Author: Scott Chamberlain
Date: 2020-06-25

# sofa introduction

#### Scott Chamberlain

#### 2020-06-25

Make sure your CouchDB installation is running.

## Install sofa

Stable version

    install.packages("sofa")

Development version

    remotes::install_github("ropensci/sofa")

Load library

    library(sofa)

## sofa package API

The following is a breakdown of the major groups of functions - note that not all are included.

create a CouchDB client connection

- `Cushion`

work with databases

- `db_alldocs`
- `db_changes`
- `db_compact`
- `db_create`
- `db_delete`
- `db_explain`
- `db_info`
- `db_list`
- `db_query`
- `db_replicate`
- `db_revisions`
- `db_index`
- `db_index_create`
- `db_index_delete`

work with views/design documents

- `design_create`
- `design_create_`
- `design_delete`
- `design_get`
- `design_head`
- `design_info`
- `design_search`
- `design_search_many`

work with documents

- `doc_create`
- `doc_delete`
- `doc_get`
- `doc_head`
- `doc_update`
- `db_bulk_create`
- `db_bulk_update`
- `doc_attach_create`
- `doc_attach_delete`
- `doc_attach_get`
- `doc_attach_info`

## Create a connection client

If your CouchDB instance requires username and password make sure to pass those to `Cushion$new`

    (x <- Cushion$new(user="admin", pwd="password"))
    #> <sofa - cushion>
    #>   transport: http
    #>   host: 127.0.0.1
    #>   port: 5984
    #>   path:
    #>   type:
    #>   user: admin
    #>   pwd: <secret>

## Ping your server

    x$ping()
    #> $couchdb
    #> [1] "Welcome"
    #>
    #> $version
    #> [1] "3.1.0"
    #>
    #> $git_sha
    #> [1] "ff0feea20"
    #>
    #> $uuid
    #> [1] "30ed570659e8b72d688cfab563811c53"
    #>
    #> $features
    #> $features[[1]]
    #> [1] "access-ready"
    #>
    #> $features[[2]]
    #> [1] "partitioned"
    #>
    #> $features[[3]]
    #> [1] "pluggable-storage-engines"
    #>
    #> $features[[4]]
    #> [1] "reshard"
    #>
    #> $features[[5]]
    #> [1] "scheduler"
    #>
    #>
    #> $vendor
    #> $vendor$name
    #> [1] "The Apache Software Foundation"

## Create a new database

    db_create(x, 'cats')
    #> $ok
    #> [1] TRUE

## List databases

    db_list(x)
    #> [1] "cats"

## Create a document

    doc1 <- '{"name": "leo", "color": "blue", "furry": true, "size": 1}'
    doc_create(x, dbname = "cats", doc1, docid = "bluecat")
    #> $ok
    #> [1] TRUE
    #>
    #> $id
    #> [1] "bluecat"
    #>
    #> $rev
    #> [1] "1-41784f190c466d990684003a958c9f39"

and another!

    doc2 <- '{"name": "samson", "color": "red", "furry": false, "size": 3}'
    doc_create(x, dbname = "cats", doc2)
    #> $ok
    #> [1] TRUE
    #>
    #> $id
    #> [1] "3e80ffb4c86ccbf35d2c3b3314000bfa"
    #>
    #> $rev
    #> [1] "1-08aef850a23f5ff95869c9cf5d9604dc"

and one more, cause 3’s company

    doc3 <- '{"name": "matilda", "color": "green", "furry": false, "size": 5, "age": 2}'
    doc_create(x, dbname = "cats", doc3)
    #> $ok
    #> [1] TRUE
    #>
    #> $id
    #> [1] "3e80ffb4c86ccbf35d2c3b3314001a3a"
    #>
    #> $rev
    #> [1] "1-953d3cfbbebb977fb75940c2bb0c93a1"

Note how we used a document id in the first document creation, but not in the second and third. Using a document id is optional.

Also note that the third document has an additional field “age”.

