GoCQL：将字符串转换为时间戳 [英] GoCQL : Marshal string into timestamp

问题描述

我正在开发带有聚类列的时间序列数据模型，即

I am developing a time series data model with clustering column i.e.

CREATE TABLE events (
    id text,
    time timestamp,
    type text,
    val double,
    PRIMARY KEY (id, time)
) WITH CLUSTERING ORDER BY (time DESC)

我希望针对分区列 id和集群列 time执行选择。例如，id：='1'，时间戳：='2017-10-09'

I wish to perform a select against the partition column 'id' and clustering column 'time'. For example, id:='1', timestamp:='2017-10-09'

query := "SELECT id, time, type, val FROM events WHERE id=? AND time>=?"
iterable := Cassandra.Session.Query(query, id, timestamp).Consistency(gocql.One).Iter()
for iterable.MapScan(m) {
        found = true
        event = Event{
                ID:       m["id"].(string),
                Time:     m["time"].(time.Time),
                Type:     m["type"].(string),
                Val:      m["val"].(float64),
        }
}

检查iterable.Close（）的err后，发现编组错误

After checking err on iterable.Close(), found an error in marshalling

{错误 ：[无法将字符串编组为时间戳]}

{"errors":["can not marshal string into timestamp"]}

我该如何解决？

推荐答案

下面是我如何通过将（时间戳）字符串文字转换为类型time来解决此问题的方法。

Here is how I end up solving this by transforming string literal (of timestamp) to type time.Time

timestamp = "2017-10-09T13:25:00.000Z"
tsAfter,err = time.Parse(model.TimeLayout, timestamp)
if err != nil {
    errs = append(errs, err.Error())
}

log.Printf("GET param [id = %s]", idStr)
log.Printf("GET param [after = %s]", tsAfter.String())

m := map[string]interface{}{}
query := "SELECT id, time, type, val FROM events WHERE id = ? AND time >= ?"
iterable := cql.Session.Query(query, idStr, tsAfter).Consistency(gocql.One).Iter()

for iterable.MapScan(m) {
    eventList = append(eventList, model.Event{
        ID:         m["id"].(string),
        Time:       m["time"].(time.Time),
        Type:       m["type"].(string),
        Val:        m["val"].(float64),
    })
    m = map[string]interface{}{}
}

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