Accessing storage synchronously with ionic 2 storage service - ionic2

One of the recurring problems i've been having with ionic 2 is it's storage service. I have successfully set and retrieved stored data. However, when i store something, it is inaccessible on other pages unless i refresh the page/application.
Example one: Editing a contact
I push to an edit contact page, make changes, then saveEdits. saveEdits successfully makes the change to the right contact but fails to update the contact list UNTIL the application is refreshed.
HTML:
<button (click)="saveEdits(newName, newPostCode)"ion-button round>Save Edits</button>
TypeScript:
saveEdits(newName, newPostCode){
console.log("saveid"+this.id);
this.name = newName; //saves property
this.postcode = newPostCode; //saves property
this.items[this.id] = {"id": this.id, "Name": newName, "PostCode": newPostCode};
this.storage.set('myStore',this.items);
//this.navCtrl.pop(ContactPage);
}
Example two: Accessing contacts on another page
On another page i iterate through contacts and display them in a radio alert box list. Again, the contacts are displayed successfully, but when I add a contact on the add contact page, the new contact does not appear on the radio alert box list.
addDests(){
console.log('adddests');
{
let alert = this.alertCtrl.create();
alert.setTitle('Choose Friend');
for(let i = 0; i<this.items.length; i++){
console.log('hello');
alert.addInput({
type: 'radio',
label: this.items[i].Name,
value: this.items[i].PostCode,
checked: false
});
}
alert.addButton('Cancel');
alert.addButton({
text: 'OK',
handler: data => {
console.log(data);
}
});
alert.present();
}
}

You're changing the reference the variable is pointing to:
this.items[this.id] = {"id": this.id, "Name": newName, "PostCode": newPostCode};
I assume that your LIST is iterating (ngFor) over the array referenced by this.items? If yes, update directly the properties of this.items[this.id] instead of re-initializing it.
this.items[this.id].Name = newName;
this.items[this.id].PostCode = newPostCode;
(By the way, I'd recommend to be consistent with your property naming: either Id and Name, or id and name (capital letters matter!)).
Your "list" view will always be refreshed if the references to the objects being used are not changed. The only exception would be an update made in a callback given to a third-part library. In that case, you can use NgZone to "force" Angular to take the update into account.
Also, have a look at Alexander's great advice about Observable.

You should use Angular provider(s) with Observable property to notify subscribers (other pages & components) about changes.
For example read this article: http://blog.angular-university.io/how-to-build-angular2-apps-using-rxjs-observable-data-services-pitfalls-to-avoid/
There are a lot of information on this: https://www.google.com/search?q=angular+provider+observable

