I have a list of model class objects. Such as -
List<ModelChannel> allChannels = [];
I have added elements in this list from json. Model Class variables are-
final String channelid;
final String channelname;
final String channeltype;
final String categoryname;
final String channelimage;
final String channelurl;
Here categorytype contains country information. I want to divide the list country wise dynamically. I have intended to use 2d list where each row will contain all the channels of a specific country. Is this the right approach? If yes how to implement this and if not what will be the right one?
If I understand correctly, you are looking for groupBy function from collection package.
Add this package to your pubspec.yaml:
dependencies:
collection: any
And use groupBy:
import 'package:collection/collection.dart';
...
final groupByCountry = groupBy(allChannels, (ModelChannel e) => e.categoryname);
List<List<ModelChannel>> countryList = [];
List<String> channelType = [];
allChannels.forEach((element) {
if (channelType.isEmpty) {
channelType.add(element.channeltype);
} else {
if (channelType.contains(element.channeltype)) {
} else {
channelType.add(element.channeltype);
}
}
});
channelType.forEach((countryCode) {
List<ModelChannel> t = [];
allChannels.forEach((element) {
if (element.channeltype == countryCode) {
t.add(element);
}
});
countryList.add(t);
});
Related
i want to filter a list of student in java. I have a student class in kotlin like this.
class Student(
var id: String? = null,
var firstName: String? = null,
var lastName: String? = null
) {
constructor(entity: StudentCourse?): this() {
if (entity != null) {
this.id = entity.id.id
this.name = entity.name
}
}
}
class StudentCourse (#EmbeddedId open var id: StudentCourseId) {
constructor() : this(StudentCourseId())
open var name: Boolean? = null
}
#Embeddable
open class StudentCourseId: Serializable {
open var id: String? = null
open var deptName: String? = null
}
this is the list i want to filter :
var students: List<Student> = listOf(
Student("14adbv45", "dan", "GEG"),
Student("96adbv42","Bob", "Bowyer"),
Student("30adbv45","Emily", "Eden")
)
I do this
List<students> studentListContainsFirstNameBob = students.stream()
.map(StudentCourse)
.filter(e -> e.getFirstName.equals("Bob"))
.flatMap(List::stream);
but it doesn't work.
How can i do it please
There are multiple issues in your code.
For example in this part:
constructor(entity: StudentCourse?): this() {
if (entity != null) {
this.id = entity.id.id
this.name = entity.name
}
}
The entity.name refers to StudentCourse#name, but this property is actually of Boolean type, so comparing it to String doe snot make much sense. You have also doubled .id which is incorrect.
Next thing, I am not sure what this snipped should do, was the intention to link a student with given course? If so, you would probably like to add a list of students to a course, or a list of courses to a student (which sounds more correct).
Finally, when it comes to filtering a list, you can get students with first name Bob in this way:
var studentListContainsFirstNameBob: List<Student> = students
.filter { it.firstName.equals("Bob") }
.toList()
Mind the it variable refers to the element from the list, it could also be written:
var studentListContainsFirstNameBob: List<Student> = students
.filter { student -> student.firstName.equals("Bob") }
.toList()
I have BrandList in my Firebase like this;
How can I convert or equalize this Firebase List to List.
I tried this;
var brandsRef = _firestore.collection("vehicles1").where("Brands");
List brandsList = brandsRef;
But I got this error "A value of type 'Query<Map<String, dynamic>>' can't be assigned to a variable of type 'List'."
You need to use the document Id to get the query and then you can get the data which returns a Map.
From that Map, you can supply the key to retrieve the value. In this case, the key is "Brands".
var brandsQuery = await _firestore.collection("vehicles1").doc(document Id).get();
List brandList = brandsQuery.data()["Brands"];
First I would suggest to create a model of your class Brand in addition to the jsonSerialization classics:
class Brands {
Brands({this.brandName});
List<String> brandName;
Map<String, dynamic> toMap() {
return {
'Brands': brandName,
};
}
factory Brands.fromMap(Map<String, dynamic> map) {
return Brands(
brandName: List<String>.from(map['Brands']),
);
}
String toJson() => json.encode(toMap());
factory Brands.fromJson(String source) => Brands.fromMap(json.decode(source));
}
Then you need to add a few steps to the way you retreive elements:
var response = _firestore.collection("vehicles1").where("Brands").get();
final results =
List<Map<String, dynamic>>.from(response.docs.map((e) => e.data()));
Brands brands =
results.map((e) => Brands.fromMap(e)).toList();
I have one list of complex object. How can I distinct the list using their IDs?
I cant use toSet and similars, because the hashcode from the objects all are diferent.
1) Vanilla Dart
Loop through the list, adding IDs to a set as you go. Whenever you add an ID to the set that didn't already exist, add that element to a new list of distinct values.
void main() {
var list = [
Data('a'),
Data('a'),
Data('b'),
Data('c'),
];
var idSet = <String>{};
var distinct = <Data>[];
for (var d in list) {
if (idSet.add(d.id)) {
distinct.add(d);
}
}
}
class Data {
Data(this.id);
final String id;
}
2) Packages
Several packages exist that expand on default the Iterable utility methods, such as flinq or darq. They add a distinct method you can call to easily get a list of unique members of a list based on some property of the members.
import 'package:darq/darq.dart';
void main() {
var list = [
Data('a'),
Data('a'),
Data('b'),
Data('c'),
];
var distinct = list.distinct((d) => d.id).toList();
}
(Disclaimer, I am the maintainer of darq.)
