func buildCollection(h group, c index.Collection) group {
getField := func(f string, g index.Group, c index.Collection) interface{} {
if StringSliceEqual(g.Field(f), c.Field(f)) {
return nil
}
return g.Field(f)
}
for _, k := range c.Keys() {
g := c.Get(k)
g = index.FirstTrackAttr(attr.Strings("AlbumArtist"), g)
g = index.CommonGroupAttr([]attr.Interface{attr.Strings("Artist")}, g)
h.Groups = append(h.Groups, group{
Name: g.Name(),
Key: k,
AlbumArtist: getField("AlbumArtist", g, c),
Artist: getField("Artist", g, c),
})
}
return h
}
