问题

The Q&A is currently a subject of meta discussion - please, do participate. Current plan is to split where possible (and no canonicals exist) into separate Q&As. The answer to the question is a community wiki and the question intended to become one when the status of the Q&A itself is resolved.

Preface

This Q&A strives to become a collection and a reference target for common errors encountered during development in Google Apps Script language in hopes to improve long-term maintainability of google-apps-script tag.

There are several similar and successful undergoings in other languages and general-purpose tags (see c++, android, php, php again), and this one follows suit.

Why it exists?

The amount of questions from both new and experienced developers regarding the meaning and solutions to errors encountered during development and production that can be effectively reduced to a single answer is substantial. At the time of writing, even running a query only by language tag yields:

"Cannot find method" 8 pages
"Cannot read property" 9 pages
"Cannot call ... in this context" 5 pages
"You do not have permission" 11 pages

Linking to a most relevant duplicate is hard and time-consuming for volunteers due to the need to consider nuances and often poorly-worded titles.

What it consists of?

Entries in this Q&A contain are designed as to provide info on how to:

parse the error message structure
understand what the error entails
consistently reproduce (where applicable)
resolve the issue
provide a link to canonical Q&A (where possible)

What this is not?

The scope of the Q&A is limited to common (not trivial). This is not:

a catch-all guide or "best practices" collection
a reference for general ECMAScript errors
GAS documentation
a resources list (we have a tag wiki for that)

What to add?

When adding an entry, please, consider the following:

is the error common enough (see "why" section for examples)?
can the solution be described concisely and be applicable for most cases?

回答1:

Preface

The initial answer provides a guide on general and built-in service-related errors.
Entries addressing issues with services listed in official reference are welcome.

This is an ongoing project and will be constantly updated.

General errors

Message

TypeError: Cannot read property 'property name here' from undefined (or null)

Description

The error message indicates that you are trying to access a property on an Object instance, but during runtime the value actually held by variable is a special data type undefined. Typically, the error occurres when accessing nested properties of an object.

A variation of this error with numeric value in place of property name indicates that an instance of Array was expected. As arrays in JavaScript are objects, everything mentioned here is true about them as well.

There is a special case of dynamically constructed objects such as event objects that are only available in specific contexts like making an HTTP request to the app or invoking a function via time or event-based trigger.

The error is a TypeError because an "object" is expected, but "undefined" is received

How to fix

Using default values
Logical OR || operator in JavaScript has an intersting property of evaluating the right-hand side iff the left-hand is falsy. Since objects in JS are truthy, and undefined and null are falsy, an expression like (myVar || {}).myProp [(myVar || [])[index] for arrays] will guarantee that no error is thrown and the property is at least undefined.

One can also provide default values: (myVar || { myProp : 2 }) guarantees accessing myProp to return 2 by default. Same goes for arrays: (myVar || [1,2,3]).
Checking for type
Especially true for the special case, typeof operator combined with an if statement and a comparison operator will either allow a function to run outside of its designated context (i.e. for debugging purposes) or introduce branching logic depending on whether the object is present or not.

One can control how strict the check should be:
- lax ("not undefined"): if(typeof myVar !== "undefined") { //do something; }
- strict ("proper objects only"): if(typeof myVar === "object" && myVar) { //do stuff }

Related Q&As

Parsing order of GAS project as the source of the issue

Message

Cannot convert some value to data type

Description

The error is thrown due to passing an argument of different type than a method expects. Common mistake that causes the error is an accidental coercion of a number to string.

How to reproduce

function testConversionError() {
  const ss = SpreadsheetApp.getActiveSheet();
  ss.getRange("42.0",1);
}

How to fix

Make sure that the value referenced in the error message is of data type required by documentation and convert as needed.

Message

Cannot call Service and method name from this context

Description

This error happens on a context mismatch and is specific to container-bound scripts. Primary use case that results in the error is trying to call a method only available in one document type (usually, getUi() as it is shared by several services) from another (i.e. DocumentApp.getUi() from a spreadsheet).

Secondary, but also prominent case is a result of calling a service not explicitly allowed to be called from a custom function (usually a function marked by special JSDoc-style comment @customfunction and used as a formula).

How to reproduce

For bound script context mismatch, declare and run this function in a script project tied to Google Sheets (or anything other than Google Docs):

function testContextMismatch() {
  const doc = DocumentApp.getUi();
}

Note that calling a DocumentApp.getActiveDocument() will simply result in null on mismatch, and the execution will succeed.

