I'm pretty new to Android app development so please forgive my naivety.
I'm currently trying to develop an app that can pull data from a google spreadsheet and write data to it.
I've completed the quickstart tutorial so my code is the same as that right now. It all works correctly.
My issue is I need to be able to read from my own spreadsheet and I don't really understand the code used so I'm struggling to know where to start.
I've looked at this to try and implement the authorisation in fewer steps which I thought might make the code easier to understand - but again my lack of knowledge means I don't know how this fits into all the methods I currently have.
I've looked at the developer documentation and tried to replace the code from the quickstart which retrieves data from the app with this:
ValueRange result = service.spreadsheets().values().get(spreadsheetId, range).execute();
int numRows = result.getValues() != null ? result.getValues().size() : 0;
System.out.printf("%d rows retrieved.", numRows);
But again this is different to the code I already have so doesn't fit in as the getDataFromApi() method requires a return statement. I've tried just changing the spreadsheetId to that of my own spreadsheet and changing the range value to the cells I need,
/**
* Fetch a list of names and majors of students in a sample spreadsheet:
* https://docs.google.com/spreadsheets/d/1BxiMVs0XRA5nFMdKvBdBZjgmUUqptlbs74OgvE2upms/edit
* #return List of names and majors
* #throws IOException
*/
private List<String> getDataFromApi() throws IOException {
String spreadsheetId = "1-hL78Jm9-HijPx9UHthFxcXatkIhA2FR-AQ1lrCUbEg";
String range = "Go Mix 12 0506!B6:D";
List<String> results = new ArrayList<String>();
ValueRange response = this.mService.spreadsheets().values()
.get(spreadsheetId, range)
.execute();
List<List<Object>> values = response.getValues();
if (values != null) {
results.add("Name, Major");
for (List row : values) {
results.add(row.get(1) + ", " + row.get(3));
}
}
return results;
}
but I'm clearly going about it wrong because I get this error:
Invalid index 3, size is 3
I've also followed up to video 15 on this tutorial but it bypasses the need for any authorisation so didn't help.
Basically I've hit a brick wall and need someone to explain to me in simple terms how I can either work with the code from the quickstart tutorial to work with my own spreadsheet and fix that error! OR (more preferable to myself) explain how to do it myself from scratch. NB the spreadsheet cannot be public so I will need authorisation.
I hope that all makes sense!
You are asking to retrieve three columns of data (B through D), but then attempting to read a fourth column (rows.get(3)). In Java (and in most programming languages), lists and arrays are 0-based. So if you want the first item, you call list.get(0), and if you want the third you call list.get(2). This is evident based on the fact that the error message tells you your index of 3 is invalid since the list is size 3 -- you're attempting to read something beyond the end of the list.
I'm trying to test out Firebase to allow users to post comments using push. I want to display the data I retrieve with the following;
fbl.child('sell').limit(20).on("value", function(fbdata) {
// handle data display here
}
The problem is the data is returned in order of oldest to newest - I want it in reversed order. Can Firebase do this?
Since this answer was written, Firebase has added a feature that allows ordering by any child or by value. So there are now four ways to order data: by key, by value, by priority, or by the value of any named child. See this blog post that introduces the new ordering capabilities.
The basic approaches remain the same though:
1. Add a child property with the inverted timestamp and then order on that.
2. Read the children in ascending order and then invert them on the client.
Firebase supports retrieving child nodes of a collection in two ways:
by name
by priority
What you're getting now is by name, which happens to be chronological. That's no coincidence btw: when you push an item into a collection, the name is generated to ensure the children are ordered in this way. To quote the Firebase documentation for push:
The unique name generated by push() is prefixed with a client-generated timestamp so that the resulting list will be chronologically-sorted.
The Firebase guide on ordered data has this to say on the topic:
How Data is Ordered
By default, children at a Firebase node are sorted lexicographically by name. Using push() can generate child names that naturally sort chronologically, but many applications require their data to be sorted in other ways. Firebase lets developers specify the ordering of items in a list by specifying a custom priority for each item.
