duandong9195 2018-01-08 10:35
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将数据范围传递到HTML模板

I have inserted dummy data into the database.

The sample print function prints 13 and its square as per the code in the console. But I need to pass the entire data to the HTML template(index) where I can see a table of all the numbers passed with their respective square number.

How to pass this data in index HTML?

Number x Number = SquareNumber 1 x 1 = 1 2 x 2 = 4 3 x 3 = 9 ... and so on.

func main() {

    db, err := sql.Open("mysql", "root:@/godb")
    if err != nil {
        panic(err.Error())  
    }

    defer db.Close() 

 stmtIns, err := db.Prepare("INSERT INTO squarenum VALUES(?, ?, ? )") // ? = 
placeholder
    if err != nil {
        panic(err.Error()) }

    defer stmtIns.Close() 

 stmtOut, err := db.Prepare("SELECT squareNum FROM squareNum WHERE number = 
 ?")
    if err != nil {
        panic(err.Error()) 
    }

    defer stmtOut.Close()

    for i := 1; i < 50; i++ {
        _, err = stmtIns.Exec(0,i, (i * i)) 
        if err != nil {
            panic(err.Error()) 
        }
    }

    err = stmtOut.QueryRow(13).Scan(&squareNum) // WHERE number = 13
    if err != nil {
 panic(err.Error()) // proper error handling instead of panic in your app

    }
    tRes:=pageData{}
    tRes.SquareNum=squareNum
    fmt.Printf("The square number of 13 is: %d 
", squareNum)


    // Query another number.. 1 maybe?
    err = stmtOut.QueryRow(1).Scan(&squareNum) // WHERE number = 1
    if err != nil {
 panic(err.Error()) // proper error handling instead of panic in your app
    }
    fmt.Printf("The square number of 1 is: %d 
", squareNum)
    http.HandleFunc("/",idx)
    http.ListenAndServe(":8888", nil)
}

func idx(w http.ResponseWriter, r *http.Request) {

    pd := pageData{
        SquareNum: squareNum,
        }

    err := tpl.ExecuteTemplate(w, "index.html", pd)
    if err != nil {
        log.Println("LOGGED", err)
http.Error(w, "Internal server error", http.StatusInternalServerError)
        return
    }
}
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1条回答 默认 最新

  • dtg78700 2018-01-08 11:24
    关注
    package main

import (
    "html/template"
    "os"
)

// here is your template
const tplString = `
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>{{.Title}}</title>
</head>
<body>
{{range .Dummies}}
<div>Square of {{.Number}} is {{.Square}}</div>
{{end}}
</body>
</html>
`

var (
    tpl *template.Template
    err error
)

// the dummydata you talked about
type DummyData struct {
    Number int
    Square int
}

//some PageData just with dummies and a title
type PageData struct {
    Title   string
    Dummies []*DummyData
}

//here you would be using your sql queries
func createSomeDummies(amount int) []*DummyData {
    dummies := make([]*DummyData, amount)
    for i := 0; i < amount; i++ {
        dd := new(DummyData)
        dd.Number = i
        dd.Square = i * i
        dummies[i] = dd
    }
    return dummies
}

func main() {
    pd := new(PageData)
    pd.Title = "Hello Dummies"
    pd.Dummies = createSomeDummies(10)

    tpl = template.New("index")
    tpl, err = tpl.Parse(tplString)
    if err != nil {
        panic(err)
    }
    err = tpl.Execute(os.Stdout, pd)
    if err != nil {
        panic(err)
    }
}

    This Snippet creates a PageData struct to hold the array of dummydata entries and a Title for the webpage.

    type PageData struct {
    Title   string
    Dummies []*DummyData
}

    It then uses a function to create 10 dummydata structs. This array is then assigned to the Dummmies field of the PageData.

    pd.Dummies = createSomeDummies(10)

    This function is a placeholder for your sql query function you just have to loop over your sql rows instead of manually creating them like i do.

    func createSomeDummies(amount int) []*DummyData {
    dummies := make([]*DummyData, amount)
    for i := 0; i < amount; i++ {
        dd := new(DummyData)
        dd.Number = i
        dd.Square = i * i
        dummies[i] = dd
    }
    return dummies
}

    The Template itself inserts the title like so: <title>{{.Title}}</title>

    The Dummies themselves are inserted by a range template directive that works like a for iterator. The one thing to be careful about is that inside this loop all data points to the DummyData item and not the PageData

    {{range .Dummies}}
<div>Square of {{.Number}} is {{.Square}}</div>
{{end}}

    Then the template is parsed. Errors will halt execution and print the error message.

    tpl = template.New("index")
tpl, err = tpl.Parse(tplString)
if err != nil {
    panic(err)
}

    And finally the template will be rendered to Stdout. For use in a http Handler you would have to use the http.ResponseWriter instead. Once again errors halt execution and print the error message.

    err = tpl.Execute(os.Stdout, pd)
if err != nil {
    panic(err)
}

    Working Example here: Go Playground

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论

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