For custom functions, use the function declared below in any cell as a formula:

/**
 * @customfunction
 */
function testConversionError() {
  const ui = SpreadsheetApp.getUi();
  ui.alert(`UI is out of scope of custom function`);
}

How to fix

Context mismatch is easily fixed by changing the service on which the method is called.
Custom functions cannot be made to call these services, use custom menus or dialogs.

Message

Cannot find method Method name here

The parameters param names do not match the method signature for method name

Description

This error has a notoriously confusing message for newcomers. What it says is that a type mismatch occurred in one or more of the arguments passed when the method in question was called.

There is no method with the signature that corresponds to how you called it, hence "not found"

How to fix

The only fix here is to read the documentation carefully and check if order and inferred type of parameters are correct (using a good IDE with autocomplete will help). Sometimes, though, the issue happens because one expects the value to be of a certain type while at runtime it is of another. There are several tips for preventing such issues:

Setting up type guards (typeof myVar === "string" and similar).
Adding a validator to fix the type dynamically thanks to JavaScript being dynamically typed.

Sample

/**
 * @summary pure arg validator boilerplate
 * @param {function (any) : any}
 * @param {...any} args
 * @returns {any[]}
 */
const validate = (guard, ...args) => args.map(guard);

const functionWithValidator = (...args) => {
  const guard = (arg) => typeof arg !== "number" ? parseInt(arg) : arg;

  const [a,b,c] = validate(guard, ...args);
  
  const asObject = { a, b, c };
  
  console.log(asObject);
  
  return asObject;
};

//driver IIFE
(() => {
  functionWithValidator("1 apple",2,"0x5");
})()

Messages

You do not have permission to perform that action

The script does not have permission to perform that action

Description

The error indicates that one of the APIs or services accessed lacks sufficient permissions from the user. Every service method that has an authorization section in its documentation requires at least one of the scopes to be authorized.

As GAS essentially wraps around Google APIs for development convenience, most of the scopes listed in OAuth 2.0 scopes for APIs reference can be used, although if one is listed in the corresponding docs it may be better to use it as there are some inconsistencies.

Note that custom functions run without authorization. Calling a function from a Google sheet cell is the most common cause of this error.

How to fix

If a function calling the service is ran from the script editor, you are automatically prompted to authorize it with relevant scopes. Albeit useful for quick manual tests, it is best practice to set scopes explicitly in application manifest (appscript.json). Besides, automatic scopes are usually too broad to pass the review if one intends to publish the app.

The field oauthScopes in manifest file (View -> Show manifest file if in code editor) should look something like this:

  "oauthScopes": [
    "https://www.googleapis.com/auth/script.container.ui",
    "https://www.googleapis.com/auth/userinfo.email",
    //etc
  ]

For custom functions, you can fix it by switching to calling the function from a menu or a button as custom functions cannot be authorized.

For those developing editor Add-ons this error means an unhandled authorization lifecycle mode: one has to abort before calls to services that require authorization in case auth mode is AuthMode.NONE.

Related causes and solutions

@OnlyCurrentDoc limiting script access scope
Scopes autodetection

Message

ReferenceError: service name is not defined

Description

The most common cause is using an advanced service without enabling it. When such a service is enabled, a variable under the specified identifier is attached to global scope that the developer can reference directly. Thus, when a disabled service is referenced, a ReferenceError is thrown.

How to fix

Go to "Resources -> Advanced Google Services" menu and enable the service referenced. Note that the identifier should equal the global variable referenced. For more detailed explanation, read the official guide.

If one hasn't referenced any advanced services then the error points to an undeclared variable being referenced.

Message

The script completed but did not return anything.

Script function not found: doGet or doPost

Description

This is not an error per se (as the HTTP response code returned is 200 and the execution is marked as successful, but is commonly regarded as one. The message appears when trying to make a request / access from browser a script deployed as a Web App.

There are two primary reasons why this would happen:

There is no doGet or doPost trigger function
Triggers above do not return an HtmlOutput or TextOutput instance

How to fix

For the first reason, simply provide a doGet or doPost trigger (or both) function. For the second, make sure that all routes of your app end with creation of TextOutput or HtmlOutput:

//doGet returning HTML
function doGet(e) {
  return HtmlService.createHtmlOutput("<p>Some text</p>");
}

//doPost returning text
function doPost(e) {
  const { parameters } = e;
  const echoed = JSON.stringify(parameters);
  return ContentService.createTextOutput(echoed);
}

Note that there should be only one trigger function declared - treat them as entry points to your application.

If the trigger relies on parameter / parameters to route responses, make sure that the request URL is structured as "baseURL/exec?query" or "baseURL/dev?query" where query contains parameters to pass.

Related Q&As

Redeploying after declaring triggers

Message

We're sorry, a server error occurred. Please wait a bit and try again.

