []Student
// Data I want to update
update := &Student{
Name: e_name.Text, // entry name widget
Phone: e_phone.Text, // entry widget : phone
}
// looping through our slice and update the data meeting our criteria
// _ is to ignore index
// e is the element/data in the myStudentData slice
for _, e := range myStudentData {
// checking data criteria
if l_name.Text == e.Name {
// if criteria mathed, append updated data else
TempData = append(TempData, *update)
} else {
// else append old data in TempData slice
TempData = append(TempData, e)
}
}
// first
myStudentData = TempData
// convert data to json & write to file
// first argument is data source // 2nd is prefix // third is indent
result, _ := json.MarshalIndent(myStudentData, "", " ")
// write data to file
// 1st argument is file name
// 2nd is our data(result) from marshalindent
// 3rd is the file permission.
ioutil.WriteFile("myFile_name.txt", result, 0644)
// refresh & empty entry box and refresh list
e_name.Text = ""
e_phone.Text = ""
e_name.Refresh()
e_phone.Refresh()
// refresh list also
list.Refresh() // if not working cut code and paste after list widget
})
// update widget tree and add update button also
// show and run
w.SetContent(
// lets create Hsplite container
container.NewHSplit(
// first argument is list of data
list,
// 2nd is
// vbox container
// show both label
container.NewVBox(
l_name, l_phone, e_name,
e_phone, submit_btn, del_button,
update_button,
),
),
)
w.ShowAndRun()
}
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