Trying to see when database content has changed.

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1

Hi, I;m new to observable and I’m trying to work out how I would make this Loki database observable to see when items are added/deleted/changed.

Not sure where the viewof goes or if I would be plopping in yeild or mutable to expose the data.

Any help welcome.

2

One of the ways you could approach this is to use Observable’s mutable operator, which lets you assign the value of a cell from another cell, and trigger any downstream cells with (non-mutable) references to that mutable cell to run again.

Here’s a suggestion that does that:

The basic steps are:

  1. Any cell that wants to mutate your database references mutable te_items exclusively, and never te_items (otherwise, you’d likely get an infinite loop).
  2. After the cell mutates the database, it reassigns mutable te_items to itself to trigger downstream cells to run. (It’s generally better to use a copy-on-write technique here similar to React state, but that’s not possible given that this database is inherently mutable.)
  3. Any cell that you want to run automatically whenever te_items changes just references te_items as normal.
  4. But, if a cell depends on a specific mutation (such as the find cell depending on the add_data cell that inserts the tyrfing record), that cell must include a reference to the cell that applies the mutation. That’s because Observable runs cells in topological order.

Hope this helps.

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3

Thanks so much, that really helped a lot in my understanding of observable.

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