stringvalidator: Support json string validation

[k-yomo]

Terraform CLI and Framework Versions

❯ terraform version
Terraform v1.3.6
on darwin_arm64
...

❯ go list -m github.com/hashicorp/terraform-plugin-framework
github.com/hashicorp/terraform-plugin-framework v1.0.0

Use Cases

[]validator.String{
  stringvalidator.JSON(),
},

Proposal

It would be very handy if we have json string validator in this package to validate if the given string is valid json or not.

Additional Information

Equivalent implementation in terraform-plugin-sdk package
https://github.com/hashicorp/terraform-plugin-sdk/blob/aa73507131cb35683a6408b4d06252991fecb868/helper/validation/strings.go#L209-L222

Code of Conduct

• I agree to follow this project's Code of Conduct

[bflad]

Hi @k-yomo 👋 Thank you for raising this feature request.

While it technically would not be difficult to implement this validator in this Go module, an intention of terraform-plugin-framework's extensible type system is to allow provider developers, or the ecosystem at large, to create custom types that can cover specific use cases. Otherwise, this Go module could wind up trying to cover an extremely broad area of all possible string encodings, formats, etc. which is unmaintainable for one project.

Ideally a custom JSON string type with validation baked into it would be created rather than requiring provider developers to separately implement the JSON validation. Future iterations on that concept would help handle syntactical versus semantic equality, which will help prevent Terraform errors or reported drift in cases where inconsequential whitespace differences can occur. We are hoping to have an initial prototype of this done early next month.

[k-yomo]

@bflad

Ideally a custom JSON string type with validation baked into it would be created rather than requiring provider developers to separately implement the JSON validation. Future iterations on that concept would help handle syntactical versus semantic equality, which will help prevent Terraform errors or reported drift in cases where inconsequential whitespace differences can occur. We are hoping to have an initial prototype of this done early next month.

Thank you for the comment! It sounds great and can't wait it!!

[bflad]

A new github.com/hashicorp/terraform-plugin-framework-jsontypes Go module is now available with a custom type implementation for JSON strings. The types there perform JSON validation automatically and the normalized type supports ignoring differences in whitespace and property ordering (per the JSON specification). If you can, please give it a try and let us know how it goes. If you would like additional documentation on using custom types, please refer to the custom types documentation. Thanks so much.

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