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        /__\ || |   / __\___  _   _  ___| |__    /   \/ __\
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A Collection of R functions for CouchDB access

The R4CouchDB package provides a collection of functions for basic database and document management operations such as add and delete.

Every cdbFunction() gets and emits a list containing the connection set up. With the cdbIni() function the cdb$serverName is set to "localhost" as a default. There are some examples below the demo folder.

Note: Check out sofa, from @recology_ another R package to interact with CouchDB.

Getting started

  • download latest version or clone repository

  • open a shell and install the package with:

       R CMD INSTALL R4CouchDB

    dependencies (bitopts, RCurl, RJSONIO) can be installed in the same way

  • an easier way for those who have devtools installed is

       library(devtools)
   install_github('R4CouchDB', 'wactbprot', subdir = 'R4CouchDB')

    (see e.g. http://www.inside-r.org/packages/cran/devtools/docs/install_github)

  • open R shell and load library with:

       library(R4CouchDB)

  • generate a connection object (list) with:

       foo <- cdbIni()

  • play around with foo

       foo$queryParam <- "count=10"
   cdbGetUuidS(foo)$res

  • or make a twitter_db and fill up some search results from the request http://search.twitter.com/search.json?q=couchdb

       foo$newDBName  <- "japan_db"
   foo            <- cdbMakeDB(foo)
   u              <- "http://search.twitter.com/search.json?q=japan&rpp=100&page=10"
   res            <- fromJSON(getURLContent(u))
   lapply(res$results,
              function(i){
                   foo$dataList <- i
                   cdbAddDoc(foo)$error
               })

  • get angry and write a ticket or mail

Problems

untar

If you get somenthing like this:

    untar2(tarfile, files, list, exdir) : unsupported entry type ‘x’

on installation you can try

   export R_INSTALL_TAR=tar

and than

   R CMD INSTALL R4CouchDB_latest_

\r

In cdbIni I added with 0.1.2 the lines:

   cdb$toJSON <- function(lst){
     jsn <- toJSON(lst, collapse = "")
     jsn <- gsub("\\r","\\\\r",jsn)
     return(jsn)
   }

The point is: one can have a

   {"a":"\r"}

in the database but one can not send it back this way. A \r is here replaced by \r resulting in \r in the database. The gsub statement behaves like this:

   > gsub("\\r","\\\\r","\r")
   [1] "\\r"
   > gsub("\\r","\\\\r","\\r")
   [1] "\\r"
   > gsub("\\r","\\\\r","\\\r")
   [1] "\\\\r"
   > gsub("\\r","\\\\r","\\\\r")
   [1] "\\\\r"

I'm not happy with this but have no better solution for the moment.