The simplest way to get the behavior you want is to also specify an always-decreasing priority when you add the item:
var ref = new Firebase('https://your.firebaseio.com/sell');
var item = ref.push();
item.setWithPriority(yourObject, 0 - Date.now());
Update
You'll also have to retrieve the children differently:
fbl.child('sell').startAt().limitToLast(20).on('child_added', function(fbdata) {
console.log(fbdata.exportVal());
})
In my test using on('child_added' ensures that the last few children added are returned in reverse chronological order. Using on('value' on the other hand, returns them in the order of their name.
Be sure to read the section "Reading ordered data", which explains the usage of the child_* events to retrieve (ordered) children.
A bin to demonstrate this: http://jsbin.com/nonawe/3/watch?js,console
Since firebase 2.0.x you can use limitLast() to achieve that:
fbl.child('sell').orderByValue().limitLast(20).on("value", function(fbdataSnapshot) {
// fbdataSnapshot is returned in the ascending order
// you will still need to order these 20 items in
// in a descending order
}
Here's a link to the announcement: More querying capabilities in Firebase
To augment Frank's answer, it's also possible to grab the most recent records--even if you haven't bothered to order them using priorities--by simply using endAt().limit(x) like this demo:
var fb = new Firebase(URL);
// listen for all changes and update
fb.endAt().limit(100).on('value', update);
// print the output of our array
function update(snap) {
var list = [];
snap.forEach(function(ss) {
var data = ss.val();
data['.priority'] = ss.getPriority();
data['.name'] = ss.name();
list.unshift(data);
});
// print/process the results...
}
Note that this is quite performant even up to perhaps a thousand records (assuming the payloads are small). For more robust usages, Frank's answer is authoritative and much more scalable.
This brute force can also be optimized to work with bigger data or more records by doing things like monitoring child_added/child_removed/child_moved events in lieu of value, and using a debounce to apply DOM updates in bulk instead of individually.
DOM updates, naturally, are a stinker regardless of the approach, once you get into the hundreds of elements, so the debounce approach (or a React.js solution, which is essentially an uber debounce) is a great tool to have.
There is really no way but seems we have the recyclerview we can have this
query=mCommentsReference.orderByChild("date_added");
query.keepSynced(true);
// Initialize Views
mRecyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
mManager = new LinearLayoutManager(getContext());
// mManager.setReverseLayout(false);
mManager.setReverseLayout(true);
mManager.setStackFromEnd(true);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(mManager);
I have a date variable (long) and wanted to keep the newest items on top of the list. So what I did was:
Add a new long field 'dateInverse'
Add a new method called 'getDateInverse', which just returns: Long.MAX_VALUE - date;
Create my query with: .orderByChild("dateInverse")
Presto! :p
You are searching limitTolast(Int x) .This will give you the last "x" higher elements of your database (they are in ascending order) but they are the "x" higher elements
if you got in your database {10,300,150,240,2,24,220}
this method:
myFirebaseRef.orderByChild("highScore").limitToLast(4)
will retrive you : {150,220,240,300}
In Android there is a way to actually reverse the data in an Arraylist of objects through the Adapter. In my case I could not use the LayoutManager to reverse the results in descending order since I was using a horizontal Recyclerview to display the data. Setting the following parameters to the recyclerview messed up my UI experience:
llManager.setReverseLayout(true);
llManager.setStackFromEnd(true);
The only working way I found around this was through the BindViewHolder method of the RecyclerView adapter:
#Override
public void onBindViewHolder(final RecyclerView.ViewHolder holder, int position) {
final SuperPost superPost = superList.get(getItemCount() - position - 1);
}
Hope this answer will help all the devs out there who are struggling with this issue in Firebase.
Firebase: How to display a thread of items in reverse order with a limit for each request and an indicator for a "load more" button.
This will get the last 10 items of the list
FBRef.child("childName")
.limitToLast(loadMoreLimit) // loadMoreLimit = 10 for example
This will get the last 10 items. Grab the id of the last record in the list and save for the load more functionality. Next, convert the collection of objects into and an array and do a list.reverse().
LOAD MORE Functionality: The next call will do two things, it will get the next sequence of list items based on the reference id from the first request and give you an indicator if you need to display the "load more" button.
this.FBRef
.child("childName")
.endAt(null, lastThreadId) // Get this from the previous step
.limitToLast(loadMoreLimit+2)
You will need to strip the first and last item of this object collection. The first item is the reference to get this list. The last item is an indicator for the show more button.
