This is going to be a series of posts in which I'll show how I managed to get a simple yet functional ReactJS application working. I plan to write 1 blog post per major component detailing how it works and integrates into the app.

This was my start with ReactJS and I worked in this application for almost 1 month as seen by the git commits here. I went from 0% ReactJS knowledge to to some % knowledge of how things work in this UI\presentation framework.

Motivation

The motivation to learn it is that it's mainstream nowadays. ReactJS is also used to develop mobile apps... besides that, for a job application test I had to develop a To Do application with a set of requirements.

Requirements

Programming assignment for web development candidates

You can choose any programming language and web development framework, database, and web server you like. The web application you need to build is a basic todo list application with the following requirements:

- Users can view their todo list;
- Users can add, remove, modify and delete todo entries;
- Each todo entry includes a single line of text, due date and priority;
- Users can assign priorities and due dates to the entries;
- Users can sort todo lists using due date and priority;
- Users can mark an entry as completed;
- You don't need to spend time on UI/UX design, if you do, it will be a bonus;
- Provide a RESTful API which will allow a third-party application to trigger actions on your app (same actions available in the app);
- Provide authentication and authorization service for both the app and the API;
- As complementary item to the last requirement, you should be able to create users in the system via an interface, eg a signup/register screen.

Web Tech Stack

I took the challenge! Developed a SPA - Single Page Application using ReactJS. Why not!? I also used Visual Studio Code as the IDE in tandem with the web tech stack in which I'm experienced with: C#, ASP.NET Core Web API, SQL Server, etc.

The App

The following is the app's homepage:

Figure 1 - App home page

The left side menu when clicked gives access to the Todos form and grid.

Figure 2 - Left side menu

The right side menu allows the user to login\logout and check their profile.

Figure 3 - Right side menu

In order to be able to access the Todos form\grid the user must be authenticated.

Figure 4 - Todo form + grid

Database

Everything was developed in Mac OS and as such the database that stores todo data is an SQL Server container image running in Docker.

Figure 5 - SQL Server database image running in Docker

Web API

The Web API was implemented using an ASP.NET Core Web API project. There's also a Swagger protected help page configured.

Figure 6 - Web API Swagger help page

Source code structure

The following screenshots show how the code is structured:

Figure 7 - App structure in Visual Studio Code Explorer window

- src folder holds all the source code files for the ReactJs app.

- TodoApi holds the source code files for an ASP.NET Web API project.

The ReactJS project skeleton was created\bootstrapped with Create React App as described in the README file.

Expanding the src folder we have this:

Figure 8 - ReactJS SPA app source code files

Expanding the TodoApi folder we have this:

Figure 9 - Todo ASP.NET Web API source code files

App dependencies

The ReactJS app uses the following dependencies as listed in package.json:

"dependencies": {

"@auth0/auth0-spa-js": "^1.6.3",

"@date-io/date-fns": "^1.3.13",

"@material-ui/core": "^4.9.1",

"@material-ui/icons": "^4.9.1",

"@material-ui/pickers": "^3.2.10",

"@testing-library/jest-dom": "^5.1.1",

"@testing-library/react": "^9.4.0",

"@testing-library/user-event": "^8.1.0",

"axios": "^0.19.2",

"date-fns": "^2.9.0",

"formik": "^2.1.4",

"moment": "^2.24.0",

"react": "^16.12.0",

"react-dom": "^16.12.0",

"react-router-dom": "^5.1.2",

"react-scripts": "^3.3.1",

"react-toastify": "^5.5.0",

"yup": "^0.28.1"

},

Git history

The git history is a nice way to remember what I did along the way:

Git History on master by all authors

Adding Auth0 placeholders...
340657a (HEAD -> master, origin/master) by Leniel Macaferi , Sat May 02 2020 (54 minutes ago)
1 file changed, 2 insertions(+), 2 deletions(-)

Small fixes...
5b98458 by Leniel Macaferi , Fri Feb 21 2020 (2 months ago)
2 files changed, 3 insertions(+), 3 deletions(-)

