This random PR taught me how to strongly type my generic Angular component

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My modern Angular course: angularstart.com/
In this video, we investigate how to use custom directives, TypeScript generics, and ngTemplateContextGuard to add strong typing to the ng-templates in the generic table component from the last video.
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Previous video (ngTemplateOutlet): • ngTemplateOutlet is WA...
Source code (untyped): github.com/joshuamorony/ng-te...
Source code (typed): github.com/joshuamorony/ng-te...
Chau's PR: github.com/joshuamorony/ng-te...
Chau's RU-vid: / chautran
Chau's Twitter: / nartc1410
0:00 Introduction
1:26 What's wrong?
3:55 Removing magic strings
7:09 Using TypeScript Generics
13:34 Using Generics with Directives
16:37 Using ngTemplateContextGuard
21:18 Star syntax
23:03 Conclusion
#angular #typescript
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Опубликовано:

30 июн 2024

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Комментарии : 66

@JoshuaMorony 11 месяцев назад

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@nikolitilden8224 Год назад

Hey just wanted to mention something that might be useful (hopefully) for future videos. It would be really nice if you mention the version of Angular/Typescript you are currently using for a video if there is something like "this might be fixed in the future". I only found out because I went to your repo and checked the package.json file. Heck, it might be better just to throw a quick visual at the beginning of all videos with all the relevant versioning used in a project, or maybe just throw it in the comments. Hope this is a good suggestion! Love your videos! ❤

@SebastianPerezTeres 2 месяца назад

Awesome video, thank you for this! I love the fact that it is possible to get typed context like this, however complicated it may be. I recommend looking into an alternative approach using CDK Component Portal, I like that it forces component users to create a component that implements certain interface. For example my table component may define a row input as @Input() rowRenderer: ComponentType, usually TableRow interface would declare a method that get's called as soon as the component is attached (e.g. onTableRowInit) this gives the developer complete flexibility over what to display and a clear interface to implement, which avoids all this directives and generics complexity. IMO :)

@vOnez212 Год назад

This is the kind of content I need. Thanks for sharing.

@beratsulimani9823 Год назад

Thanks a lot Josh, for the great explanation and sharing advanced content with us.

@robocop30301 Год назад

This is absolute gold. Great video Josh -- much appreciated.

@johnnycopes Год назад

Thanks for a great video! You did a nice job breaking down the process piece by piece and explaining how to implement the static type guard. I've been using the ngTemplateContext pattern for years, but the technique of strongly typing the data in the template always eluded me. Looking forward to the next video on refacoring this work to use the structural directive syntax

@mikemarkovich69 4 месяца назад

This is a great video. I spent some time poking through the table from the angular CDK repo and this is close to the solution they used for that. Of course, it wasn't explained at all, let alone with this much clarity. Thanks for helping everyone understand these concepts.

@williamxsp Год назад

Incredible content. Thanks Josh and Chau

@ChauTran Год назад

Thank you

@oleksandrsanzharevskyy8709 11 месяцев назад

YOU are the LEGEND! Thanks a lot! Short and clear, love your videos.

@CraigShearer Год назад

Amazing. I'll be changing some of my own ngTemplate/ngTemplateOutlet code tomorrow to make it more type safe!

@JustPassingByHere Год назад

Good stuff as always Josh! Thanks so much!

@hefesto706 Год назад

Excellent video, please keep doing this, im learning a lot with you

@xocomil Год назад

I love this video. It is so tempting to want to know everything. Admitting you learned a lot and shared with us what you learned was a great choice. I learned a lot in this video. Thank you for making this. Also, Chau is terrific.

@xocomil Год назад

I like to think about generics as boxes. So a Box is an empty box that could hold anything. A Box is a box that contains only books. I like to use the analogy of moving. If you don't write what is in a box on the outside, it could hold anything, and you have to open it to know what room it is for. However, much like generics, if you write what the box contains on the outside, you can move it to the appropriate room and be confident in what it contains. Generics are the same idea. You tell the code what this generic contains, and it doesn't need to unpack everything to use it. In fact, unpacking a collection that isn't generic is called "unboxing."

@CraigShearer Год назад

@@xocomil A very good analogy, Jason!

@ancientelevator9 Год назад

Looking forward to the star syntax video!

@hansschenker Год назад

Yes Joshua you transfered your knowlege onto me! Using a directive for Typescript Typing - a little strange although working!

@haroldpepete Год назад

that was really awesome, i knew about structural directive, yet this information using type in template i didn't know it, thanks

@michaelvexler Год назад

mint! you are doing brilliant work!

@praveensripati3407 Год назад

Great content!🔥 Thanks for sharing.

@giorgimerabishvili8194 Год назад

The best Angular channel!

@juanaarean Год назад

Great content!! as always, thanks a lot!!

@deyssog4263 10 месяцев назад

Great video, thanks for that! Keep it up

@johnbarton4001 Год назад

dude this is awesome. gonna cmd+shift+F my project for template variables and see where I can use this. love the content

@ChauTran Год назад

Nice! Just wanted to point out that if your component (and template) aren't generics, then it is significantly simpler to add type-safety 😋

@johnbarton4001 Год назад

@@ChauTran yea definitely. should be stated that this approach is great for dumb components that can expect any Input data shape. so if the Input is type "any", this is a great way to type it. is this what you mean?