Related

APEX row selector part 2

This is a follow on to "APEX row selector" posted 5 days ago.
The problem was collecting multiple values from an interactive grid. From the excellent links to post supplied I was able to achieve this. However, the next part of the project is to open an edit dialog page and update multiple values.
I added this code to the attribute of the interactive grid:
function (config)
{
var $ = apex.jQuery,
toolbarData = $.apex.interactiveGrid.copyDefaultToolbar(),
toolbarGroup = toolbarData.toolbarFind("actions3");
toolbarGroup.controls.push(
{
type: "BUTTON",
action: "updateCar",
label: "Edit Selected Cars",
hot: true,
});
config.toolbarData = toolbarData;
config.initActions = function (actions)
{
// Defining the action for activate button
actions.add(
{
name: "updateCar",
label: "Edit Selected Cars",
action: updateCar
});
}
function updateCar(event, focusElement)
{
var i, records, model, record,
view = apex.region("ig_car").widget().interactiveGrid("getCurrentView");
var vid = "";
model = view.model;
records = view.getSelectedRecords();
if (records.length > 0)
{
for (i = 0; i < records.length; i++)
{
record = records[i];
alert("Under Development " + record[1]);
vid = vid + record[1] + "||";
apex.item("P18_CAR").setValue(vid);
// need to open next page here and pass parameters
}
}
}
return config;
}
I need to know how to open a form and have the parameter values available to pass to an oracle update script.
Thank you for any help you can provide. I did find some posts but I really need a good example. I have tried everything to no avail.
There are various ways you could do this. Here's one way, perhaps someone else will offer a more efficient option.
The JavaScript options for navigation in APEX are documented here:
https://docs.oracle.com/en/database/oracle/application-express/19.1/aexjs/apex.navigation.html
Since you're trying to open a separate page, you probably want to use apex.navigation.dialog, which is what APEX automatically uses when opening modal pages from reports, buttons, etc.
However, as noted in the doc, the URL for the navigation must be generated server-side for security purposes. You need a dynamic URL (one not known when the page renders), so you'll need a workaround to generate it. Once you have the URL, navigating to it is easy. So how do you get the URL? Ajax.
Create an Ajax process to generate the URL
Under the processing tab of the report/grid page, right-click Ajax Callback and select Create Process.
Set Name to GET_FORM_URL.
Set PL/SQL code to the following
code:
declare
l_url varchar2(512);
begin
l_url := apex_page.get_url(
p_application => :APP_ID,
p_page => 3,
p_items => 'P3_ITEM_NAME',
p_values => apex_application.g_x01
);
apex_json.open_object();
apex_json.write('url', l_url);
apex_json.close_object();
end;
Note that I'm using apex_item.get_url to get the URL, this is an alternative to apex_util.prepare_url. I'm also using apex_json to emit JSON for the response to the client.
Also, the reference to apex_application.g_x01 is important, as this will contain the selected values from the calling page. You'll see how this was set in the next step.
Open the URL with JavaScript
Enter the following code in the Function and Global Variable Declaration attribute of the calling page:
function openFormPage(ids) {
apex.server.process(
'GET_FORM_URL',
{
x01: ids.join(':')
},
{
success: function (data) {
var funcBody = data.url.replace(/^"javascript:/, '').replace(/\"$/,'');
new Function(funcBody).call(window);
},
error: function (jqXHR, textStatus, errorThrown) {
console.error(errorThrown);
// handle error
}
}
);
}
