custom_json_handling.ts

// Similar to `insert_js_dates.ts` but testing custom JSON handling
//
// JSON.stringify does not handle BigInt data types by default, so we'll provide
// a custom serializer before passing it to the JSON.stringify function.
//
// This example also shows how you can serialize Date objects in a custom way.
import { createClient } from "@clickhouse/client-web";

const valueSerializer = (value: unknown): unknown => {
  if (value instanceof Date) {
    // if you would have put this in the `replacer` parameter of JSON.stringify, (e.x: JSON.stringify(obj, replacerFn))
    // it would have been an ISO string, but since we are serializing before `stringify`ing,
    // it will convert it before the `.toJSON()` method has been called
    return value.getTime();
  }

  if (typeof value === "bigint") {
    return value.toString();
  }

  if (Array.isArray(value)) {
    return value.map(valueSerializer);
  }

  if (typeof value === "object" && value !== null) {
    return Object.fromEntries(
      Object.entries(value).map(([k, v]) => [k, valueSerializer(v)]),
    );
  }

  return value;
};

const tableName = "inserts_custom_json_handling_web";
const client = createClient({
  json: {
    parse: JSON.parse,
    stringify: (obj: unknown) => JSON.stringify(valueSerializer(obj)),
  },
});
await client.command({
  query: `DROP TABLE IF EXISTS ${tableName}`,
});
await client.command({
  query: `
    CREATE TABLE ${tableName}
    (id UInt64, dt DateTime64(3, 'UTC'))
    ENGINE MergeTree()
    ORDER BY (id)
  `,
});
await client.insert({
  table: tableName,
  values: [
    {
      id: BigInt(250000000000000200),
      dt: new Date(),
    },
  ],
  format: "JSONEachRow",
});
const rows = await client.query({
  query: `SELECT * FROM ${tableName}`,
  format: "JSONEachRow",
});
console.info(await rows.json());
await client.close();