- Added Roles claim... it's retrieved from Auth0 access_token; - Improved footer; - Added missing toastify messages; - Improved Profile.
2cd5cd3 by Leniel Macaferi , Tue Feb 11 2020 (3 months ago)
5 files changed, 84 insertions(+), 19 deletions(-)

- Added Bearer token support to Swagger so that it's now possible to authorize with a token prior to testing the Web API endpoints; - In TodoItemsController the current user is now extracted while getting Todos so that the user can only retrieve their todos; - Added User property to TodoItem model; - Externalized getUser from Auth0 so that it can be called from stateful ReactJS components like Todo.js; - Made use of getUser() on Todo component; - Beautified Profile component.
b704348 by Leniel Macaferi , Mon Feb 10 2020 (3 months ago)
8 files changed, 122 insertions(+), 19 deletions(-)

- Added scopes and protected Get Todos Web API call with read:todos scope. https://auth0.com/docs/quickstart/backend/aspnet-core-webapi/01-authorization#validate-access-tokens - Added Profile component
13a8675 by Leniel Macaferi , Sun Feb 09 2020 (3 months ago)
13 files changed, 173 insertions(+), 62 deletions(-)

- Made Get Todos protected by using [Authorize] attribute; - Added JwtBearer support to the ASP.NET Core Web API; - Moved BrowserRouter to index.js so that the works as expected. More info here: https://stackoverflow.com/q/60123391/114029 - Externalized getTokenSilently in Auth.js to be able to pass it to axios request interceptor.
ab74c14 by Leniel Macaferi , Sat Feb 08 2020 (3 months ago)
12 files changed, 182 insertions(+), 51 deletions(-)

Added Auth0 to be able to authenticate and authorize users. https://auth0.com/
7ab2538 by Leniel Macaferi , Fri Feb 07 2020 (3 months ago)
9 files changed, 892 insertions(+), 170 deletions(-)

- Added search todo functionality; - Improved the todos table by adding Table pagination actions and made the header sticky; - Improved todo form by disabling the save button when there are errors or when the form is not dirty yet, that is, the user has not changed anything yet; - Added global error message with the help of toastify;
2d59cf4 by Leniel Macaferi , Thu Feb 06 2020 (3 months ago)
5 files changed, 190 insertions(+), 44 deletions(-)

- Commented out InMemoryDatabase in the Web API project and started using a full featured SQL Server database with UseSqlServer. Accomplished that on Mac OS side using Docker and a Developer version of SQL Server 2017; More info here: https://database.guide/how-to-install-sql-server-on-a-mac/ https://stackoverflow.com/a/60080206/114029 - Added Swagger to the Web API project; https://docs.microsoft.com/en-us/aspnet/core/tutorials/getting-started-with-swashbuckle?view=aspnetcore-3.1&tabs=visual-studio - Changed Web API default port from 7777 to 8888; - Improved global Progress bar. Set its position to absolute so that it won't push content down when it is displayed; - Moved todo related components to their own folder.
581da74 by Leniel Macaferi , Wed Feb 05 2020 (3 months ago)
16 files changed, 72 insertions(+), 29 deletions(-)

- Added cancel button to todo form. This is useful when the user is editing a todo and wants to cancel the action; - Implemented an improved version of todo form using the HOC [Higher Order Component] withFormik; this allowed passing a parent component [Todo] function down to the child component EnhancedTodoForm which is hooked to the the TodoForm component; Amazing stuff! :-) https://jaredpalmer.com/formik/docs/api/withFormik - route icons are now dynamically retrieved; - Added react-toastify libray to be able to show customized messages to user. https://github.com/fkhadra/react-toastify
469e858 by Leniel Macaferi , Tue Feb 04 2020 (3 months ago)
12 files changed, 328 insertions(+), 100 deletions(-)

