Node-RED + DB2 - msg：string [18]“无响应对象”

Question

所以，我是Node-RED的初学者，需要通过流程创建一个带有DB2查询的简单API。我正在使用node-red-contrib-db2来实现这一目标。问题是，我设法将结果传递给调试器节点的几个有效负载，由时间戳或HTTP请求触发。但是，我无法在HTTP回复中获得这些结果而无法找到原因。是db2插件还是我的问题？

下面导出的节点：

[{"id":"96197abb.fd4098","type":"http in","z":"b4aa8db5.217028","name":"","url":"/wastes","method":"get","upload":false,"swaggerDoc":"","x":150,"y":140,"wires":[["9affb306.caf7e"]]},{"id":"bda39d37.edb418","type":"http response","z":"b4aa8db5.217028","name":"","statusCode":"200","headers":{},"x":940,"y":100,"wires":[]},{"id":"41708443.e4670c","type":"inject","z":"b4aa8db5.217028","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":220,"y":40,"wires":[["22a6e217.ead65e"]]},{"id":"9d1e6783.eb246","type":"ibmdb","z":"b4aa8db5.217028","mydb":"3a218407.1cca74","name":"IOCDATA","x":560,"y":40,"wires":[["80e51c1b.23b378"],[]]},{"id":"80e51c1b.23b378","type":"debug","z":"b4aa8db5.217028","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":730,"y":40,"wires":[]},{"id":"22a6e217.ead65e","type":"function","z":"b4aa8db5.217028","name":"SQL Query","func":"msg.database = \"iocdata\";\nmsg.payload = \"select * from viseu.waste_view\";\nreturn msg;","outputs":1,"noerr":0,"x":390,"y":40,"wires":[["9d1e6783.eb246"]]},{"id":"4a6bd014.f39868","type":"ibmdb","z":"b4aa8db5.217028","mydb":"3a218407.1cca74","name":"IOCDATA","x":500,"y":140,"wires":[["bda39d37.edb418","74e28d3e.039be4"],[]]},{"id":"9affb306.caf7e","type":"function","z":"b4aa8db5.217028","name":"SQL Query","func":"msg.database = \"iocdata\";\nmsg.payload = \"select * from viseu.waste_view where id = 1\";\nreturn msg;","outputs":1,"noerr":0,"x":330,"y":140,"wires":[["4a6bd014.f39868"]]},{"id":"74e28d3e.039be4","type":"debug","z":"b4aa8db5.217028","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":950,"y":180,"wires":[]},{"id":"3a218407.1cca74","type":"IbmDBdatabase","z":"","host":"10.102.0.62","port":"50002","db":"iocdata"}]

Answer 1

这是您正在使用的ibmdb节点的问题 - 它在发送结果时不会重复使用收到的消息。这意味着HTTP In节点提供的msg.req和msg.res属性在到达HTTP响应节点时不会在消息上设置。这意味着响应节点不会响应什么请求。

要解决此问题，一种不理想的方法是使用ibmdb节点之前的Change节点在流上下文中存储msg.req和msg.res，然后将它们复制回ibmdb节点之后的msg。这并不理想，因为它一次只能处理一个请求。

最好针对ibmdb节点提出问题。

Answer 2

我设法在我的流程中取得了成功，但代价是许多变通办法和变量杂乱。但它现在正在运作。选择count +选择行+连接行，当达到计数值时设置msg.complete。这是代码：

