lua/5.1/kong/db/schema/init.lua:1244: attempt to index a nil value about kong

[pravin-raha]

Thanks @nateslo, I checked with your first solution. Now it's working fine

[nateslo]

Hi @pravin-raha. I believe the issue is config.{field_name} in your entity_checks which are nested inside of the config table. If the entity_checks are moved to the top level (sibling of fields), then validation succeeds.

return {
    name = "oidc-acl",
    fields = {
        { consumer = typedefs.no_consumer },
        { protocols = typedefs.protocols_http },
        {
            config = {
                type = "record",
                fields = {
                    { whitelist = { type = "array", elements = { type = "string" }, required = false } },
                    { blacklist = { type = "array", elements = { type = "string" }, required = false } },
                    { userinfo_header_name = { type = "string", required = false, default = "x-userinfo" } }
                },
            },
        },
    },
    -- entity checks moved to top level
    entity_checks = {  
      { only_one_of = { "config.whitelist", "config.blacklist" }, },
      { at_least_one_of = { "config.whitelist", "config.blacklist" }, },
  },
}

Compare this to the ACL plugin, which has a very similar schema: https://github.com/Kong/kong/blob/master/kong/plugins/acl/schema.lua

Alternately, I believe that you can remove config. from the field names and keep entity_checks inside the config table

return {
    name = "oidc-acl",
    fields = {
        { consumer = typedefs.no_consumer },
        { protocols = typedefs.protocols_http },
        {
            config = {
                type = "record",
                fields = {
                    { whitelist = { type = "array", elements = { type = "string" }, required = false } },
                    { blacklist = { type = "array", elements = { type = "string" }, required = false } },
                    { userinfo_header_name = { type = "string", required = false, default = "x-userinfo" } }
                },
                entity_checks = {
                  { only_one_of = { "whitelist", "blacklist" }, }, -- "config." removed
                  { at_least_one_of = { "whitelist", "blacklist" }, }, -- "config." removed
              },
            },
        },
    },
}

Both pass a validation unit test but I'll let someone with more context explain the differences between the two approaches