feat: decode extensions from response via BindExtensions option

[hgiasac]

The response map may also contain an entry with key extensions. To decode this field you need to bind a struct or map pointer. The client will optionally unmarshal the field using json decoder.

var q struct {
    User struct {
        ID   string `graphql:"id"`
        Name string `graphql:"name"`
    }
}

var ext struct {
    ID     int    `json:"id"`
    Domain string `json:"domain"`
}

err := client.Query(context.Background(), &q, map[string]interface{}{}, graphql.BindExtensions(&ext))
if err != nil {
    t.Fatal(err)
}

[github-actions[bot]]

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