JSON Schema to GraphQL Fragment

jsonSchemaToGraphQLFragment.js

//Thank you ChatGPT

function jsonSchemaToGraphQLFragment(schema, typeName, setPrefix = false) {
  // Helper function to resolve $ref references within the schema
  function resolveRef(ref, defs) {
    const refPath = ref.replace(/^#\/\$defs\//, '');
    return defs[refPath];
  }

  // Helper function to process each field in the schema
  function processField(fieldName, fieldSchema, defs, indentLevel, isParent = false) {
    const indent = '  '.repeat(indentLevel);
    const prefixedFieldName = isParent && setPrefix ? `${typeName}_${fieldName} : ${fieldName}` : fieldName;

    if (fieldSchema.$ref) {
      // Resolve the reference and process the resolved schema
      const resolvedSchema = resolveRef(fieldSchema.$ref, defs);
      return processField(prefixedFieldName, resolvedSchema, defs, indentLevel, isParent);
    }

    if (fieldSchema.type === 'object' && fieldSchema.properties) {
      // Process nested object fields
      const nestedFields = Object.entries(fieldSchema.properties)
        .map(([key, value]) => processField(key, value, defs, indentLevel + 1))
        .join('\n');
      return `${indent}${prefixedFieldName} {\n${nestedFields}\n${indent}}`;
    }

    if (fieldSchema.type === 'array' && fieldSchema.items) {
      // Process array fields
      const arrayFields = processField(prefixedFieldName, fieldSchema.items, defs, indentLevel);
      return arrayFields;
    }

    // Treat as scalar field
    return `${indent}${prefixedFieldName}`;
  }

  // Main function to process the schema
  const fields = Object.entries(schema.properties)
    .map(([key, value]) => processField(key, value, schema.$defs || {}, 1, true))
    .join('\n');

  return `
... on ${typeName}  {
${fields}
}`.trim();
}