Convert JSON array into CSV
The issue is not really that the JSON that you show is an array, but that each element of the array (of which you only have one) is a fairly complex structure. It is straight forward to extract the relevant data from each array entry into a shorter flat array and convert that into CSV with @csv in jq:
jq -r '.[] | [
.id,
.link,
.metadata."@context",
.metadata."@type",
.metadata.name,
.metadata.inLanguage,
.metadata.image,
.metadata.author[0]."@type",
.metadata.author[0].name,
.metadata.license."@type",
.metadata.license.url,
.metadata.license.name
] | @csv' file.json
... but notice how I'm forced to decide that we're only ever interested in the first author (the .metadata.author sub-structure is an array).
The output:
"4","https://pressbooks.online.ucf.edu/amnatgov/","http://schema.org","Book","American Government","en","https://pressbooks.online.ucf.edu/app/uploads/sites/4/2020/01/American-Government.png","Person","OpenStax","CreativeWork","https://creativecommons.org/licenses/by/4.0/","CC BY (Attribution)"
To create author name strings that are concatenations of all author names (and similarly for author types), with ; as delimiter, you could instead of .metadata.author[0].name in the above use [.metadata.author[].name]|join(";") (and [.metadata.author[]."@type"]|join(";") for the type), so that your command becomes
jq -r '.[] | [
.id,
.link,
.metadata."@context",
.metadata."@type",
.metadata.name,
.metadata.inLanguage,
.metadata.image,
( [ .metadata.author[]."@type" ] | join(";") ),
( [ .metadata.author[].name ] | join(";") ),
.metadata.license."@type",
.metadata.license.url,
.metadata.license.name
] | @csv' file.json
Using Miller (https://github.com/johnkerl/miller) you can "flat" the JSON, running
mlr --j2c cat input.json >output.csv
+----+---------------------------------------------+-------------------+----------------+---------------------+---------------------+------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------+---------------------------------------+-------------------------+------------------------+------------------------+--------------------------------+-------------------------------+------------------------+----------------------------------------------+-----------------------+-----------------------------------------------------+---------------------------------------------------------------------------+-----------------------------------------------------------------+
| id | link | metadata:@context | metadata:@type | metadata:name | metadata:inLanguage | metadata:copyrightYear | metadata:disambiguatingDescription | metadata:image | metadata:isBasedOn | metadata:author:0:@type | metadata:author:0:name | metadata:datePublished | metadata:copyrightHolder:@type | metadata:copyrightHolder:name | metadata:license:@type | metadata:license:url | metadata:license:name | _links:api:0:href | _links:metadata:0:href | _links:self:0:href |
+----+---------------------------------------------+-------------------+----------------+---------------------+---------------------+------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------+---------------------------------------+-------------------------+------------------------+------------------------+--------------------------------+-------------------------------+------------------------+----------------------------------------------+-----------------------+-----------------------------------------------------+---------------------------------------------------------------------------+-----------------------------------------------------------------+
| 4 | https://pressbooks.online.ucf.edu/amnatgov/ | http://schema.org | Book | American Government | en | 2016 | The content of this textbook has been developed and arranged to provide a logical progression from the fundamental principles of institutional design at the founding, to avenues of political participation, to thorough coverage of the political structures that constitute American government. The book builds upon what students have already learned and emphasizes connections between topics as well as between theory and applications. The goal of each section is to enable students not just to recognize concepts, but to work with them in ways that will be useful in later courses, future careers, and as engaged citizens. | https://pressbooks.online.ucf.edu/app/uploads/sites/4/2020/01/American-Government.png | https://ucf-dev.pb.unizin.org/pos2041 | Person | OpenStax | 2016-01-06 | Organization | cnxamgov | CreativeWork | https://creativecommons.org/licenses/by/4.0/ | CC BY (Attribution) | https://pressbooks.online.ucf.edu/amnatgov/wp-json/ | https://pressbooks.online.ucf.edu/amnatgov/wp-json/pressbooks/v2/metadata | https://pressbooks.online.ucf.edu/wp-json/pressbooks/v2/books/4 |
+----+---------------------------------------------+-------------------+----------------+---------------------+---------------------+------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------+---------------------------------------+-------------------------+------------------------+------------------------+--------------------------------+-------------------------------+------------------------+----------------------------------------------+-----------------------+-----------------------------------------------------+---------------------------------------------------------------------------+-----------------------------------------------------------------+
and then extract the fields you want and renaming them using
mlr -I --csv cut -f "id","link","metadata:@context","metadata:@type","metadata:name","metadata:inLanguage","metadata:image","metadata:author:0:@type","metadata:author:0:name","metadata:license:@type","metadata:license:url","metadata:license:name" \
then label id,link,context,type,name,inLanguage,image,author_type,author_name,license_type,license_url,license_name output.csv
The output will be
+----+---------------------------------------------+-------------------+------+---------------------+------------+---------------------------------------------------------------------------------------+-------------+-------------+--------------+----------------------------------------------+---------------------+
| id | link | context | type | name | inLanguage | image | author_type | author_name | license_type | license_url | license_name |
+----+---------------------------------------------+-------------------+------+---------------------+------------+---------------------------------------------------------------------------------------+-------------+-------------+--------------+----------------------------------------------+---------------------+
| 4 | https://pressbooks.online.ucf.edu/amnatgov/ | http://schema.org | Book | American Government | en | https://pressbooks.online.ucf.edu/app/uploads/sites/4/2020/01/American-Government.png | Person | OpenStax | CreativeWork | https://creativecommons.org/licenses/by/4.0/ | CC BY (Attribution) |
+----+---------------------------------------------+-------------------+------+---------------------+------------+---------------------------------------------------------------------------------------+-------------+-------------+--------------+----------------------------------------------+---------------------+