storing only 3 records based on hardwareid

src/controllers/tanksController.js

@@ -958,6 +958,7 @@ exports.calculateCapacity = async (req, reply) => {
 };
 
 
+
 exports.IotDevice = async (req, reply) => {
   try {
     const { hardwareId, mode, tanks } = req.body;
@@ -973,20 +974,32 @@ exports.IotDevice = async (req, reply) => {
       tankHeight: tank.tankHeight,
       maxLevel: tank.maxLevel,
       minLevel: tank.minLevel,
-      date:date,
+      date: date,
-      time:time
+      time: time
     }));
 
-    // create a new IOttank document with the provided data
+    // create a new IotData document with the provided data
     const ottank = new IotData({ hardwareId, mode, tanks: tankDocuments, date, time });
 
     // save the document to MongoDB
     await ottank.save();
-    // get the latest document sorted in descending order of date and time
-    const latestOttank = await IotData.findOne({ hardwareId }).sort({ date: -1, time: -1 });
 
-    // send the latest document
+    // delete previous records except the three latest ones
-    reply.code(200).send({ latestOttank });
+    const previousRecords = await IotData.find({ hardwareId })
+      .sort({ date: -1, time: -1 })
+      .skip(3); // skip the three latest documents
+
+    for (const record of previousRecords) {
+      await record.remove();
+    }
+
+    // get the latest three documents sorted in descending order of date and time
+    const latestOttanks = await IotData.find({ hardwareId })
+      .sort({ date: -1, time: -1 })
+      .limit(3);
+
+    // send the latest documents
+    reply.code(200).send({ latestOttanks });
   } catch (err) {
     // send an error response
     reply.code(500).send({ error: err.message });
@@ -994,6 +1007,7 @@ exports.IotDevice = async (req, reply) => {
 };
 
 
+
 exports.getIotD = async(req, reply) => {
   try {
     await IotData.find({hardwareId: req.query.hardwareId})