add flags to qri save for setting individual components of a save

[b5]

I'm having a semi-frustrating time always having to create a dataset.yaml or dataset.json just to update a transform script. What I'd like to be able to do from the CLI is one of two things. The first would be providing json/yaml snippits for each component. In each of these cases the _file argument would be a file that only defines that component, not an entire dataset:

$ qri save --meta meta_file.json me/dataset
$ qri save --structure structure_file.json me/dataset

$ qri save --viz viz_file.yaml me/dataset
$ qri save --transform transform_file.json me/dataset

# we already support this:
$ qri save --body file.csv me/dataset

The second would be providing a raw script as a file as a shortcut for "default settings, but with this file":
qri save --transform tf_file.star me/dataset
ditto for viz scripts:
qri save --viz template_file.html me/dataset
This would just do the right thing, populating a component with defaults (like setting syntax to html or starlark) and setting the scriptPath to the supplied path argument

In a later PR it'd be great to leverage the qri values we embed into datasets to intelligently accept a dataset.json definition, but if passed to a specific component argument, we would traverse to and only use that component of the supplied dataset. For example this:

qri save --meta other_dataset.json me/dataset

would be the same as saying "I've exported some other dataset as other_dataset.json, please copy it's meta component onto me/dataset. This is future work. For now it'd be great if we errored if you passed a file that had "qri": "ds" in the top level to any component argument

[dustmop]

I'm not a huge of having a flag for each component, leads to too many flags that are similar things but are also mutually exclusive. I would prefer --component <component_name>. Both --file and --body are somewhat special in how they work, for example, either can be used to create a new dataset, while --component couldn't be.

[b5]

In the alternative you're outlining I would do qri save --component structure --file st_file.json? Just making sure.

Agreed on the many/too many flags issue. I want to make sure I understand the alternative, but for I can see this adding up to overloading the --file flag a whole bunch instead of flags for each component:

# do what I was mentioning above, inferring this is a default transform
$ qri save --file transform.star me/dataset

# skip the whole --component thing, instead let users specify components with "qri" : "st" top level values
$ qri save --file component_file.json me/dataset

This would have a few implications:

• data, script, and viz file extensions would need to be mutually exclusive
• can't compose multiple components from different source files in a single save invocation (b/c no moar flag slots)

What about dropping the --component business altogether, and just loading up --file with new tricks? After working with Qri a bunch I really just want this flow of applying stuff from one dataset to another, which overloading the --file flag would satisfy:

$ qri get transform.script me/dataset_a > transform.star
$ qri save --file transform.star me/dataset_b

I like this approach more b/c all I have to think about is the --file flag, no more bending the mental model around which flag to use when.

Toughts? cc @camhunt

[dustmop]

In the alternative you're outlining I would do qri save --component structure --file st_file.json?

Yes, this was the possibility I was thinking of.

What about dropping the --component business altogether, and just loading up --file with new tricks?

I think this is an even better idea. Also, we can allow changing multiple components by passing multiple --flag values:

qri save --file change_meta.json --file change_structure.json me/my_dataset

To do this we would change --file to use a StringSliceVar: https://godoc.org/github.com/spf13/pflag#StringSliceVar

[b5]

so looks like we only have to get the multiple --file flags working to close this out. We've also added .star -> transform with a scriptPath and .html -> viz with a scriptPath.

[dustmop]

This is working now, closing this issue.