post a JSON file with curl

curl_post_json.md

How do you POST a JSON file with curl??

You can post a json file with curl like so:

curl -X POST -H "Content-Type: application/json" -d @FILENAME DESTINATION

so for example:

curl -X POST -H "Content-Type: application/json" -d @../data/cats.json http://localhost:8080/mSfvMwNAfj

you can post a little blob of geojson, like so:

curl -X POST -H "Content-Type: application/json" -d '{"type":"Feature","properties":{"COUNTY":"M","PRECINCT":4505.0,"AREA":24330472.48801},"geometry":{"type":"Polygon","coordinates":[[[-122.579029970781065,45.53373981165327],[-122.579036751674209,45.533742065313575],[-122.579532751335037,45.533906068395808],[-122.579961749295705,45.534067060396104],[-122.580146749064056,45.534114065074704],[-122.581902757566823,45.534772060883959],[-122.582770766094569,45.535128058282019],[-122.583461773870638,45.535383050711246],[-122.584275765662781,45.535596050402262],[-122.584926770675438,45.535732043153857],[-122.585534768605342,45.535823041352423],[-122.586393777046183,45.535863042628513],[-122.586845771939593,45.535841037753478],[-122.587166778711079,45.535850042847976],[-122.587593783117342,45.535829037919441],[-122.587900782381638,45.535804036638346],[-122.588290773918729,45.535750036812139],[-122.588704782064923,45.535671034778389],[-122.589196776268082,45.535561035548149],[-122.589239647326053,45.535550318867173],[-122.589320708749753,45.536124484404517],[-122.589304695035338,45.537268231315537],[-122.59947923271595,45.53740953002616],[-122.599372142997979,45.537656509885132],[-122.601520781310597,45.537617244011571],[-122.601391421360532,45.543541079913162],[-122.578671442407,45.552336859399695],[-122.578672106607101,45.55230042862145],[-122.578693794893084,45.551092987187559],[-122.578713188347777,45.549969468845575],[-122.579029970781065,45.53373981165327]]]}}' http://localhost:8080/mSfvMwNAfj

Don't try to post a big blob, your terminal will hate you and you will hate yourself. It will go on forever and ever.

Use the syntax above (curl -X POST -H "Content-Type: application/json" -d @FILENAME DESTINATION) to specify a file instead.

Btw. curl supports json directly

from man curl:

--json
(HTTP) Sends the specified JSON data in a POST request to the HTTP server. --json works as a shortcut for passing on these three options:

           --data [arg]
           --header "Content-Type: application/json"
           --header "Accept: application/json"

          There is no verification that the passed in data is actual JSON or that the syntax is correct.

          If you start the data with the letter @, the rest should be a file name to read the data from, or a single dash (-) if you want curl to read the data from stdin. Posting data from a file named 'foobar' would thus be done with --json @foobar and to instead read the data from stdin, use --json @-.

          If this option is used more than once on the same command line, the additional data pieces will be concatenated to the previous before sending.

          The headers this option sets can be overridden with -H, --header as usual.

          --json can be used several times in a command line

          Examples:
           curl --json '{ "drink": "coffe" }' https://example.com
           curl --json '{ "drink":' --json ' "coffe" }' https://example.com
           curl --json @prepared https://example.com
           curl --json @- https://example.com < json.txt

          See also --data-binary and --data-raw. This option is mutually exclusive to -F, --form and -I, --head and -T, --upload-file. Added in 7.82.0.

@JaSei this is true as of v7.82.0! That feature was released 2022-03-05, so older systems may still benefit from this older advice. 👴

refs:

• https://curl.se/docs/manpage.html#--json
• https://curl.se/docs/releases.html

Thanks, this worked for loading a local file.

curl -X POST -H "Content-Type: application/json" -d @../data/cats.json