Golang Struct for Nested Objects-CodePudding

I am currently creating a golang api using GoFiber V2.

I have the following document structure for a music track in a Mongo database:

{
    "_id" : ObjectId("63cc26cb86ae1611380e1206"),
    "active" : 1,
    "exclusive" : "false",
    "track_title" : "Burn Slow (sting)",
    "artist_id" : "395",
    "artist_name" : "David Hollandsworth",
    "album_title" : "Cult Justice 23",
    "composer" : "David Hollandsworth",
    "duration" : "00:16",
    "publisher" : "FlikTrax, LLC",
    "description" : "T.V. drama, rural tension, apprehension. Style: \"Hell on Wheels\" soundtrack.",
    "url_path" : "davidhollandsworth/cultjustice23/burn-slow-sting.wav",
    "vocal_type" : "instrumental",
    "beats_per_minute" : "80",
    "file_path_compressed" : "davidhollandsworth/cultjustice23/burn-slow-sting.mp3",
    "file_path_uncompressed" : "davidhollandsworth/cultjustice23/burn-slow-sting.wav",

    "genres" : [ 
        "Tension", 
        "Americana", 
        "Tv Drama"
    ],
    "genres_keys" : [ 
        "tension", 
        "americana", 
        "tv drama"
    ],
    "moods" : [ 
        "tension", 
        "bluesy", 
        "spacey"
    ],
    "styles" : [ 
        "tv drama", 
        "unsolved mystery", 
        "western"
    ],
    "instruments" : [ 
        "dobro", 
        "banjo", 
        "percussion"
    ],
    "keywords" : [ 
        "rural-tension", 
        " showdown", 
        " apprehension", 
        " uncertainty", 
        " light-tension", 
        " strings-tension", 
        " heartland", 
        " trouble", 
        " uneasy", 
        " cautious", 
        " outlaw", 
        " yellowstone", 
        " bayou", 
        " gritty", 
        " swampy", 
        " swamp-people", 
        " southern", 
        " uncertain", 
        " drama", 
        " apprehension", 
        " bluesy", 
        " blues", 
        " shack", 
        " poor-folk", 
        " primitive"
    ],
    "sounds_like" : [ 
        "Brian Tyler", 
        "Max Richter", 
        "T.V. Drama"
    ],
    "resembles_song" : [ 
        "Hell on Wheels", 
        "Yellowstone", 
        "Rural/Outlaw/Tension"
    ],
    "last_modified" : 1674323659,
    "variation_count" : 5,
    "variations" : {
        "_id" : ObjectId("63cc26bc86ae1611380e1200"),
        "track_title" : "Burn Slow",
        "artist_name" : "David Hollandsworth",
        "master_track_id" : "63cc26bc86ae1611380e1200",
        "master_track" : ObjectId("63cc26bc86ae1611380e1200"),
        "merged" : 1,
        "variation_count" : 5,
        "variations" : {
            "63cc26bc86ae1611380e1200" : {
                "track_id" : "63cc26bc86ae1611380e1200",
                "track_title" : "Burn Slow",
                "artist_name" : "David Hollandsworth"
            },
            "63cc26c086ae1611380e1203" : {
                "track_id" : "63cc26c086ae1611380e1203",
                "track_title" : "Burn Slow (bed mix)",
                "artist_name" : "David Hollandsworth"
            },
            "63cc26c386ae1611380e1204" : {
                "track_id" : "63cc26c386ae1611380e1204",
                "track_title" : "Burn Slow (cutdown)",
                "artist_name" : "David Hollandsworth"
            },
            "63cc26c786ae1611380e1205" : {
                "track_id" : "63cc26c786ae1611380e1205",
                "track_title" : "Burn Slow (lows and perc)",
                "artist_name" : "David Hollandsworth"
            },
            "63cc26cb86ae1611380e1206" : {
                "track_id" : "63cc26cb86ae1611380e1206",
                "track_title" : "Burn Slow (sting)",
                "artist_name" : "David Hollandsworth"
            }
        }
    }
}

