How do I overload LINQ IQueryable<TEntity> Where() to accept column name

Question

I would like to modify the following to accept the column name which will be searched in the Where method, something like:

        public TEntity GetEntity(int val)
        {
            TEntity entity = _DbContext.Set<TEntity>()
                   .Where(e => e.Id == val)
                   .FirstOrDefault();
            return entity;
        }

to be changed to

        public TEntity GetEntity(int val, string colName)
        {
            TEntity entity = _DbContext.Set<TEntity>()
                   .WhereWithColName(val, colName)
                   .FirstOrDefault();
            return entity;
        }

Expression trees still too complex for me...

Answer 1

OK, solved it:

public static IQueryable<TEntity> WhereById<TEntity, TKey>(this IQueryable<TEntity> query, TKey value, string colName)
            where TEntity : class
{
    var param = Expression.Parameter(typeof(TEntity), "e");
    var propAccess = Expression.PropertyOrField(param, colName);
    var valExpr = Expression.Constant(value);

    var predicate = Expression.Equal(propAccess,valExpr);

    var predicateLambda = Expression.Lambda<Func<TEntity, bool>>(predicate, param);

    return query.Where(predicateLambda);
}

and the calling function is then:

public TEntity GetEntity(int val, string colName)
{
    TEntity entity = _DbContext.Set<TEntity>()
           .WhereById<TEntity, int>(val, colName)
           .FirstOrDefault();
    return entity;
}