[{"id":"96197abb.fd4098","type":"http in","z":"b4aa8db5.217028","name":"","url":"/wastes","method":"get","upload":false,"swaggerDoc":"","x":90,"y":140,"wires":[["d5f42a96.83f688"]]},{"id":"bda39d37.edb418","type":"http response","z":"b4aa8db5.217028","name":"","statusCode":"200","headers":{},"x":980,"y":260,"wires":[]},{"id":"4a6bd014.f39868","type":"ibmdb","z":"b4aa8db5.217028","mydb":"3a218407.1cca74","name":"SELECT waste_view","x":360,"y":200,"wires":[["35f99a5a.c7f87e"],[]]},{"id":"9affb306.caf7e","type":"function","z":"b4aa8db5.217028","name":"SQL Query","func":"msg.database = \"iocdata\";\nmsg.payload = \"select count(*) from viseu.waste_view\";\n\nreturn msg;","outputs":1,"noerr":0,"x":170,"y":200,"wires":[["4a6bd014.f39868"]]},{"id":"74e28d3e.039be4","type":"debug","z":"b4aa8db5.217028","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":890,"y":380,"wires":[]},{"id":"d5f42a96.83f688","type":"change","z":"b4aa8db5.217028","name":"","rules":[{"t":"set","p":"req","pt":"flow","to":"req","tot":"msg"},{"t":"set","p":"res","pt":"flow","to":"res","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":260,"y":140,"wires":[["9affb306.caf7e"]]},{"id":"c3ebb136.aa8988","type":"change","z":"b4aa8db5.217028","name":"","rules":[{"t":"set","p":"req","pt":"msg","to":"req","tot":"flow"},{"t":"set","p":"res","pt":"msg","to":"res","tot":"flow"}],"action":"","property":"","from":"","to":"","reg":false,"x":800,"y":260,"wires":[["bda39d37.edb418"]]},{"id":"ca59ece2.844b3","type":"join","z":"b4aa8db5.217028","name":"","mode":"custom","build":"array","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"","count":"","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":630,"y":260,"wires":[["c3ebb136.aa8988","74e28d3e.039be4"]]},{"id":"35f99a5a.c7f87e","type":"function","z":"b4aa8db5.217028","name":"SQL Query","func":"msg.rowcount = msg.payload[1];\nmsg.database = \"iocdata\";\nmsg.payload = \"select * from viseu.waste_view\";// fetch first \" + msg.count[1] + \" rows only\";\n\nreturn msg;","outputs":1,"noerr":0,"x":550,"y":200,"wires":[["327a8ae.a8ce2f6"]]},{"id":"2666e2ba.41dc8e","type":"ibmdb","z":"b4aa8db5.217028","mydb":"3a218407.1cca74","name":"SELECT waste_view","x":800,"y":200,"wires":[["9008e06f.bf6d7"],[]]},{"id":"ec61a7f3.68cf8","type":"debug","z":"b4aa8db5.217028","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"count","x":650,"y":320,"wires":[]},{"id":"327a8ae.a8ce2f6","type":"change","z":"b4aa8db5.217028","name":"","rules":[{"t":"set","p":"rowcount","pt":"flow","to":"rowcount","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":670,"y":140,"wires":[["2666e2ba.41dc8e"]]},{"id":"90204f2d.8bafe8","type":"change","z":"b4aa8db5.217028","name":"","rules":[{"t":"set","p":"rowcount","pt":"msg","to":"rowcount","tot":"flow"}],"action":"","property":"","from":"","to":"","reg":false,"x":310,"y":320,"wires":[["6888cd0d.d00064"]]},{"id":"9008e06f.bf6d7","type":"counter","z":"b4aa8db5.217028","name":"","init":"0","step":"1","lower":"","upper":"","mode":"increment","outputs":"1","x":220,"y":260,"wires":[["90204f2d.8bafe8"]]},{"id":"6888cd0d.d00064","type":"function","z":"b4aa8db5.217028","name":"if rowcount === count","func":"if (msg.count === msg.rowcount) {\n    msg.complete = true;\n}\n\nreturn msg;","outputs":1,"noerr":0,"x":440,"y":260,"wires":[["ca59ece2.844b3","ec61a7f3.68cf8","a63f6ad6.26f08"]]},{"id":"a63f6ad6.26f08","type":"debug","z":"b4aa8db5.217028","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"rowcount","x":660,"y":380,"wires":[]},{"id":"3a218407.1cca74","type":"IbmDBdatabase","z":"","host":"10.102.0.62","port":"50002","db":"iocdata"}]

编辑21/02/2018：之前的解决方案并不是很好，因为计数器神秘地保存了它的值，我无法按照我的意愿重置它。这使得计数器超过了所希望的rowcount值。所以，我必须在一个函数节点中创建自己的计数器。下面的新代码：