Try to use this extension:
extension IterableExtension<T> on Iterable<T> {
Iterable<T> distinctBy(Object getCompareValue(T e)) {
var result = <T>[];
this.forEach((element) {
if (!result.any((x) => getCompareValue(x) == getCompareValue(element)))
result.add(element);
});
return result;
}
}
Using:
var distinctList = someList.distinctBy((x) => x.oid);
Or you can use a hash there.
I am trying to retrieve a list of user generated Lists from a specified website. I do not want System generated lists (eg MicroFeed) nor Document Libraries. Using the Microsoft example I have this code:
public static void LoadLists(Microsoft.SharePoint.Client.Web web, List<String> foldersList)
{
var ctx = web.Context;
ListCollection collList = web.Lists;
IEnumerable<List> listInfo = ctx.LoadQuery(
collList.Include(
list => list.Title,
list => list.Fields.Include(
field => field.Title,
field => field.InternalName)));
ctx.ExecuteQuery();
foreach (List oList in listInfo)
{
FieldCollection collField = oList.Fields;
foreach (Microsoft.SharePoint.Client.Field oField in collField)
{
Regex regEx = new Regex("name", RegexOptions.IgnoreCase);
if (regEx.IsMatch(oField.InternalName))
{
Console.WriteLine("List: {0} \n\t Field Title: {1} \n\t Field Internal Name: {2}",
oList.Title, oField.Title, oField.InternalName);
}
}
}
}
However this returns all Lists and Document Libraries (and heaven knows what else). Is there an easy way to just get back the user defined lists? Here is an example of what I would like to get:
And looking at the documentation from Microsoft they seems to use the term list to refer to actual lists (tables) and document libraries (folders). What is the proper nomenclature for getting the list that is really just like an excel spreadsheet of data? Finally, is it possible for lists (tables) to be nested in side a Document Libraries? I can't seem to be able to do this, but I wanted to check since I am new to SharePoint.
Thanks!
So after having to lookup lots of examples (not from Microsoft, thank you) and stepping thru actual responses, here is the code for loading only the Lists and their field columns (not hidden) created by the user. I am sure that this could be optimized/cleaned up (for example not having to run the secondary queries to get List attributes, but it gave me access denied in original query), but it is working for me. Also needs some loving care for try-catches in case things go south.
First a couple of classes to hold the data:
public class SharePointColumn
{
public string Title { get; set; }
public string InternalName { get; set; }
public string TypeAsString { get; set; }
}
public class SharePointLibrary
{
public SharePointLibrary()
{
Columns = new List<SharePointColumn>();
}
public string Title { get; set; }
public Boolean IsList { get; set; } // If true a list, else DocumentLibrary
public List<SharePointColumn> Columns { get; set; }
}
Then the real code.
public static void LoadLists(Microsoft.SharePoint.Client.Web web, List<SharePointLibrary> sharePointLibraries)
{
var ctx = web.Context;
ListCollection collList = web.Lists;
IEnumerable<List> listInfo = ctx.LoadQuery(
collList.Include(
list => list.Title,
list => list.Fields.Include(
field => field.Title,
field => field.InternalName,
field => field.Hidden,
field => field.TypeAsString)));
ctx.ExecuteQuery();
foreach (List oList in listInfo)
{
// Had to add these because trying to add in above query failed
ctx.Load(oList);
ctx.ExecuteQuery();
// 544 Base Template is MicroFeed
if (oList.Hidden == false && oList.IsCatalog == false && (!oList.IsObjectPropertyInstantiated("IsSiteAssetsLibrary") || oList.IsSiteAssetsLibrary == false) &&
oList.BaseType != BaseType.DocumentLibrary && oList.BaseTemplate != 544)
{
FieldCollection collField = oList.Fields;
SharePointLibrary lib = new SharePointLibrary
{
Title = oList.Title,
IsList = true,
Columns = new List<SharePointColumn>()
};
foreach (Microsoft.SharePoint.Client.Field oField in collField)
{
if (!oField.Hidden)
{
SharePointColumn col = new SharePointColumn();
col.Title = oField.Title;
col.InternalName = oField.InternalName;
col.TypeAsString = oField.TypeAsString;
lib.Columns.Add(col);
}
}
sharePointLibraries.Add(lib);
}
}
}
I'm receiving the following error while trying to add elements from my for loop to my List...
NoSuchMethodError: The method 'addAll' was called on null.
Receiver: null
Tried calling: addAll("LrWr826cd3Y")
Here is my code...
Future getData() async {
//Map videoId;
String url = 'https://Youtube API';
var httpClient = createHttpClient();
var response = await httpClient.read(url);
Map data = JSON.decode(response);
var videos = data['items']; //returns a List of Maps
List searchTitles;
List searchIds;
List searchImages;
for (var items in videos) {
//iterate over the list
Map myMap = items; //store each map
final video = (myMap['id'] as Map);
print(video['videoId']);
searchIds.addAll(video['videoId']);
final details = (myMap['snippet'] as Map);
final videoimage = (details['thumbnails'] as Map);
final medium = (videoimage['medium'] as Map);
}
setState(() { });
if (!mounted) return;
}
print(video['videoId']); successfully lists the 3 Youtube video ids as Strings. searchIds.addAll(video['videoId']); throws the error. I've tried both searchIds.add and searchIds.addAll. Where am I going wrong?
I would like to eventually push these lists to my List class here..
class CardInfo {
//Constructor
List id;
List title;
List video;
CardInfo.fromJson(List json) {
this.id;
this.title;
this.video;
}
}
You are not instantiating your searchIds object. add this
List searchIds = new ArrayList<>();
(Or)
List searchIds = new List();