Add new metadata using the Tridion (2011) event system

Question

I have a question that I am struggeling with. A positive answer would help me to remove a piece of unwanted customization.

Is it possible to add metadata from the event system to a component where the field is not present in the metadata schema? The reason I ask this, is that I am creating a dynamic implementation where content is retrieved using metadata.

Some of the fields I would like to display are in the content tab of the component. This to make sure the Content Managers can find these fields. Because of this, I would like to add these fields to metadata during publishing. This to make this content available as metadata in the Broker database, where I can use the Broker API to retrieve these fields.

I have read a post on setting a value in a page's metadata by using the following fragment that Nuno provided:

    Itemfields meta = new ItemFields(page.Metadata, page.MetadataSchema);
    SingleLineTextField categorisationField = (SingleLineTextField)meta["categorisation"];
    categorisationField.Value = "Some value";
    page.Metadata = meta.ToXml();

What I tried was to get the metadata as an XML fragment, and manually add the node to the metadata section (using the correct schema namespace). I then set the components metadata by using component.Metadata = metadata; (where metadata is the XML fragment). The component has/had a metadata schema attached.

So my question is: Does the publisher use the in-memory component representation, where the metadata entry is present, or does it get a new copy of the component when publishing. If the latter is the case, I will need to add a .save() and beforehand add the field to the schema.

Any thoughts? Is this possible, or is there a good alternative?

Answer 1

I see your point, there is an old PS implementation called Metadata Processor that performs the following logic.

1. At publishing time there an special syntax written at the beginning of the template that writes the Output variable, that special syntax will instruct which design fields should be considered metadata.
2. At deployment time a Deployer Processor (Metadata Processor) will read that special syntax and put it in Metadata.

This solution is not free since it was developed by PS.

Other option that you can use if to write something similar by using the AddMetadata method available in your Template Building Blocks, it will add any metadata to the package (your design fields for instance) then you will need to write a deployer extension to read it and put in Custom Meta - Check this post AddMetadata.

Answer 2

Please read my blog posts on TridionDeveloper.com, titled Querying ECL Metadata in the Broker and ECL event handlers. In there I handle the exact same topic (but then related to ECL).

In the first article, I discuss the options you have available on how to get additional Metadata added at Publishing time. Mind you I am not using the unsupported approach of adding Metadata which does not conform to the Schema (because I find that a too dirty approach, but it is used in the field and does work as you can read in Eric's answer). So I actually have Metadata Schema fields which I populate at Publishing time (using a TBB).

The sample code for the TBB is available on GitHub Gist.

In the second article I discuss doing the same via an Event Handler, as I noticed that my TBB approach didn't always work flawlessly, and also that the Event Handler approach wasn't such a problem as I initially thought.

The example Event Handler is available on Google Code and SDL Tridion World.

To come back on your question directly; does the publisher use the in-memory Component representation (or the Package Item)? No it doesn't, it requests the actual source for the item directly from the database. I found this out while trying to make ECL external metadata available in the Broker.