[{"id":"96197abb.fd4098","type":"http in","z":"b4aa8db5.217028","name":"","url":"/wastes","method":"get","upload":false,"swaggerDoc":"","x":90,"y":60,"wires":[["d5f42a96.83f688"]]},{"id":"bda39d37.edb418","type":"http response","z":"b4aa8db5.217028","name":"","statusCode":"200","headers":{},"x":720,"y":220,"wires":[]},{"id":"4a6bd014.f39868","type":"ibmdb","z":"b4aa8db5.217028","mydb":"3a218407.1cca74","name":"SELECT waste_view","x":740,"y":60,"wires":[["35f99a5a.c7f87e"],[]]},{"id":"9affb306.caf7e","type":"function","z":"b4aa8db5.217028","name":"SQL Query","func":"msg.database = \"iocdata\";\nmsg.payload = \"select count(*) from viseu.waste_view\";\n\nreturn msg;","outputs":1,"noerr":0,"x":530,"y":60,"wires":[["4a6bd014.f39868"]]},{"id":"74e28d3e.039be4","type":"debug","z":"b4aa8db5.217028","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","x":550,"y":280,"wires":[]},{"id":"d5f42a96.83f688","type":"change","z":"b4aa8db5.217028","name":"save req and res","rules":[{"t":"set","p":"req","pt":"flow","to":"req","tot":"msg"},{"t":"set","p":"res","pt":"flow","to":"res","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":290,"y":60,"wires":[["9affb306.caf7e"]]},{"id":"ca59ece2.844b3","type":"join","z":"b4aa8db5.217028","name":"","mode":"custom","build":"array","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"","count":"msg.count","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":390,"y":220,"wires":[["74e28d3e.039be4","c3ebb136.aa8988"]]},{"id":"35f99a5a.c7f87e","type":"function","z":"b4aa8db5.217028","name":"SQL Query","func":"msg.rowcount = msg.payload[1];\nmsg.database = \"iocdata\";\nmsg.payload = \"select * from viseu.waste_view\";\n\nreturn msg;","outputs":1,"noerr":0,"x":950,"y":60,"wires":[["327a8ae.a8ce2f6"]]},{"id":"2666e2ba.41dc8e","type":"ibmdb","z":"b4aa8db5.217028","mydb":"3a218407.1cca74","name":"SELECT waste_view","x":380,"y":140,"wires":[["90204f2d.8bafe8"],[]]},{"id":"327a8ae.a8ce2f6","type":"change","z":"b4aa8db5.217028","name":"save rowcount","rules":[{"t":"set","p":"rowcount","pt":"flow","to":"rowcount","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":160,"y":140,"wires":[["2666e2ba.41dc8e"]]},{"id":"90204f2d.8bafe8","type":"change","z":"b4aa8db5.217028","name":"get rowcount and count","rules":[{"t":"set","p":"rowcount","pt":"msg","to":"rowcount","tot":"flow"},{"t":"set","p":"count","pt":"msg","to":"count","tot":"flow"}],"action":"","property":"","from":"","to":"","reg":false,"x":630,"y":140,"wires":[["6888cd0d.d00064"]]},{"id":"6888cd0d.d00064","type":"function","z":"b4aa8db5.217028","name":"if count === rowcount","func":"//fix: msg.count ultrapassa msg.rowcount\nmsg.count = msg.count+1 || 1;\n\nif (msg.count === msg.rowcount) {\n    msg.complete = true;\n    msg.count = 0;\n}\n\nreturn msg;","outputs":1,"noerr":0,"x":880,"y":140,"wires":[["82ecfa98.9473d8"]]},{"id":"c3ebb136.aa8988","type":"change","z":"b4aa8db5.217028","name":"get req, res","rules":[{"t":"set","p":"req","pt":"msg","to":"req","tot":"flow"},{"t":"set","p":"res","pt":"msg","to":"res","tot":"flow"}],"action":"","property":"","from":"","to":"","reg":false,"x":550,"y":220,"wires":[["bda39d37.edb418"]]},{"id":"82ecfa98.9473d8","type":"change","z":"b4aa8db5.217028","name":"save count","rules":[{"t":"set","p":"count","pt":"flow","to":"count","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":210,"y":220,"wires":[["ca59ece2.844b3"]]},{"id":"3a218407.1cca74","type":"IbmDBdatabase","z":"","host":"10.102.0.69","port":"50002","db":"iocdata"}]