Item schema: add more detail to the code sample

[tyssejc]

Issue

The point of a schema is to impose strict rules around how data should be structured.

It's not clear from the code sample:

• what the type of each value should be
• what the minimum/maximum length should be
• what regex pattern it should match

https://github.com/searchdiscovery/client-jnj-ga4-dl-spec/blob/c89eb6b620313668e77041fae439c8a7a32e34a7/schemas/item.md?plain=1#L7-L36

As a result, at least one property ("price") has been implemented as a string and not a number. This was missed in QA and UAT.

Suggestions

1. express as a TypeScript interface

interface EventMessage {
  item_id: string;
  price: number;
  affiliation?: string;
}

2. express as JSON schema

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "type": "object",
  "properties": {
    "affiliation": {
      "type": "string"
    },
    "item_id": {
      "type": "string"
    },
    "price": {
       "type": "number",
       "pattern": "/\d+\.\d{2,}"
  },
  "required": [
    "item_id"
  ]
}

The nice thing about JSON Schema is that those rules can be ingested by automated testing software and used in assertions.

adding comments to the code sample is not sufficient!