ibm-cloud - 如何从 Node-red msg.payload 中选择 Cloudant 数据？

Question

我必须从 cloudant 数据库中读取数据。结果 msg.payload 具有如下值：

[{"_id":"0de4df1286119588b8529a01ce7ae88c","_rev":"2-6702cf5c73c76536d403caaae37f9f99","payload":{"direction":"out","count":"-1","timestamp":"2016-10-06T13:25:24.262Z"}},{"_id":"1cf44a5241cc413a21920b069942851c","_rev":"1-f0f2271864d39b5ca633fe284590ae99","payload":{"direction":"out","count":"-1","timestamp":"2016-10-06T14:38:11.920Z"}},{"_id":"970049cb8ec6e3853d50f65f520ad385","_rev":"1-f7642fc0eab3938388138e04ce1d2c26","payload":{"direction":"IN","count":"1","timestamp":"2016-10-06T13:25:16.286Z"}}]

我想从上面的有效负载中选择所有 _id。

我尝试使用 msg.payload._id 但它不起作用。结果显示为“{}”

Answer 1

问题是有效负载对象是一个数组对象（这对于从数据库查询返回的结果集是有意义的）

您需要在调试节点输出过滤器中包含数组索引

.payload[0]._id

这将从_id数组中的第一个条目给出