I have a bundle (content type) called "nbt_text" and a bundle "nbt_book".
nbt_books stands for book node-type, and
nbt_text -- for text node_type.
nbt_text there is a field of "entity reference" type which keeps the information about books related to current
Everything is fine but now the client asked me to add some extra fields, to be specific he wants the following thing: each reference field should contain not only the reference itself but also a field containing some bibliographical data, for example book pages where current text can be found.
In other words, the "related book" field should become now a kind of container that has two fields: entity reference field and a text field.
How can I obtain that? Am I to to write my own field module from scratch or I can someway use already existing great "entity reference" and "text" fields?
You will ask me why not simply add these fields to the bunch but the reason is that there can be not only one related books but lots of it. In that case the only way to use default fields would be keeping field data arrays in right order which is completely undesirable for editors.