How to link many objects to a singular object in Parse.com - android

I am making an android application that uses Parse.com as its server backend.I want to enable users to post comments to poems uploaded but am stuck on how to link many comments to a particular poem Object.Does anyone have an idea of how to do that?Any help will be appreciated.

You create the comment as an instance of class=comment that is separate from the Poem instance, saving the object ID that parse returns on 'insert comment'.
Then, as a child of Poem object, you have 'comments' attribute under which you insert ArrayType pointer to the ID returned by the previous insert to the comment class.
'{"comments":{"__op":"Add","objects":[{"__type":"Pointer",
"className":"Comment","objectId":"$returnValueOfCommentInsert"}]}}'
The pointer type entity is added (ptrToComment) is added to an array of pointers sitting in 'comments' entity inside Poem object.
This assumes use of Rest API.

Reading the documentation is a good start. How about the section on Andriod Relational Data?

Related

How to add the data from an api without Pojo

I am getting data from an api which cannot be converted into pojo so am not able to get the data in a normal manner
Data that i am getting
{"TABLE_DATA":"
{\"data\":[
[\"Tiger Nixon\",\"System
Architect\",\"Edinburgh\",\"5421\",\"2011/04/25\",\"$320,800\"],
[\"Garrett
Winters\",\"Accountant\",\"Tokyo\",\"8422\",\"2011/07/25\",\"$170,750\"],
[\"Ashton Cox\",\"Junior Technical
Author\",\"SanFrancisco\",\"1562\",\"2009/01/12\",\"$86,000\"],
[\"Cedric Kelly\",\"Senior Javascript
Developer\",\"Edinburgh\",\"6224\",\"2012/03/29\",\"$433,060\"],
[\"Airi
Satou\",\"Accountant\",\"Tokyo\",\"5407\",\"2008/11/28\",\"$162,700\"],
[\"Brielle Williamson\",\"Integration Specialist\",\"New
York\",\"4804\",\"2012/12/02\",\"$372,000\"],
[\"Herrod Chandler\",\"Sales Assistant\",\"San
Francisco\",\"9608\",\"2012/08/06\",\"$137,500\"],
[\"Rhona Davidson\",\"Integration
Specialist\",\"Tokyo\",\"6200\",\"2010/10/14\",\"$327,900\"],
[\"Colleen Hurst\",\"Javascript Developer\",\"San
Francisco\",\"2360\",\"2009/09/15\",\"$205,500\"],
[\"Sonya Frost\",\"Software
Engineer\",\"Edinburgh\",\"1667\",\"2008/12/13\",\"$103,600\"],
[\"Jena Gaines\",\"Office
Manager\",\"London\",\"3814\",\"2008/12/19\",\"$90,560\"]`
there is no pojo available This is my first time working in an API any guide will be helpful. I am receiving the following data using retofit and rxjava2.
Data format is post method .
This is a jquery format. You may try to use this https://javacodegeeks.com/2013/02/jquery-datatables-and-java-integration.html
Look also this topic stackoverflow.com/questions/48942253/how-to-implement-jquery-datatable-in-android-any-library
The service you get data from may have an opportunity to set data format, you must specify it in your GET query, look in the API documentation.
That looks a lot like a .csv file. CSV files were the old format of Comma Separated Values, built from Tabular data.
Each row is one object and each column is its attribute/field. You can read about CSV files here.
Approach 1
Filter out using string manipulation the extra symbols of slashes and quotes. Delimit at the square braces (more info here) and then reading each delimited comma separated value text by any CSV reading library. Here's a tutorial using Apache Commons CSV library to read CSV files in Java.
Approach 2
Instead of using any library, if your response set is small and you don't need as much parsing optimization, write your object class's constructor to take in each row, filter out the useless symbols (using string manipulation) and initialize your object's fields.
All steps involved:
Clean response and remove unnecessary symbols using string manipulation.
Build a POJO class to keep one row of the dataset. Have its constructor to take in the first row of your dataset to initialize its attributes.
Build a list format or ArrayList format of your previous class with additional methods to sort, search or call by indices as required.
Build a constructor for this list object class to read in your cleaned string response and iterate over it to build Employee objects and adding them to your list.

Firestore search across custom objects array

I try to make an app on Android for services reviews, every review is save like an element in the document "user" like this-
Everytime the user save a report I have see if inside the reports the field "plate" is existing comparing with the new one, I try query using the examples in the page arrays in Firebase
In the code i tried get with "whereEqualTo" method search by "reports.plate" or with the method "whereArrayContains" with the same field (the filter uid exits but in the first image doesn't show) any idea how i can search the document when some of the custom elements fields is equal
maybe sorry in advance for the english i'm practicing
Thanks in advance