In this case, I'm using apex.server.process to call the server-side PL/SQL process. Note that I'm passing the value of ids.join(':') to x01. That value will become accessible in the PL/SQL code as apex_application.g_x01. You can use additional items, or you can pass a colon-delimited string of values to just one item (as I'm doing).
The URL that's returned to the client will not be a standard URL, it will be a JavaScript snippet that includes the URL. You'll need to remove the leading and trailing parts and use what's left to generate a dynamic function in JavaScript.
This is generally frowned upon, but I believe it's safe enough in this context since I know I can trust that the response from the process call is not malicious JavaScript code.
Add a security check!!!
Because you're creating a dynamic way to generate URLs to open page 3 (or whatever page you're targeting), you need to ensure that the modal page is protected. On that page, create a Before Header process that validates the value of P3_ITEM_NAME. If the user isn't supposed to be able to access those values, then throw an exception.

How to observe a computed property in EmberJS? Creating a FB like notification feature

I am building notification feature for my app just like Facebook's notification. I have almost made it work but just unable to observe a computed property.
Here is the scenario:
There are many deals and when a deal is updated(like it's name/ price is changed), the notification is sent through RabbitMQ. The object payload that we send, it has an attribute "status" which could be 'read' or 'unread'.
controller:
notificationsCount: function() {
var notifications = this.get('notifications');
var unreadCount = 0;
for (var i = 0; i < notifications.length; i++) {
if (notifications[i].status == 'unread') {
unreadCount++;
}
}
return unreadCount;
}.property('notifications.[]'),
Here, initially 'notifications' is an empty array. All the notifications coming from RMQ as object payloads goes inside this. This 'unreadCount' is what I want to show kinda like a small badge over the notification icon.
When I click the notification icon, all the notifications' status should change to 'read' from 'unread'.
controller:
action:{
readNotifications: function () {
var notifications = this.get('notifications');
for (var i = 0; i < notifications.length; i++) {
notifications[i].status = 'read';
}
},
}
Through debugging, I found everything is working fine till this point. But what I want is, once the user clicks the notification icon and all the notifications are marked as read, the notificationCount should be set as zero as there are no more any notifications that is unread.
Theoretically, I have to either observe notificationsCount or execute notificationsCount once inside readNotifications action. But I couldn't find a way to do it. If there is any other way, feel free to share.
Thanks in advance.
The short of it is that you should define your notificationsCount computed property to listen to notifications.#each.status instead of notifications.[]. .[] triggers when the array contents change (elements are added or removed), while an .#each.prop triggers when the prop property on any array element changes.
Refer to the relevant Ember.js docs for details on this.
Additionally, you can make your code more concise using NativeArray methods (because, since you are already using the .property() shorthand, you do have prototype extension enabled). Your entire notificationsCount could be written as
notificationsCount: function() {
return this.get('notifications').filterBy('status', 'unread').length;
}.property('notifications.#each.status'),
and your action as
readNotifications: function () {
this.get('notifications').setEach('status', 'read');
},

