Lessons

Let's go through how to serialize and deserialize arrays T[] and lists List<T> using System.Text.Json: how collections in C# map to JSON arrays, how to save data to a file and read it back, what to watch out for with null, empty collections and polymorphism. Everything with clear examples using files and serializer settings.

How to serialize and deserialize dictionaries to JSON using System.Text.Json: from simple cases with string keys to numeric and nested objects. We'll go over why complex objects can't be used as keys, how JsonSerializerOptions options (for example, PropertyNamingPolicy) affect things, and when it's better to replace a dictionary with a list of pairs. With practical examples, JSON snippets, and a breakdown of pitfalls.

In this lecture we go through how to serialize and deserialize multi-level structures in C# using System.Text.Json: trees, graphs with potential cycles, nested collections and attributes. We'll discuss JsonSerializer, the ReferenceHandler. IgnoreCycles option, the JsonIgnore attribute, storing references via identifiers and practical patterns for real apps (catalogs, employees, authors/books).

In this lecture we look at what cyclic references are and why they break serialization: by default System.Text.Json throws a JsonException when it detects cycles. We'll go over practical approaches: clearing references, the [JsonIgnore] attribute, switching to identifiers instead of nested objects, and enabling reference serialization via ReferenceHandler. Preserve. We'll also compare with Newtonsoft.Json capabilities and give practical recommendations for REST APIs.

How to hide collections and their fields from serialization, rename properties to match an API contract, manage null values and output formats in System.Text.Json. We'll go through attributes like [JsonIgnore], [JsonPropertyName], options JsonSerializerOptions, working with dictionaries, common pitfalls and practical interview questions.