Embedding in golang

[rajrahul]

Planning to use cue for a document validation/transformation service. We will have a golang service that accept cue scripts, execute and return the resultant JSON.

The snippet below works as long as there are no library imports.

func evalCue(input string) (string, error) {
res, err := rt.Compile("test.cue", input)
if err != nil { ... }
eval := res.Value().Eval()
return convertCUEValueToString(eval)
}

For the input below, looks like compilation removes the imports and results in error : "| // str: cannot call non-function strings.ToUpper (type |) "

body := import "strings" str : strings.ToUpper("hello world")
str, err := evalCue(body)

Any examples on how to handle this?

Thanks,
Rahul

[eonpatapon]

To use builtins you just need to import them in your go code like that:

import (
  _ "cuelang.org/go/pkg"
)

For managing imports of custom modules you will need to use load.Instances instead of Runtime.Compile.

[rajrahul]

Thanks it is working now. Is there way to pass in memory strings than to read from files on disk?

[verdverm]

I believe the plan is to provide a fs.FS option to the load config once Go 1.17 is available (really once Go 1.15 is no longer supported)

You may be able to use the Overlay option, can't recall for sure without testing.

[myitcv]

#607 (comment) indeed remains the plan.

@rajrahul depending on your use case you might be able to rely on the Overlay provided as part of https://pkg.go.dev/cuelang.org/go@v0.3.2/cue/load#Config. Otherwise, you might need to use go:embed directive (or equivalent), write to a temp directory, and load from there.

[cueckoo]

This discussion has been migrated to cue-lang/cue#992.

For more details about CUE's migration to a new home, please see cue-lang/cue#1078.