Should I denormalize or run multiple queries in DocumentDb?

I'm learning about data modeling in DocumentDb. Here's where I need some advice
Please see what my documents look like down below.
I can take two approaches here both with pros and cons.
Scenario 1:
If I keep the data denormalized (see my documents below) by keeping project team member information i.e. first, last name, email, etc. in the same document as the project, I can get the information I need in one query BUT when Jane Doe gets married and her last name changes, I'd have to update a lot of documents in the Projects collection. I'd also have to be extremely careful in making sure that all collections with documents that contain employee information get updated as well. If, for example, I update Jane Doe's name in Projects collection but forget to update the TimeSheets collection, I'd be in trouble!
Scenario 2:
If I keep data somewhat normalized and keep only EmployeeId in the project documents, I can then run three queries whenever I want to get a projects list:
Query 1 returns projects list
Query 2 would give me EmployeeId's of all project team members that appear in the first query
Query 3 for employee information i.e. first, last name, email, etc. I'd use the result of Query 2 to run this one
I can then combine all the data in my application.
The problem here is that DocumentDb seems to have a lot of limitations now. I may be reading hundreds of projects with hundreds of employees in project teams. Looks like there's no efficient way to get all employee information whose Id's appear in my second query. Again, please keep in mind that I may need to pull hundreds of employee information here. If the following SQL query is what I'd use for employee data, I may have to run the same query a few times to get all the information I need because I don't think I can have hundreds of OR statements:
SELECT e.Id, e.firstName, e.lastName, e.emailAddress
FROM Employees e
WHERE e.Id = 1111 OR e.Id = 2222
I understand that DocumentDb is still in preview and some of these limitations will be fixed. With that said, how should I approach this problem? How can I efficiently both store/manage and retrieve all project data I need -- including project team information? Is Scenario 1 a better solution or Scenario 2 or is there a better third option?
Here's what my documents look like. First, the project document:
{
id: 789,
projectName: "My first project",
startDate: "9/6/2014",
projectTeam: [
{ id: 1111, firstName: "John", lastName: "Smith", position: "Sr. Engineer" },
{ id: 2222, firstName: "Jane", lastName: "Doe", position: "Project Manager" }
]
}
And here are two employee documents which reside in the Employees collection:
{
id: 1111,
firstName: "John",
lastName: "Smith",
dateOfBirth: "1/1/1967',
emailAddresses: [
{ email: "jsmith#domain1.com", isPrimary: "true" },
{ email: "john.smith#domain2.com", isPrimary: "false" }
]
},
{
id: 2222,
firstName: "Jane",
lastName: "Doe",
dateOfBirth: "3/8/1975',
emailAddresses: [
{ email: "jane#domain1.com", isPrimary: "true" }
]
}
I believe you're on the right track in considering the trade-offs between normalizing or de-normalizing your project and employee data. As you've mentioned:
Scenario 1) If you de-normalize your data model (couple projects and employee data together) - you may find yourself having to update many projects when you update an employee.
Scenario 2) If you normalize your data model (decouple projects and employee data) - you would have to query for projects to retrieve employeeIds and then query for the employees if you wanted to get the list of employees belonging to a project.
I would pick the appropriate trade-off given your application's use case. In general, I prefer de-normalizing when you have a read-heavy application and normalizing when you have a write-heavy application.
Note that you can avoid having to make multiple roundtrips between your application and the database by leveraging DocumentDB's store procedures (queries would be performed on DocumentDB-server-side).
Here's an example store procedure for retrieving employees belonging to a specific projectId:
function(projectId) {
/* the context method can be accessed inside stored procedures and triggers*/
var context = getContext();
/* access all database operations - CRUD, query against documents in the current collection */
var collection = context.getCollection();
/* access HTTP response body and headers from the procedure */
var response = context.getResponse();
/* Callback for processing query on projectId */
var projectHandler = function(documents) {
var i;
for (i = 0; i < documents[0].projectTeam.length; i++) {
// Query for the Employees
queryOnId(documents[0].projectTeam[i].id, employeeHandler);
}
};
/* Callback for processing query on employeeId */
var employeeHandler = function(documents) {
response.setBody(response.getBody() + JSON.stringify(documents[0]));
};
/* Query on a single id and call back */
var queryOnId = function(id, callbackHandler) {
collection.queryDocuments(collection.getSelfLink(),
'SELECT * FROM c WHERE c.id = \"' + id + '\"', {},
function(err, documents) {
if (err) {
throw new Error('Error' + err.message);
}
if (documents.length < 1) {
throw 'Unable to find id';
}
callbackHandler(documents);
}
);
};
// Query on the projectId
queryOnId(projectId, projectHandler);
}
Even though DocumentDB supports limited OR statements during the preview - you can still get relatively good performance by splitting the employeeId-lookups into a bunch of asynchronous server-side queries.