## Changes feed

    db_changes(x, "cats")
    #> $results
    #> $results[[1]]
    #> $results[[1]]$seq
    #> [1] "1-g1AAAABteJzLYWBgYMpgTmHgzcvPy09JdcjLz8gvLskBCScyJNX___8_K4M5kTEXKMBubJZqnpacjK4Yh_Y8FiDJ0ACk_oNMSWTIAgD59SI-"
    #>
    #> $results[[1]]$id
    #> [1] "3e80ffb4c86ccbf35d2c3b3314000bfa"
    #>
    #> $results[[1]]$changes
    #> $results[[1]]$changes[[1]]
    #> $results[[1]]$changes[[1]]$rev
    #> [1] "1-08aef850a23f5ff95869c9cf5d9604dc"
    #>
    #>
    #>
    #>
    #> $results[[2]]
    #> $results[[2]]$seq
    #> [1] "2-g1AAAABteJzLYWBgYMpgTmHgzcvPy09JdcjLz8gvLskBCScyJNX___8_K4M5kSkXKMBubJZqnpacjK4Yh_Y8FiDJ0ACk_oNMSWTIAgD6OyI_"
    #>
    #> $results[[2]]$id
    #> [1] "3e80ffb4c86ccbf35d2c3b3314001a3a"
    #>
    #> $results[[2]]$changes
    #> $results[[2]]$changes[[1]]
    #> $results[[2]]$changes[[1]]$rev
    #> [1] "1-953d3cfbbebb977fb75940c2bb0c93a1"
    #>
    #>
    #>
    #>
    #> $results[[3]]
    #> $results[[3]]$seq
    #> [1] "3-g1AAAACLeJzLYWBgYMpgTmHgzcvPy09JdcjLz8gvLskBCScyJNX___8_K4M5kSkXKMBubJZqnpacjK4Yh_Y8FiDJ0ACk_kNNYQSbkpZiZmGaaIauJwsAaKQq8g"
    #>
    #> $results[[3]]$id
    #> [1] "bluecat"
    #>
    #> $results[[3]]$changes
    #> $results[[3]]$changes[[1]]
    #> $results[[3]]$changes[[1]]$rev
    #> [1] "1-41784f190c466d990684003a958c9f39"
    #>
    #>
    #>
    #>
    #>
    #> $last_seq
    #> [1] "3-g1AAAACLeJzLYWBgYMpgTmHgzcvPy09JdcjLz8gvLskBCScyJNX___8_K4M5kSkXKMBubJZqnpacjK4Yh_Y8FiDJ0ACk_kNNYQSbkpZiZmGaaIauJwsAaKQq8g"
    #>
    #> $pending
    #> [1] 0

## Search

The simplest search just returns the documents.

    db_query(x, dbname = "cats", selector = list(`_id` = list(`$gt` = NULL)))$docs
    #> [[1]]
    #> [[1]]$`_id`
    #> [1] "3e80ffb4c86ccbf35d2c3b3314000bfa"
    #>
    #> [[1]]$`_rev`
    #> [1] "1-08aef850a23f5ff95869c9cf5d9604dc"
    #>
    #> [[1]]$name
    #> [1] "samson"
    #>
    #> [[1]]$color
    #> [1] "red"
    #>
    #> [[1]]$furry
    #> [1] FALSE
    #>
    #> [[1]]$size
    #> [1] 3
    #>
    #>
    #> [[2]]
    #> [[2]]$`_id`
    #> [1] "3e80ffb4c86ccbf35d2c3b3314001a3a"
    #>
    #> [[2]]$`_rev`
    #> [1] "1-953d3cfbbebb977fb75940c2bb0c93a1"
    #>
    #> [[2]]$name
    #> [1] "matilda"
    #>
    #> [[2]]$color
    #> [1] "green"
    #>
    #> [[2]]$furry
    #> [1] FALSE
    #>
    #> [[2]]$size
    #> [1] 5
    #>
    #> [[2]]$age
    #> [1] 2
    #>
    #>
    #> [[3]]
    #> [[3]]$`_id`
    #> [1] "bluecat"
    #>
    #> [[3]]$`_rev`
    #> [1] "1-41784f190c466d990684003a958c9f39"
    #>
    #> [[3]]$name
    #> [1] "leo"
    #>
    #> [[3]]$color
    #> [1] "blue"
    #>
    #> [[3]]$furry
    #> [1] TRUE
    #>
    #> [[3]]$size
    #> [1] 1

Search for cats that are red

    db_query(x, dbname = "cats", selector = list(color = "red"))$docs
    #> [[1]]
    #> [[1]]$`_id`
    #> [1] "3e80ffb4c86ccbf35d2c3b3314000bfa"
    #>
    #> [[1]]$`_rev`
    #> [1] "1-08aef850a23f5ff95869c9cf5d9604dc"
    #>
    #> [[1]]$name
    #> [1] "samson"
    #>
    #> [[1]]$color
    #> [1] "red"
    #>
    #> [[1]]$furry
    #> [1] FALSE
    #>
    #> [[1]]$size
    #> [1] 3

Search for cats that are furry

    db_query(x, dbname = "cats", selector = list(furry = TRUE))$docs
    #> [[1]]
    #> [[1]]$`_id`
    #> [1] "bluecat"
    #>
    #> [[1]]$`_rev`
    #> [1] "1-41784f190c466d990684003a958c9f39"
    #>
    #> [[1]]$name
    #> [1] "leo"
    #>
    #> [[1]]$color
    #> [1] "blue"
    #>
    #> [[1]]$furry
    #> [1] TRUE
    #>
    #> [[1]]$size
    #> [1] 1

Return only certain fields

    db_query(x, dbname = "cats",
             selector = list(size = list(`$gt` = 2)),
             fields = c("name", "color"))$docs
    #> [[1]]
    #> [[1]]$name
    #> [1] "samson"
    #>
    #> [[1]]$color
    #> [1] "red"
    #>
    #>
    #> [[2]]
    #> [[2]]$name
    #> [1] "matilda"
    #>
    #> [[2]]$color
    #> [1] "green"

Convert the result of a query into a data.frame using `jsonlite`

    library('jsonlite')
    res <- db_query(x, dbname = "cats",
                     selector = list(`_id` = list(`$gt` = NULL)),
                     fields = c("name", "color", "furry", "size", "age"),
                     as = "json")

    fromJSON(res)$docs
    #>      name color furry size age
    #> 1  samson   red FALSE    3  NA
    #> 2 matilda green FALSE    5   2
    #> 3     leo  blue  TRUE    1  NA