WEBVTT

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Hi everyone.

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In this video I will show you how to do 
PATCH operation.

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Okay, now I will create one more method with PATCH.

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And I will use updateOne()

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Okay will be the @Param() will be the same

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id: string, @Body() requestBody

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Body.

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Now what is the request body.

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Right now I cannot use the

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UpdatePostDTO because

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Because it is not empty like this, right?

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I cannot remove one of that.

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I want it have a validation.

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But I want this only work for the title or the description.

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Okay.

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How we can do that.

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So I will create another DTO

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Post

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Patch

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.dto

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.ts

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.ts

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And now?

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If I create a class called Update.

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Post

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Patch

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DTO

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Now how?

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I can write a validation.

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I cannot copy anything here, but it's inside here, right?

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So for that reason, I will use a special syntax in the typescript.

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I will extends.

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Okay.

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I will extend the class.

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I will inherit from the Partial.

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Partial

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Oh, I don't know why.

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I.

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Let

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Let me find a package.

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nestjs

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Partial type

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Right here.

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We have a something called mapped type, inside the open api library here.

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Now you can see.

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You can see, it use the special syntax call PartialType and it'll use something like this

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Right.

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But.

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But why.

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I cannot use the PartialType right here.

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PartialType import from @nestjs/swagger

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I think I must install this package.

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Okay, let me install.

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Let me use PartialType from nestjs/swagger , and I will inherit it from the CreatePostDTO

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And technical

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We can easily,

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use the UpdatePostDTO, but

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I will inherit from CreatePostDTO because it later we.

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We may or may not have UpdatePostDTO

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anymore

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Right.

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So for that reason, I will inherit it from CreatePost

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DTO

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And what happened right now with, with the update right here.

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It will extend the Partial of CreatePost

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DTO

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It means it will ignore one of that, or it will ignore the title.

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Okay, that's the case of the PartialType

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Okay.

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That's it.

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Just enough for you.

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And let me show you how we can practice.

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Let me return.

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Actually, I will create one more method call Update

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Let me copy all of that

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And I will change the name to updateOne

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And we have a id and requestBody

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will be UpdatePostPatchDTO

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And now you can see, it's work, right?

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Because it's accept one or more property.

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And that for the job, but in this way, it'll not work

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And I can use a special syntax like Object.assign(post, requestBody)

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Now let's see it work or not

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I will return this.postService.updateOne

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and id and requestBody

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Right here will be 

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UpdatePostPatchDTO

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And let me, let me update.

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Let me duplicate and change to PATCH right here.

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I will only update the title.

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Let's see, if I send, now you can see, it update, right?

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Very cool.

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If I specify the description it also work because it's aceept 1 or 2.

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If I send, okay it's work, right.

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If I remove the title and I will use UpdatePost, then I send, now you can see it's worked very well

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and that's for the job of the PartialType, the PartialType, it just ignore one or more property inside

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the original DTO.

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Okay, in this case we will CreatePostDTO

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So that is, that how we can use the PartialType

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And I will not explain what is inside the Object.assign

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You can read more about that.

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In here because it is just the JavaScript knowledge.

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It just merge the type

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Okay, we just merge from here into the target type.

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Okay, now you can see, for example I have a target with a and B okay I have another object with b

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and c.

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So if I use the object.assign, it will merge it inside the final object like this.

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So that's just the object.assign. I will see you the next one.