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Design the infrastructure persistence layer

Repository Pattern

1 Repository per resource: ItemRepository
1 DbContext for the whole application

Repositories/ItemRepository.cs

public class ItemRepository : IItemRepository
{
    private readonly MyAppContext context;

    public ItemRepository(MyAppContext context)
    {
        this.context = context;
    }

    public async Task<IReadOnlyCollection<Item>> GetAllItemsAsync(CancellationToken cancellationToken)
    {
        var items = await context.Items
            .Include(x => x.NavigationProperty)
            .AsNoTracking()
            .ToListAsync(cancellationToken);
        return items;
    }

    public async Task<Item?> GetItemByIdAsync(int id, CancellationToken cancellationToken)
    {
        var item = await context.Items
            .AsNoTracking()
            .SingleOrDefaultAsync(x => x.Id == id, cancellationToken);
        return item;
    }

    public async Task<IReadOnlyCollection<Item>> GetItemsByNameAsync(string name, CancellationToken cancellationToken)
    {
        var items = await context.Items
            .Where(x => EF.Functions.Like(x.Name, $"%{name}%"))
            .AsNoTracking()
            .ToListAsync(cancellationToken);
        return items;
    }

    public async Task<Item> CreateItemAsync(Item item, CancellationToken cancellationToken)
    {
        await context.AddAsync(item, cancellationToken);
        await context.SaveChangesAsync(cancellationToken);
        return item; // it now contains its id
    }

    public async Task<bool> UpdateItemAsync(int id, Item item, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(item);

        var itemToUpdate = await context.Items.SingleOrDefaultAsync(x => x.Id == id, cancellationToken);

        if (itemToUpdate is null)
        {
            return false; // send not found from controller then
        }

        itemToUpdate.Name = item.Name;
        await context.SaveChangesAsync();
        return true;
    }

    public async Task<bool> DeleteItemAsync(int id, CancellationToken cancellationToken)
    {
        var nbAffectedRows = await context.Items.Where(x => x.Id == id).ExecuteDeleteAsync(cancellationToken);
        return nbAffectedRows == 1;
    }

Generic repository

RepositoryBase.cs

public abstract class RepositoryBase<TEntity, TCreateUpdateQuery> where TEntity : class, new()
{
    private readonly AppContext context;

    private DbSet<TEntity> dbEntities { get; }

    protected RepositoryBase(BourseContext context)
    {
        this.context = context ?? throw new ArgumentNullException(nameof(context));
        dbEntities = this.context.Set<TEntity>();
    }

    protected async Task<IReadOnlyCollection<TResult>> GetAsync<TResult>(
        Expression<Func<TEntity, TResult>> selector,
        Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>>? include = null,
        Expression<Func<TEntity, bool>>? predicate = null,
        Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>>? orderBy = null,
        Func<IQueryable<TEntity>, IQueryable<TEntity>>? skipTake = null,
        bool disableTracking = true,
        CancellationToken cancellationToken = default)
        where TResult : class
    {
        IQueryable<TEntity> query = dbEntities;

        if (include is not null)
        {
            query = include(query);
        }

        if (predicate is not null)
        {
            query = query.Where(predicate);
        }

        if (orderBy is not null)
        {
            query = orderBy(query);
        }

        if (skipTake is not null)
        {
            query = skipTake(query);
        }

        if (disableTracking)
        {
            query = query.AsNoTracking();
        }

        return await query.Select(selector).ToListAsync(cancellationToken);
    }

    public async Task<TEntity> CreateAsync(
        TEntity entity, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(entity);

        await context.AddAsync(entity, cancellationToken);
        await context.SaveChangesAsync(cancellationToken);
        return entity;
    }

    public async Task<bool> UpdateAsync(
        Expression<Func<TEntity, bool>> filterByIdExpression,
        TCreateUpdateQuery query,
        CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(query);

        var entityToUpdate = await dbEntities
            .FirstOrDefaultAsync(filterByIdExpression, cancellationToken);

        if (entityToUpdate is null)
        {
            return false;
        }

        UpdateEntityFromCreateUpdateQuery(query, entityToUpdate);
        await context.SaveChangesAsync(cancellationToken);
        return true;
    }

    public async Task<bool> DeleteAsync(
        Expression<Func<TEntity, bool>> filterByIdExpression,
        CancellationToken cancellationToken)
    {
        var nbAffectedRows = await dbEntities
            .Where(filterByIdExpression)
            .ExecuteDeleteAsync(cancellationToken);

        return nbAffectedRows > 0;
    }
}