FastMember column order preservation

Question

When using TypeAccessor.Create FastMember always seems to return a list of the columns in alphabetic sorted order. Is it possible to tell it to preserve the ordering of the columns in the class?

for example:

var testClass = new { B = "1", A = "2" };

will return column A then B from GetMembers, I'd like to get it to preserve the ordering of B then A if possible.

Tound

Curious, why exactly you need that? – Drus

kind of like the bulk insert, but I'd like to be able to throw data into other data stores too, some of which might care about ordering. @Drus – Tound

Without heavy reflection I think you cannot do that. Deep inside FastMember library author orders properties by name and seems there is no way around it. If that is a requirement, you can either ask author to add such functionality, or not use this library at all. – Drus

Other option would be to get properties with reflection once, yourself, and then reoder result of GetMembers manually. – Drus

yeah @evk that might do the trick – Tound

Answer 1

Looks like Evk is right and it can't really be done via the standard APIs. In the interest of completeness I'll leave this as the answer.

Tound

I ran into the same problem: passing a dt into a user defined table type for a stored procedure kept failing due to columns being ordered alphabetically but FastMember. Thanks for the feedback. – Rosariorosarium

Answer 2

I created a fork of this project with column order option and added a PR to the original repository. OrdinalAttribute was added to specify columns order.

The ordinal attribute can be used as shown below:

        public class ObjectReaderWithDefinedColumnsOrderType
        {
            [Ordinal(1)]
            public byte C { get; set; }
            [Ordinal(0)]
            public int? D { get; set; }
        }

• IDataReader object returned in ObjectReader.Create() will have columns order according to the defined attributes.
• If the attribute is not defined in the source class then alphabetical order is used.
• If two fields have the same Ordinal value then then alphabetical order is used.
• If the attribute is defined only for some properties then the columns are sorted by the ordinal values and then in alphabetical order (properties with no attributes are considered as -1 ordinal).

You can use my for right away or wait until the PR is merged with the original repository.

Caress

Has your pull request been processed yet? – Sly

@Martin, yes, it has been merged to master. – Caress

@Caress what the latest with this? Does it work? – Loaning

@EmilijaVilijaTrečiokaitė yes, it works and merged. Please use latest version of the component. – Caress