Month: November 2021

### previous, nextを書いていく
app.go

	var start, end, previous, next int
	
	// p はcurrentのint
	previous = p - 1
	next = p + 1

	return c.Render(content, previous, next)

html

    <nav class="pagination" role="navigation" aria-label="pagination">
      <a href="/paging?page={{.previous}}" class="pagination-previous">Previous</a>
      <a href="/paging?page={{.next}}" class="pagination-next">Next page</a>
    </nav>

ただし、previousとnextは、currentが最初もしくは最後のページの場合、非表示にする
app.go

	current = p
	previous = p - 1
	next = p + 1

    <nav class="pagination" role="navigation" aria-label="pagination">
      {{if ne .current 1}}
      <a href="/paging?page={{.previous}}" class="pagination-previous is-left">Previous</a>
      {{end}}
      <a href="/paging?page={{.next}}" class="pagination-next is-right">Next page</a>
    </nav>

うわああああああああああ、条件分岐が永遠増えていく…

これは次行こう

1. まずgetパラメータでpageの値を取得する
string型での取得

	var page int
	var s string=c.Params.Get("page")
	page, _ = strconv.Atoi(s)
	fmt.Println(page)

http://192.168.34.10:9000/paging?page=1
-> 1

2. ページのスタートと終わりの値を計算
例えば、1ページ5つの値のみを表示するとする場合、l(limit)=5として、startとendの値を求めます。

	var l int = 5
	var start, end int
	start = (p - 1) * l
	end = start + l
	fmt.Println(start)
	fmt.Println(end)

http://192.168.34.10:9000/paging?page=2
2 // 2ページ目
5 // start
10 // end

3. 配列からスライス(要素を取り出す)

	text := [15][2]string{
		{"1","content"},
		{"2","content"},
		{"3","content"},
		{"4","content"},
		{"5","content"},
		{"6","content"},
		{"7","content"},
		{"8","content"},
		{"9","content"},
		{"10","content"},
		{"11","content"},
		{"12","content"},
		{"13","content"},
		{"14","content"},
		{"15","content"},
	}
	fmt.Println(text[start:end])

http://192.168.34.10:9000/paging?page=2
-> [[6 content] [7 content] [8 content] [9 content] [10 content]]

4.全部をつなげて、templeteに出力

func (c App) Paging() revel.Result {

	var p int
	var s string=c.Params.Get("page")
	p, _ = strconv.Atoi(s)
	fmt.Println(p)

	var l int = 5
	var start, end int
	start = (p - 1) * l
	end = start + l
	fmt.Println(start)
	fmt.Println(end)

	text := [15][2]string{
		{"1","content"},
		{"2","content"},
		{"3","content"},
		{"4","content"},
		{"5","content"},
		{"6","content"},
		{"7","content"},
		{"8","content"},
		{"9","content"},
		{"10","content"},
		{"11","content"},
		{"12","content"},
		{"13","content"},
		{"14","content"},
		{"15","content"},

	}
	fmt.Println(text[start:end])
	content := text[start:end]
	return c.Render(content)
}

html側

    <h1>paging</h1>
    <ul>
    {{range .content}}
    <li>{{ index . 0 }} {{.}}</li>
    {{end}}
    </ul>

問題は、view側のページネーションのbuttonをどう実装するか…
0から作るの大変だな..

app.go

func (c App) Paging() revel.Result {

	text := [3][2]string{
		{"20211113","2021/11/13"},
		{"20211112","2021/11/12"},
		{"20211111","2021/11/11"},
	}
	fmt.Println(text)
	fmt.Println(text[0][1])
	return c.Render(text)
}

views
L indexを使う

    <ul>
    {{range .text}}
    <li>{{ index . 0 }} {{.}}</li>
    {{end}}
    </ul>

ウヒョーーーーーー

.[0] で表示できないので、かなり時間がかかりました。