I have a main Activity which creates a fragment. My fragment launches various activities for result. Both main Activity and the fragment have onActivityResult(...) methods.
The main Activity receives all the results, even those from activities started from the fragment. The (int resultCode) that is received in the main onActivityResult(...int resultCode...) is being mangled somehow. So instead of the resultCode being 100 as i've set it to, it's 64978.
So even though i'm passing the resultCode arguments on to my fragment's onActivityResult(...) the resultCode is wrong. What's going on with the result code?
Thanks!
You can call super.onActivityResult(...) in the Activity's onActivityResult() to ensure the result is passed down to the Fragment, or alternatively if you want the activity to deal with the result, you can use getActivity().startActivityForResult(...) in the Fragment when you are starting the other activities.
Related
Using LiveData to signal a fragment to update it's display based on work done off of the main thread can be done by the postValue() function instead of setValue() but it has the problem that every posted value may not be observed on the main thread in the fragment.
A simple way to solve the problem is set the value from the worker running on Dispatchers.IO using withContext. Below is simple extension function that decides if this is needed using #OptIn(ExperimentalStdlibApi::class), which suggests this is a bad idea:
companion object {
#OptIn(ExperimentalStdlibApi::class)
suspend fun WorkingDepth.resetDepthOnMain() {
if (currentCoroutineContext()[CoroutineDispatcher].toString() == "Dispatchers.Main") {
resetDepth()
} else {
coroutineScope {
withContext(Dispatchers.Main) {
// This is the technique to ensure that the main thread sees
// the notification. If done off the main thread via a post
// it is not guaranteed that the observer will get the notification.
resetDepth()
}
}
}
}
}
The "opt in" annotation is avoided by treating all dispatchers as not Dispatchers.Main. Probably the unnecessary overhead is inconsequential, but the nagging question remains why is it not built in to "set on main" instead of "post and hope off of main".
Setting off of main throws an exception, so another way is the catch the exception and then switch threads and try again.
In a simple example where the live data is supposed to show landmarks along a work path it was seen that some expected landmarks do not get shown with "post and hope".
The withContext() method already includes the optimization suggested in the question.
This is explained in the comment for the fast paths in the coroutine library:
// FAST PATH #1 -- new context is the same as the old one
...
// FAST PATH #2 -- the new dispatcher is the same as the old one (something else changed)
...
Bottom line: If you must ensure execution on Main just wrap in a withContext(Dispatchers.Main) block.
The Q&A is currently a subject of meta discussion, do participate. The current plan is to split where possible into Q&As. Answers to the A&A are community wiki and the question should become one when the status 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 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)
Table of Contents
To help you navigate the growing reference please use the TOC below:
General errors
Service-specific errors
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?
Preface
The answer provides a guide on general errors that can be encountered when working with any Google service (both built-in and advanced) or API. For errors specific to certain services, see the other answer.
Back to reference
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 a variable is a special data type undefined. Typically, the error occurs when accessing nested properties of an object.
A variation of this error with a 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 the 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. A common mistake that causes the error is 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.
The 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).
A 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 a 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 error 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 the 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 Rhino runtime (at the time of writing the 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 the 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
References
How to make error messages more meaningful
Debugging custom functions
Service-specific errors
The answer concerns built-in service-related errors. For general reference see the other answer. Entries addressing issues with services listed in official reference are welcome.
Back to reference
SpreadsheetApp
The number of rows in the range must be at least 1
This error is usually caused by calling the getRange method where the parameter that sets the number of rows happens to equal to 0. Be careful if you depend on getLastRow() call return value - only use it on non-empty sheets (getDataRange will be safer).
How to reproduce
sh.getRange(1, 1, 0, sh.getLastColumn()); //third param is the number of rows
How to fix
Adding a guard that prevents the value from ever becoming 0 should suffice. The pattern below defaults to the last row with data (optional if you only need a certain number of rows) and to 1 if that also fails:
//willFail is defined elsewhere
sh.getRange(1, 1, willFail || sh.getLastRow() || 1, sh.getLastColumn());
Error: “Reference does not exist”
The error happens when calling a custom function in a spreadsheet cell that does not return a value. The docs do mention only that one "must return a value to display", but the catch here is that an empty array is also not a valid return value (no elements to display).
How to reproduce
Call the custom function below in any Google Sheets spreadsheet cell:
/**
* #customfunction
*/
const testReferenceError = () => [];
How to fix
No specific handling is required, just make sure that length > 0.
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;
};
The coordinates of the range are outside the dimensions of the sheet.
Description
The error is a result of a 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.
Exception: You can't create a filter in a sheet that already has a filter.
Description
The message means that you are trying to call a createFilter method on a Range in a Sheet that already has a filter set (either via UI or script), thus violating the restriction on 1 filter per Sheet, to quote the documentation:
There can be at most one filter in a sheet.
How to reproduce
const testFilterExistsError = () => {
const sh = SpreadsheetApp.getActiveSheet();
const rng = sh.getDataRange();
const filter1 = rng.createFilter();
const filter2 = rng.createFilter();
};
How to fix
Add a guard that checks for the existence of the filter first. getFilter returns either a filter or null if called on a Range instance and is perfect for the job:
const testFilterGuard = () => {
const sh = SpreadsheetApp.getActiveSheet();
const rng = sh.getDataRange();
const filter = rng.getFilter() || rng.createFilter();
//do something useful;
};
UrlFetchApp
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.
Is it safe to call XGetErrorText from a error handler set by XSetErrorHandler?
