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JavaScript
Monday, April 9, 2018PrintSubscribe
Changing Field Values Via JavaScript Business Rules

Some form of validation is required in every application to help the user insert the correct data. Applications created with Code On Time app generator offer validation in the form of business rules.

Validating the Last Name field of the New Employees form.

Let’s add validation business rules the Employees controller of our sample Northwind app.

Open the Project Designer. In the Solution Explorer, switch to the Controllers tab, right-click on Employees / Business Rules node, and press New Business Rule.

Creating a new business rule on Employees controller.

Specify the following:

Property Value
Type JavaScript
Command Name Insert
Phase Before
Script
if ($row.LastName == 'Smith') {
    this.preventDefault();
    $row.LastName = null;
}

The above script will run when the user presses Save. It will check if the user has specified a Last Name of “Smith” – if so, it will cancel the save operation and clear the field.

Save the new business rule. On the toolbar, press Browse to run the app. Navigate to the Employees page and create a new record.

Creating a new employee with Last Name of "Smith".

Enter values for the employee and press Save. The save operation will not be executed, and the Last Name field will be cleared.

The Last Name field has been cleared.

Our business rule does ensure the user does not enter an incorrect value, but it does not make it clear to the user what is going on. We will want to add some feedback in the form of a message box to help the user understand.

Change the business rule as shown below:

if ($row.LastName == 'Smith') {
    this.preventDefault();
    // show message box
    $app.alert('Last Name "Smith" is not allowed.').done(function () {
        // update field value to null
        $app.input.execute({
            values: [
                { name: 'LastName', value: null }
            ]
        });
        // focus on the field
        $app.input.focus({ fieldName: 'LastName' });
    });
}

Our updated business rule has a few changes. Notice that the $app.alert function is used to display a message to the user. However, this alert will show a different form and change the current context. Attempting to update the field LastName after an alert is displayed will attempt to update a LastName field inside the alert form – which does not exist. Therefore, a done handler will need to be added to the $app.alert method call in order to execute code after the user closes the alert.

One more point to notice is that the $row variable is only in scope during the execution of the business rule. The asynchronous code in the done handler is executed when $row is out of scope. Therefore, it is necessary to use the $app.input.execute API to update the field values when the user returns to the Employees create form. The execute method accepts an object with the property values that contains a list of key value pairs. The $app.input.focus API is called in order to focus on a field called LastName as well.

Save the business rule and regenerate the project. Create a new employee with the last name of “Smith” and attempt to save. Notice that a message box now notifies the user that the last name is not allowed.

Alert message box is displayed to the user.

Press OK to close the message box. The Last Name field has been cleared and is currently focused.

The last name field is cleared and focused.

There are other ways of displaying a message to the user without interrupting the workflow. Let’s try the following:

if ($row.LastName == 'Smith') {
    this.preventDefault();
    $row.LastName = null;
    // focus and show message next to field
    this.result.focus('LastName', 'Last Name "Smith" is not allowed.');
}

The example above will clear the field, and use the result.focus() method to focus on the field, and display a message next to the input. The result can be seen below.

Focus message displayed next to the LastName field.

Another technique is to use the notification API to display a transient message to the user at the bottom of the screen.

if ($row.LastName == 'Smith') {
    this.preventDefault();
    $row.LastName = null;
    this.result.focus('LastName');
    $app.touch.notify('Last Name "Smith" is not allowed.');
}

The result can be seen below:

image

The notification will disappear after a default of 2 seconds.

Monday, September 18, 2017PrintSubscribe
Executing Requests with the Client API

All apps created with Code On Time app generator contain a single client-side API used for all server-side operations, including Select, Insert, Update, Delete, Report, Batch Edit, etc. One significant advantage of using a centralized API is that any style of user interface is able to access the same API – this has allowed the co-development of Classic and Touch UI.

Another major advantage in the client-side API is that developers are able to extend their apps with custom behavior utilizing the same data access routines – any access control rules, data controller customizations, and security restrictions will also equally apply to these custom requests.

To access the client API from custom JavaScript, simply call the method $app.execute(options) with the required parameters set on the options object. See a list of available options parameters below.

