R/query.R

In data.world: Functions and Add-Ins for Working with 'data.world' Data Sets and Projects

"data.world-r
Copyright 2018 data.world, Inc.

Licensed under the Apache License, Version 2.0 (the \"License\");
you may not use this file except in compliance with the License.

You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an \"AS IS\" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied. See the License for the specific language governing
permissions and limitations under the License.

This product includes software developed at data.world, Inc.
https://data.world"

#' Execute a query on data.world.
#'
#' @param qry Query object of type qry_sql or qry_sparql.
#' @param ... S3 method specific params.
#' @return Query results as a data frame.
#' @seealso \code{\link{sql}} \code{\link{sparql}}
#' @export
query <- function(qry, ...) {
  UseMethod("query")
}

#' @export
query.default <- function(qry, ...) {
  print("nope.")
}

#' @describeIn query Execute a SQL query on data.world.
#' @examples
#' \dontrun{
#'   sql_stmt <- data.world::qry_sql("SELECT * FROM Tables")
#'   query_results_df <- data.world::query(
#'     sql_stmt, "jonloyens/an-intro-to-dataworld-dataset")
#' }
#' @export
query.qry_sql <- function(qry, ...) {
  # Internal function to help unpack '...' param
  # TODO Promote dataset param to S3 generic when query.data.world is removed
  query_fn <- function(qry, dataset) {
    return(
      dwapi::sql(
        dataset = dataset,
        query = qry$query_string,
        query_params = qry$params
      )
    )
  }

  return(query_fn(qry, ...))
}

#' @describeIn query Execute a SPARQL query on data.world.
#' @examples
#' \dontrun{
#'   sparql_stmt <- data.world::qry_sparql("SELECT ?s ?p ?o
#'                                          WHERE {
#'                                            ?s ?p ?o.
#'                                          }")
#'   query_results_df <- data.world::query(
#'     sparql_stmt, "jonloyens/an-intro-to-dataworld-dataset")
#' }
#' @export
query.qry_sparql <- function(qry, ...) {
  # Internal function to help unpack '...' param
  # TODO Promote dataset param to S3 generic when query.data.world is removed
  query_fn <- function(qry, dataset) {
    return(
      dwapi::sparql(
        dataset = dataset,
        query = qry$query_string,
        query_params = qry$params
      )
    )
  }
  return(query_fn(qry, ...))
}

#' Constructor function for SQL queries.
#'
#' @param query_string SQL query string.
#' @param params Sequence of positional query parameters.
#' @return Object of type \code{qry_sql}.
#' @examples
#' \dontrun{
#'   sql_stmt <- data.world::qry_sql("SELECT * FROM Tables")
#' }
#' @export
qry_sql <- function(query_string, params = NULL) {
  me <- list(query_string = query_string, params = params)
  class(me) <- "qry_sql"
  return(me)
}

#' Constructor function for SPARQL queries.
#'
#' @param query_string SPARQL query string.
#' @param params Sequence of named query parameters.
#' @return Object of type \code{qry_sparql}.
#' @examples
#' \dontrun{
#'   sparql_stmt <- data.world::qry_sparql("SELECT ?s ?p ?o
#'                                          WHERE {
#'                                            ?s ?p ?o.
#'                                          }")
#' }
#' @export
qry_sparql <- function(query_string, params = NULL) {
  me <- list(query_string = query_string, params = params)
  class(me) <- "qry_sparql"
  return(me)
}