E.g.
int errorHandler(Display *dpy, XErrorEvent *err)
{
char buf[BUFLEN];
XGetErrorText(dpy, err->error_code, buf, BUFLEN);
printf("%s\n", buf)
return 0;
}
XSetErrorHandler(errorHandler);
I'm asking because the man page says you should not call any functions (directly or indirectly) on the display that will generate protocol requests but it does not tell if XGetErrorText does.
XGetErrorText doesn't generate any server traffic. It's not supposed to: the server doesn't know your locale, for example, and cannot supply localised messages. XLib can, and indeed does with a couple of local Xrm database lookups.
The source code of XGetErrorText can be viewed e.g. here. We can see that XGetErrorText calls XGetErrorDatabaseText, and this latter function is not even using its dpy parameter.
Each X extension provides its own error-event-to-error-string translation function. This function does accept a dpy parameter, but, just like XGetErrorDatabaseText is not supposed to use it too generate any server traffic. This error-handling function is by default generateed by the XEXT_GENERATE_ERROR_STRING macro here, which just encapsulates another call to XGetErrorDatabaseText.
When I setup an HKObserverQuery, the update handler always gets immediately called (something I didn't expect). It also gets called when I add data points through Health.app, as you would expect. I am tending to think I am not doing something right with the completion handler, but the docs are fairly sparse on what is supposed to happen here.
Question: Below is basically what I'm doing. Is this expected behavior, or am I missing something?
func listenForUpdates() {
let bodyMassType = HKQuantityType.quantityTypeForIdentifier(HKQuantityTypeIdentifierBodyMass)
let updateHandler: (HKObserverQuery!, HKObserverQueryCompletionHandler!, NSError!) -> Void = { query, completion, error in
if !error {
println("got an update")
// ... perform a sample query to get the actual data
completion() // is this the right thing to do?
} else {
println("observer query returned error: \(error)")
}
}
let query = HKObserverQuery(sampleType: bodyMassType, predicate: nil, updateHandler: updateHandler)
healthStore?.executeQuery(query)
}
Edit: discovered completion handler should only be called when there wasn't an error, so moved into the !error block. An error is present when the app is not authorized.
Yes, this is expected behavior. The update handler will always be called on first execution so that you can use it to fetch your initial data (from your sample query, anchored object query, etc) and populate your UI.
The completion handler is only necessary if you intend to use background delivery, it informs HealthKit that you have received and processed the data you need so that HealthKit knows to stop launching your app in the background. If you have not registered your app for background delivery, then the completion handler is essentially a no-op and you don't need to worry about it.
I am confused about the ref count in npapi. Mostly, I don't know which method will increase ref count. Can anyone explain in detail about this? For the convenience, I listed most common used NPN_* functions here and my own understanding:
NPN_CreateObject: set ref count to 0
NPN_RetainObject: inc ref count
NPN_ReleaseObject: dec ref count
NPN_Evaluate: ?? (in case return an NPObject*)
NPN_GetValue: ?? (in case return an NPObject*)
NPN_SetValue: ?? (in case set to an NPObject*)
NPN_GetProperty: ?? (in case return an NPObject*)
NPN_SetProperty: ?? (in case set to an NPObject*)
NPN_RemoveProperty: ??
NPN_Enumerate: ??
NPN_Construct: ??
another thing: is npapi do nested release? (In case NPObject* with a property of NPObject*, release parent will decrease the ref count of child).
Thanks.
There isn't room in comments to answer your question in the comment well, so I'll put it in another answer.
Any time your code gets an NPObject from a NPObject function (one of those you mentioned above), you should Release that NPObject when you're done with it. (that could be immediately, or you could save it for awhile and release it when your object gets destroyed). The same holds true with a NPVariant. It does not hold true with the arguments passed into your Invoke function, but the return value you set will get released by the browser when it's done.
When you call NPN_GetValue and get an NPObject from there, that also has to be released. This means that when the browser calls NPP_GetValue, it will release your NPObject when it's done. If you want to create a new NPObject every time the browser calls NPP_GetValue to get your NPObject, then you don't have to call NPN_RetainObject on it; the assumption in the NPAPI example is that you are saving a copy of your NPObject so that it doesn't get deleted until your plugin object gets deleted.
Since the browser will call Release for every time that it calls NPP_GetValue to get your NPObject, you need to make sure that the refcount is incremented before you return it. The reason you don't have to call it twice in the case that you're going to keep it is that NPN_CreateObject does an implicit Retain before it returns your object.
I have written up a more detailed explanation here:
http://colonelpanic.net/2009/12/memory-management-in-npapi
First, to correct a misconception: NPN_CreateObject sets the refCount to 1, not to 0. Then, when you call NPN_RetainObject it increments the refcount, and NPN_ReleaseObject will decrement it. If ReleaseObject decrements the refcount to 0, it will also free it by calling the deallocate function from your NPClass (which should delete the NPObject after doing any needed cleanup)
see: https://developer.mozilla.org/En/NPClass
beyond that, a good general rule of thumb for any of the other NPClass functions is that any time you put an NPObject in a NPVariant, you need to call NPN_RetainObject. To remember this, simply remember that when you're done with an NPVariant (one that you have used and are done with, not one that was passed as a return value), you call NPN_ReleaseVariantValue, which will release the NPString data if it's a string or the NPObject if it's an object.
So from any of the other methods, if you are returning an NPObject, you need to call NPN_RetainObject before you stuff it into the NPVariant. Also, if you save a copy of the NPObject, you should call NPN_RetainObject on it and NPN_ReleaseObject when you're done saving it. It also bears mentioning that you should never call any NPN_ method from a thread other than the main thread.
Does that help?