String Array in SharedPreferences

I need to work with a persistent String Array (n Rows, 1 column).
* On first running the app, the String Array needs to be created empty.
* On subsequent app executions the Array will be populated from a File and the contents need to be available throughout the rest of the app.
* As the app is executed, the Array needs to be able to 'grow' in row count
* As the app is executed, the Array rows need to be able to grow in length
* The user will have the option to Clear the Array of previous entries.
* At the end, the String Array contents will be written back to a File.
I find a lot of references to Putting and Getting from an existing SharedPreferences String[] but, in the newness of my Android development, I am struggling with how to proceed.
EDIT Follows...
The data itself suggests using an Array
Example:
MAIN ST. F55 63 KY08:57 12142015--------KY11:24 12142015345TMH KY13:57 12142015
MAIN ST. F56 WYE123 IN08:57 12142015--------KY11:24 12142015--------KY13:57 12142015
1ST ST. F57 --------KY08:57 12142015--------KY11:24 12142015789FPF KY13:57 12142015
1ST ST. F58 456FPF KY08:57 12142015998FPF KY11:24 12142015--------KY13:57 12142015
1ST ST. F59 789TTM KY08:57 12142015--------KY11:24 121420151234DG KY13:57 12142015
I first need to have this data in a File
Then in one GUI I check for the existence of the file.
If one exists, fine
If none exists, I create one.
Then, in subsequent GUI's, I must check for the existence of parameters
If they do not already exist, add them to the existing data lines.
If they already exist, notify the user
And so on and on.
Then when all of the current 'pass' data has been collected via multiple, separate GUI's, I have to write out the whole data-set into the file.
My reason for thinking that I need a SharedPreference approach is the need to find and check data from GUI to GUI as the user progresses through the app.
If that 'belief' is wrong, I am open to better approach suggestions.
EDIT 2 follows....
On further study of web references, I am beginning to think that perhaps the best approach for this data and how the data needs to change might be to use a SQLite approach. Any ideas about this?
Any assistance/suggestions you might have would be greatly appreciated.
i would discourage you from using sharedpreferences for anything else than preferences. means things that change rarely - really rarely and are really lightweight. do not put much data in there. less is better. the data structures underlying sharedpreferences are not a database.
another note. it is not a string list, but it would be a string set. sets are not necessarily ordered, nor do they necessarily keep their order. means - it is not rows. its a collection of strings that can come back in any fun order (usually there is some, but that depends on the implementation which i do not know)
now you could go and make your own list, your own data structure, save it into a string and read it out, use json to do exactly that or something similar, or better - use a database, which would exactly do that.
http://developer.android.com/training/basics/data-storage/databases.html
explains it, but as you'll see its something that might take some time.
now dont get me wrong, but i have to warn you about the following approach. it is valid, but has many problems and is far from thread safe. it will not be a problem as long as you only open it from the ui thread and do not keep anything in memory to cache - if you do it will create lots of problems.
your problem of adding a line and clearing can be solved by using a file. just a simple file
look here
http://developer.android.com/training/basics/data-storage/files.html#WriteInternalStorage
the change is to append when writing:
openFileOutput("filename", Context.MODE_APPEND);
see the context mode? now you can basically just write one line and append every time.
if you wanna clear the file, just deleteFile("filename")
this is as said not threadsafe, but can be a viable option if used carefully.
Please follow this step to achieve what you want with sharedPreference
create the class Parent for SharePreference
Create your empty Array
Convert Your empty array to String and put it on SharedPreference
to call your empty array from sharedPreference
Call your sharedPreference using your key
Convert the String to array
You get your array from the sharePreference
Hope it helps, and maybe this link will help you :
http://www.androidhive.info/2012/08/android-session-management-using-shared-preferences/
You can use my open-source library called prefser, which solves this problem and uses SharedPreferences and Gson under the hood. It's basically wrapper for default Android mechanism.
You can use it in the following way:
Prefser prefser = new Prefser(context); // create Prefser object
prefser.put("key", Arrays.asList("one", "two", "three")); // save array of Strings
String[] value = prefser.get("key", String[].class, new String[]{}); // read array of Strings
For more information check repository of the project, tests and README.md file.
Link: https://github.com/pwittchen/prefser
Please note, SharedPreferences have some limitations and shouldn't be used for storing large amount of data. If you expect a lot of data, consider using SQLite database or another type of database (e.g. with NoSQL or similar approach if you strive for simplicity).
OK, based on the data, how it needs to be manipulated and the pros and cons of using a SharedPreferences approach, I have decided to go with a SQLite approach.
With that approach I should be able to readily check:
* if the necessary table exists (if not create it)
* if the necessary Field1 + Field2 exists (if not create a new record)
* and I will be able to modify the record's Field3 contents as needed
Then when the user's actions are complete I can convert the SQLite table 'records' into strings and write them out as a File and then either DROP or PURGE the associated SQLite table (until needed next time).
I sincerely appreciate all of your suggestions.
Thank you.

How to set relationships between objects on Parse?

I have a parse object named Card and another called Category. I have 15 categories and gazillions of cards. I want to attach each card to one of the categories but in Parse when I try to set a relationship it redirects me to a screen where I actually have to create another category, but I just wanna choose from the existing ones.
What am I doing wrong?
Answer is simple, should just have used the Pointer type of relationship.

Implementing OR Condition using Parse Android SDK?

I am new to Parse and i am working on a Project that uses Android PARSE Sdk so i was wondering on how can i make a where query with or condition using the android sdk.
I want to make a query like this [Psuedo code]
Select * from employ where employId is ("1","2","3")
I found this on parse documentation, i don't know if it helps or not.
Edit:
This is what i found on PARSE but its not working
String[] id= {"1","2","3"};
query.whereContainedIn("employId ", Arrays.asList(id));
It returns me an empty list but if i query them one by one i get result... Can anyone tell me whats wrong ?
You can use whereContainedIn to select specific rows. See this post you can get more ideas. https://www.parse.com/questions/different-arrays-and-wherecontainedin-for-android.
List<String> employId = new ArrayList<String>();
employId.add("1"); employId.add("2"); employId.add("2");
query.whereContainedIn("employId", employId);
If you are still not clear. check this https://www.parse.com/docs/android_guide#queries
I have found the solution and i must say its pretty lame of PARSE to not mention this anywhere in there documentation.
The problem was that the values that i was using inwhereContainedIn method were of type String but in reality they were pointers to another table's row.
I was trying to get the values using only there ids[as it is displayed on parse] but instead i had to pass the whole object in order to retrieve them. That was the reason on why it was returning empty list.
The thing is Even though it displays IDs [pointer to object in a table] we cant search using only ID's instead we have to use complete Parse objects if we want to search a table based on Specific Object.

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