Clojure: parse json and extract values - json

Question

I'm making an API call and using Cheshire to parse the JSON:
(defn fetch_headlines [source]
(let [articlesUrl (str "https://newsapi.org/v2/top-headlines?sources="
source
"&apiKey=a688e6494c444902b1fc9cb93c61d6987")]
(-> articlesUrl
client/get
generate-string
parse-string)))
The JSON payload:
{"status" 200, "headers" {"access-control-allow-headers" "x-api-key,
authorization", "content-type" "application/json; charset=utf-8",
"access-control-allow-origin" "*", "content-length" "7434",
"connection" "close", "pragma" "no-cache", "expires" "-1",
"access-control-allow-methods" "GET", "date" "Thu, 28 Mar 2019
20:22:16 GMT", "x-cached-result" "false", "cache-control" "no-cache"},
"body"
"{\"status\":\"ok\",\"totalResults\":10,\"articles\":[{\"source\":{\"id\":\"cnn\",\"name\":\"CNN\"},\"author\":null,\"title\":\"Trump:
Mueller probe was 'attempted takeover' of government - CNN
Video\",\"description\":\"In a Fox News interview with Sean Hannity,
President Trump called special counsel Robert Mueller's probe an
\\"attempted takeover of our
government.\\"\",\"url\":\"http://us.cnn.com/videos/politics/2019/03/28/trump-mueller-probe-attempted-takeover-hannity-cpt-sot-vpx.cnn\",\"urlToImage\":\"https://cdn.cnn.com/cnnnext/dam/assets/190324191527-06-trump-mueller-reaction-0324-super-tease.jpg\",\"publishedAt\":\"2019-03-28T20:09:04.1891948Z\",\"content\":\"Chat
with us in Facebook Messenger. Find out what's happening in the world
as it
unfolds.\"},{\"source\":{\"id\":\"cnn\",\"name\":\"CNN\"},\"author\":null,\"title\":\"James
Clapper reacts to call he should be investigated - CNN
Video\",\"description\":\"Former Director of National Intelligence
James Clapper reacts to White House press secretary Sarah Sanders
saying he and other former intelligence officials should be
investigated after special counsel Robert Mueller did not establish
collusion between the
Tr…\",\"url\":\"http://us.cnn.com/videos/politics/2019/03/26/james-clapper-reponse-mueller-report-sarah-sanders-criticism-bts-ac360-vpx.cnn\",\"urlToImage\":\"https://cdn.cnn.com/cnnnext/dam/assets/190325211210-james-clapper-ac360-03252019-super-tease.jpg\",\"publishedAt\":\"2019-03-28T20:08:43.1736236Z\",\"content\":\"Chat
with us in Facebook Messenger. Find out what's happening in the world
as it
unfolds.\"},{\"source\":{\"id\":\"cnn\",\"name\":\"CNN\"},\"author\":\"Maegan
Vazquez, CNN\",\"title\":\"Trump set for first rally since Mueller
investigation ended\",\"description\":\"President Donald Trump, making
his first appearance before supporters since Robert Mueller ended his
investigation, is set to speak during a rally in Grand Rapids,
Michigan Thursday
night.\",\"url\":\"http://us.cnn.com/2019/03/28/politics/donald-trump-grand-rapids-rally/index.html\",\"urlToImage\":\"https://cdn.cnn.com/cnnnext/dam/assets/190321115403-07-donald-trump-lead-image-super-tease.jpg\",\"publishedAt\":\"2019-03-28T19:49:26Z\",\"content\":\"Washington
(CNN)President Donald Trump, making his first appearance before
supporters since Robert Mueller ended his investigation, is set to
speak during a rally in Grand Rapids, Michigan Thursday
night.\r\nThe rally follows a chaotic week in Washington, preci…
[+2099
chars]\"},{\"source\":{\"id\":\"cnn\",\"name\":\"CNN\"},\"author\":\"Katelyn
Polantz, CNN\",\"title\":\"Judge orders Justice Dept. to turn over
Comey memos\",\"description\":\"A federal judge has ordered that the
James Comey memos are turned over, in a court case brought by CNN and
other media organizations for access to the documents memorializing
former FBI Director's interactions with President Donald
Trump.\",\"url\":\"http://us.cnn.com/2019/03/28/politics/james-comey-memo-lawsuit/index.html\",\"urlToImage\":\"https://cdn.cnn.com/cnnnext/dam/assets/181209143047-comey-1207-super-tease.jpg\",\"publishedAt\":\"2019-03-28T19:14:45Z\",\"content\":\"Washington
(CNN)A federal judge has ordered that the Justice Department and FBI
submit James Comey's memos in full to the court under seal, in a court
case brought by CNN and other media organizations for access to the
documents memorializing the former FBI d… [+1043
chars]\"},{\"source\":{\"id\":\"cnn\",\"name\":\"CNN\"},\"author\":\"Clare
Foran and Manu Raju, CNN\",\"title\":\"Pelosi calls AG's summary of
Mueller report 'arrogant'\",\"description\":\"House Speaker Nancy
Pelosi on Thursday criticized Attorney General William Barr's summary
of special counsel Robert Mueller's report, calling it
\\"condescending\\" and \\"arrogant\\" and saying \\"it wasn't
the right thing to
do.\\"\",\"url\":\"http://us.cnn.com/2019/03/28/politics/pelosi-mueller-report-congress-barr-summary/index.html\",\"urlToImage\":\"https://cdn.cnn.com/cnnnext/dam/assets/190328130240-02-nancy-pelosi-03282019-super-tease.jpg\",\"publishedAt\":\"2019-03-28T18:48:25Z\",\"content\":null},{\"source\":{\"id\":\"cnn\",\"name\":\"CNN\"},\"author\":\"Analysis
