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Json – R Query of a Wikimedia server

I am trying to query the Cameo database.

If I use the URL https://cameo.mfa.org/api.php?action=query&pageids=17051&prop=extracts&format=json, then I get, online, a valid output.

However, if I use:

library(httr)
library(jsonlite)

base_url <- "https://cameo.mfa.org/api.php"

query_param <- list(action  = "query",
                    pageids = "17051",
                    format = "json",
                    prop = "extracts"
)

parsed_content <- httr::GET(base_url, query_param)

jsonlite::fromJSON(content(parsed_content, as = "text", encoding = "UTF-8"))

Then jsonlite fails because the output is in html format and not json.

Do you have any advice on this?

Tags:

2

Answers


  1. 0

    A bit different approach:

    library(httr)
library(jsonlite)

url <- httr::parse_url("https://cameo.mfa.org/api.php")
url$query <- list(
  action = "query",
  pageids = "17051",
  format = "json",
  prop = "extracts"
)

json <- jsonlite::fromJSON(httr::build_url(url))


json$query$pages
#> $`17051`
#> $`17051`$pageid
#> [1] 17051
#> 
#> $`17051`$ns
#> [1] 0
#> 
#> $`17051`$title
#> [1] "Copper"
#> 
#> $`17051`$extract
#> [1] "<h2><span id="Description">Description</span></h2>n<p>A reddish-brown, ductile, metallic element. Copper is present [...]"

    Created on 2023-07-03 with reprex v2.0.2

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  2. 0

    The second argument to httr::GET is config=, which is not where you should be assigning query_param. Instead name it as query=query_param.

    res <- httr::GET(base_url, query = query_param)
res
# Response [https://cameo.mfa.org/api.php?action=query&pageids=17051&format=json&prop=extracts]
#   Date: 2023-07-03 15:06
#   Status: 200
#   Content-Type: application/json; charset=utf-8
#   Size: 5.22 kB
str(httr::content(res))
# List of 3
#  $ batchcomplete: chr ""
#  $ warnings     :List of 1
#   ..$ extracts:List of 1
#   .. ..$ *: chr "HTML may be malformed and/or unbalanced and may omit inline images. Use at your own risk. Known problems are li"| __truncated__
#  $ query        :List of 1
#   ..$ pages:List of 1
#   .. ..$ 17051:List of 4
#   .. .. ..$ pageid : int 17051
#   .. .. ..$ ns     : int 0
#   .. .. ..$ title  : chr "Copper"
#   .. .. ..$ extract: chr "<h2><span id="Description">Description</span></h2>n<p>A reddish-brown, ductile, metallic element. Copper is "| __truncated__
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