Feature: Adding Context to Validate Method about jsonschema HOT 2 CLOSED

I didn't specify use case: i make call to database in Validate.

I've done bad WA which works only if jsonschema.NewCompiler() is not singelton. Maybe you tell me the better solution. I guess the compiler must be singleton in production.

I simply passed the ctx through my own ExtCompiler and ExtSchema, like this:"

ctx:= context.Context
compiler := jsonschema.NewCompiler()
compiler.RegisterExtension("mgsFormat", MgsFormatMeta, mgsFormatCompiler{Ctx})

mgsFormatCompiler:

type mgsFormatCompiler struct {
	ctx context.Context
}

func (compiler mgsFormatCompiler) Compile(ctx jsonschema.CompilerContext, m map[string]interface{}) (jsonschema.ExtSchema, error) {
	if mgsFormatRaw, ok := m["mgsFormat"]; ok {
		return compiledMgsFormat{compiler.ctx}, nil
	}

	return nil, nil
}

compiledMgsFormat

type compiledMgsFormat struct {
	ctx context.Context
}
func (f compiledMgsFormat) Validate(ctx jsonschema.ValidationContext, v interface{}) error {
  ctx := f.ctx
  //call to DB
}

from jsonschema.

@voronovmaksim

ideally schema validation must be pure. I mean, if you repeatedly validate a json with schema, then it should always produce same result. if you have keyword that is making decisions based on the data from a database this will break.

ideally keywords are not supposed to do any IO during validation. So I am not keen in adding context.Context to Validate Method

but as a workaround for your use case:

you would want to pass different context.Context for each validation. but the code you shown above is capturing ctx during compilation. If you are always compiling before each validation (i.e discarding compiling schema after each validation) it might work

you can use https://github.com/timandy/routine to pass context. but it uses internal goroutine ID for this (which may change in future Golang versions). you can use it as follows:

import "github.com/timandy/routine"

// create global variable for holding thread local context
var threadLocal = routine.NewThreadLocal[*context.Context]()

func doSchemaValidation(ctx *context.Context, sch *Schema, instance interface{}) error {
     threadLocal.set(ctx)
}

type compiledMgsFormat struct {}
func (f compiledMgsFormat) Validate(ctx jsonschema.ValidationContext, v interface{}) error {
  ctx := threadLocal.get()
  //call to DB
}

from jsonschema.