#4 added basic services/models/interfaces to work with tracks

src/interfaces/IAlbumDto.ts

-import { Document, ObjectId } from "mongoose"
+import IAlbum from "./IAlbum"
 import IArtist from "./IArtist"
 
-export default interface IAlbumDto extends Document{
-    title: string
+export default interface IAlbumDto{
+    title: IAlbum['title']
     artist: IArtist['_id']
-    releaseYear: Date
+    releaseYear: IAlbum['releaseYear']
     coverImage: File
 }
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src/interfaces/ITrack.ts

+import { Types } from "mongoose";import IAlbum from "./IAlbum";
+
+export default interface ITrack{
+    _id: Types.ObjectId
+    title: string
+    album: IAlbum['_id']
+    length: number
+}
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src/interfaces/ITrackDto.ts

+import ITrack from "./ITrack";
+
+export default interface ITrackDto {
+    title: ITrack['title']
+    album: ITrack['album']
+    length: ITrack['length']
+}
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src/models/Track.ts

+import mongoose from "mongoose";
+import ITrack from "../interfaces/ITrack";
+
+
+const Schema = mongoose.Schema
+
+const TrackSchema = new Schema<ITrack>({
+    title:{
+        type: String,
+        require: true
+    },
+    album:{
+        type: Schema.Types.ObjectId,
+        ref: 'Album',
+        required: true
+    },
+    length:{
+        type: Number,
+        required: true
+    }
+})
+
+export const Track = mongoose.model<ITrack>('Track', TrackSchema)
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src/services/tracksService.ts

+import { Request } from "express";
+import { EStatuses } from "../enum/EStatuses";
+import IResponse from "../interfaces/IResponse";
+import ITrack from "../interfaces/ITrack";
+import ITrackDto from "../interfaces/ITrackDto";
+import { Track } from "../models/Track";
+
+
+export class TracksService {
+
+    public getTracks = async(req: Request): Promise<IResponse<ITrack[] | null>> => {
+        try{
+            let data
+            if (req.query.album){
+                data = await Track.find({album: req.query.album}).populate('album')
+            } else{
+                data = await Track.find().populate('album')
+            }
+            const response: IResponse<ITrack[] | null> = {
+                status: EStatuses.SUCCESS,
+                result: data,
+                message: 'Tracks found'
+            }
+            return response
+        } catch(err: unknown){
+            const error = err as Error 
+            const response: IResponse<null> = {
+                status: EStatuses.FAILURE,
+                result: null,
+                message: error.message
+            }
+            return response
+        }
+    }
+
+    public addTrack = async(trackDto: ITrackDto): Promise<IResponse<ITrack | null>> => {
+        try {
+            if (trackDto.title.trim() === '' || !trackDto.album || !trackDto.length || trackDto.length <= 0) throw new Error('All fields should exist and have valid value')
+            const album = new Track(trackDto)
+            const data = await album.save()
+            const response: IResponse<ITrack> = {
+                status: EStatuses.SUCCESS,
+                result: data,
+                message: 'Album added'
+            }
+            return response
+        } catch(err: unknown){
+            const error = err as Error 
+            const response: IResponse<null> = {
+                status: EStatuses.FAILURE,
+                result: null,
+                message: error.message
+            }
+            return response
+        }
+    }
+}
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