chromedp中如何根据登录状态运行不同的代码？

在Golang实战开发的过程中，我们经常会遇到一些这样那样的问题，然后要卡好半天，等问题解决了才发现原来一些细节知识点还是没有掌握好。今天golang学习网就整理分享《chromedp中如何根据登录状态运行不同的代码？》，聊聊，希望可以帮助到正在努力赚钱的你。

演示代码：

package main

import (
    "context"
    "log"
    "time"

    "github.com/chromedp/cdproto/cdp"
    "github.com/chromedp/cdproto/target"
    "github.com/chromedp/chromedp"
    "github.com/chromedp/chromedp/kb"
)

func getTargetId(ctx context.Context, title string) (targetId target.ID) {
    targets, err := chromedp.Targets(ctx)
    if err != nil {
        log.Fatalln(err)
    }

    for _, t := range targets {
        // log.Printf("title %s , ID %s \n", t.Title, t.TargetID)
        if title == t.Title {
            return t.TargetID
        }
    }
    return ""
}

func main() {
    options := append(chromedp.DefaultExecAllocatorOptions[:],
        chromedp.Flag(`headless`, false),
        chromedp.DisableGPU,
        chromedp.Flag(`disable-extensions`, false),
        chromedp.Flag(`enable-automation`, false),
        chromedp.UserAgent(`Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36`),
    )

    allocCtx, cancel := chromedp.NewExecAllocator(context.Background(), options...)
    defer cancel()

    task1Ctx, cancel := chromedp.NewContext(allocCtx)
    defer cancel()

    if err := chromedp.Run(task1Ctx,
        chromedp.Navigate("https://stackoverflow.com/questions/69672682/how-to-run-different-codes-according-to-login-status-in-chromedp"),
    ); err != nil {
        log.Printf("navigate stackoverflow.com err : %v\n", err)
    }

    task2Ctx, cancel := chromedp.NewContext(task1Ctx)
    defer cancel()

    var id []cdp.NodeID
    //add timeout 10 seconds
    tCtx, cancel := context.WithTimeout(task2Ctx, 10*time.Second)
    defer cancel()
    if err := chromedp.Run(tCtx,
        chromedp.Navigate("https://github.com/chromedp/chromedp"),
        //user info button upper right corner
        chromedp.NodeIDs(`body > div.position-relative.js-header-wrapper > header > div.Header-item.position-relative.mr-0.d-none.d-md-flex`, &id, chromedp.ByQuery),
    ); err != nil {
        log.Printf("whether need login err : %v\n", err)
    }

    //get targetid by title
    id_task2Ctx := getTargetId(task1Ctx, "GitHub - chromedp/chromedp: A faster, simpler way to drive browsers supporting the Chrome DevTools Protocol.")

    //return to the tab 
    task2Ctx, cancel = chromedp.NewContext(task1Ctx, chromedp.WithTargetID(id_task2Ctx))
    defer cancel()
    if err := chromedp.Run(task2Ctx,
        chromedp.Navigate("https://github.com/chromedp/chromedp"),
    ); err != nil {
        log.Printf("navigate chromedp err : %v\n", err)
    }

    //determine whether login is required
    if len(id) == 0 {
        // code for login
        if err := chromedp.Run(task2Ctx,
            //click sign in
            chromedp.Click(`body > div.position-relative.js-header-wrapper > header > div > div.HeaderMenu.HeaderMenu--logged-out.position-fixed.top-0.right-0.bottom-0.height-fit.position-lg-relative.d-lg-flex.flex-justify-between.flex-items-center.flex-auto > div.d-lg-flex.flex-items-center.px-3.px-lg-0.text-center.text-lg-left > div.position-relative.mr-3.mb-4.mb-lg-0.d-inline-block > a`, chromedp.ByQuery),
            chromedp.SendKeys(`#login_field`, `XXX`),
            chromedp.SendKeys(`#password`, `XXX`+kb.Enter),
        ); err != nil {
            log.Printf("login err : %v\n", err)
        }
    }

    if err := chromedp.Run(task2Ctx,
        //click master
        chromedp.Click(`#branch-select-menu > summary`, chromedp.ByQuery),
        //click tag
        chromedp.Click(`#branch-select-menu > div > div > input-demux > tab-container > div.SelectMenu-tabs > button:nth-child(2)`, chromedp.ByQuery),
        //wait tags list visible
        chromedp.WaitVisible(`#tags-menu > ref-selector > div > div > div > a:nth-child(1)`, chromedp.ByQuery),
        //click v0.6.6
        chromedp.Click(`//*[@id="tags-menu"]/ref-selector/div/div/div/a/span[text()="v0.6.6"]`, chromedp.BySearch),
        chromedp.Sleep(20*time.Second),
    ); err != nil {
        log.Printf("logined err : %v\n", err)
    }

