云数据存储查询，关键在哪里？

Question

我在 Google 云数据存储上存储了一些数据。

查询数据不是问题，我可以使用迭代器获取数据的属性。例子; https://cloud.google.com/datastore/docs/concepts/queries#projection_queries

var priorities []int
var percents []float64
it := client.Run(ctx, query)
for {
    var task Task
    if _, err := it.Next(&task); err == iterator.Done {
            break
    } else if err != nil {
            log.Fatal(err)
    }
    priorities = append(priorities, task.Priority)
    percents = append(percents, task.PercentComplete)
}

我可以毫无问题地访问实体的属性，但不知道如何 read/access 键。

如何获得钥匙？

Answer 1

可以看到here that the iterator returns the associated key when calling Next. In the example above it is not needed and is therefore discarded by using the blank identifier，即_, err := it.Next(&task)。如果您想要钥匙，请不要丢弃它：

for {
    var task Task
    key, err := it.Next(&task)
    if err != nil && err != iterator.Done {
         return err
    } else if err == iterator.Done {
         break
    }
    priorities = append(priorities, task.Priority)
    percents = append(percents, task.PercentComplete)

    // do something with key
}

云数据存储查询，关键在哪里？

Cloud datastore queries, where is the key?

google-app-engine

go

google-cloud-datastore