c# - How to get list of database table primary key columns in EF Core

Question

ASP.NET Core MVC application using EF Core. In Linq to SQL, this code returns list of database table primary key columns names:

    /// <summary>
    /// Database primary key names
    /// </summary>
    public IList<string> DatabasePrimaryKey(Type dbContextPocoType)
    {
        List<string> pk = new List<string>();

        foreach (PropertyInfo p in dbContextPocoType.GetProperties())
        {
            var ca = p.GetCustomAttributes(typeof(ColumnAttribute), true);

            if (ca.Length == 0) continue;
            var atr = (ColumnAttribute)ca.Single();

            if (!atr.IsPrimaryKey) continue;
            pk.Add(atr.Name);
        }

        return pk;
    }

In EF Core I tried

var entry = ctx.Entry(dbContextPocoType);
var primaryKey = entry.Metadata.FindPrimaryKey();

IList<string>  keys = primaryKey.Properties.Select(x => x.Name).ToList();
return keys;

But this returns C# property names - how to get database table column names in EF Core?

Update: using answer I created this method:

    public IList<string> DatabasePrimaryKey<TPoco>()
    {
        var entry = ctx.Entry(typeof(TPoco));
        var primaryKey = entry.Metadata.FindPrimaryKey();
        var entityType = ctx.Model.FindEntityType(typeof(TPoco).Name);
        var schema = entityType.GetSchema();
        var tableName = entityType.GetTableName();
        IList<string> keys = primaryKey.Properties
             .Select(x => x.GetColumnName(StoreObjectIdentifier.Table(tableName, schema)))
             .ToList();
        return keys;
    }

Can this method be improved?

question from:https://stackoverflow.com/questions/65837188/how-to-get-list-of-database-table-primary-key-columns-in-ef-core

Answer 1

In EF Core 3.x You could try the IProperty extension method GetColumnName instead.

var entry = ctx.Entry(dbContextPocoType);
var primaryKey = entry.Metadata.FindPrimaryKey();
var primaryKeyColumns = primaryKey.Properties
                     .Select(property => property.GetColumnName())
                     .ToList()

return primaryKeyColumns;

For EF Core 5, you need to use the overload that accepts a StoreObjectIdentifier: GetColumnName(IProperty, StoreObjectIdentifier).

Update for EF 5:

public IList<string> DatabasePrimaryKey<TPoco>()
{
    var entityType = ctx.Model.FindEntityType(typeof(TPoco));
    var primaryKey = entityType.FindPrimaryKey();
    var schema = entityType.GetSchema();
    var tableName = entityType.GetTableName();
    var storeObjectIdentifier = StoreObjectIdentifier.Table(tableName, schema);
    IList<string> primaryKeyColumns = primaryKey.Properties
        .Select(x => x.GetColumnName(storeObjectIdentifier))
        .ToList();
    return primaryKeyColumns;
}