I'm trying to create a data store with an array reader. in each of the record, there is an array of fields. However, I only need some of the fields in the record. How can I setup the array reader so that only part of the record is mapped to the data store?
For each field in the reader, just add a 'mapping' item and set it equal to the index of the item in the array it is for. eg:
var arrData = [
['Col 1', 'Col 2', 'Col 3']
['Col 1', 'Col 2', 'Col 3']
['Col 1', 'Col 2', 'Col 3']
];
var reader = new Ext.data.ArrayReader({}, [
{name: 'First Column', mapping: 0},
{name: 'Third Column', mapping: 2},
]);
This will exclude the 2nd column (zero based index)
Related
Here is my multi-dimensional array:
newItem = [['ID', ['item 1A','item 1B','item 1C']], ['Address',['item 2A','item 2B','item 2C']], ['Req',['item 3A', 'item 3B', 'item 3C']]]
I'm trying to extract it into a new array in the below format:
newArr = [['item 1A', 'item 2A', 'item 3A'], ['item 1B', 'item 2B', 'item 3B'], ['item 1C', 'item 2C', 'item 3C']]
Tried several ways with map, flat, etc but was unable to achieve the desired result.
Looking for help here.
What you want is transposing the matrix, and you can simply use map to achieve this:
const newItem = [
['ID', ['item 1A', 'item 1B', 'item 1C']],
['Address', ['item 2A', 'item 2B', 'item 2C']],
['Req', ['item 3A', 'item 3B', 'item 3C']]
]
const matrix = newItem.map(item => item[1]) // turn the array into matrix
const newArr = matrix[0].map((_, i) => matrix.map(item => item[i])) // transpose the matrix
console.log(newArr)
Is there other solution to use R.applySpec without inserting the the unchanged keys value?(without needs to type id and name keys in the example, because later the keys will be change dynamically). Thank you.
Here is my input data
const data = [
[
{ id: 'data1', name: 'it is data 1', itemId: 'item1' },
{ id: 'data1', name: 'it is data 1', itemId: 'item2' }
],
[
{ id: 'data2', name: 'it is data 2', itemId: 'item1' }
],
[
{ id: 'data3', name: 'it is data 3', itemId: 'item1' },
{ id: 'data3', name: 'it is data 3', itemId: 'item2' }
]
]
And the output
[
{
id: 'data1', // this one doesn't change
name: 'it is data 1', // this one doesn't change
itemId: [ 'item1', 'item2' ]
},
{
id: 'data2', // this one doesn't change
name: 'it is data 2', // this one doesn't change
itemId: [ 'item1' ]
},
{
id: 'data3', // this one doesn't change
name: 'it is data 3', // this one doesn't change
itemId: [ 'item1', 'item2' ]
}
]
The solution to get the output using Ramda
const result = R.map(
R.applySpec({
id: R.path([0, 'id']),
name: R.path([0, 'name']), // don't need to type id or name again
itemId: R.pluck('itemId')
})
)(data)
We could certainly write something in Ramda like this:
const convert = map (lift (mergeRight) (head, pipe (pluck ('itemId'), objOf('itemId'))))
const data = [[{id: 'data1', name: 'it is data 1', itemId: 'item1'}, {id: 'data1', name: 'it is data 1', itemId: 'item2'}], [{id: 'data2', name: 'it is data 2', itemId: 'item1'}], [{id: 'data3', name: 'it is data 3', itemId: 'item1'}, {id: 'data3', name: 'it is data 3', itemId: 'item2'}]]
console .log (convert (data))
.as-console-wrapper {min-height: 100% !important; top: 0}
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.27.0/ramda.js"></script>
<script> const {map, lift, mergeRight, head, pipe, pluck, objOf} = R </script>
I'm not sure whether I find that more or less readable than a ES6/Ramda version, though:
const convert = map (
reduce ((a, {itemId, ...rest}) => ({...rest, itemId: [...(a .itemId || []), itemId]}), {})
)
or a plain ES6 version:
const convert = data => data .map (
ds => ds .reduce (
(a, {itemId, ...rest}) => ({...rest, itemId: [...(a .itemId || []), itemId]}),
{}
)
)
The question about applySpec is interesting. This function lets you build a new object out of the old one, but you have to entirely describe the new object. There is another function, evolve, which keeps intact all the properties of the input object, replacing only those specifically mentioned, by applying a function to their current value. But the input to the functions in evolve accepts only the current value, unlike applySpec which has access to the entire original object.
I could see some rationale for a function combining these behaviors. But I don't have a clear API in my head for how it should work. If you have some thoughts on this, and want to make a proposal, the Ramda team is always looking for suggestions.
I have a normalised Redux data structure indexed by a string ID. Amongst other properties, each object in the state has a sequenceNumber which is used to display it in order in a list or grid. The items can be dragged and dropped to reorder them.
I'm struggling to find a neat, pure approach to updating the sequence numbers. What is a good way to do this in a Redux reducer?
My current state data structure is essentially:
{
'asdf': { title: 'Item 1', sequence: 0, ... },
'1234': { title: 'Item 2', sequence: 1, ... },
'zzzz': { title: 'Item 3', sequence: 2, ... }
}
My action is
{ type: REORDER_ITEMS, oldRow: 1, newRow: 0 }
Which should result in the state
{
'asdf': { title: 'Item 1', sequence: 1, ... },
'1234': { title: 'Item 2', sequence: 0, ... },
'zzzz': { title: 'Item 3', sequence: 2, ... }
}
My current reducer uses Object.keys(state).reduce() to loop through the items and modify the sequence one by one, depending on whether they are equal, greater or lesser than the desired row numbers. Is there a neater way to manage this?
