public static async fromExisting()

in packages/aws-rfdk/lib/lambdas/nodejs/lib/dynamodb/composite-table.ts [41:88]
38 lines of code
12 McCabe index (conditional complexity)

  public static async fromExisting(client: DynamoDBClient, tableName: string): Promise<CompositeStringIndexTable> {
    // Determine the key schema of the table
    // We let this throw if the table does not exist.

    // See: https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/DynamoDB.html#describeTable-property
    const describeResponse = await client.send(new DescribeTableCommand({ TableName: tableName }));
    if (!describeResponse.Table) {
      throw Error(`Could not describeTable for Table '${tableName}'`);
    }
    const keySchema = describeResponse.Table.KeySchema;
    if (!keySchema) {
      throw Error(`Could not get KeySchema for Table '${tableName}'`);
    }
    const attributes = describeResponse.Table.AttributeDefinitions;
    if (!attributes) {
      throw Error(`Could not get Attributes for Table '${tableName}'`);
    }

    // Find the names of the Primary & Sort keys.
    const hashIndex: number = keySchema.findIndex(item => item.KeyType === 'HASH');
    const sortIndex: number = keySchema.findIndex(item => item.KeyType === 'RANGE');
    if (hashIndex < 0 || sortIndex < 0) {
      console.debug(`Error initializing DynamoDatabase. KeySchema: ${JSON.stringify(keySchema)}`);
      if (hashIndex < 0) {
        throw Error(`Could not find PrimaryKey of Table '${tableName}'`);
      } else {
        throw Error(`Could not find SortKey of Table '${tableName}'`);
      }
    }
    const primaryKey = keySchema[hashIndex].AttributeName;
    const sortKey = keySchema[sortIndex].AttributeName;

    // Make sure that the primary & sort key types are both string types
    // (( We didn't make this flexible enough for other attribute types for the key ))
    if ('S' !== attributes.find(item => item.AttributeName === primaryKey)?.AttributeType) {
      throw Error(`Primary key '${primaryKey}' must be string type`);
    }
    if ('S' !== attributes.find(item => item.AttributeName === sortKey)?.AttributeType) {
      throw Error(`Sort key '${sortKey}' must be string type`);
    }

    return new CompositeStringIndexTable(
      client,
      tableName,
      primaryKey!,
      sortKey!,
    );
  }