remove unused json fields when parsing to reduce memory/file size of the final json

README.md

@@ -22,9 +22,9 @@ You can build the SQL script before making the comm/user though.
 
 - - since right now it just changes the upvotes to be negative or whatever the score is
 
-- Remove the json fields from comments and posts that don't get used for importing, so that the final array of trees of posts/nested comments takes up less memory/space.
+- Remove the json fields from comments and posts that don't get used for importing, so that the final array of trees of posts/nested comments takes up less memory/space. ✔
 
-- Save the final json to a file and read it through StreamArray, so that the memory is freed once the archive has finished processing
+- Save the final json to a file and read it through StreamArray, so that the memory is freed once the archive has finished processing ✔
 
 ## references
 

src/index.js

@@ -32,7 +32,7 @@ var args = yargs(process.argv.slice(2))
     })
     .string(['comm', 'user', 'output', 'posts', 'comments'])
     .nargs(['comm', 'user', 'output', 'posts', 'comments'], 1)
-    .demandOption(['comm', 'user', 'output', 'posts', 'comments'])
+    .demandOption(['comm', 'user',  'posts', 'comments'])
     .help('h')
     .alias('h', 'help')
     .epilog("git: https://git.stardust.wtf/starlight/reddit-lemmy-importer")
@@ -44,8 +44,6 @@ processPostsAndComments(args.posts, args.comments, (result) => {
   console.log(result)
 }); */
 
-console.log(args.output?.trim())
-
 function printThreadStructure(thread, level = 0) {
     thread.forEach(item => {
       var out = '';
@@ -65,29 +63,34 @@ async function unflatten(postsFile, commentsFile) {
         //console.log('Thread Structure:');
         //printThreadStructure(result);
         
-        const resultOutput = `${result[0].subreddit}-threads.json`;
+        const subredditName = result[0].subreddit_name_prefixed.slice(2);
+        const resultOutput = `${subredditName}-threads.json`;
 
         // Write the result to a file
         writeFileSync(resultOutput, JSON.stringify(result, null, 2));
 
         result = {};
         
+        // read the threads through a stream
         const pipeline = createReadStream(resultOutput).pipe(streamArray.withParser());
         
         // empty the sql file if it exists
         existsSync(args.output) ? writeFileSync(args.output, '') : null
-        const sqlOutput = createWriteStream(args.output, {flags: "a"});
+        // write the sql to the user specified path, or use [subredditname].sql if none is chosen
+        const sqlOutput = createWriteStream(args.output?.trim() ? args.output : `${subredditName}.sql`, {flags: "a"});
 
         var threadCounter = 0;
 
+        // create an sql query to make a lemmy thread for each json object
         pipeline.on('data', (thread) => {
           sqlOutput.write(writeSql(thread.value, args.comm, args.user));
           threadCounter++;
         });
 
+        // close the stream and say how many threads are processed and where its saved
         pipeline.on('end', () => {
           sqlOutput.close();
-          console.log(`Finished processing ${threadCounter} threads, sql saved to ${resultOutput}`);
+          console.log(`Finished processing ${threadCounter} threads, sql saved to ${sqlOutput.path}.`);
         });
 
         // old

src/parser.js

@@ -41,8 +41,26 @@ class ProcessingContext {
     }
 }
 
+// remove all fields from jsonObj that arent in the allowedKeys array
+function filterJsonKeys(jsonObj, allowedKeys) {
+    // Input validation
+    if (typeof jsonObj !== 'object' || jsonObj === null) {
+        throw new TypeError('Input must be an object');
+    }
+    
+    return Object.fromEntries(
+        Object.entries(jsonObj)
+            .filter(([key]) => allowedKeys.includes(key))
+    );
+}
+
 async function processPostsAndComments(postsFile, commentsFile) {
     const context = new ProcessingContext();
+
+    // allowed fields
+    // reduced the size of my dummy json to about 31% of its size without the filters
+    const submissionKeysAllowed = ["author", "author_flair_text", "created_utc", "edited", "gallery_data", "is_gallery", "locked", "media_metadata", "name", "parent_id", "score", "selftext", "stickied", "subreddit_name_prefixed", "title", "url"];
+    const commentKeysAllowed = ["author", "author_flair_text", "body", "created_utc", "link_id", "name", "parent_id", "score", "subreddit_name_prefixed"];
     
     // Process posts first
     const postsStream = createInterface({
@@ -52,7 +70,7 @@ async function processPostsAndComments(postsFile, commentsFile) {
 
     for await (const line of postsStream) {
         if (line.trim()) {
-            const post = JSON.parse(line);
+            const post = filterJsonKeys(JSON.parse(line), submissionKeysAllowed);
             context.processItem(post);
         }
     }
@@ -65,7 +83,7 @@ async function processPostsAndComments(postsFile, commentsFile) {
 
     for await (const line of commentsStream) {
         if (line.trim()) {
-            const comment = JSON.parse(line);
+            const comment = filterJsonKeys(JSON.parse(line), commentKeysAllowed);
             context.processItem(comment);
         }
     }