Use appsettings.json to configure DbContext mapping

Question

I'm using .netCore and Entity Framework to get some data from an SQL Database.
I have setup a DbContext

public partial class DashboardContext : DbContext
{
    public NotfallDashboardContext(DbContextOptions<NotfallDashboardContext> options) : base(options) {}

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<DashboardData>(entity =>
        {
            ...
        }
    }

    public virtual DbSet<DashboardData> DashboardData { get; set; }
}

and inject it into my controller with the following setup

services.AddDbContext<DashboardContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DashboardDatabase")));

Now the DashboardData class uses the Table Attirbute to connect to the correct table and schema.

[Table("TableName", Schema = "dbo")]
public partial class DashboardData
{
    ...
}

What i would like to do, is to extract these two strings "TableName" and "dbo" into my appsettings.json configuration. I already added the configuration to appsettings, made a TableConfiguration class and setup dependency injection:

TableConfiguration.cs

public class TableConfiguration
{
    public string DatabaseView { get; set; }
    public string DatabaseSchema { get; set; }
}

appsettings.json

"TableConfiguration": {
    "DatabaseTable": "TableName",
    "DatabaseSchema": "dbo"
}

startup.cs

services.Configure<TableConfiguration>(Configuration.GetSection("TableConfiguration"));

Is it possible to inject or otherwise use the configuration in the DasboardData Attribute?

Possible duplicate of [Dynamically changing schema in Entity Framework Core](http://stackoverflow.com/questions/39499470/dynamically-changing-schema-in-entity-framework-core) — Venkata Dorisala, Nov 22 '16 at 15:22

score 5 · Accepted Answer · answered Nov 22 '16 at 15:13

In your Startup.cs:

services.Configure<TableConfiguration>(Configuration.GetSection("TableConfiguration"));

Then, inject IOptions<TableConfiguration> tableConf into your context and store it for later usage by your OnModelCreating():

public class DashboardContext : DbContext
{
    private readonly TableConfiguration tableConf;

    public DashboardContext(DbContextOptions<DashboardContext> options, IOptions<TableConfiguration> tableConf) : base(options)
    {
        this.tableConf = tableConf.Value;
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<DashboardData>(entity =>
        {
            entity.ToTable(this.tableConf.DatabaseTable, this.tableConf.DatabaseSchema);
        });
    }

    public virtual DbSet<DashboardData> DashboardData { get; set; }
}

Exactly what i was looking for! Thank you – Thomas Schneiter Nov 22 '16 at 15:36 — Thomas Schneiter, Nov 22 '16 at 15:36

Use appsettings.json to configure DbContext mapping

1 Answers1