Setting a Page Metadata field value using the event system,

Question

I am writing an event which is executed on page save and I need to validate one of the Page metadata fields. If it is blank then I have to set that value from the Structure Group Metadata field,

public void Validate(RepositoryLocalObject page)
    {
        try
        {
            var metadata = new ItemFields(page.Metadata, page.MetadataSchema);

            var categorisation = ((EmbeddedSchemaField)metadata["categorisation"]).Value;
            if (categorisation == null)
            {
                var item = page.OrganizationalItem;
                if (item.Metadata != null && item.MetadataSchema != null)
                {
                    var parentMetaData = new ItemFields(item.Metadata, item.MetadataSchema);
                    if (parentMetaData != null)
                    {
                        EmbeddedSchemaField pageFields = (EmbeddedSchemaField)metadata["categorisation"];

                        var parenetCategorisation = ((EmbeddedSchemaField)parentMetaData["categorisation"]).Value;

                        pageFields.Value = parenetCategorisation;

                        if (parenetCategorisation != null)
                        {
                            page.Metadata["categorisation"].InnerText = pageFields.ToString(); 
                        }
                    }
                }
            }

        }
        catch(Exception ex)
        {
            throw new Exception("Not all section fields have been set " + ex.Message + " " + ex.StackTrace);
        }
    }

I am getting the error on the below line,

 page.Metadata["categorisation"].InnerText = pageFields.ToString(); 

Could anyone suggest that how to set this value to page metadata fields?

Answer 1

Something along these lines (untested code)

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

Answer 2

Page.Metadata is an XmlElement, you cannot access it 'page.Metadata["categorisation"]'. You will have to set the entire metadata of the Page.

page.Metadata = metadata.ToXml();