@Valky1954 Год назад

thanks for showing and explaining.

@dawidniegrebecki2205 Год назад

Fantastic video!

@nickolaizein7465 Год назад

Interisting and usefull information, thank you.

@chrisodillman3355 Год назад

I recently got a new job where i will work mostly with angular. Your channel has so many interesting topics.. wow.

@p.s29 Год назад

Thank you for making this

@collinsk8754 Год назад

🙌Respect! Excellent work! 💯

@stefanitotokocopullo2739 Год назад

Great video. Thank you. Very helpfull.

@Tomas-ir8xl Год назад

Try out ng-polymorpheus from Tinkoff. The library should help get rid of some of the type checking boilerplate.

@tinmancode Год назад

This is awesome

@sourishdutta9600 Год назад

This one is really awesome. Can you create more reusable components that are type safe like this one. Thank you so much. 👌

@JoshuaMorony Год назад

Anything specific you'd like to see?

@sourishdutta9600 Год назад

@@JoshuaMorony Any widgets or cdk that you can think of, that we are regularly using in our projects. Like side bar, navbar (nested), linked with the router. If we changed the route from the window search url that activated route of the sidebar will be automatically showing activated. One more thing is using generics how we can get more advantages in angular. I know in react there are multiple use cases with typescript like polymorphic component and custom hooks. I want to know how angular uses generics in material component or other libraries ant design component. One scenario like if how we can strongly typed the component that are passing through ng-content. Content projection is one of the key feature for reusability right. Thank you so much for sharing. 🙏👌🤘

@101stvar Год назад

Thanks for the great video, currently I am implementing this directive type checking. I am wondering is it possible to use input (data) from app-table component and use it to calculate and display possible values in the next templates. Just to avoid using multiple directive inputs (appTableHeader, appTableRow) It would be the perfect solution if we had a situation to work with n templates in complex components

@pedrofernandes2005 Год назад

Good video

@fredhair Год назад

I'm doing a similar thing for work but I'm passing the columns for my table as an array of keyof | TemplateRef and not using ContentChildren. I really don't want to have to add extra templates for when I just want the table to simply output the value of the row[column]. All's working well but I can't get decent type checking on the TemplateRef that I'm passing in. I like Angular but god this sort of thing is just awful in Angular compared to other frameworks. I much prefer working with Solid (so I'm glad to see Angular 16+ introducing signals) but I just loathe not being able to use TSX.. :(

@omergronich778 Год назад

Nice!

@YordiDavid Год назад

Thx, great video! Is there a way to call a method in the TableComponent from our ng-template ?

@ChauTran Год назад

Yes. If you expose that method on the TemplateRefContext

@victory_lucky Год назад

And now I understand how the star '*' directives work🤭

@hubertboguski Год назад

Hi Josh, would you ever do livestreams? Would love to see angular 14 live builds

@JoshuaMorony Год назад

I don't know if I'm cut out for live streams, I can't even deal with my wife looking over my shoulder when I code!

@hubertboguski Год назад

@@JoshuaMorony haha, if u ever do do it tho i have a feelin ppl would like it. and that way youd be able to teach your wife to code too haha! but either way i appreciate the vids brother

@USONOFAV 5 месяцев назад

Dang! making template reference type safe is hairy thing todo. I hope Angular team can come up with a better way to do content projection in a type safe way.

@rkrao8582 Год назад

How do you make testing works with this approach?

@aleksandarveselinovic5985 Год назад

How would you pass different custom components depending on the employee's data? For example, if there is a date in the employees you would create a date picker from NgBoostrap, or if there is a boolean in data then you would use your custom toggle component?

@tinmancode Год назад

Are you building a form builder. I guess you would need a factory component that can create other components based on input resource type it should process. Then you'll need a good or okay enough generic interface to express your source input(data type, name, validations, optionals and miscellaneous data) that be based to your factory component. Take a look at react mui or ng zoro

@deveshwarjaiswal9095 Год назад

please make a video on global error handler service for nx workspace (angular), like i have 1 host and 4 remotes and i want a single error handler service to show error messages and a single loader service

@porcinetdu6944 10 месяцев назад

Is there a way not to pass the object again in the directive ([appTableHeader]=inventory) ? I use observable and it means another subscription

@KillerBlade 9 месяцев назад

Exact content i was looking for, but i noticed that you said object type excludes primitive type, but that's not the case, it does includes them too.

@KillerBlade 9 месяцев назад

I rechecked and I was wrong about this, apologies for just anyone stumble upon this. 😅

@ambarvita8513 Год назад

next videos is pagging :D

@markwheeldon164 Год назад

Legen-dary!

@ToJak91 Год назад

So, at my work we have this awefull grid, and I wanted to implement something based on this instead. What we have not, have a JSON layer on top of it. And my rules is, it has to be easier and perform better than what we got currently. With that in mind, does anyone have a good solution to sort the table, by clicking on the header, without having to do all sort of mapping (which would begin to make things less logical, for all my backend minded colleagues, compared to the inefficient thing we got now)?

@noraneco6762 Год назад

Can this be achieved using ng-content and what's the difference?

@ChauTran Год назад

ng-content won't work because you cannot pass context back to ng-content. In the example, Table component is what iterates through the Array of items then we allow customization via TemplateRef; we can then pass each item in ngFor back to the TemplateRef if it's provided. ng-content won't have this