Cannot set currently-valued fields to null in update mutation about graffiti-mongoose

[zopf]

Here's my hack to make deletions possible: wellth-app@886e8f3

[zopf]

... and then I made this middleware that I can drop into my Koa stack to grab null variables from things that look like mutations and add their paths to the deletions argument:

function getPathsToNull(tree, parentPath) {
  const nullPaths = [];
  for (const key in tree) {
    if (tree[key] === null) {
      // add to null paths
      nullPaths.push(
        parentPath ?
          [parentPath, key].join('.') :
          key
      );
    } else if (tree[key] instanceof Object) {
      // descend
      nullPaths.push.apply(nullPaths, getPathsToNull(
        tree[key],
        parentPath ?
          [parentPath, key].join('.') :
          key
      ));
    }
  }
  return nullPaths;
}

function * handleNullVariables(next) {
  const body = this.request.body;
  const { query, variables } = Object.assign({}, body, this.query);
  // TODO: properly parse the full query AST to determine if actually an add/update mutation
  if (query && /mutation[\s\S]*{\s*(update|add)[a-zA-Z_]+\s*\(/i.test(query)) {
    const parsedVariables = (typeof variables === 'string' && variables.length > 0) ?
          JSON.parse(variables) : variables;

    for (const key in parsedVariables) {
      if ({}.hasOwnProperty.call(parsedVariables, key)) {
        const deletions = getPathsToNull(parsedVariables[key]);
        if (deletions && parsedVariables[key] !== null) {
          parsedVariables[key].deletions = deletions;
        }
      }
    }

    const correctedVariables = JSON.stringify(parsedVariables);
    // set both GET and POST vars
    this.request.body.variables = correctedVariables;
    this.query.variables = correctedVariables;
  }
  yield next;
}

export default handleNullVariables;