add boxpositions
We need to track positions of samples, for example passages of celllines, and to easily identify empty positions in boxes. What I plan to do is:
- a boxpositions table, with fields id, box_id, row, column
- a routine (controller somewhere) that automatically create positions in this table when a new box is added to the table boxes
- add relationships in BREADs. For example, in the passages BREAD, add a oneToMany relationship to boxpositions to indicate where the samples of this passage are stored. This implies having a pivot table boxposition_passages.