public static MemberInitExpression InitType <TEntity>(IEnumerable <SelectColumn> columns, Expression node, AutoQueryableProfile profile)
{
var expressions = new Dictionary <string, Expression>();
foreach (SelectColumn subColumn in columns)
{
Expression ex = GetMemberExpression <TEntity>(node, subColumn, profile);
expressions.Add(subColumn.Name, ex);
}
Type type = null;
if (profile.UseBaseType)
{
type = node.Type;
}
else
{
var properties = GetTypeProperties(expressions);
type = RuntimeTypeBuilder.GetRuntimeType(node.Type, properties);
}
NewExpression ctor = Expression.New(type);
return(Expression.MemberInit(ctor, expressions.Select(p => Expression.Bind(type.GetProperty(p.Key, BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance), p.Value))));
}
public static Expression <Func <TEntity, object> > GetSelector <TEntity>(string columns)
{
Dictionary <string, Expression> memberExpressions = new Dictionary <string, Expression>();
ParameterExpression parameter = Expression.Parameter(typeof(TEntity), "p");
var properties = new Dictionary <string, object>();
foreach (string column in columns.Split(','))
{
var cols = column.Split('.');
var ex = GetMemberExpression(parameter, cols, 0);
if (ex == null)
{
continue;
}
string propName = column.Replace(".", "");
memberExpressions.Add(propName, ex);
if (ex is MemberExpression)
{
properties.Add(propName, (ex as MemberExpression).Member as PropertyInfo);
}
if (ex is MethodCallExpression)
{
var callExpression = (ex as MethodCallExpression);
properties.Add(propName, ex.Type);
}
}
var dynamicType = RuntimeTypeBuilder.GetRuntimeType <TEntity>(properties);
var ctor = Expression.New(dynamicType);
var memberAssignments = dynamicType.GetProperties(BindingFlags.Public | BindingFlags.Instance)
.Select(p =>
{
return(Expression.Bind(p, memberExpressions.Single(me => me.Key == p.Name).Value));
});
var memberInit = Expression.MemberInit(ctor, memberAssignments);
return(Expression.Lambda <Func <TEntity, object> >(memberInit, parameter));
}