# @node-red/runtime/flows/setFlows API rev check Issue?

**URL:** <https://discourse.nodered.org/t/node-red-runtime-flows-setflows-api-rev-check-issue/12945>\
**Category:** General\
**Created:** [5 July 2019 08:14 UTC](https://discourse.nodered.org/t/node-red-runtime-flows-setflows-api-rev-check-issue/12945 "2019-07-05T08:14:53Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![fabik111](https://avatars.discourse-cdn.com/v4/letter/f/b77776/32.png) [@fabik111](https://discourse.nodered.org/u/fabik111)\
**Post date:** [5 July 2019 08:14 UTC](https://discourse.nodered.org/t/node-red-runtime-flows-setflows-api-rev-check-issue/12945/1 "2019-07-05T08:14:53Z")

</div>

Hi,  
I'm trying to upload at run time a flows (collection of flow) using the setFlows function API but I got an unspecified stopping error.  
Following the call stack in debug mode I've landed into @node-red/runtime/lib/api/flows.js where there is the setFlows implementation.  
In the function I've found this check (lines 73-83) on flow's rev:

```auto
    if (flows.hasOwnProperty('rev')) {
      var currentVersion = runtime.nodes.getFlows().rev;
      if (currentVersion !== flows.rev) {
        var err;
        err = new Error();
        err.code = "version_mismatch";
        err.status = 409;
        //TODO: log warning
        return reject(err);
         }
  }

```

Obviously the importing flow's rev and the current flow's rev are different, and I enter in the error state.  
I've deleted these lines and now I am able to load flows without error.

Why I should not load flows with a different rev version? This check is a bug?

---

<div class="post-metadata">

**Author:** ![knolleary](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/knolleary/32/3_2.png) [@knolleary](https://discourse.nodered.org/u/knolleary)\
**Post date:** [5 July 2019 09:41 UTC](https://discourse.nodered.org/t/node-red-runtime-flows-setflows-api-rev-check-issue/12945/2 "2019-07-05T09:41:53Z")

</div>

Hi @fabik111

the api is described here: [POST /flows : Node-RED](https://nodered.org/docs/api/admin/methods/post/flows/)

The important part is here:

> If `v2` of the API is being used, the request should include `rev` property that is set to the latest `rev` value known to the requestor. If this value matches the `rev` value of the active flows in the runtime, the request will succeed.  
> If it does not match, this indicates the runtime is using a newer version of flows and the request is rejected with a `409` status code. This allows the requestor to resolve any differences and resubmit the request.

The `rev` property your client sends should be the `rev` of the flows it last loaded from the runtime. This tells the runtime if the client is making updates on top of the latest flows, or if other updates have happened in the runtime that the client doesn't know about. This ensures a client cannot accidentally overwrite flows it does not know about.

The response of the request will include the new `rev` value for the flows that have been deployed.

This all only applies if you set the `Node-RED-API-Version` header to `v2`. If you don't provide that header (or set it to `v1`) then you can just provide the flow without the `rev` and you won't need to deal with the conflict checking.

---

<div class="post-metadata">

**Author:** ![fabik111](https://avatars.discourse-cdn.com/v4/letter/f/b77776/32.png) [@fabik111](https://discourse.nodered.org/u/fabik111)\
**Post date:** [5 July 2019 12:23 UTC](https://discourse.nodered.org/t/node-red-runtime-flows-setflows-api-rev-check-issue/12945/3 "2019-07-05T12:23:59Z")

</div>

Thank you for your response.  
A couple of clarifications:

- I'm using [Node-RED module APIs](https://nodered.org/docs/api/modules) not [Admin HTTP API](https://nodered.org/docs/api/admin)
- Your response inspired me to send as parameter of setFlows(opts) an object without rev version, like this:

```auto
{
   user:'fabik',
   flows:{flows:saved.flows}, //saved is a flows object with flows and rev properties
 }

```

I had to add a layer `flows` because the function `runtime.nodes.setFlows` called inside `setFlows` has `flows.flows` as argument (@node-red/runtime/lib/api/flows.js line 84)

```auto
apiPromise = runtime.nodes.setFlows(flows.flows,deploymentType);

```

Maybe, in order to manage an object flows without rev, should be implemented an else branch like this:

```auto
 if (flows.hasOwnProperty('rev')) {
   var currentVersion = runtime.nodes.getFlows().rev;
   if (currentVersion !== flows.rev) {
     var err;
     err = new Error();
     err.code = "version_mismatch";
     err.status = 409;
     //TODO: log warning
     return reject(err);
  }
 apiPromise = runtime.nodes.setFlows(flows.flows,deploymentType);
 }else{
apiPromise = runtime.nodes.setFlows(flows,deploymentType);
}
               

```

Thank you again for your help  
BR