# Flux: Problem using value from a query in a Flux script **URL:** \ **Category:** InfluxDB 2\ **Tags:** flux\ **Created:** [March 10, 2023, 2:25am UTC](https://community.influxdata.com/t/flux-problem-using-value-from-a-query-in-a-flux-script/28997 "2023-03-10T02:25:48Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![David00](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/david00/32/5242_2.png) [@David00](https://community.influxdata.com/u/David00)\ **Post date:** [March 10, 2023, 2:25am UTC](https://community.influxdata.com/t/flux-problem-using-value-from-a-query-in-a-flux-script/28997/1 "2023-03-10T02:25:48Z")
Hi, I’m working with InfluxDB 2.6 and trying to learn Flux. I have a decent handle on the basics, I think, but I’m finally stuck after slowly working towards my goal all day. Using the InfluxDB REPL, I’m running my script to extract a few meaningful datapoints out of a dataset, and then subtract them from one another. I’ve managed to put this script together on my own so far: ```auto // Get all of today's data from the ifHCOutOctets field of the ifTable measurement, and store it in out_data. out_data = from(bucket: "CPI") |> range(start: today()) |> filter(fn: (r) => r["_measurement"] == "ifTable") |> filter(fn: (r) => r["_field"] == "ifHCOutOctets") |> filter(fn: (r) => r["agent_host"] == "172.25.75.2") |> filter(fn: (r) => r["ifDescr"] == "TenGigabitEthernet0/0/0") // Get all of today's data from the ifHCInOctets field of the ifTable measurement, and store it in in_data. in_data = from(bucket: "CPI") |> range(start: today()) |> filter(fn: (r) => r["_measurement"] == "ifTable") |> filter(fn: (r) => r["_field"] == "ifHCInOctets") |> filter(fn: (r) => r["agent_host"] == "172.25.75.2") |> filter(fn: (r) => r["ifDescr"] == "TenGigabitEthernet0/0/0") // Get the min and max values of each of the datasets from above. out_max = out_data |> max() |> findRecord(idx: 0, fn: (key) => key._field == "ifHCOutOctets") out_min = out_data |> min() |> findRecord(idx: 0, fn: (key) => key._field == "ifHCOutOctets") out_max out_min ``` … and I’m simply trying to use the actual numeric value from `out_max` and `out_min` so I can subtract them. When I run this script in the REPL, it complains about no data being returned: > Error: failed to execute query: 400 Bad Request: error in query specification while starting program: this Flux script returns no streaming data. Consider adding a “yield” or invoking streaming functions directly, without performing an assignment This tells me that the `findRecord()` must not be working, so let’s comment those function calls out and try again: > Error: failed to execute query: 400 Bad Request: failed to initialize execute state: tried to produce more than one result with the name “\_result” Ok, great - there’s data there now. Let’s look only at `out_max` since the REPL complains about trying to show both `out_min` and `out_max`: ```auto out_max Result: _result Table: keys: [_start, _stop, _field, _measurement, agent_host, host, ifDescr, ifIndex] _start:time _stop:time _field:string _measurement:string agent_host:string host:string ifDescr:string ifIndex:string _time:time _value:int ------------------------------ ------------------------------ ---------------------- ---------------------- ---------------------- ---------------------- ----------------------- ---------------------- ------------------------------ -------------------------- 2023-03-10T00:00:00.000000000Z 2023-03-10T02:05:59.709855693Z ifHCOutOctets ifTable 172.25.75.2 a0b9499291be TenGigabitEthernet0/0/0 1 2023-03-10T02:04:00.000000000Z 63001463681217 ``` Looks promising, but I can’t seem to get the `_value` out of it. I tried accessing the `._value` parameter on out\_max: ```auto out_max._value Error: failed to execute query: 400 Bad Request: error @31:1-31:8: expected {A with _value: B} (record) but found stream[{ C with ifDescr: F, agent_host: E, _value: D, _time: time, _stop: time, _start: time, _measurement: string, _field: string, }] ``` Ok, so `._value` is expecting a record, but I gave it a stream instead. After crawling through the API docs for an hour, I came across [the documentation for `findRecord()`](https://docs.influxdata.com/flux/v0.x/stdlib/universe/findrecord/), which states: > `findRecord()` returns a row at a specified index as a record from