Property Description Default Value
controller The controller to direct the request to. (required)
view The view of the controller to use. grid1
done
success
Callback function when the request was send and received successfully. First argument contains the results. List of records can be found under the result property equal to the name of the controller.
fail
error
Callback function when the request failed.
command The name of the command to execute. “Select”
argument The argument of the command to execute.
lastCommand The last command name.
lastCommandArgument The last command argument.
pageSize The number of records to return in a single page. 100
pageIndex The page number to return. 0
filter An array of field filter objects. Each object must have 3 properties:
- “field” specifies the field name
- “operation” specifies the filter operation to perform
- “value” specifies the value of the filter. For operations with two operands (such as “between”), specify an array of two values.
values An array of field value objects. Each object can have the following properties:
- “name” specifies the name of the field matching the one defined in the controller.
- “value” specifies the current value of the field.
- “newValue” specifies the new value.
- “modified” specifies that the new value will be used in any Insert or Update expressions. Setting “newValue” will set “modified” to true by default.
selectedValues An array of strings that contain the primary keys of the selected records. Used for batch update.
tags Specify a list of tags that can be processed on the server.
requiresData Specifies if data should be returned to the client. true
requiresAggregates Specifies if aggregates defined on the view should be returned with the request. false
fieldFilter Specifies a list of fields to include in the response for each record. Not setting this value will return all fields.
format Specifies if field values should be formatted when the results are returned. true
includeRawResponse Specifies if the result should include the raw response in the rawResponse property. false

The simplest way to test your queries is to use the Developer Tools Console, available in most modern browsers.

First, browse to your running site in your favorite browser. Press “F12” to bring up Developer Tools. Switch to the Console tab.

Using the Console tab of Developer Tools to test the $app.execute() API.

You may now begin typing in $app.execute() requests in the console. Note the use of console.log(result), which will print the JavaScript object to the console when the request returns.

The following examples will use the online Northwind sample.

Select

The simplest use case for using the API is to request a page of data. See the following example below on how to fetch the first 10 records from the Orders table where the field “ShipCountry” is equal to “USA”.

$app.execute({
    controller: 'Orders',
    pageSize: 10,
    filter: [
        { field: 'ShipCountry', operator: '=', value: 'USA' }
    ],
    done: function (result) {
        console.log(result);
    }
})

The result shown in the Developer Tools Console.

Selecting 10 orders with a filter.

Insert

In order to insert records to a particular table, the request must specify the “Insert” command and a list of field values. This list is represented by the values property. Each field value object contains a field name. Values that will be assigned to the new record are stored in the field value’s newValue property. The primary key of the table is added as a field value object with the property value equal to null in order for the response to return the new primary key of the inserted record.

$app.execute({
    controller: 'Orders',
    command: 'Insert',
    values: [
        { name: 'OrderID', value: null },
        { name: 'ShipCity', newValue: 'San Diego' },
        { name: 'ShipCountry', newValue: 'USA' }
    ],
    done: function (result) {
        console.log(result);
    }
})

See the results below.

Inserting a record using the $app.execute() API.

Refreshing the view in the browser window will reveal the new record.

The new record is displayed in the grid.

Update

When performing operations on an existing record, either the primary key or an array of selected values must be specified. New field values must be specified in the newValue property.

$app.execute({
    controller: 'Orders',
    command: 'Update',
    values: [
        { name: 'OrderID', value: 11083 },
        { name: 'OrderDate', newValue: new Date() }
    ],
    done: function (result) {
        console.log(result);
    }
})

The result is shown below.

Updating an order via the $app.execute() API.

The result can be seen by refreshing the list of orders.

The updated field value is visible by refreshing the page.

Delete

Delete operations must specify the primary key in the values array.

$app.execute({
    controller: 'Orders',
    command: 'Delete',
    values: [
        { name: 'OrderID', value: 11079 }
    ],
    done: function (result) {
        console.log(result);
    }
})

See result below.

Deleting a record.

The rowsAffected property will be equal to “1” if the record was successfully deleted.

Monday, September 26, 2016PrintSubscribe
Conditional Visibility in View Templates

Conditional visibility on data fields and categories allows hiding or showing page elements based on field values. View templates give the ability to define custom presentations. When a custom template is defined for the view, the client library is not able to determine which page elements should be displayed or hidden based on the conditional visibility expressions. As such, the creator of view templates must mark up the template in order to bind these expressions with the correct elements.

When the template has been correctly defined, data fields, categories, and even custom page elements will be able to displayed or hidden depending on field values. For example, a large label is displayed in the sample below when the order has been shipped past the required date.

Warning displayed in New Order form conditionally.

Let’s use the create form for Orders in the Northwind sample database.

Arranging Data Fields into Categories

First, let’s rearrange the data fields into multiple categories, in order to control visibility of each category, instead of each individual data field. The user will only be able to enter shipping information if a shipped date is assigned.

Start the Project Designer. In the Project Explorer, switch to the Controllers tab. Right-click on “Orders / createForm1” view node, and press New Category.

Creating a new category for "createForm1" view of Orders controller.

