CouchDB vhosts and URL rewrites for multiple arguments

Question

I've tried reading the CouchDB documentation, but I find it a bit vague in this area (FAUXTON, vhost specification). I've searched and read the responses on stackoverflow for "couchdb vhosts" and "couchdb rewrite url" and tried to apply the advice I can gleen there. Still stuck on this and would appreciate some specific direction if anyone can provide it.

I have around 1900 documents in a couchDB database. Each document has a "type" key. I've made 30 design documents, one per "type". Each design docuemnt has a view called "all" that returns all rows of the document of that type.

In the information below, dasvm01.com is not the actual server. It is behind a company firewall and not accessible to the outside world. I've tried to use it consistently, forgive me if I have errored anywhere.

So, now I can execute a GET like this from a browser:

dasvm01.com:5984/registryservice/_design/airplaneidtypes/_view/all

My immediate goal is to shorten this to:

dasvm01.com:5984/registryservice/airplaneidtypes

or

dasvm01.com:5984/registryservice/airplaneidtypes/all

To this end, I added a rewrites function to the airplaneidtypes design doc:

{
  "_id": "_design/airplaneidtypes",
  "_rev": "11-c28b41a718017cbcd65f82f4acc611cb",
  "views": {
    "all": {
      "map": "function (doc) 
           {  if(doc.ddoc === 'airplaneidtypes') 
               {    emit(doc._rev,doc);  }
           }"
    }
  },
  "language": "javascript",
  "rewrites": [
    {
      "from": "/airplaneidtypes",
      "to": "registryservice/_design/airplaneidtypes/_rewrite",
      "method": "GET"
    }
  ]
}

Now I think that I need to update the CouchDB daemon:vhosts setting: I took a crack at it, but I really had no level of confidence and it doesn't seem to work. In Fauxton, I have:

daemons     
auth_cache {couch_auth_cache, start_link, []}
... 
vhosts {dasvm01.com:5984, /registryservice/_design/airplaneidtypes/_rewrite, []}

Not sure if this is: - close, - way off, - not the correct place, - just needs quotes...

What can you tell me? I don't understand default the notation in Fauxton is trying to convey:

vhosts

    Virtual hosts manager. Provides dynamic add of vhosts without restart, wildcards support and dynamic routing via pattern matching
        [daemons]
            vhosts={couch_httpd_vhost, start_link, []}

Ultimately, I want/hope to allow the user to pass multiple key:value pairs on the URL and then rewrite them into a MANGO query. The user would pass something like this:

dasvm01.com:5984/registryservice/airplaneidtypes/model/A320/variant/251N

that would get rewritten into the MANGO query:

    {
    "selector": {
        "model": "A320",
        "variant": {"$eq": "251N"}
    },
    "fields": [
        "_id",
        "_rev",
        "status",
        "model",
        "variant",
        "variant-type",
        "oem",
        "historicaloem",
        "displaymodel",
        "actsmodel"
    ]
}

Megidd · Answer 1 · 2018-04-23T06:54:13.010

Ultimately, I want/hope to allow the user to pass multiple key:value pairs on the URL and then rewrite them into a MANGO query. The user would pass something like this:

dasvm01.com:5984/registryservice/airplaneidtypes/model/A320/variant/251N

I'm not sure which server-side technology you're using, but in the case of NodeJS/ExpressJS, you can do this:

User sends the following GET request from within the browser to ExpressJS server:

GET /registryservice/airplaneidtypes/model/A320/variant/251N

The ExpressJS which is running on dasvm01.com and listening on (for example) port 8080 receives the GET request and handles it like this:

app.get('/registryservice/:typeId/model/:modelId/variant/:variantId', (req, res)=>{

  // Now you have acess to req.params object
  // You can use them as you wish:

  mango_query = {
      "selector": {
          "model": `${req.params.modelId}`,
          "variant": {"$eq": `${req.params.variantId}`}
      },
      "fields": [
          "_id",
          "_rev",
          // ...
      ]
  }
  // You can communicate with CouchDB by making HTTP requests
  // to CouchDB server which is running (for example) on 127.0.0.1 and listening
  // on port 5984

  // For sending HTTP requests, you might use `node-fetch` package
})

Basically, the above idea is to use route parameters of ExpressJS server, so that you can re-route the user requests.

CouchDB vhosts and URL rewrites for multiple arguments

1 Answers1