No ability in plugin schema to have a record with dynamic fields

[jaxtonw]

Is there an existing issue for this?

• I have searched the existing issues

Kong version ($ kong version)

Kong 2.8.4

Current Behavior

When defining a Kong plugin's schema, there is no way to allow for a record that does not have it's field attribute defined.

Minimal example:

local typedefs = require "kong.db.schema.typedefs"

return {
  name = "example",
  fields = {
    { consumer = typedefs.no_consumer },
    { config = {
        type = "record",
        fields = {
          { some_string = { type = "string", required = true } },
          { dynamic_record = { type = "record", required = false } }
        }
      }
    }
  }
}

The field some_string is fine, however dynamic_record produces a schema violation error: dynamic_record: field of type 'record' must declare 'fields'.

The inability to explicitly allow for a dynamic record as one of the fields is limiting. I want my users to be able to explicitly specify arbitrary key and value pairs as dynamic_record. I want both of these dynamic_records to be valid by the schema.

dynamic_record:
  key1: "value1"

dynamic_record:
  key1: 1
  key2: "other_value"

Expected Behavior

Should accept an arbitrary record type as a field

Steps To Reproduce

1. Create a plugin schema
2. Have one of the fields be of type record and do not define a field

Anything else?

The lack of documentation about fields that are of type record is ultimately the most addressable concern here. However, there should be a way to work around this as well.

[jaxtonw]

Update:

A workaround was attempted that was not successful. Setting the fields for the record as fields = {} resulted in the schema violation error going away. However, when applying a configuration where dynamic_record has an added attribute, the configuration fails, as expected.

[Water-Melon]

No, currently this is not supported. However, there is another workaround, which is to define dynamic_record as a string. Then, in your plugin, try to decode this string as JSON, for example:

local record = cjson.decode(conf.dynamic_record)

[github-actions]

This issue is marked as stale because it has been open for 14 days with no activity.

[jaxtonw]

thanks for the suggestion @Water-Melon! That was quite helpful. I ended up doing something slightly different though.

local typedefs = require "kong.db.schema.typedefs"

return {
  name = "example",
  fields = {
    { consumer = typedefs.no_consumer },
    { config = {
        type = "record",
        fields = {
          { some_string = { type = "string", required = true } },
          { dynamic_record = { type = "array", required = false,
            elements = {
                type = "record",
                fields = {
                  { key= { type = "string", required = true } },
                  { value= { type = "string", required = true } }
                }
              }
            } 
          }
        }
      }
    }
  }
}

This allowed me to also enforce types for both the keys and values. Not quite what was originally desired, but it works for me.

dynamic_record:
  - key: "keyname"
    value: "value"

Going forward, we should document that dynamic records are not supported and that these are valid workarounds when desired.

[github-actions]

This issue is marked as stale because it has been open for 14 days with no activity.

[github-actions]

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