So you are trying to populate defaults => sections => contents right?
By default Strapi only goes one level deep (so defaults => sections) but you can customize the population. Replace the default find
service with the example from our documentation here: https://strapi.io/documentation/v3.x/concepts/services.html#find
And we need to customize the population array:
Path: ./api/default/services/default.js
module.exports = {
/**
* Promise to fetch all records
*
* @return {Promise}
*/
find(params, populate) {
return strapi.query('default').find(params, ["section", "section.content"]);
},
};