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