sofa (version 0.3.0)

db_query: Query a database.

Description

Query a database.

Usage

db_query(cushion, dbname, query = NULL, selector = NULL, limit = NULL,
  skip = NULL, sort = NULL, fields = NULL, use_index = NULL,
  as = "list", ...)

Arguments

cushion

A Cushion object. Required.

dbname

Database name

query

(character) instead of using the other parameters, you can compose one R list or json blob here

selector

(json) - JSON object describing criteria used to select documents. More information provided in the section on selector syntax. See the query_tutorial in this package, and the selectors docs http://docs.couchdb.org/en/2.0.0/api/database/find.html#find-selectors

limit

(number) - Maximum number of results returned. Default is 25. Optional

skip

(number) - Skip the first 'n' results, where 'n' is the value specified. Optional

sort

(json) - JSON array following sort syntax. Optional. See http://docs.couchdb.org/en/2.0.0/api/database/find.html#find-sort For some reason, sort doesn't work often, not sure why.

fields

(json) - JSON array specifying which fields of each object should be returned. If it is omitted, the entire object is returned. More information provided in the section on filtering fields. Optional See http://docs.couchdb.org/en/2.0.0/api/database/find.html#find-filter

use_index

(json) - Instruct a query to use a specific index. Specified either as <design_document> or ["<design_document>", "<index_name>"]. Optional

as

(character) One of list (default) or json

...

Curl args passed on to HttpClient

Value

JSON as a character string or a list (determined by the as parameter)

Examples

# NOT RUN {
## create a connection
(x <- Cushion$new())

file <- system.file("examples/omdb.json", package = "sofa")
strs <- readLines(file)

## create a database
if ("omdb" %in% db_list(x)) {
  invisible(db_delete(x, dbname="omdb"))
}
db_create(x, dbname='omdb')

## add some documents
invisible(db_bulk_create(x, "omdb", strs))

## query all in one json blob
db_query(x, dbname = "omdb", query = '{
  "selector": {
    "_id": {
      "$gt": null
    }
  }
}')

## query with each parameter
db_query(x, dbname = "omdb",
  selector = list(`_id` = list(`$gt` = NULL)))

db_query(x, dbname = "omdb",
  selector = list(`_id` = list(`$gt` = NULL)), limit = 3)

# fields
## single field works
db_query(x, dbname = "omdb",
  selector = list(`_id` = list(`$gt` = NULL)), limit = 3,
  fields = c('_id', 'Actors', 'imdbRating'))

## as well as many fields
db_query(x, dbname = "omdb",
  selector = list(`_id` = list(`$gt` = NULL)), limit = 3,
  fields = '_id')

## other queries
db_query(x, dbname = "omdb",
  selector = list(Year = list(`$gt` = "2013")))

db_query(x, dbname = "omdb", selector = list(Rated = "R"))

db_query(x, dbname = "omdb",
  selector = list(Rated = "PG", Language = "English"))

db_query(x, dbname = "omdb", selector = list(
  `$or` = list(
    list(Director = "Jon Favreau"),
    list(Director = "Spike Lee")
  )
), fields = c("_id", "Director"))

## when selector vars are of same name, use a JSON string
## b/c R doesn't let you have a list with same name slots
db_query(x, dbname = "omdb", query = '{
  "selector": {
    "Year": {"$gte": "1990"},
    "Year": {"$lte": "2000"},
    "$not": {"Year": "1998"}
  },
  "fields": ["_id", "Year"]
}')

## regex
db_query(x, dbname = "omdb", selector = list(
  Director = list(`$regex` = "^R")
), fields = c("_id", "Director"))

# }