the first table in a stream of tables that matches the specified predicate function. So, we know that `out_max` is clearly a stream, since one of the error messages above told it was a stream… so why isn’t `findRecord` working? I also found additional context in the [extract scalar values page](https://docs.influxdata.com/influxdb/v2.6/query-data/flux/scalar-values/#table-extraction). The table keys stored in `out_max` are clearly listed as `Table: keys: [_start, _stop, _field, _measurement, agent_host, host, ifDescr, ifIndex]`, and my function call for findRecord specifies that I want to search for the key named `_measurement` that has a value of `ifHCOutOctets`, which does in fact exist as demonstrated in the output above when I printed the entire `out_max` variable. Thank you for your time. ---
**Author:** ![Anaisdg](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/anaisdg/32/6401_2.png) [@Anaisdg](https://community.influxdata.com/u/Anaisdg)\ **Post date:** [March 19, 2023, 7:24pm UTC](https://community.influxdata.com/t/flux-problem-using-value-from-a-query-in-a-flux-script/28997/2 "2023-03-19T19:24:08Z")
Hello @David00, I applaud your research. You’re very close. I find it easier to use findRecord like so if you’ve already limited your stream to one table: ```auto // do the same for the out_max as well out_min = out_data |> min() |> findRecord(idx: 0, fn: (key) => true) ``` Now you can do the following ```auto array.from(rows: [{diff: out_min._value - out_max._value}]) |> yield(name: "spread") ``` That being said, you might be interested in the following function: > **[spread() function | Flux 0.x Documentation](https://docs.influxdata.com/flux/v0.x/stdlib/universe/spread/)** > > spread() returns the difference between the minimum and maximum values in a specified column. Additionally, you might find the following blog useful: > **[How to Extract Values & Visualize Scalars with Flux and InfluxDB](https://www.influxdata.com/blog/tldr-tech-tips-how-to-extract-values-visualize-scalars-and-perform-custom-aggregations-with-flux-and-influxdb/)** > > In this post, we learn how to use the reduce(), findColumn(), and findRecord() Flux functions to perform custom aggregations with InfluxDB. ---
**Author:** ![David00](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/david00/32/5242_2.png) [@David00](https://community.influxdata.com/u/David00)\ **Post date:** [March 20, 2023, 6:47pm UTC](https://community.influxdata.com/t/flux-problem-using-value-from-a-query-in-a-flux-script/28997/3 "2023-03-20T18:47:41Z")
Hi @Anaisdg, Thanks so much for finding this and providing assistance. I was very close indeed, and it looks like the largest missing piece to the puzzle was my understanding of the Flux REPL. I thought the `influx query` command was the same thing as the REPL, but I see it’s not. When I use the actual REPL utility, it’s much easier to get feedback on what’s happening with my Flux queries. Also, thank you for the link to the blog post about working with values. That’s very helpful! I had seen the link to the docs about working with scalars too, but couldn’t make much use of it since I was using the `influx query` command instead of the REPL. For anyone else who might find this helpful in the future, here are some details on the Flux REPL: > But in short, you don’t need to build it from source - you can just download the compiled binary from one of the [Flux releases](https://github.com/influxdata/flux/releases). Then, you can execute it and configure your datasource as a variable. My InfluxDB server is running as a Docker container, so this example will work to get Flux working with a container that has port 8086 exposed to the host, or, with a natively installed InfluxDB server: ```auto david@influx:~$ which flux /usr/local/bin/flux david@influx:~$ flux > data = from( bucket: "MYBUCKET", host: "http://127.0.0.1:8086", org: "MYORG", token: "MYTOKEN==" ) > data |> range(start: -1h) ``` ---
**Author:** ![Anaisdg](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/anaisdg/32/6401_2.png) [@Anaisdg](https://community.influxdata.com/u/Anaisdg)\ **Post date:** [March 21, 2023, 6:10pm UTC](https://community.influxdata.com/t/flux-problem-using-value-from-a-query-in-a-flux-script/28997/4 "2023-03-21T18:10:29Z")
Hello @David00, I’m happy you’ve figured it out!