- Added request and response interceptors to axios: https://github.com/axios/axios#interceptors ... this will allow a hooking place to display toasts (messages) to the user. This is one of the next thing to be added; - Added a menu tp AppBar using a Drawer component" https://material-ui.com/components/drawers/; - Started using react-router: https://github.com/ReactTraining/react-router; - routes are exported from routes.js; - Added About and Home pages.
7412ec3 by Leniel Macaferi , Mon Feb 03 2020 (3 months ago)
17 files changed, 3682 insertions(+), 3186 deletions(-)

- Got editTodo working; - Improved themes; - Removed unused npm packages.
4afd71e by Leniel Macaferi , Sat Feb 01 2020 (3 months ago)
8 files changed, 158 insertions(+), 866 deletions(-)

- Delete todo(s) done; - WIP Edit todo; - Added axiosInterceptor which handles  the animation when any Web API is called. It shows a Material-UI ; - Externalized custom styles in themes.js; - Many improvements in Todos table.
9d3e032 by Leniel Macaferi , Fri Jan 31 2020 (3 months ago)
13 files changed, 236 insertions(+), 139 deletions(-)

Handling setSelected after deletion happens...
9be189f by Leniel Macaferi , Thu Jan 30 2020 (3 months ago)
1 file changed, 8 insertions(+), 3 deletions(-)

Added delete todo functionality with a gotcha: https://stackoverflow.com/a/33846760/114029
5ad3cbd by Leniel Macaferi , Thu Jan 30 2020 (3 months ago)
7 files changed, 77 insertions(+), 52 deletions(-)

Added material UI Table component to be able to better visualize and operate on Todos. https://material-ui.com/components/tables/
febb4b3 by Leniel Macaferi , Thu Jan 30 2020 (3 months ago)
3 files changed, 371 insertions(+), 17 deletions(-)

- Created a global theme with createMuiTheme; - Improved AppBar - Got addTodo POST call to Web API working and TodoList updating as expected.
6f8a5fb by Leniel Macaferi , Thu Jan 30 2020 (3 months ago)
8 files changed, 700 insertions(+), 174 deletions(-)

Styled App structure and TodoForm with Material UI components.
38f169d by Leniel Macaferi , Wed Jan 29 2020 (3 months ago)
8 files changed, 357 insertions(+), 196 deletions(-)

Got Formik form fields working with material-ui https://material-ui.com/.
b309899 by Leniel Macaferi , Wed Jan 29 2020 (3 months ago)
10 files changed, 1027 insertions(+), 246 deletions(-)

- Added formik, yup and react-formik-ui. - Created a Todo form with formik.
bd8b355 by Leniel Macaferi , Mon Jan 27 2020 (3 months ago)
7 files changed, 771 insertions(+), 60 deletions(-)

Started integrating UI with Web API...
614c68e by Leniel Macaferi , Sun Jan 26 2020 (3 months ago)
9 files changed, 243 insertions(+), 83 deletions(-)

- Added ASP.NET Core 3.1 Todo Web API https://docs.microsoft.com/en-us/aspnet/core/tutorials/first-web-api?view=aspnetcore-3.1&tabs=visual-studio-code
06ce6d3 by Leniel Macaferi , Sun Jan 26 2020 (3 months ago)
15 files changed, 409 insertions(+), 4 deletions(-)

- Added handleChange event handler to todo-item component; - Handled todo complete state with setState; - Added Bootstrap: https://getbootstrap.com/
c15ff51 by Leniel Macaferi , Sat Jan 25 2020 (3 months ago)
8 files changed, 147 insertions(+), 38 deletions(-)

Converted some functional components to ES6 classes.
64dad12 by Leniel Macaferi , Sat Jan 25 2020 (3 months ago)
3 files changed, 53 insertions(+), 30 deletions(-)

- Got todo items displayed from a todo list JSON file. - Used array.map to create a React TodoItem component dynamically avoiding code repetition.
84cf3fc by Leniel Macaferi , Sat Jan 25 2020 (3 months ago)
5 files changed, 94 insertions(+), 25 deletions(-)

Created basic components and applied some styles including dynamic styling with JavaScript.
90ac727 by Leniel Macaferi , Sat Jan 25 2020 (3 months ago)
6 files changed, 128 insertions(+), 18 deletions(-)

