Question about making json object from file directory

[shanekoss]

I'm attempting to scan a folder and its subfolders to make a json object of the entire directory. So far I have this:

struct json_node;
using json_node_ptr = std::shared_ptr<json_node>;

struct json_node
{
    std::string id;
    std::vector<json_node_ptr> children;
    
    json_node(std::string _id)
    : id{ _id }
    {
    }
};

void to_json(nlohmann::json& j, const json_node_ptr& node)
{
    j = {{node->id, node->children}};
}

int main (int argc, char* argv[])
{
    std::vector<std::string> values = {"Folder 1","Folder 2","Folder 3","Folder 4","fileInFolder"};
    std::vector<json_node_ptr> parents;
    
    for(int i = 0; i < values.size(); i++)
    {
        if ( i == 0 ) {
            auto root = std::make_shared<json_node>(values[0]);
            parents.push_back(root);
        } else {
            parents.push_back(std::make_shared<json_node>(values[i]));
            parents[i-1]->children.push_back(parents[i]);
        }
    }
  
    nlohmann::json j = parents[0];
    std::cout << j.dump(2) << std::endl;
    
    
    return 0;
}

which works somewhat - it returns this:

{ "Folder 1": [ { "Folder 2": [ { "Folder 3": [ { "Folder 4": [ { "fileInFolder": [] } ] } ] } ] } ] }

and i'd like to have the last item as a string in the array - not another object - like so:

{ "Folder 1": [ { "Folder 2": [ { "Folder 3": [ { "Folder 4": [ "fileInFolder" ] } ] } ] } ] }

More importantly - not sure how to adapt this to handle multiple files (vectors) in the directory - (not just the single vector I have here) so that all files and folders are represented correctly in the object. Any pointers would be appreciated!

[nlohmann]

Is the json_node struct mandatory or just a vehicle to get toward the solution? That is, would it be sufficient if you had a json make_path(std::vector<std::string>) function?

[shanekoss]

@nlohmann - thanks for the quick reply! That struct isn't mandatory at all. I wasn't sure how to approach it.

[nlohmann]

This seems so closed to a std::accumulate, but I did not get it to run. Another approach should be JSON Pointers, something like:

json j;
std::string p = "/Folder 1/0/Folder 2/0/Folder 3/0/Folder 4/0";
j[json::json_pointer(p)] = "fileInFolder";

This produces

{
    "Folder 1": [
        {
            "Folder 2": [
                {
                    "Folder 3": [
                        {
                            "Folder 4": [
                                "fileInFolder"
                            ]
                        }
                    ]
                }
            ]
        }
    ]
}

If this is what you want, then it should be easy to generate the string from the vector.

[nlohmann]

(See https://nlohmann.github.io/json/classnlohmann_1_1basic__json_a8ab61397c10f18b305520da7073b2b45.html#a8ab61397c10f18b305520da7073b2b45 for some information on the interface)

[shanekoss]

@nlohmann - that is super helpful. Thanks for the info and speedy reply.

for anyone finding this - also helpful to add the initial file as array so you can push_back to it like so:

    std::string one ="/folder 1/0/folder 2/0/folder 3/0/folder 4";
    if(j[json::json_pointer(one)] == nullptr){
        j[json::json_pointer(one)] = {"fileToAdd"};
    }
    else{
        j[json::json_pointer(one)].push_back("fileToAdd");
    }