feat(schema): Use Neo4j DateTime type for created and modfied fields

[alastair]

This was originally set to String, but it's nice to have it as a datatype that allows us to do more detailed filtering.

This isn't affected by #91 because we will always have a full datetime for created and modified.

An addition to this is to integrate #112 at a later stage.

One issue that I saw, I can perform this mutation (adding created.formatted):

mutation {
  CreateRating(
creator: "https://testuser.trompa-solid.upf.edu/profile/card#me"
        ratingValue: 8
        bestRating: 10
        worstRating: 1
        created: {formatted: "2021-03-10T15:24:38.369017+00:00"}
) {
identifier
}
}

but this one fails:

mutation {
  UpdateRating (
    identifier: "05d9272c-3d00-48dc-ab25-bdab147291ea"
    created: {formatted:"2021-03-10T15:24:38.369017+00:00"}
  ) {
    identifier
  }
}

with this message:

{
  "errors": [
    {
      "message": "No such field: formatted",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "UpdateRating"
      ],
      "extensions": {
        "code": "INTERNAL_SERVER_ERROR",
        "exception": {
          "errors": [
            {
              "message": "No such field: formatted",
              "locations": [],
              "path": [
                "UpdateRating"
              ]
            }
          ],
          "stacktrace": [
            "Error: No such field: formatted",
            "    at new CombinedError (/app/node_modules/graphql-tools/src/stitching/errors.ts:90:5)",
            "    at Object.checkResultAndHandleErrors (/app/node_modules/graphql-tools/src/stitching/errors.ts:111:11)",
            "    at CheckResultAndHandleErrors.transformResult (/app/node_modules/graphql-tools/src/transforms/CheckResultAndHandleErrors.ts:15:12)",
            "    at /app/node_modules/graphql-tools/src/transforms/transforms.ts:37:45",
            "    at Array.reduce (<anonymous>)",
            "    at applyResultTransforms (/app/node_modules/graphql-tools/src/transforms/transforms.ts:35:21)",
            "    at /app/node_modules/graphql-tools/src/stitching/delegateToSchema.ts:104:12",
            "    at step (/app/node_modules/graphql-tools/dist/stitching/delegateToSchema.js:32:23)",
            "    at Object.next (/app/node_modules/graphql-tools/dist/stitching/delegateToSchema.js:13:53)",
            "    at fulfilled (/app/node_modules/graphql-tools/dist/stitching/delegateToSchema.js:4:58)"
          ]
        }
      }
    }
  ],
  "data": {
    "UpdateRating": null
  }
}

@ChristiaanScheermeijer thinks it's related to neo4j-graphql/neo4j-graphql-js#547

[ChristiaanScheermeijer]

Looks good. If we set the created and updated properties automatically, nobody would need to update or set these properties manually. We might even remove them from the update/create mutations.

[alastair]

Yes, I like the idea of removing them from the mutations.

[alastair]

why action == Update twice?

[alastair]

sorry, just saw the other commit that changed it to Merge

[ChristiaanScheermeijer]

Yes, that was wrong. Fixed it right after.

[alastair]

I can't approve my own PR! but it looks good by me

[alastair]

I just had a thought here: What if the type has no 'created' or 'modified' fields? Here you will try and add them anyway.
All of the existing models implement ThingInterface and so have these fields, but some of the types that I defined for supporting the Annotations schema don't include them. I can add them in, but I think it makes sense that this transformer also supports the case where they're not present

[ChristiaanScheermeijer]

Oh, that's a very good point. I'd assumed every type would contain these properties...