Added .eslintrc.json and modified app name.
f1953ac by Leniel Macaferi , Fri Jan 24 2020 (3 months ago)
4 files changed, 14480 insertions(+), 1 deletion(-)

Initial commit from Create React App
04291f4 by Leniel Macaferi , Fri Jan 24 2020 (3 months ago)
18 files changed, 9789 insertions(+)

Source code

GitHub repository: https://github.com/leniel/ReactToDo

Figure 10 - GitHub repo with % of source code by type

Next

So stay tuned because in the next part I'll start covering the components in a top down approach, that is, we'll start looking at the index.js file where everything gets hooked up.

Today I had to customize the standard @Html.ValidationSummary that comes with ASP.NET MVC. Searched for it as always using Google and found this question at StackOverflow with two promising answers. One of them presented a nice approach that is the creation of a custom partial view called ValidationSummary.cshtml that lives in the standard Views\Shared folder. Initially I was afraid of implementing this because as one of the commenters said it didn’t play ball with jQuery Validate. I decided to experiment and see what would happen in my case. Guess what? It didn’t play ball with jQuery Validate. So it’s not OK. I was not satisfied and did further investigation regarding Microsoft's jquery.validate.unobtrusive.js file and it led me to the correct implementation to get the custom Validation Summary working with jQuery Validate. Let’s look at the code that Microsoft uses to fill the Validation Summary with errors:

function onErrors(event, validator) {  // 'this' is the form element
    var container = $(this).find("[data-valmsg-summary=true]"),
        list = container.find("ul");

    if (list && list.length && validator.errorList.length) {
        list.empty();
        container.addClass("validation-summary-errors").removeClass("validation-summary-valid");

        $.each(validator.errorList, function () {
            $("<li />").html(this.message).appendTo(list);
        });
    }
}

As we can see the code looks for a container that has a data attribute [data-valmsg-summary=true]. So when creating our custom Validation Summary template we must add that data attribute to our <div> container like this:

@model ModelStateDictionary

<div class='@(Html.ViewData.ModelState.IsValid ? "validation-summary-valid" : "validation-summary-errors") panel panel-danger'
     data-valmsg-summary="true">
    <div class="panel-heading">
        @Localization.CorrectErrors
    </div>
    <div class="panel-body">
        <ul>
            @foreach (var modelError in Model.SelectMany(keyValuePair => keyValuePair.Value.Errors))
            {
                <li>@modelError.ErrorMessage</li>
            }
        </ul>
    </div>
</div>

This Partial View approach gives you total control over what HTML structure/tags, CSS classes, etc you want applied to the validation summary.

Two things to take not in the above code:

1 - When the form is accessed for the 1st time, ModelState.IsValid is true and the CSS class validation-summary-valid is applied to the containing <div>.This is so so that it conforms to the standard ValidationSummary that comes with ASP.NET MVC and because this CSS class is used by jQuery unobtrusive validation code.
The standard Site.css file that comes with an empty ASP.NET MVC project also uses this very CSS class to hide the validation summary initially. It has this CSS rule:

.validation-summary-valid {
    display: none;
}

When post backing the form data, the view Model may pass the unobtrusive client side validation but may not pass the server side validation and in this case ModelState.IsValid will be false. Again to be conformant with jquery validate unobtrusive code we must set the class validation-summary-errors to the validation summary container. This is imperative; if we do not do this, then we won’t see the validation errors that come from the server side since the validation summary will be hidden.

2 - panel panel-danger are Bootstrap’s CSS classes that give some charming to our custom ValidationSummary. You can check Bootstrap 3 panel component here.

Following the above simple HTML structure it’s possible to make the custom validation summary compatible with jQuery Validate.

Here’s the end result:

To get the above look & feel I changed some CSS classes in ~/Content/Site.css file to override Bootstrap’s CSS. Here are them:

.panel-body {
    padding: 10px;
}

ul, ol
{
    margin-bottom: 0;
    padding-left: 17px;
}

.panel
{
    margin-bottom: 0;
}

.form-group {
    margin-bottom: 0;
}

As a final take on this matter, it’d be great if the standard ASP.NET MVC @Html.ValidationSummary had a method overload accepting a template name. Let’s hope that in the future this gets added.

