Accessing nested JSON array

Question

I have the following JSON:

{
 "reviews": [
 {
 "reviewId": "123",
 "authorName": "author",
 "comments": [
 {
 "userComment": {
 "text": "text",
 "lastModified": {
 "seconds": "1580461776",
 "nanos": 1
 },
 "starRating": 5,
 "reviewerLanguage": "GB",
 "appVersionCode": "",
 "appVersionName": "",
 "thumbsUpCount": 0,
 "thumbsDownCount": 0
 }
 }
 ]
 }
 ]
}

From this all I want to access is the starRating (but with the potential for multiple reviews) I have managed to deserialize the JSON into a C# object correctly and have checked this when debugging my code.

So far I have:

var appReview = JsonConvert.DeserializeObject<appData>(appJson);
var reviews = appReview.Reviews;
int reviewCount = reviews.Length;
for (int i = 0; i < reviewCount; i++)
{
 Console.WriteLine(reviews[0].Comments[0].UserComment.StarRating); 
}

However I don't just want the star rating of this specific review as in the future there will be more reviews and star ratings, therefore I need to select all of the reviews in the JSON and get an average of the star rating? Because of that, I'm not sure accessing them with the [0] index is correct. Hopefully I have explained that well enough - can anyone please point me in the correct direction?

• Frauke: So, each review can have several comments, and each of those comments can have a star rating? So in effect each review can have multiple ratings? That seems very odd - are you sure that's what you want?

Answer 1

If you are comfortable using linq then I would suggest something like this:

var ratings = appReview.Reviews
 .SelectMany(r => r.Comments.Select(c => c.UserComment.StarRating));

This should get you a list of ratings. This works by selecting the StarRating from the Comments then SelectMany flattens the arrays to a single array.

Then you can use get the average like so:

var average = ratings.Average();

Try it online