by Chris Cillizza, CNN Editor-at-large\",\"title\":\"The 43 most
outrageous lines from Donald Trump's phone interview with Sean
Hannity\",\"description\":\"There's no \\"reporter\\" that President
Donald Trump likes more than Fox News' Sean Hannity -- largely due to
Hannity's unwavering, puppy dog-like support for the President. Trump
likes to reward people who play nice with him, which brings us to the
45-minute
ph…\",\"url\":\"http://us.cnn.com/2019/03/28/politics/sean-hannity-donald-trump-mueller/index.html\",\"urlToImage\":\"https://cdn.cnn.com/cnnnext/dam/assets/190328140149-01-hannity-trump-file-super-tease.jpg\",\"publishedAt\":\"2019-03-28T18:44:21Z\",\"content\":\"(CNN)There's
no \\"reporter\\" that President Donald Trump likes more than Fox
News' Sean Hannity -- largely due to Hannity's unwavering, puppy
dog-like support for the President. Trump likes to reward people who
play nice with him, which brings us to the 45-minu… [+14785
chars]\"},{\"source\":{\"id\":\"cnn\",\"name\":\"CNN\"},\"author\":null,\"title\":\"Puerto
Rico Gov.: I'll punch the bully in the mouth - CNN
Video\",\"description\":\"In an exclusive interview with CNN, Puerto
Rico Governor Ricardo Rosselló said he would not sit back and allow
his officials to be bullied by the White
House.\",\"url\":\"http://us.cnn.com/videos/politics/2019/03/28/ricardo-rossello-trump-bully-puerto-rico-sot-vpx.cnn\",\"urlToImage\":\"https://cdn.cnn.com/cnnnext/dam/assets/190328123504-puerto-rico-gov-ricardo-rosello-super-tease.jpg\",\"publishedAt\":\"2019-03-28T18:08:33.7312458Z\",\"content\":\"Chat
with us in Facebook Messenger. Find out what's happening in the world
as it
unfolds.\"},{\"source\":{\"id\":\"cnn\",\"name\":\"CNN\"},\"author\":\"Jeremy
Herb, Manu Raju and Ted Barrett, CNN\",\"title\":\"Jared Kushner
interviewed by Senate Intelligence
Committee\",\"description\":\"President Donald Trump's son-in-law
Jared Kushner returned to the Senate Intelligence Committee for a
closed door interview Thursday as part of the committee's Russia
investigation.\",\"url\":\"http://us.cnn.com/2019/03/28/politics/jared-kushner-senate-intelligence/index.html\",\"urlToImage\":\"https://cdn.cnn.com/cnnnext/dam/assets/180302124221-30-jared-kushner-super-tease.jpg\",\"publishedAt\":\"2019-03-28T16:21:29Z\",\"content\":null},{\"source\":{\"id\":\"cnn\",\"name\":\"CNN\"},\"author\":\"Jeremy
Herb and Laura Jarrett, CNN\",\"title\":\"Mueller report more than 300
pages, sources say\",\"description\":\"Special counsel Robert
Mueller's confidential report on the Russia investigation is more than
300 pages, according to a Justice Department official and a second
source with knowledge of the
matter.\",\"url\":\"http://us.cnn.com/2019/03/28/politics/mueller-report-pages/index.html\",\"urlToImage\":\"https://cdn.cnn.com/cnnnext/dam/assets/190324130054-05-russia-investigation-0324-super-tease.jpg\",\"publishedAt\":\"2019-03-28T15:52:01Z\",\"content\":null},{\"source\":{\"id\":\"cnn\",\"name\":\"CNN\"},\"author\":\"Jim
Acosta and Kevin Liptak, CNN\",\"title\":\"Exclusive: Puerto Rico
governor warns White House over funding\",\"description\":\"Tensions
are escalating between President Donald Trump and Puerto Rico's
governor over disaster relief efforts that have been slow in coming
for the still-battered island after Hurricane
Maria.\",\"url\":\"http://us.cnn.com/2019/03/28/politics/ricardo-rossell-donald-trump-puerto-rico-funding/index.html\",\"urlToImage\":\"https://cdn.cnn.com/cnnnext/dam/assets/180920230539-pr-storm-of-controversy-rossello-trump-super-tease.jpg\",\"publishedAt\":\"2019-03-28T15:19:39Z\",\"content\":null}]}",
"trace-redirects"
["https://newsapi.org/v2/top-headlines?sources=cnn&apiKey=a688e6494c444902b1fc9cb93c61d687"]}
I'd like to extract to extract the URLs from the returned JSON payload, I've tried this:
(defn fetch_headlines [source]
(let [articlesUrl (str "https://newsapi.org/v2/top-headlines?sources="
source
"&apiKey=a688e6494c444902b1fc9cb93c61d697")]
(-> articlesUrl
client/get
generate-string
parse-string
(get-in ["source" "url"]))))
But I get a nil result, any ideas?
SOLUTION based on user feedback:
(defn fetch-headlines [source]
(let [articlesUrl (str "https://newsapi.org/v2/top-headlines?sources="
source
"&apiKey=a688e6494c444902b1fc9cb93c61d697")]
(-> articlesUrl
client/get
:body
parse-string
(get-in ["articles" 0 "url"]))))

Answer 1

What you need is inside the body key, but the value corresponding to that key is still a string and not yet a clojure map. When you look for source, you're getting nil back because that key doesn't exist (it should be inside body, after correctly parsing the string into json).
Once you've properly parsed the body value, it should be something like:
(let [index-of-article 0]
(get-in response ["body" "articles" index-of-article "url"]))
where index-of-article is the positional index of the article you want, since articles contains a vector of articles.