static bool IsSupportedType(Type propertyType)
{
return(Types.IsStructured(propertyType) || Types.TypeToDbType.ContainsKey(propertyType) || propertyType.IsEnum);
}
static Action <DbCommand, object> CreateAddParametersAction(Type type)
{
var obj = Expression.Parameter(typeof(object), "obj");
var parameters = Expression.Parameter(type, "parameters");
var cmd = Expression.Parameter(typeof(DbCommand), "cmd");
var dataParam = Expression.Parameter(typeof(DbParameter), "dataParam");
var lines = new List <Expression>
{
Expression.Assign(parameters, Expression.Convert(obj, type))
};
var createParameter = typeof(DbCommand).GetMethod("CreateParameter", Type.EmptyTypes);
foreach (var prop in type.GetProperties(BindingFlags.Public | BindingFlags.Instance))
{
var propertyType = prop.PropertyType;
if (!IsSupportedType(propertyType))
{
continue;
}
lines.Add(Expression.Assign(dataParam, Expression.Call(cmd, createParameter)));
lines.Add(Expression.Assign(Expression.Property(dataParam, "ParameterName"), Expression.Constant("@" + prop.Name)));
if (Types.IsStructured(propertyType))
{
if (propertyType != typeof(TableType))
{
throw new NotSupportedException($"Parameter {dataParam.Name} implements {nameof(IEnumerable<SqlDataRecord>)} but type name is unknown. Please wrap parameter by calling {nameof(Extensions.WithTypeName)}");
}
lines.Add(Expression.IfThen(
Expression.Not(Expression.TypeIs(cmd, typeof(DbCommand))),
Expression.Throw(Expression.New(typeof(NotSupportedException).GetConstructor(new[] { typeof(string) }), Expression.Constant("Structured parameters are supported only for SqlCommand")))
));
lines.Add(Expression.Assign(Expression.Property(Expression.Convert(dataParam, typeof(SqlParameter)), "SqlDbType"), Expression.Constant(SqlDbType.Structured)));
lines.Add(Expression.Assign(Expression.Property(Expression.Convert(dataParam, typeof(SqlParameter)), "TypeName"), Expression.Property(Expression.Property(parameters, prop.Name), "TypeName")));
}
else if (propertyType.IsEnum)
{
lines.Add(Expression.Assign(Expression.Property(dataParam, "DbType"), Expression.Constant(DbType.Int32)));
}
else
{
lines.Add(Expression.Assign(Expression.Property(dataParam, "DbType"), Expression.Constant(Types.TypeToDbType[propertyType])));
}
if (Types.CanBeNull(propertyType))
{
lines.Add(Expression.IfThenElse(
Expression.Equal(Expression.Property(parameters, prop.Name), Expression.Constant(null)),
Expression.Assign(Expression.Property(dataParam, "Value"), Expression.Convert(Expression.Field(null, typeof(DBNull), "Value"), typeof(object))),
Expression.Assign(Expression.Property(dataParam, "Value"), PropertyValue(parameters, prop))
));
}
else
{
lines.Add(Expression.Assign(Expression.Property(dataParam, "Value"), PropertyValue(parameters, prop)));
}
lines.Add(Expression.Call(Expression.Property(cmd, "Parameters"), typeof(DbParameterCollection).GetMethod("Add", new[] { typeof(object) }), dataParam));
}
var block = Expression.Block(new[] { dataParam, parameters }, lines);
return(Expression.Lambda <Action <DbCommand, object> >(block, cmd, obj).Compile());
}