I have a bunch of other logic that will keep everything clean. You will need to add this code only for the load more functionality.
list = snapObjectAsArray; // The list is an array from snapObject
lastItemId = key; // get the first key of the list
if (list.length < loadMoreLimit+1) {
lastItemId = false;
}
if (list.length > loadMoreLimit+1) {
list.pop();
}
if (list.length > loadMoreLimit) {
list.shift();
}
// Return the list.reverse() and lastItemId
// If lastItemId is an ID, it will be used for the next reference and a flag to show the "load more" button.
}
I'm using ReactFire for easy Firebase integration.
Basically, it helps me storing the datas into the component state, as an array. Then, all I have to use is the reverse() function (read more)
Here is how I achieve this :
import React, { Component, PropTypes } from 'react';
import ReactMixin from 'react-mixin';
import ReactFireMixin from 'reactfire';
import Firebase from '../../../utils/firebaseUtils'; // Firebase.initializeApp(config);
#ReactMixin.decorate(ReactFireMixin)
export default class Add extends Component {
constructor(args) {
super(args);
this.state = {
articles: []
};
}
componentWillMount() {
let ref = Firebase.database().ref('articles').orderByChild('insertDate').limitToLast(10);
this.bindAsArray(ref, 'articles'); // bind retrieved data to this.state.articles
}
render() {
return (
<div>
{
this.state.articles.reverse().map(function(article) {
return <div>{article.title}</div>
})
}
</div>
);
}
}
There is a better way. You should order by negative server timestamp. How to get negative server timestamp even offline? There is an hidden field which helps. Related snippet from documentation:
var offsetRef = new Firebase("https://<YOUR-FIREBASE-APP>.firebaseio.com/.info/serverTimeOffset");
offsetRef.on("value", function(snap) {
var offset = snap.val();
var estimatedServerTimeMs = new Date().getTime() + offset;
});
To add to Dave Vávra's answer, I use a negative timestamp as my sort_key like so
Setting
const timestamp = new Date().getTime();
const data = {
name: 'John Doe',
city: 'New York',
sort_key: timestamp * -1 // Gets the negative value of the timestamp
}
Getting
const ref = firebase.database().ref('business-images').child(id);
const query = ref.orderByChild('sort_key');
return $firebaseArray(query); // AngularFire function
This fetches all objects from newest to oldest. You can also $indexOn the sortKey to make it run even faster
I had this problem too, I found a very simple solution to this that doesn't involved manipulating the data in anyway. If you are rending the result to the DOM, in a list of some sort. You can use flexbox and setup a class to reverse the elements in their container.
.reverse {
display: flex;
flex-direction: column-reverse;
}
myarray.reverse(); or this.myitems = items.map(item => item).reverse();
I did this by prepend.
query.orderByChild('sell').limitToLast(4).on("value", function(snapshot){
snapshot.forEach(function (childSnapshot) {
// PREPEND
});
});
Someone has pointed out that there are 2 ways to do this:
Manipulate the data client-side
Make a query that will order the data
The easiest way that I have found to do this is to use option 1, but through a LinkedList. I just append each of the objects to the front of the stack. It is flexible enough to still allow the list to be used in a ListView or RecyclerView. This way even though they come in order oldest to newest, you can still view, or retrieve, newest to oldest.
You can add a column named orderColumn where you save time as
Long refrenceTime = "large future time";
Long currentTime = "currentTime";
Long order = refrenceTime - currentTime;
now save Long order in column named orderColumn and when you retrieve data
as orderBy(orderColumn) you will get what you need.
just use reverse() on the array , suppose if you are storing the values to an array items[] then do a this.items.reverse()
ref.subscribe(snapshots => {
this.loading.dismiss();
this.items = [];
snapshots.forEach(snapshot => {
this.items.push(snapshot);
});
**this.items.reverse();**
},
For me it was limitToLast that worked. I also found out that limitLast is NOT a function:)
const query = messagesRef.orderBy('createdAt', 'asc').limitToLast(25);
The above is what worked for me.
PRINT in reverse order
Let's think outside the box... If your information will be printed directly into user's screen (without any content that needs to be modified in a consecutive order, like a sum or something), simply print from bottom to top.