I assembled a sample ASP.NET MVC project and uploaded it to GitHub. Feel free to play with it and adapt it to your use case. Here’s it is: https://github.com/leniel/AspNetMvcCustomHtmlValidationSummary

Happy coding!

This post is about dynamic text alignment with C#.

Scenario: I wanted to implement a dropdownlist with list items left aligned based on a string format. This is the initial appearance of the dropdown with no text alignment applied:

Figure 1 - DropDownList with Text not aligned

See that because Hospital names that come before => have different lengths, it doesn’t look good. Start and End dates are not aligned due to this.

So I thought about adding some caring to this and remembered that C# supports what I want to do. It’s called Composite Formatting. This when used with the Alignment Component allows some nice implementations.

The optional alignment component is a signed integer indicating the preferred formatted field width. If the value of alignment is less than the length of the formatted string, alignment is ignored and the length of the formatted string is used as the field width. The formatted data in the field is right-aligned if alignment is positive and left-aligned if alignment is negative. If padding is necessary, white space is used. The comma is required if alignment is specified.

Look at the following action method that lies within an ASP.NET MVC app. It’s responsible for adding list items to the dropdown show above…

[GET("Reports")]
public virtual ActionResult Index()
{
    ReportViewModel model = new ReportViewModel();

    // Getting the length of the lengthiest FictitiousName using Max query operator
    var maxLength = Database.Assessments.Max(a => a.Hospital.FictitiousName.Length);

    // Here’s the dynamic part: maxLength is used inside a format string to right align all strings, hence the minus sign. Doing this all strings will be equally left aligned (by maxLength) no matter their size.
    // {0}, {1} and {2} are positional parameters.
    string format = "{0, -" + maxLength + "} => {1} - {2}";

    List<SelectListItem> items = new List<SelectListItem>();

    foreach(Assessment a in Database.Assessments)
    {
        SelectListItem item = new SelectListItem();

        // Here's where the format string is used...
        item.Text = string.Format(format,
            a.Hospital.FictitiousName, a.StartDate.ToShortDateString(), a.EndDate.ToShortDateString());

        // This is necessary so that white spaces are respected when rendering the HTML code.
        item.Text = item.Text.Replace(" ", HttpUtility.HtmlDecode("&nbsp;"));

        item.Value = a.AssessmentId.ToString();

        items.Add(item);
    }

    model.Assessments = new SelectList(items.OrderBy(i => i.Text), "Value", "Text");

    return View(model);
}

With this code, now the result (really better to spot the dates) is this:

Figure 2 - DropDownList with Text aligned using a format string dynamically built

maxLength in this case = 20. This is the length of “Unimed Volta Redonda” (the lengthiest string in the list) in this specific case. The format string uses this value to left align this and all other strings with smaller lengths “equally” adding white spaces to compensate the smaller strings.

One really import thing to take into consideration when doing what this post proposes is to use a monospaced font or fixed-width font, because its letters and characters each occupy the same amount of horizontal space. If you don’t use this kind of font, you won’t get the desired result.

This is the Razor view code:

<div id="reports">

@Html.LabelFor(m => m.Assessments)&nbsp;
@Html.DropDownListFor(m => m.AssessmentId, Model.Assessments,
string.Format(Localization.SelectValue2, Localization.Assessment),
new { data_bind="value: selectedAssessment" } )

</div>

So in order to make it work I added this CSS code:

#reports select
{
    font-family: 'Courier New'; /* well known monospaced font */
    width: auto;
}

Happy C# dynamic text aligning to everyone!

This is a handy piece of code that I used last year in one of my projects. I had scheduled to post it but it was just after I saw this question at StackOverflow that I decided to write about it. So here it is…

Let’s say you want a nice UI experience and to achieve that you wanna colorize/highlight a table row according to a given value present in a column of this row.
This is a simple task when we use jQuery.