EmberJS - Adding an item to the store does not update view

I have a one to many relationship in the model of the application to relevantUsers. Now I want to iterate via the {{#each}} helper over those values. Which works.
content: function()
{
return this.get('controllers.application.model.relevantUsers');
}.property('controllers.application.model.relevantUsers'),
And when removing an item from the relevantUsers the view updates. But when adding a new relevantUser nothing happens. The user gets added to the data store, but the view does not update. Am I missing something?
This is how I create a new user
// Create new user
var relevantUser = this.store.createRecord('relevantUser', relevantUserData);
// And push it to remote
relevantUser.save();
In my application, I've done it like [CoffeeScript] :
video = self.store.createRecord 'video', id: #Id, title: #Title, thumbnailUrl: #ThumbnailUrl
#Formats.map (i) -> //Formats is simple JavaScript array.
format = self.store.createRecord 'format', itag: i.itag, quality: i.quality, resolution: i.resolution, type: i.type, url: i.url
video.get('formats').then (f) ->
f.pushObject format
The difference, is, that I use .pushObject() method here. As #fanta wrote in his comment, you have to get array that has relationship with model, so it will notify all observers.
More example code.

Adding item to filtered result from ember-data

I have a DS.Store which uses the DS.RESTAdapter and a ChatMessage object defined as such:
App.ChatMessage = DS.Model.extend({
contents: DS.attr('string'),
roomId: DS.attr('string')
});
Note that a chat message exists in a room (not shown for simplicity), so in my chat messages controller (which extends Ember.ArrayController) I only want to load messages for the room the user is currently in:
loadMessages: function(){
var room_id = App.getPath("current_room.id");
this.set("content", App.store.find(App.ChatMessage, {room_id: room_id});
}
This sets the content to a DS.AdapterPopulatedModelArray and my view happily displays all the returned chat messages in an {{#each}} block.
Now it comes to adding a new message, I have the following in the same controller:
postMessage: function(contents) {
var room_id = App.getPath("current_room.id");
App.store.createRecord(App.ChatMessage, {
contents: contents,
room_id: room_id
});
App.store.commit();
}
This initiates an ajax request to save the message on the server, all good so far, but it doesn't update the view. This pretty much makes sense as it's a filtered result and if I remove the room_id filter on App.store.find then it updates as expected.
Trying this.pushObject(message) with the message record returned from App.store.createRecord raises an error.
How do I manually add the item to the results? There doesn't seem to be a way as far as I can tell as both DS.AdapterPopulatedModelArray and DS.FilteredModelArray are immutable.
so couple of thoughts:
(reference: https://github.com/emberjs/data/issues/190)
how to listen for new records in the datastore
a normal Model.find()/findQuery() will return you an AdapterPopulatedModelArray, but that array will stand on its own... it wont know that anything new has been loaded into the database
a Model.find() with no params (or store.findAll()) will return you ALL records a FilteredModelArray, and ember-data will "register" it into a list, and any new records loaded into the database will be added to this array.
calling Model.filter(func) will give you back a FilteredModelArray, which is also registered with the store... and any new records in the store will cause ember-data to "updateModelArrays", meaning it will call your filter function with the new record, and if you return true, then it will stick it into your existing array.
SO WHAT I ENDED UP DOING: was immediately after creating the store, I call store.findAll(), which gives me back an array of all models for a type... and I attach that to the store... then anywhere else in the code, I can addArrayObservers to those lists.. something like:
App.MyModel = DS.Model.extend()
App.store = DS.Store.create()
App.store.allMyModels = App.store.findAll(App.MyModel)
//some other place in the app... a list controller perhaps
App.store.allMyModels.addArrayObserver({
arrayWillChange: function(arr, start, removeCount, addCount) {}
arrayDidChange: function(arr, start, removeCount, addCount) {}
})
how to push a model into one of those "immutable" arrays:
First to note: all Ember-Data Model instances (records) have a clientId property... which is a unique integer that identifies the model in the datastore cache whether or not it has a real server-id yet (example: right after doing a Model.createRecord).
so the AdapterPopulatedModelArray itself has a "content" property... which is an array of these clientId's... and when you iterate over the AdapterPopulatedModelArray, the iterator loops over these clientId's and hands you back the full model instances (records) that map to each clientId.
SO WHAT I HAVE DONE
(this doesn't mean it's "right"!) is to watch those findAll arrays, and push new clientId's into the content property of the AdapterPopulatedModelArray... SOMETHING LIKE:
arrayDidChange:function(arr, start, removeCount, addCount){
if (addCount == 0) {return;} //only care about adds right now... not removes...
arr.slice(start, start+addCount).forEach(function(item) {
//push clientId of this item into AdapterPopulatedModelArray content list
self.getPath('list.content').pushObject(item.get('clientId'));
});
}
what I can say is: "its working for me" :) will it break on the next ember-data update? totally possible
For those still struggling with this, you can get yourself a dynamic DS.FilteredArray instead of a static DS.AdapterPopulatedRecordArray by using the store.filter method. It takes 3 parameters: type, query and finally a filter callback.
loadMessages: function() {
var self = this,
room_id = App.getPath('current_room.id');
this.store.filter(App.ChatMessage, {room_id: room_id}, function (msg) {
return msg.get('roomId') === room_id;
})
// set content only after promise has resolved
.then(function (messages) {
self.set('content', messages);
});
}
You could also do this in the model hook without the extra clutter, because the model hook will accept a promise directly:
model: function() {
var self = this,
room_id = App.getPath("current_room.id");
return this.store.filter(App.ChatMessage, {room_id: room_id}, function (msg) {
return msg.get('roomId') === room_id;
});
}
My reading of the source (DS.Store.find) shows that what you'd actually be receiving in this instance is an AdapterPopulatedModelArray. A FilteredModelArray would auto-update as you create records. There are passing tests for this behaviour.
As of ember.data 1.13 store.filter was marked for removal, see the following ember blog post.
The feature was made available as a mixin. The GitHub page contains the following note
We recommend that you refactor away from using this addon. Below is a short guide for the three filter use scenarios and how to best refactor each.
Why? Simply put, it's far more performant (and not a memory leak) for you to manage filtering yourself via a specialized computed property tailored specifically for your needs