Add JSON Column Enhancements article

docs/en/Community-Articles/2023-10-30-Enhancements-to-JSON-column-mapping/POST.md

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+# EF Core 8 - Enhancements to JSON column mapping
+
+In this article, we will examine the enhancements introduced in EF Core 8 for the JSON column feature, building upon the foundation laid by [JSON columns in Entity Framework Core 7](https://community.abp.io/posts/json-columns-in-entity-framework-core-7-cjaom76j).
+
+## The entity classes we will be using in the article
+
+```csharp
+public class Person
+{
+    public int Id { get; set; }
+    [Required]
+    public string Name { get; set; }
+    [Required]
+    public ContactDetails ContactDetails { get; set; }
+}
+
+public class ContactDetails
+{
+    public List<Address> Addresses { get; set; } = new();
+    public string? Phone { get; set; }
+}
+
+public class Address
+{
+    public Address(string street, string city, string postcode, string country)
+    {
+        Street = street;
+        City = city;
+        Postcode = postcode;
+        Country = country;
+    }
+
+    public string Street { get; set; }
+    public string City { get; set; }
+    public string Postcode { get; set; }
+    public string Country { get; set; }
+    public bool IsMainAddress { get; set; }
+}
+```
+
+## The DbContext class we will be using in the article
+
+```csharp
+public class AppDbContext : DbContext
+{
+    public DbSet<Person> Persons { get; set; } = null!;
+
+    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+    {
+#if SQLSERVER
+        optionsBuilder.UseSqlServer("Server=localhost;Database=EfCore8Json;Trusted_Connection=True;TrustServerCertificate=True");
+#elif SQLITE
+        optionsBuilder.UseSqlite("Data Source=EfCore8Json.db");
+#endif
+        base.OnConfiguring(optionsBuilder);
+    }
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        modelBuilder.Entity<Person>(b =>
+        {
+            b.ToTable("Persons");
+            b.HasKey(x => x.Id);
+            b.Property(x => x.Name).IsRequired();
+            b.OwnsOne(x => x.ContactDetails, cb =>
+            {
+                cb.ToJson();
+                cb.Property(x => x.Phone);
+                cb.OwnsMany(x => x.Addresses);
+            });
+        });
+
+        base.OnModelCreating(modelBuilder);
+    }
+}
+```
+
+## Translate element access into JSON arrays
+
+EF Core 8 supports indexing in JSON arrays when executing queries. For example, the following query returns individuals whose first address is the main address in the database:
+
+```csharp
+var query = dbContext.Persons
+    .Select(x => x.ContactDetails.Addresses[0])
+    .Where(x => x.IsMainAddress == true)
+    .ToListAsync();
+```
+
+The generated SQL query is as follows when using SQL Server:
+
+```sql
+SELECT JSON_QUERY([p].[ContactDetails], '$.Addresses[0]'), [p].[Id]
+FROM [Persons] AS [p]
+WHERE CAST(JSON_VALUE([p].[ContactDetails], '$.Addresses[0].IsMainAddress') AS bit) = CAST(1 AS bit)
+```
+
+> Note: If you attempt to access an index that is outside of the array, it will return null.
+
+## JSON Columns for SQLite
+
+In EF Core 7, JSON column mapping was supported for Azure SQL/SQL Server. In EF Core 8, this support has been extended to include SQLite as well.
+
+### Queries into JSON columns
+
+The following query returns individuals whose first address is the main address in the database:
+
+```csharp
+var query = dbContext.Persons
+    .Select(x => x.ContactDetails.Addresses[0])
+    .Where(x => x.IsMainAddress == true)
+    .ToListAsync();
+```
+
+The generated SQL query is as follows when using SQLite:
+
+```sql
+SELECT "p"."ContactDetails" ->> '$.Addresses[0]', "p"."Id"
+FROM "Persons" AS "p"
+WHERE "p"."ContactDetails" ->> '$.Addresses[0].IsMainAddress' = 0
+```
+
+## References
+
+- [EF Core 8 - Enhancements to JSON column mapping](https://learn.microsoft.com/en-us/ef/core/what-is-new/ef-core-8.0/whatsnew#enhancements-to-json-column-mapping)