如何从特定产品ID的产品列表中提取产品？

如何解决如何从特定产品ID的产品列表中提取产品？

请帮助我！

    List<String> Id= ["MES9-7t73JhFzAEoL6J","MES91YJevIAthak253M"];

    List<Product> products =
          [
            Product(
              id: 'MES9-2',categories: 'AC1,AC2,AC3,N1,Pn1,P',title: 'Red Shirt',description: 'A red shirt - it is pretty red!',price: 29.99,imageUrl:
                'https://cdn.pixabay.com/photo/2016/10/02/22/17/red-tshirt-1710578_1280.jpg',),Product(
             categories:' pn2,N2,N3,Pn2,Pn3',id: 'MES91YJevIAthak253M',title: 'Trousers',description: 'A nice pair of trousers.',price: 59.99,imageUrl:
              'https://upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Trousers%2C_dress_%28AM_1960.022-8%29.jpg/512px-Trousers%2C_dress_%28AM_1960.022-8%29.jpg',];

=>如何从产品ID与ID列表中的字符串相同的_items列表中提取产品。

解决方法

您需要运行两个for循环来提取与您拥有的产品ID列表相对应的产品列表。第一个循环将根据您获得的ID的长度运行，第二个循环将根据产品的长度运行。它将在if条件中匹配两个ID，并将匹配的产品添加到 #Creating empty geojson to collect features drawn on map: feature_collection = { 'type': 'FeatureCollection','features': []} #Handling items drawn on map: def handle_draw(self,action,geo_json): """Do something with the GeoJSON when it's drawn on the map""" feature_collection['features'].append(geo_json) #Generate Basemap: satellite = basemap_to_tiles(basemaps.Esri.WorldImagery) osmap = basemap_to_tiles(basemaps.OpenStreetMap.Mapnik) mymap = Map(layers=(osmap,satellite),center=(55,0),zoom=5,scroll_wheel_zoom=True) #Generate controls on map: center=[55,0] #where to start on map: middle of UK marker = Marker(location=center,draggable=False) #Draw shapes on map: dc = DrawControl(marker={'shapeOptions': {'color': '#0000FF'}},rectangle={'shapeOptions': {'color': '#0000FF'}},circlemarker={}) dc.on_draw(handle_draw) #call function what to do with objects drawn on maps #Add all controls to the actual map: mymap.add_control(dc) #add #Generate GEOJSON which could contain data to be displayed on map: geo_json = GeoJSON(data={},style={},hover_style={}) mymap.add_layer(geo_json) #add to map object mymap 列表中。

foundProducts

,

尝试一下：

final product = products.firstWhere((p) => Id.contains(p.id));

,

您只需要遍历列表，找到匹配项并返回即可。您可以通过firsWhere()进行操作。

因此，您将不得不使用list iterate dart遍历Id

//you have the List<Product> we are taking the variable as products
List<Product> products = ....

// this will store the item which matches the id
var item;
Id.forEach((id){
  //now using first where
  products.firstWhere((item) => item.id == id,orElse: () => null);
});

// now printing the item and check for the nullability
print(item ?? 'No products found'); // You will get the matching the Product matching the item id

请注意： firstWhere()，给出与任何ID匹配的列表中找到的第一项。因此，您只会选择一种产品。我只想满足一个要求。

我有一个演示给您。在这里，您可以了解其工作原理

演示

class Product {
  double price;
  String id,categories,title,description,imageUrl;
  
  Product({
    this.id,this.categories,this.title,this.description,this.price,this.imageUrl
  });
}

void main() {
  var result;
  List<String> id = ["MES9-7t73JhFzAEoL6J","MES91YJevIAthak253M"];
  List<Product> products = [
    Product(
      id: 'MES9-2',categories: 'AC1,AC2,AC3,N1,Pn1,P',title: 'Red Shirt',description: 'A red shirt - it is pretty red!',price: 29.99,imageUrl:
          'https://cdn.pixabay.com/photo/2016/10/02/22/17/red-t-shirt-1710578_1280.jpg',),Product(
      categories:' pn2,N2,N3,Pn2,Pn3',id: 'MES91YJevIAthak253M',title: 'Trousers',description: 'A nice pair of trousers.',price: 59.99,imageUrl:
          'https://upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Trousers%2C_dress_%28AM_1960.022-8%29.jpg/512px-Trousers%2C_dress_%28AM_1960.022-8%29.jpg',)
  ];
  
  // Here is what we're doing the main operation
  id.forEach((id){
    result = products.firstWhere((item) => item.id == id,orElse: () => null);
  });
  
  //printing the result
  print(result ?? "No items found");
  // similary you can get the result item via result.id
  print("RESULT: ${result.id},${result.categories},${result.title}");
}

输出

Instance of 'Product' // so this is the instance of the product
RESULT: MES91YJevIAthak253M,pn2,Pn3,Trousers