Go模板无法与if和range一起正常使用 [英] Go template doesn't work correctly with if and range

问题描述

https://play.golang.org/p/iQConmYgIN0

PortfolioTemplate 无法正确处理 if .此 if 制动外部 Range .该如何解决?

PortfolioTemplate does not handle if properly. This if brakes outer Range. How to fix this?

推荐答案

使用模板函数可能是一种更好的方法.

Using a template function might be a better way to do this.

在下面的代码示例中，我定义了一个 font 函数，该函数将从 Yield 类型(此示例中提取并移至顶部)确定颜色.

In the following code example, I defined a font function which would determine the color from a Yield type (which I extracted and moved to top for this example).

代码示例:

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "html/template"
)

type Yield struct {
    Currency string  `json:"currency"`
    Value    float64 `json:"value"`
}

const portfolioJson = `{
    "payload": {
        "positions": [
            {
                "balance": 300,
                "expectedYield": {
                    "currency": "RUB",
                    "value": 1314
                },
                "ticker": "SBERP"
            },
            {
                "balance": 4,
                "expectedYield": {
                    "currency": "USD",
                    "value": -14.87
                },
                "ticker": "MA"
            }
        ]
    }
}`

const PortfolioTemplate = `
<ol>
    {{range .Payload.Positions}}
        <li>
            <strong>{{.Ticker}}</strong> {{.Balance}} ( 

                <font color="{{.ExpectedYield | font }}">

                {{.ExpectedYield.Value}}</font> {{.ExpectedYield.Currency}}
            )   
        </li>
    {{end}}
</ol>
`

type Portfolio struct {
    Payload struct {
        Positions []struct {
            Ticker        string  `json:"ticker"`
            Balance       float64 `json:"balance"`
            ExpectedYield Yield   `json:"expectedYield"`
        }
    } `json:"payload"`
}

func (portfolio *Portfolio) Prettify() string {
    fontColor := func(y Yield) string {
        if y.Value > 0 {
            return "green"
        }

        return "red"
    }

    t := template.New("Portfolio")

    buff := bytes.Buffer{}
    tpl := template.Must(t.Funcs(template.FuncMap{"font": fontColor}).Parse(PortfolioTemplate))
    _ = tpl.Execute(&buff, portfolio)
    return buff.String()
}

func main() {
    var portfolio Portfolio
    _ = json.Unmarshal([]byte(portfolioJson), &portfolio)
    fmt.Println(portfolio.Prettify())
}

输出:

<ol>

        <li>
            <strong>SBERP</strong> 300 (

                <font color="green">

                1314</font> RUB
            )
        </li>

        <li>
            <strong>MA</strong> 4 (

                <font color="red">

                -14.87</font> USD
            )
        </li>

</ol>

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