# `@biblioteksentralen/marc`

Package for representating MARC records in TypeScript and serialize to/from MARC XML and JSON.

The JSON serialization is compatible with the schema defined by <https://www.npmjs.com/package/@natlibfi/marc-record>

## Usage

### Parsing and serializing XML

```ts
import { parseMarcXml, serializeMarcXml } from "@biblioteksentralen/marc";

const xmlRecord = `
<record xmlns="http://www.loc.gov/MARC21/slim">
  <leader>00000cam^a22001937i^4500</leader>
  <controlfield tag="001">000030000</controlfield>
  <controlfield tag="003">FI-MELINDA</controlfield>
  <controlfield tag="005">20141221175522.0</controlfield>
  <controlfield tag="008">890208s1988^^^^sw^|||||||||||||||||swe||</controlfield>
  <datafield tag="020" ind1=" " ind2=" ">
    <subfield code="a">91-38-61844-3</subfield>
    <subfield code="q">inb.</subfield>
  </datafield>
  <datafield tag="100" ind1="0" ind2=" ">
    <subfield code="a">Durö, Robert.</subfield>
  </datafield>
  <datafield tag="245" ind1="1" ind2="0">
    <subfield code="a">Konkurrensöverlägsenhet :</subfield>
    <subfield code="b">i tio konkreta steg /</subfield>
    <subfield code="c">Robert Durö.</subfield>
  </datafield>
</record>
`;

const record = parseMarcXml(xmlRecord);
const title = record
  .getSubfieldValues("245", /a|b|n|p/)
  .join(" ")
  ?.trim();

const xml = serializeMarcXml(record);
```

### Serializing Line MARC

```ts
import {
  createControlField,
  createDataField,
  createSubfield,
  serializeLineMarc
} from "@biblioteksentralen/marc";

const record = new MarcRecord({
  leader: "...",
  fields: [
    createControlField(...),
    createDataField(...),
  ]
});

const lineMarc = serializeLineMarc(record);
```

### Serializing and deserializing as JSON

The MarcRecord class can be JSON serialized:

```ts
const serializedRecord = JSON.stringify(record);
```

and deserialized:

```ts
const record = MarcRecord.fromJSON(JSON.parse(serializedRecord));
```

Standalone fields can also be deserialized using the `createDataField` function – useful for tests:

```ts
const field = createDataField({
  tag: "020",
  subfields: [{ code: "a", value: "9788283982701" }],
});
```

### JSON Schema validation

The package exports a JSON schema that can be used to validate JSON serialized
MARC record structure using AJV or other JSON Schema validators.

```ts
import Ajv from "ajv";
import { createMarcSchema } from "@biblioteksentralen/marc";

const schema = createMarcSchema();
const ajv = new Ajv();
const validate = ajv.compile(schema);
const result = validate(record.toJSON());
```

## Changelog

- 0.4.0: Line MARC serialization: Remove linebreaks and trim surrounding whitespace
- 0.3.0: Upgrade to Zod 4
- 0.2.0: Removed the logger argument from `MarcRecord.fromJSON()`.