redocly-cli/packages/core/src/rules/oas3/array-parameter-serialization.ts

import { Oas3Rule, Oas3Visitor } from '../../visitors';
import { isRef } from '../../ref-utils';
import { Oas3_1Schema, Oas3Parameter } from '../../typings/openapi';

export type ArrayParameterSerializationOptions = {
  in?: string[];
};

export const ArrayParameterSerialization: Oas3Rule = (
  options: ArrayParameterSerializationOptions
): Oas3Visitor => {
  return {
    Parameter: {
      leave(node: Oas3Parameter, ctx) {
        if (!node.schema) {
          return;
        }
        const schema = isRef(node.schema)
          ? ctx.resolve<Oas3_1Schema>(node.schema).node
          : (node.schema as Oas3_1Schema);

        if (schema && shouldReportMissingStyleAndExplode(node, schema, options)) {
          ctx.report({
            message: `Parameter \`${node.name}\` should have \`style\` and \`explode \` fields`,
            location: ctx.location,
          });
        }
      },
    },
  };
};

function shouldReportMissingStyleAndExplode(
  node: Oas3Parameter,
  schema: Oas3_1Schema,
  options: ArrayParameterSerializationOptions
) {
  return (
    (schema.type === 'array' || schema.items || schema.prefixItems) &&
    (node.style === undefined || node.explode === undefined) &&
    (!options.in || (node.in && options.in?.includes(node.in)))
  );
}