Feature/unique directive

[darrellwarde]

Description

Adds an assertConstrains function to the Neo4jGraphQL class which can be used to assert unique node property constraints indicated by a new @unique directive exist.

Overview of features:

• By default, @id and @unique directives indicate that a unique node property constraint should exist for the property mapped to the GraphQL field.
• @id has a new boolean option, unique, which is true by default, which let's users disable this new behaviour.
• Compatible with both the label argument of the @node directive, and the @alias directive.
• Option to create missing constraints on running of assertConstraints.

UPDATE:

Instead of using the desired SHOW CONSTRAINTS (https://neo4j.com/docs/cypher-manual/4.3/constraints/examples/#administration-constraints-list-constraint), this has to use CALL db.constraints (https://neo4j.com/docs/cypher-manual/4.1/administration/constraints/#administration-constraints-list-constraint) to maintain compatibility with 4.1.

Introduced a parsing function which outputs in the same object format as SHOW CONSTRAINTS, and left the code for SHOW CONSTRAINTS present under TODO blocks so that swapping out is simple when 4.1 reaches end-of-life.

Issue

#206

Checklist

The following requirements should have been met (depending on the changes in the branch):

• Documentation has been updated
• TCK tests have been updated
• Integration tests have been updated
• Example applications have been updated
• New files have copyright header
• CLA (https://neo4j.com/developer/cla/) has been signed

[neo4j-team-graphql]

Thanks for the documentation updates.

The preview documentation has now been torn down - reopening this PR will republish it.

[angrykoala]

Looks good. A few minor comments

[darrellwarde]

Thanks for the comments @angrykoala - looks like I need to rewrite the whole thing anyway because my current solution isn't 4.1 compatible!!! 👿

[danstarns]

I noticed that when I create a node through the GraphQL API the Neo4j Error is propagated to the users. What do you think and would there be a possibility to throw something more generic, just to ensure that we don't leak any info about the backend?

Example Error:

{
  "errors": [
    {
      "message": "Node(7108) already exists with label `Movie` and property `title` = 'Some Title'",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "createMovies"
      ],
      "extensions": {
        "code": "INTERNAL_SERVER_ERROR",
        "exception": {
          "code": "Neo.ClientError.Schema.ConstraintValidationFailed",
          "name": "Neo4jError",
          "stacktrace": [
            "Neo4jError: Node(7108) already exists with label `Movie` and property `title` = 'Some Title'",
            ": ",
            "    at captureStacktrace (C:\\code\\neo4j\\graphql\\node_modules\\neo4j-driver-core\\lib\\result.js:239:17)",
            "    at new Result (C:\\code\\neo4j\\graphql\\node_modules\\neo4j-driver-core\\lib\\result.js:59:23)",
            "    at newCompletedResult (C:\\code\\neo4j\\graphql\\node_modules\\neo4j-driver-core\\lib\\transaction.js:372:12)",
            "    at Object.run (C:\\code\\neo4j\\graphql\\node_modules\\neo4j-driver-core\\lib\\transaction.js:226:20)",
            "    at Transaction.run (C:\\code\\neo4j\\graphql\\node_modules\\neo4j-driver-core\\lib\\transaction.js:98:34)",
            "    at C:\\code\\neo4j\\graphql\\packages\\graphql\\src\\utils\\execute.ts:94:35",
            "    at TransactionExecutor._safeExecuteTransactionWork (C:\\code\\neo4j\\graphql\\node_modules\\neo4j-driver-core\\lib\\internal\\transaction-executor.js:92:26)",
            "    at TransactionExecutor._executeTransactionInsidePromise (C:\\code\\neo4j\\graphql\\node_modules\\neo4j-driver-core\\lib\\internal\\transaction-executor.js:83:34)",
            "    at C:\\code\\neo4j\\graphql\\node_modules\\neo4j-driver-core\\lib\\internal\\transaction-executor.js:40:19",
            "    at new Promise (<anonymous>)"
          ]
        }
      }
    }
  ],
  "data": null
}

[angrykoala]

Looking nice, just minor style/legibility proposals