Cannot load FileAttachment into Mosiac in Observable Notebook

[josesho]

All the examples on the Mosaic site load data from URLs or a local file (presumably for use in a Framework project).

However, there are no working examples for loading a FileAttachment as data, and I can't seem to get it to work either loadCSV(), loadParquet(), or loadObjects().

Exemplar notebook here: https://observablehq.com/@josesho/mosaic-troubleshoot-loading-data

Any help here is appreciated!

[jheer]

Hi @josesho! We include examples of using Mosaic in Observable Framework here: https://idl.uw.edu/mosaic-framework-example/mosaic-duckdb-wasm

Framework provides a sql property in the YAML front matter that is easier to use than FileAttachment.

You can use a file attachment, however. You must first instantiate the FileAttachment and then use it to get a URL to the file (as opposed to loading it directly). You can then use that URL as input to a load query generator such loadCSV(), and then you have to execute the query. (And, you have to do all of this in a way that "plays nice" with the Observable Reactive runtime, ensuring that the load queries complete prior to making other API calls... this is why the sql front matter is so much nicer.)

Finally, here is an example using Mosaic in an Observable notebook (not Framework): https://observablehq.com/@uwdata/mosaic-cross-filter-flights-10m. Here the file URL is hard-coded, but one could use a FileAttachment to get a file URL instead.

[josesho]

Got it! Just for future reference I did

athletes = await FileAttachment("athletes.csv").url()

and passed athletes directly to loadCSV().

Thanks!