I use the WebGrid that comes with ASP.NET MVC to display data on a web page using an HTML <table> element. It’s available in the namespace System.Web.Helpers. The approach described in this post is useful not only with the WebGrid but with any framework/language you use to output HTML code since the manipulation is done on the client side with jQuery.

Take this screen as an example:

Figure 1 - HTML table with last column Active to be hidden displaying values Yes and No

We want hide the last column “Active” and color the row which has a value Yes in this same column.

The above statement can be accomplished with the following code:

(function ($)
{
    hideColumnColorRow = function (column)
    {
        $('td:nth-child(' + column + '),th:nth-child( ' + column + ')').hide();

        $('tr').find('td:nth-child(' + column + '):contains(Yes)').parent().css('backgroundColor', 'LightGreen'); // Could be an hexadecimal value as #EE3B3B 
    };

})(jQuery);

The hideColumnColorRow function* takes the column number as a parameter. It hides the column <td> and its header <th> using jQuery’s supper useful nth-child selector. Then for each table row <tr> it traverses the row’s columns and looks at the value of each column using :contains selector. If it finds a value = ‘Yes’ it’ll assign a background color to the column’s parent, that in this case is the <tr> (the row) using its CSS backgroundColor property.

So, taking Figure 1 as an example, the above code can be used in an ASP.NET MVC view this way:

<script type="text/javascript">

    $(document).ready(function ()
    {
        hideColumnColorRow(5); // Hiding the 5th column and colorizing the row for which this column has a value = Yes
    });

</script>

* I’ve placed the jQuery/JavaScript function inside a file named custom.js. It resides inside the Scripts folder of the sample app available here. There’s no need to reference this script file in the view page because with the introduction of ASP.NET 4.5 we now have an all new Bundling and Minification Support for CSS and JavaScript files.

When the the app is run, this is the result:

Figure 2 - HTML table with column Active hidden and highlighted rows based on its value

This is a really interesting requirement that one can implement in no time thanks to the power of jQuery. jQuery is one of the most fascinating things when we talk about software development. Its creator “John Resig” should be awarded a Computer Science Nobel Prize if that existed. Well it could be the Turing Award.

Anyone should take a look at jQuery and start using it as early as possible. It’s a must have today. I simply love it!

Source code
I’ve put together a sample ASP.NET MVC 4 (uses NET Framework 4.5) so that you can try this out. You can run the app using the recently launched Visual Studio 11 Beta. You can download the free Visual Studio 11 Express Beta for Web here and the app code here.

Hope it helps.

Blogger recently launched gadgets support for dynamic views. This is really cool and was a missing piece to go with dynamic views.

One of the things that I really didn’t like about the gadget bar is that it’s hidden (docked) in the right side of the window. It’s difficult to see and so I Googled about an undocked version but couldn’t find it.

Figure 1 - Blogger docked gadgets sidebar (barely visible) or could we say hidden?

Here I show you how to get an undocked version so that your visitors can enjoy the gadgets bar in its full glory. Follow these simple steps:

1 - Select the Template option at draft.blogger.com

2 - Click the Customize button

3 - In the Window that opens select Advanced

4 - Select Add CSS

5 - Copy & paste the following piece of code in the Add custom CSS field

#gadget-dock
{
    right: 0;
}

6 - Click Apply to blog button in the window top right corner

You won’t see the change applied immediately.

Now go and open your blog and you should see an undocked gadgets bar!

Figure 2 - Blogger undocked gadgets sidebar (now visible)

I hope blogger gives the option to customize this without the need for CSS code. It’ll be easier for its users and will provide a better experience for blog’s visitors…

EDIT

To answer Hannah’s question: if you also want to customize the background colors of the gadgets bar, you can apply these styles following the same procedure described above:

.gadget-icons
{
    background-color: red;
}

.gadget-title
{
    background-color: red;
}

.gadget-selected .gadget-icons
{
    background-color: yellow;
}

One thing to remember here is that as the gadgets’ icons are white you must choose a background color that’s not too much whitish.

Play with the colors and enjoy!