flag redefined - panic searching by key in YouTube data API 3

Question

I am trying to search YouTube video by key like in the golang example. I modified that code a little to let it search by different keys several times.

When I search once it is ok.

func main() {
    result1, err1 := SearchYoutubeByKey("hello")

    if err1 != nil {
        panic(err1)
    }
    fmt.Println(result1)

    // result2, err2 := SearchYoutubeByKey("world")
    // if err2 != nil {
    //  panic(err2)
    // }
    // fmt.Println(result2)
}

But if I search twice ...

func main() {
    result1, err1 := SearchYoutubeByKey("hello")

    if err1 != nil {
        panic(err1)
    }
    fmt.Println(result1)

    result2, err2 := SearchYoutubeByKey("world")
    if err2 != nil {
        panic(err2)
    }
    fmt.Println(result2)
}

... then it panics with error message ...

flag redefined: query

... on line ...

query := flag.String("query", str, "Search term")

Full code:

package main

import (
    "code.google.com/p/google-api-go-client/googleapi/transport"
    "code.google.com/p/google-api-go-client/youtube/v3"
    "flag"
    "fmt"
    "net/http"
)

var (
    maxResults = flag.Int64("max-results", 25, "Max YouTube results")
    service    *youtube.Service
    response   *youtube.SearchListResponse
)

const developerKey = "youtube developer key"

type YoutubeSearchResult struct {
    Title, YoutubeId string
}

func SearchYoutubeByKey(str string) (result []*YoutubeSearchResult, err error) {
    query := flag.String("query", str, "Search term")
    flag.Parse()

    client := &http.Client{
        Transport: &transport.APIKey{Key: developerKey},
    }

    service, err = youtube.New(client)
    if err != nil {
        return
    }

    // Make the API call to YouTube.
    call := service.Search.List("id,snippet").
        Q(*query).
        MaxResults(*maxResults)
    response, err = call.Do()
    if err != nil {
        return
    }

    // Iterate through each item and add it to the correct list.
    for _, item := range response.Items {
        switch item.Id.Kind {
        case "youtube#video":
            result = append(result, &YoutubeSearchResult{Title: item.Snippet.Title, YoutubeId: item.Id.VideoId})
        }
    }
    return
}

func main() {


    result1, err1 := SearchYoutubeByKey("hello")

    if err1 != nil {
        panic(err1)
    }
    fmt.Println(result1)

    result2, err2 := SearchYoutubeByKey("world")
    if err2 != nil {
        panic(err2)
    }
    fmt.Println(result2)
}

So it is impossible to use this code on a website. Only the first user will be able to search first time, the others will fail.

I cannot change flag during runtime but how to search by 2 different keys in one program?

Update

working solution:

package main

import (
    "code.google.com/p/google-api-go-client/googleapi/transport"
    "code.google.com/p/google-api-go-client/youtube/v3"
    "flag"
    "fmt"
    "net/http"
)

var (
    maxResults = flag.Int64("max-results", 25, "Max YouTube results")
    service    *youtube.Service
    response   *youtube.SearchListResponse
    query      = flag.String("query", "str", "Search term")
)

const developerKey = "youtube api key"

type YoutubeSearchResult struct {
    Title, YoutubeId string
}

func SearchYoutubeByKey(str string) (result []*YoutubeSearchResult, err error) {
    flag.Parse()

    client := &http.Client{
        Transport: &transport.APIKey{Key: developerKey},
    }

    service, err = youtube.New(client)
    if err != nil {
        return
    }

    // Make the API call to YouTube.
    call := service.Search.List("id,snippet").
        Q(str).
        MaxResults(*maxResults)
    response, err = call.Do()
    if err != nil {
        return
    }

    // Iterate through each item and add it to the correct list.
    for _, item := range response.Items {
        switch item.Id.Kind {
        case "youtube#video":
            result = append(result, &YoutubeSearchResult{Title: item.Snippet.Title, YoutubeId: item.Id.VideoId})
        }
    }
    return
}

func main() {
    result1, err1 := SearchYoutubeByKey("hello")

    if err1 != nil {
        panic(err1)
    }
    fmt.Println(result1)

    result2, err2 := SearchYoutubeByKey("world")
    if err2 != nil {
        panic(err2)
    }
    fmt.Println(result2)
}

score 2 · Accepted Answer · answered Apr 14 '15 at 15:00

2

The panic message tells you exactly what's wrong. Your command line flags should be defined only once. If you try to redefine them during runtime, it panics.

answered Apr 14 '15 at 15:00

Ainar-G

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I guessed about that, how to solve it? how to search by 2 different keys during runtime – Maxim Yefremov Apr 14 '15 at 15:11
@efr Why do you use `flag` package there in the first place? From the YouTube example, it seems like you just need to pass `str` directly to `Q`. – Ainar-G Apr 14 '15 at 15:20
from the link above: `query = flag.String("query", "Google", "Search term")` - glag is used to set search key. How should I pass `str` directly to `Q`? – Maxim Yefremov Apr 15 '15 at 00:51
3

@efr Please read the [`flag` package documentation](http://golang.org/pkg/flag/) and what it's used for. In your case, you should just omit the `flag` part and call `Q(str)` instead of `Q(*query)`. – Ainar-G Apr 15 '15 at 11:46

flag redefined - panic searching by key in YouTube data API 3

Update

1 Answers1