}

我期望看到什么？

1、如果没有登录，会点击登录并登录，然后点击master > tags > v0.6.6

2、登录后会点击master >标签> v0.6.6

我看到了什么？

1、如果未登录，运行代码，有时会报错：

2021/10/22 12:45:42 登录错误：找不到给定 id 的节点 (-32000)

2、如果已登录，运行代码，会打开“https://github.com/chromedp/chromedp”两个标签

正确答案

package main

import (
    "context"
    "log"
    "time"

    "github.com/chromedp/cdproto/cdp"
    "github.com/chromedp/cdproto/target"
    "github.com/chromedp/chromedp"
    "github.com/chromedp/chromedp/kb"
)

func getTargetId(ctx context.Context, title string) (targetId target.ID) {
    targets, err := chromedp.Targets(ctx)
    if err != nil {
        log.Fatalln(err)
    }

    for _, t := range targets {
        // log.Printf("title %s , ID %s \n", t.Title, t.TargetID)
        if title == t.Title {
            return t.TargetID
        }
    }
    return ""
}

func main() {
    options := append(chromedp.DefaultExecAllocatorOptions[:],
        chromedp.Flag(`headless`, false),
        chromedp.DisableGPU,
        chromedp.Flag(`disable-extensions`, false),
        chromedp.Flag(`enable-automation`, false),
        chromedp.UserAgent(`Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36`),
    )

    allocCtx, cancel := chromedp.NewExecAllocator(context.Background(), options...)
    defer cancel()

    // task1Ctx, cancel := chromedp.NewContext(allocCtx, chromedp.WithDebugf(log.Printf))
    task1Ctx, cancel := chromedp.NewContext(allocCtx)
    defer cancel()

    if err := chromedp.Run(task1Ctx,
        chromedp.Navigate("https://stackoverflow.com/questions/69672682/how-to-run-different-codes-according-to-login-status-in-chromedp"),
    ); err != nil {
        log.Printf("navigate stackoverflow.com err : %v\n", err)
    }

    task2Ctx, cancel := chromedp.NewContext(task1Ctx)
    defer cancel()

    var id []cdp.NodeID
    //add timeout 15 seconds
    task2Ctx, cancel = context.WithTimeout(task2Ctx, 15*time.Second)
    defer cancel()
    if err := chromedp.Run(task2Ctx,
        chromedp.Navigate("https://github.com/chromedp/chromedp"),
        //user info button upper right corner
        chromedp.NodeIDs(`body > div.position-relative.js-header-wrapper > header > div.Header-item.position-relative.mr-0.d-none.d-md-flex`, &id, chromedp.ByQuery),
    ); err != nil {
        log.Printf("whether need login err : %v\n", err)
    }

    //get targetid by title, task2Ctx stopped, get targetid from task1Ctx only!
    id_task2Ctx := getTargetId(task1Ctx, "GitHub - chromedp/chromedp: A faster, simpler way to drive browsers supporting the Chrome DevTools Protocol.")

    //determine whether login is required
    if len(id) == 0 {
        //return to the tab
        task2Ctx, cancel = chromedp.NewContext(task1Ctx, chromedp.WithTargetID(id_task2Ctx))
        defer cancel()
        // code for login
        if err := chromedp.Run(task2Ctx,
            //click sign in
            chromedp.Click(`body > div.position-relative.js-header-wrapper > header > div > div.HeaderMenu.HeaderMenu--logged-out.position-fixed.top-0.right-0.bottom-0.height-fit.position-lg-relative.d-lg-flex.flex-justify-between.flex-items-center.flex-auto > div.d-lg-flex.flex-items-center.px-3.px-lg-0.text-center.text-lg-left > div.position-relative.mr-3.mb-4.mb-lg-0.d-inline-block > a`, chromedp.ByQuery),
            chromedp.SendKeys(`#login_field`, `XXX`),
            chromedp.SendKeys(`#password`, `XXX`+kb.Enter),
        ); err != nil {
            log.Printf("login err : %v\n", err)
        }
    }

    if err := chromedp.Run(task2Ctx,
        //click master
        chromedp.Click(`#branch-select-menu > summary`, chromedp.ByQuery),
        //wait Tags visible
        chromedp.WaitVisible(`#branch-select-menu > div > div > input-demux > tab-container > div.SelectMenu-tabs > button:nth-child(2)`, chromedp.ByQuery),
        //click Tags
        chromedp.Click(`#branch-select-menu > div > div > input-demux > tab-container > div.SelectMenu-tabs > button:nth-child(2)`, chromedp.ByQuery),
        //wait tags-list child visible
        chromedp.WaitVisible(`#tags-menu > ref-selector > div > div > div > a:nth-child(1)`, chromedp.ByQuery),
        //click v0.6.6
        chromedp.Click(`//*[@id="tags-menu"]/ref-selector/div/div/div/a/span[text()="v0.6.6"]`, chromedp.BySearch),
        chromedp.Sleep(15*time.Second),
    ); err != nil {
        log.Printf("logined err : %v\n", err)
    }

}

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