Currently I have the following struct for the track in my Golang model:

type Track struct {
    ID                   primitive.ObjectID `bson:"_id, omitempty" json:"_id"`
    TrackTitle           string             `bson:"track_title" json:"track_title"`
    ArtistId             string             `bson:"artist_id" json:"artist_id"`
    ArtistName           string             `bson:"artist_name" json:"artist_name"`
    AlbumTitle           string             `bson:"album_title" json:"album_title"`
    Composer             string             `bson:"composer" json:"composer"`
    Publisher            string             `bson:"publisher" json:"publisher"`
    Description          string             `bson:"description" json:"description"`
    Duration             string             `bson:"duration" json:"duration"`
    UrlPath              string             `bson:"url_path" json:"url_path"`
    VocalType            string             `bson:"vocal_type" json:"vocal_type"`
    BeatsPerMinute       string             `bson:"beats_per_minute" json:"beats_per_minute"`
    FilePathCompressed   string             `bson:"file_path_compressed" json:"bfile_path_compressed"`
    FilePathUncompressed string             `bson:"file_path_uncompressed" json:"file_path_uncompressed"`
    PreviewURL           string             `bson:"preview_url" json:"preview_url"`
    Genres               []interface{}      `bson:"genres" json:"genres"`
    GenresKeys           []interface{}      `bson:"genres_keys" json:"genres_keys"`
    Moods                []interface{}      `bson:"moods" json:"moods"`
    Styles               []interface{}      `bson:"styles" json:"styles"`
    Instruments          []interface{}      `bson:"instruments" json:"instruments"`
    Keywords             []interface{}      `bson:"keywords" json:"keywords"`
    SoundsLike           []interface{}      `bson:"sounds_like" json:"sounds_like"`
    ResemblesSong        []interface{}      `bson:"resembles_song" json:"resembles_song"`
    LastModified         int                `bson:"last_modified" json:"last_modified"`
    VariationCount       int                `bson:"variation_count" json:"variation_count"`
}

Currently all document fields are being decoded properly as JSON, however I'm at an impasse right now on how to struct the embedded "variations.variations" field (note that there variations within variations). The structure of the embedded variations is an object with no key, rather a mongo ID string which is dynamic.

I have tried implementing a custom structs and interface types but to no avail.

If anyone has run into this issue before, any help would be appreciated.

CodePudding user response：

I suggest to avoid using interface{} (or any) whenever possible, use concrete types. E.g. genres is a string array, in Go use []string.

For the variations.variations field you may use a map with string key and a struct type describing its elements.

type Track struct {
    ID                   primitive.ObjectID `bson:"_id, omitempty" json:"_id"`
    TrackTitle           string             `bson:"track_title" json:"track_title"`
    ArtistId             string             `bson:"artist_id" json:"artist_id"`
    ArtistName           string             `bson:"artist_name" json:"artist_name"`
    AlbumTitle           string             `bson:"album_title" json:"album_title"`
    Composer             string             `bson:"composer" json:"composer"`
    Publisher            string             `bson:"publisher" json:"publisher"`
    Description          string             `bson:"description" json:"description"`
    Duration             string             `bson:"duration" json:"duration"`
    UrlPath              string             `bson:"url_path" json:"url_path"`
    VocalType            string             `bson:"vocal_type" json:"vocal_type"`
    BeatsPerMinute       string             `bson:"beats_per_minute" json:"beats_per_minute"`
    FilePathCompressed   string             `bson:"file_path_compressed" json:"bfile_path_compressed"`
    FilePathUncompressed string             `bson:"file_path_uncompressed" json:"file_path_uncompressed"`
    PreviewURL           string             `bson:"preview_url" json:"preview_url"`
    Genres               []string           `bson:"genres" json:"genres"`
    GenresKeys           []string           `bson:"genres_keys" json:"genres_keys"`
    Moods                []string           `bson:"moods" json:"moods"`
    Styles               []string           `bson:"styles" json:"styles"`
    Instruments          []string           `bson:"instruments" json:"instruments"`
    Keywords             []string           `bson:"keywords" json:"keywords"`
    SoundsLike           []string           `bson:"sounds_like" json:"sounds_like"`
    ResemblesSong        []string           `bson:"resembles_song" json:"resembles_song"`
    LastModified         int                `bson:"last_modified" json:"last_modified"`
    VariationCount       int                `bson:"variation_count" json:"variation_count"`
    Variations           Variations         `bson:"variations" json:"variations"`
}

type Variations struct {
    ID             primitive.ObjectID   `bson:"_id" json:"_id"`
    TrackTitle     string               `bson:"track_title" json:"track_title"`
    ArtistName     string               `bson:"artist_name" json:"artist_name"`
    MasterTrackID  string               `bson:"master_track_id" json:"master_track_id"`
    MasterTrack    primitive.ObjectID   `bson:"master_track" json:"master_track"`
    Merged         int                  `bson:"merged" json:"merged"`
    VariationCount int                  `bson:"variation_count" json:"variation_count"`
    Variations     map[string]Variation `bson:"variations" json:"variations"`
}

type Variation struct {
    TrackID    string `bson:"track_id" json:"track_id"`
    TrackTitle string `bson:"track_title" json:"track_title"`
    ArtistName string `bson:"artist_name" json:"artist_name"`
}