Description

This one is the most cryptic errors and can occur at any point with nearly any service (although DriveApp usage is particularly susceptible to it). The error usually indicates a problem on Google's side that either goes away in a couple of hours / days or gets fixed in the process.

How to fix

There is no silver bullet for that one and usually there is nothing you can do apart from filing an issue on issue tracker or contacting support if you have a GSuite account. Before doing that one can try the following common remedies:

For bound scripts - creating a new document and copying over the existing project and data.
Switch to using an advanced Drive service (always remember to enable it first).
There might be a problem with a regular expression if the error points to a line with one.

Don't bash your head against this error - try locating affected code, file or star an issue and move on

Syntax error without apparent issues

This error is likely to be caused by using an ES6 syntax (for example, arrow functions) while using the deprecated V8 runtime (at the time of writing GAS platform uses V8).

How to fix

Open "appscript.json" manifest file and check if runtimeVersion is set to "V8", change it if not or remove any ES6 features otherwise.

Quota-related errors

There are several errors related to quotas imposed on service usage. Google has a comprehensive list of those, but as a general rule of thumb, if a message matches "too many" pattern, you are likely to have exceeded the respective quota.

Most likely errors encountered:

Service invoked too many times: service name
There are too many scripts running
Service using too much computer time for one day
This script has too many triggers

How to fix

In most cases, the only fix is to wait until the quota is refreshed or switch to another account (unless the script is deployed as a Web App with permission to "run as me", in which case owner's quotas will be shared across all users).

To quote documentation at the time:

Daily quotas are refreshed at the end of a 24-hour window; the exact time of this refresh, however, varies between users.

Note that some services such as MailApp have methods like getRemainingDailyQuota that can check the remaining quota.

In the case of exceeding maximum number of triggers one can check how many are installed via getProjectTriggers() (or check "My triggers" tab) and act accordingly to reduce the number (for example, by using deleteTrigger(trigger) to get rid of some).

Related canonical Q&As

How are daily limitations being applied and refreshed?
"Maximum execution time exceeded" problem
Optimizing service calls to reduce execution time

Service-specific errors

SpreadsheetApp

Message

The number of rows or cells in the data does not match the number of rows or cells in the range. The data has N but the range has M.

Description

The error points to a mismatch in dimensions of range in relation to values. Usually, the issue arises when using setValues() method when the matrix of values is smaller or bigger than the range.

How to reproduce

function testOutOfRange() {
    const ss = SpreadsheetApp.getActiveSpreadsheet();
    const sh = ss.getActiveSheet();
    const rng = sh.getActiveRange();
    const vals = rng.getValues();

    try {
        vals.push([]);
        rng.setValues(vals);
    } catch (error) {
        const ui = SpreadsheetApp.getUi();
        ui.alert(error.message);
    }
}

How to fix

If it is routinely expected for values to get out of bounds, implement a guard that catches such states, for example:

const checkBounds = (rng, values) => {
    const targetRows = rng.getHeight();
    const targetCols = rng.getWidth();

    const { length } = values;
    const [firstRow] = values;

    return length === targetRows &&
        firstRow.length === targetCols;
};

Message

The coordinates of the range are outside the dimensions of the sheet.

Description

The error is a result of collision between two issues:

The Range is out of bounds (getRange() does not throw on requesting a non-existent range)
Trying to call a method on a Range instance referring to a non-existent dimension of the sheet.

How to reproduce

function testOB() {
  const ss = SpreadsheetApp.getActiveSpreadsheet();
  const sh = ss.getActiveSheet();
  const rng = sh.getRange(sh.getMaxRows() + 1, 1);
  rng.insertCheckboxes();
}

How to fix

Check that number of rows (getMaxRow()) and columns (getMaxColumns()) are both greater or equal to the parameters passed to getRange() method call and change them accordingly.

UrlFetchApp

Message

Attribute provided with no value: url

Description

The error is specific to UrlFetchApp service and happens when fetch or fetchAll method gets called with an empty string or non-string value.

How to reproduce

const response = UrlFetchApp.fetch("", {});

How to fix

Make sure that a string containing a URI (not necessarily valid) is passed to the method as its first argument. As its common root cause is accessing a non-existent property on an object or array, check whether your accessors return an actual value.

References

How to make error messages more meaningful
Debugging custom functions

来源：https://stackoverflow.com/questions/62336082/how-to-solve-common-errors-in-google-apps-script-development

标签

debugging

google-apps-script

google-api

google-apps-script-addon

How to solve common errors in Google Apps Script development [closed]

问题

回答1:

General errors

Service-specific errors

SpreadsheetApp

UrlFetchApp

References