DKNet

Check whether a mapped table exists

Part of DKNet.EfCore.Relational.Helpers. Query INFORMATION_SCHEMA.TABLES using the entity mapped table and, when known, schema.

Use the Quick Start console project. Set DKNET_DOCS_DB to a PostgreSQL connection string with permission to create tables in a dedicated empty database. Each example uses EnsureCreatedAsync or whole-model creation; run each against its own database.

using Microsoft.EntityFrameworkCore;
using DKNet.EfCore.Relational.Helpers;

var connectionString = Environment.GetEnvironmentVariable("DKNET_DOCS_DB")
    ?? throw new InvalidOperationException("Set DKNET_DOCS_DB to an empty PostgreSQL database.");
var o = new DbContextOptionsBuilder<DemoDb>();
o.UseNpgsql(connectionString);
await using var db = new DemoDb(o.Options);
await db.Database.EnsureCreatedAsync();
Console.WriteLine(await db.TableExistsAsync<Item>()); // True

public sealed class DemoDb(DbContextOptions<DemoDb> options) : DbContext(options)
{
    public DbSet<Item> Items => Set<Item>();
}
public sealed class Item
{
    public int Id { get; set; }
    public string Name { get; set; } = "";
}

The scalar query names its projected column Value for EF composition and uses SingleAsync with the caller cancellation token. It does not query entity rows.

⚠️ Gotchas & limits

• A type absent from the model throws InvalidOperationException before querying. A valid table with zero entity rows still exists.
• Permissions failures, timeouts, connection failures and cancellation propagate; they are not converted to false. This differs from the earlier target-table probe behavior.
• The catalog query is for SQL Server and PostgreSQL; SQLite does not supply INFORMATION_SCHEMA.TABLES. A null schema causes a name-only lookup across catalog schemas.

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