You could normalize a step further : Extract the sequence in a separate state slice and store the order as an array of ids.
{
items : {
'asdf': { title: 'Item 1', ... },
'1234': { title: 'Item 2', ... },
'zzzz': { title: 'Item 3', ... }
},
sequence: ['1234', 'asdf', 'zzzz']
}
This way, you could have a separate reducer to handle actions modifying your sequence, only using array operations.
I have the following expression:
public mySentences:Array<string> = [
{id: 1, text: 'Sentence 1'},
{id: 2, text: 'Sentence 2'},
{id: 3, text: 'Sentence 3'},
{id: 4, text: 'Sentenc4 '},
];
which is not working because my array is not of type string rather contains a list of objects. How I can delcare my array to contain a list of objects?
*without a new component which declaring the a class for sentence which seem a waste
I assume you're using typescript.
To be extra cautious you can define your type as an array of objects that need to match certain interface:
type MyArrayType = Array<{id: number, text: string}>;
const arr: MyArrayType = [
{id: 1, text: 'Sentence 1'},
{id: 2, text: 'Sentence 2'},
{id: 3, text: 'Sentence 3'},
{id: 4, text: 'Sentenc4 '},
];
Or short syntax without defining a custom type:
const arr: Array<{id: number, text: string}> = [...];
public mySentences:Array<Object> = [
{id: 1, text: 'Sentence 1'},
{id: 2, text: 'Sentence 2'},
{id: 3, text: 'Sentence 3'},
{id: 4, text: 'Sentenc4 '},
];
Or rather,
export interface type{
id:number;
text:string;
}
public mySentences:type[] = [
{id: 1, text: 'Sentence 1'},
{id: 2, text: 'Sentence 2'},
{id: 3, text: 'Sentence 3'},
{id: 4, text: 'Sentenc4 '},
];
Another approach that is especially useful if you want to store data coming from an external API or a DB would be this:
Create a class that represent your data model
export class Data{
private id:number;
private text: string;
constructor(id,text) {
this.id = id;
this.text = text;
}
In your component class you create an empty array of type Data and populate this array whenever you get a response from API or whatever data source you are using
export class AppComponent {
private search_key: string;
private dataList: Data[] = [];
getWikiData() {
this.httpService.getDataFromAPI()
.subscribe(data => {
this.parseData(data);
});
}
parseData(jsonData: string) {
//considering you get your data in json arrays
for (let i = 0; i < jsonData[1].length; i++) {
const data = new WikiData(jsonData[1][i], jsonData[2][i]);
this.wikiData.push(data);
}
}
}
First, generate an Interface
Assuming you are using TypeScript & Angular CLI, you can generate one by using the following command
ng g interface car
After that set the data types of its properties
// car.interface.ts
export interface car {
id: number;
eco: boolean;
wheels: number;
name: string;
}
You can now import your interface in the class that you want.
import {car} from "app/interfaces/car.interface";
And update the collection/array of car objects by pushing items in the array.
this.car.push({
id: 12345,
eco: true,
wheels: 4,
name: 'Tesla Model S',
});
More on interfaces:
An interface is a TypeScript artifact, it is not part of ECMAScript. An interface is a way to define a contract on a function with respect to the arguments and their type. Along with functions, an interface can also be used with a Class as well to define custom types.
An interface is an abstract type, it does not contain any code as a class does. It only defines the 'signature' or shape of an API. During transpilation, an interface will not generate any code, it is only used by Typescript for type checking during development. - https://angular-2-training-book.rangle.io/handout/features/interfaces.html
public mySentences:Array<any> = [
{id: 1, text: 'Sentence 1'},
{id: 2, text: 'Sentence 2'},
{id: 3, text: 'Sentence 3'},
{id: 4, text: 'Sentenc4 '},
];
OR
public mySentences:Array<object> = [
{id: 1, text: 'Sentence 1'},
{id: 2, text: 'Sentence 2'},
{id: 3, text: 'Sentence 3'},
{id: 4, text: 'Sentenc4 '},
];
Datatype: array_name:datatype[]=[];
Example string: users:string[]=[];
For array of objects:
Objecttype: object_name:objecttype[]=[{}];
Example user: Users:user[]=[{}];
And if in some cases it's coming undefined in binding, make sure to initialize it on Oninit().
type NumberArray = Array<{id: number, text: string}>;
const arr: NumberArray = [
{id: 0, text: 'Number 0'},
{id: 1, text: 'Number 1'},
{id: 2, text: 'Number 2'},
{id: 3, text: 'Number 3 '},
{id: 4, text: 'Number 4 '},
{id: 5, text: 'Number 5 '},
];
Does anyone know why AngularJS not selecting options on <select multiple> if ng-model is an array of integer?
$scope.selected = [1, 3]
$scope.options = [
{id: 1, title: 'option 1'},
{id: 2, title: 'option 2'},
{id: 3, title: 'option 3'}
]
Everything works just fine if $scope.selected = ['1', '3'] is array of string. I need to get it working without using ng-options.
Here is JSFiddle:
http://jsfiddle.net/maxflex/3jfk8/19/