App Script REST style API in doGet() and doPost()

restWebService.gs

function doGet(e) {
  // Look up the function for the specified endpoint
  var handler = getEndpointHandlers[e.parameter.action];
  if (handler) {
    // Call the appropriate function for the endpoint
    return handler(e);
  } else {
    // Return an error if the endpoint is not recognized
    return ContentService.createTextOutput("Error: Invalid GET endpoint.").setMimeType(ContentService.MimeType.TEXT);
  }
}

function doPost(e) {
  // Look up the function for the specified endpoint
  var handler = getEndpointHandlers[e.parameter.action];
  if (handler) {
    // Call the appropriate function for the endpoint
    return handler(e);
  } else {
    // Return an error if the endpoint is not recognized
    return ContentService.createTextOutput("Error: Invalid POST endpoint.").setMimeType(ContentService.MimeType.TEXT);
  }
}

// ROUTES: containing functions to handle GET requests to different endpoints
var getEndpointHandlers = {
  'apnSearch': bqApnSearch,
  'users': getUsers,
  'schemas': getSchemas,
  'schema': getSchema,
  'properties': propSearch
};

// ROUTES: containing functions to handle POST requests to different endpoints
var postEndpointHandlers = {
  'bqImportCsv': bqImportCsv,
  'bqDeleteTable': bqDeleteTable,
  'properties': propSearch
};

// TODO: add examples for parameter handling/parsing parameters passed to handler
// https://script.google.com/macros/s/<macro_id>/exec?action=apnSearch/3938844&fields=name,address,phone

function getSchemas(e) {
  var schemas = ['parcels','dsd','ced','listings']
  return ContentService.createTextOutput(JSON.stringify(schemas)).setMimeType(ContentService.MimeType.JSON);
  //return ContentService.createTextOutput(JSON.stringify(schema)).setMimeType(ContentService.MimeType.JSON);
}