Wsrtjtyk

I am new to ionic 3 and angular. Basically I wanted to create a list with header (data from MySQL database through PHP API). The header will display the category while the items will go to ion-item section.

However when I try to call the 2nd ngFor it throws me error as shown below in the picture. I notice a lot people use GET method while I am using POST method which are harder to find solution out there. Please enlighten, thanks in advance.

JSON

home.ts

this.storage.get('username').then((val) => {

  let headers: any = new HttpHeaders({ 'Content-Type': 'application/x-www-form-urlencoded' }),

    options: any = { "username": val },

    url: any = "path_to_my_api";



  this.http.post(url, options, headers)

    .subscribe((data: any) => {

      this.prods = data.products;

    },

      (error: any) => {

        console.log(error);

      });

});

home.html

<ion-list *ngFor="let prod of prods | async">

    <ion-list-header>

      {{prod.category}}

    </ion-list-header>

    <ion-item *ngFor="let myitem of prod.item | async">

        <ion-avatar item-start>



        </ion-avatar>

        <h2>haha{{myitem.code}}</h2>

      </ion-item>

  </ion-list>

Try this

Logic:

this.http.post(url, options, headers)

  .subscribe((data: any) => {

    const categoryMap = data.products.reduce((categories, prod) => {

      if (categories[prod.category]) {

        categories[prod.category].push(prod);

      } else {

        categories[prod.category] = [prod];

      }



      return categories;

    }, {});



    this.categories = Object.keys(categoryMap).map(category => ({

      category,

      products: categoryMap[category]

    });

  }, (error: any) => {

    console.log(error);

  });

Template:

<ion-list *ngFor="let cat of categories | async">

  <ion-list-header>

    {{cat.category}}

  </ion-list-header>

  <ion-item *ngFor="let prod of cat.products | async"> <!-- not sure if async pipe is necessary here though -->

    <ion-avatar item-start></ion-avatar>

    <h2>haha{{prod.item.code}}</h2>

  </ion-item>

</ion-list>

To clarify, the final structure of your data will look like this:

this.categories = [

  {

    category: "Beer Bottles",

    products: [

      {

        item: {code: 'whatever'},

        category: "Beer Bottles"

      },

      {

        item: {code: 'something else'},

        category: "Beer Bottles"

      },

      ...etc.

    ]

  },

  {

    category: "Beer Draught",

    products: [ ...relevant products as above]

  }

]