So, instead of inserting each new block of content to the end of the print space (A += B), add that block to the beginning (A = B+A).
If you'll include the elements as a consecutive ordered list, the DOM can put the numbers for you if you insert each element as a List Item (<li>) inside an Ordered Lists (<ol>).
This way you save space from your database, avoiding unnecesary reversed data.
I have been working on an application where I need to write and update data to a spreadsheet using google spreadsheet api. I have followed the Android Quickstart provided by google Google Sheets API
Android Quickstart and was able to retreive data from the google spreadsheet but I am not able to understand how to write data. Please help
If you followed the Quickstart tutorial correctly, then it you are few steps from learning how to write data.
In the code provided in the Quickstart tutorial, change the line
private static final String[] SCOPES = { SheetsScopes.SPREADSHEETS_READONLY };
to:
private static final String[] SCOPES = { SheetsScopes.SPREADSHEETS };
This will grant access to write on a spreadsheet.
And instead of something like
ValueRange response = this.mService.spreadsheets().values()
.get(spreadsheetId, range)
.execute();
List<List<Object>> values = response.getValues();
you must create your own ValueRange instance, valueRange in this example, and then write:
this.mService.spreadsheets().values().update(spreadsheetId, range, valueRange)
.setValueInputOption("RAW")
.execute();
Choose the ValueInputOption of your preference.
After a lot of searching for a concrete example and not finding it, only here I was able to get something that worked for me, with the addition that I put for beginners like me. Thanks to #Veiga
Object a1 = new Object();
a1 = "TEST Row 1 Column A";
Object b1 = new Object();
b1 = "TEST Row 1 Column B";
Object a2 = new Object();
a2 = "TEST Row 2 Column A";
Object b2 = new Object();
b2 = "TEST Row 2 Column B";
ValueRange valueRange = new ValueRange();
valueRange.setValues(
Arrays.asList(
Arrays.asList(a1, b1),
Arrays.asList(a2, b2)));
this.mService.spreadsheets().values().update(spreadsheetId, "A1:B2", valueRange)
.setValueInputOption("RAW")
.execute();
I leave this concrete example, because other threads that I saw, throw compilation problems such as "List<String> is not acceptable as List<Object>".
But I thank those collaborators, example #k9yosh in the answer to How to assign a value to a ValueRange variable in java?
, because they were also an inspiration for me to develop a concrete solution to this case.
Please try going through Manage List-based and Cell-based Feeds to read and modify worksheets and data in Google Sheets.
However, since you're looking for the latest, as indicated in your post's title, and since version 4 of the Google Sheets API is now available, the following references will be very helpful too:
Google Sheets API v4
Migrate to the Google Sheets API
When I retrieve my data it contains brackets { and unique id such as - JSDHGJDGJJSKA ... I want to make it cleaner and get rid of the brackets for e.g. my output is:
{-JfFQQRYnhiKeuN5ERGX={msg=Monday},-JfFQAhQQWIFAUuV1nD4={msg=this is test}}
I want to get rid of the brackets and the word msg and retrieve just one of the message at random.
I want my output to be if I pick up a random message:
Monday
if I pick up another at random
this is test
Any ideas on how to achieve this will be greatly appreciated.
This will retrieve a random message from the object you've shown in your question.
function getRandomMessage(data) {
if( !data ) { return null; }
var keys = Object.keys(data);
var randomKey = keys[ Math.floor(Math.random()*keys.length) ];
return data[randomKey];
}
Keep in mind that this assumes you have a small number of records. If you start getting into the thousands, you'll need a more robust solution than just grabbing the entire data set.
When I used this I was able to retrieve my data for eg. I save as Book -> title: "The book of death"
here is the code to retrieve the title:Retrieve data-
String title = (String) snapshot.child("title").getValue();
It worked after I used and I didnt used push since push creates its unique ID and its complex for my level to deal with it so I used:Saving data-
Map<String, Object> title= new HashMap<String, Object>();
title.put("title", "This is a working message");
f.child("Book").updateChildren(title);
and everything worked out. I hope it helps everyone who has having these issues. With update children you can use auto increment for your id.
are you getting data in string ? and If you are using string then it is easy , you can use the method of replace eg: yourString.replace("a","b")