Define the following settings:

Property Value
Header Text Ship Info
Visible When
$row.ShippedDate != null

Press OK to save the category. Next, drag data fields ShipVia, Freight, ShipName, ShipAddress, ShipCity, ShipRegion, ShipPostalCode, and ShipCountry into the new category.

Dragging shipping fields onto the second category in Orders.     Data fields have been separated into two categories in "createForm1" view of Orders controller.

Adding Data Field Visibility

Users should not be able to set the shipped date until the order date has been set. Let’s add a data field conditional visibility expression to ShippedDate data field.

Double-click on “Orders / Views / createForm1 / c1 – New Orders / ShippedDate” data field node.

Selecting ShippedDate data field in Orders controller.

Make the following change:

Property Value
Visible When
$row.OrderDate != null

Press OK to save the data field.

Adding the View Template

Let’s add a custom view template for editForm1 of Orders controller.

On the toolbar, press Develop to open the project in Visual Studio. In the Solution Explorer, right-click on the “WebSite” node and press “Add / New Folder”.

Adding a new folder to the project

Give this new folder the name “Views”. Next, right-click on the folder and press “Add / HTML Page”.

Adding a new HTML page to the Views folder.

Give this page the name “Orders.createForm1.html”. Replace the contents of the file with the following:

<div data-container="collapsible" data-header-text="New Order">
    <div data-container="row">
        <div data-control="description">Enter new order information below.</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="CustomerID">CustomerID</div>
        <div data-control="field" data-field="CustomerID">CustomerID</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="EmployeeID">EmployeeID</div>
        <div data-control="field" data-field="EmployeeID">EmployeeID</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="OrderDate">OrderDate</div>
        <div data-control="field" data-field="OrderDate">OrderDate</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="RequiredDate">RequiredDate</div>
        <div data-control="field" data-field="RequiredDate">RequiredDate</div>
    </div>
    <div data-container="row" data-visibility="f:ShippedDate">
        <div data-control="label" data-field="ShippedDate">ShippedDate</div>
        <div data-control="field" data-field="ShippedDate">ShippedDate</div>
    </div>
    <div data-container="row" data-visible-when="$row.RequiredDate < $row.ShippedDate">
        <h3 style="color:red">WARNING: THIS ORDER HAS BEEN SHIPPED LATE</h3>
    </div>
</div>
<div data-container="collapsible" data-header-text="Ship Info" data-visibility="c:c2">
    <div data-container="row">
        <div data-control="description">Enter shipping information below.</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="ShipVia">ShipVia</div>
        <div data-control="field" data-field="ShipVia">ShipVia</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="Freight">Freight</div>
        <div data-control="field" data-field="Freight">Freight</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="ShipName">ShipName</div>
        <div data-control="field" data-field="ShipName">ShipName</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="ShipAddress">ShipAddress</div>
        <div data-control="field" data-field="ShipAddress">ShipAddress</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="ShipCity">ShipCity</div>
        <div data-control="field" data-field="ShipCity">ShipCity</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="ShipRegion">ShipRegion</div>
        <div data-control="field" data-field="ShipRegion">ShipRegion</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="ShipPostalCode">ShipPostalCode</div>
        <div data-control="field" data-field="ShipPostalCode">ShipPostalCode</div>
    </div>
    <div data-container="row">
        <div data-control="label" data-field="ShipCountry">ShipCountry</div>
        <div data-control="field" data-field="ShipCountry">ShipCountry</div>
    </div>
</div>

Notice that there are three highlighted pieces in the sample above.

The yellow highlight shows how to apply data field-level visibility to an element by using the attribute “data-visibility”, and setting the value to “f:” followed by the name of the field. This will inherit the visibility from the field “ShippedDate”.

The green highlight shows how to apply category-level visibility to an element. Use the attribute “data-visibility”, and set the value to “c:” followed by the category ID. The example will inherit visibility from the category “c2”.

The orange highlight shows how to use custom JavaScript expressions to set visibility. Use the attribute “data-visible-when”, and set the value to your JavaScript visibility expression.

Switch back to the browser, navigate to the Orders page, and create a new order. Notice that the OrderDate data field, custom header, and shipping category are hidden.

When Order Date is not set, ShippedDate and ship info are hidden.

Enter a value for Order Date. Notice that the Shipped Date data field will appear.

The ShippedDate data field appears when OrderDate is set.

Enter a value for Shipped Date. The Ship Info category will appear.

Ship Info category appears when Shipped Date is set.

If the Shipped Date is after the Required Date, the warning text will appear.

A warning appears when the Shipped Date is after the Required Date.