How can I inline parameters in EFCore?

Question

Then track performance of query you can invoke ToQueryString method. If you have a lot of parameters in query it just add @p1, @p2, etc. What to do if you want inline it?

Answer 1

You can just use this expression visitor for inline parameters:

public class ParameterReplacer : System.Linq.Expressions.ExpressionVisitor
{
    protected override Expression VisitMember(MemberExpression node)
    {
        if (node.Expression is ConstantExpression constantExpression)
        {
            var container = constantExpression.Value;
            var member = node.Member;

            if (member is System.Reflection.FieldInfo field)
            {
                var value = field.GetValue(container);
                if (value is string or not IEnumerable)
                {
                    return Expression.Constant(value, field.FieldType);
                }
            }
            else if (member is System.Reflection.PropertyInfo property)
            {
                var value = property.GetValue(container);
                if (value is string or not IEnumerable)
                {
                    return Expression.Constant(value, property.PropertyType);
                }
            }
        }

        return base.VisitMember(node);
    }

    public static IQueryable<T> ReplaceParamToConst<T>(IQueryable<T> query)
    {
        var replacer = new ParameterReplacer();
        return query.Provider.CreateQuery<T>(replacer.Visit(query.Expression));
    }
}

Usage: ParameterReplacer.ReplaceParamToConst(query).ToQueryString();