can anyone help me to remove typename and unwanted fields from graph QL from flutter.how to get response as in postman. Iam using the package https://pub.dev/packages/graphql
I had the same issue, I could not find a simple way to disable __typename,
so I wrote a small program,
T removeTypename<T>(T data) =>
_removeUnwantedKeys(data, ['__typename']);
T _removeUnwantedKeys<T>(T data, List keysToRemove) {
if (data is Map && data.containsAnyOf(keysToRemove)) {
Map d = {};
data.forEach((key, value) {
if (!keysToRemove.contains(key)) d[key] = _removeUnwantedKeys(value,keysToRemove);
});
return d as T;
} else if (data is List)
return data.map((c) => _removeUnwantedKeys(c,keysToRemove)).toList() as T;
else
return data;
}
extension MapsMadeEasy<U, V> on Map<U, V>? {
bool containsAnyOf(List keys) {
if (this == null) return false;
return this!.entries.any((element) => keys.contains(element.key));
}
}
Related
How to search for 2 different parameters in a dart list?
Is there a simple method?
Can I solve the problem using contains?
void _runFilter(String searchKeyword) {
List<Product> results = [];
if (searchKeyword.isEmpty) {
results = allProducts;
} else {
results = allProducts.where(
(element) =>
element.name.toLowerCase().contains(searchKeyword.toLowerCase()) || element.image.toLowerCase().contains(searchKeyword.toLowerCase()),
),
)
.toList();
results = results +
allProducts
.where(
(element) => element.image.toLowerCase().contains(
searchKeyword.toLowerCase(),
),
)
.toList();
}
// refresh the UI
setState(() {
filteredProducts = results;
});
}
You can write all sorts of if-else-combinations in a closure. If you use the {} notation instead of => it will become clearer. Something like this will accomplish what you are looking for:
results = allProducts.where( (element) {
if ( element.name.toLowerCase().contains(searchKeyword.toLowerCase()) {
return true;
} else if ( element.image.toLowerCase().contains(searchKeyword.toLowerCase()) {
return true;
} else {
return false;
}
}).toList();
If this step is clear, you can then try to combine individual statements into a boolean combination via || or && if this looks more convenient in your code.
I am still coming up to speed with dart and wanted to know if there was an easier way to not execute a statement if the value is null. See example below:
I can always do the if statements below for setting field3 and field4, but felt like something like field5 should work. But when I try to do that, it complains that a null check operator is used on a null value.
Also I don't want to change the Map to have a dynamic value.
Is there a single one liner to do what I am trying to do, or do I just need to check for null before setting the value.
Map<String, Object> myMap = {};
print('running now');
try {
myMap['field1'] = DummyClass.getString('hello');
myMap['field2'] = DummyClass.getString('good');
//Is there a more concise way to do this than the 2 options below?
if (DummyClass.getOptionalString('goodbye') != null) {
myMap['field3'] = DummyClass.getOptionalString('goodbye')!;
}
String? temp = DummyClass.getOptionalString('go');
if (temp != null) {
myMap['field4'] = temp;
}
// This gives an error 'null check operator used on a null value'
// myMap['field5'] ??= DummyClass.getOptionalString('to')!;
} catch (e) {
print('error condition, $e');
}
print(myMap);
}
class DummyClass {
static String getString(String? strParam) {
String? retString = getOptionalString(strParam);
if (retString == null) {
throw ('nulls are not allowed');
}
return retString;
}
static String? getOptionalString(String? strParam) {
if (strParam == null || strParam.length < 3) {
return null;
}
return strParam;
}
}
There's no built-in way to do what you want, but you could write a function (or extension method) to do it. For example:
extension MapTrySet<K, V> on Map<K, V> {
void trySet(K key, V? value) {
if (value != null) {
this[key] = value;
}
}
}
and then you could do:
myMap.trySet('field3', DummyClass.getOptionalString('goodbye'));
myMap.trySet('field4', DummyClass.getOptionalString('go'));
Alternatively, if you really want to use normal Map syntax, you could create your own Map class that has a void operator []=(K key, V? value) override and does nothing when the value is null, but that probably would not be worth the effort.
The issue is that the ??= operator assigns to the left if it is null. Expanded, it would look something like this:
a ??= b;
// Equivalent to:
if (a == null) {
a = b;
}
Which is not something that you're trying to achieve. AFAIK, there is no such operator yet in Dart. However, you can try this:
final possiblyNullValue = '';
final myMap = <String, String>{};
myMap['key'] = possiblyNullValue ?? myMap['key'];
// Equivalent to:
if (possiblyNullValue != null) {
myMap['key'] = possiblyNullValue;
}
// or:
myMap['key'] = possiblyNullValue != null? possiblyNullValue : myMap['key'];
Which would work in your case as a one-liner.
You could create your map with all entries, even null, and then filter the null values out:
void main() {
try {
final myMap = <String, dynamic>{
'field1': DummyClass.getString('hello'),
'field2': DummyClass.getString('good'),
'field3': DummyClass.getOptionalString('goodbye'),
'field4': DummyClass.getOptionalString('go'),
}..removeWhere((k, v) => v == null);
print(myMap);
} catch (e) {
print('error condition, $e');
}
}
I am writing and extension for OpenXML like shown in the sample. I would like to avoid having to pass the WorkbookPart as parameter. Is there any way to get the WorkbookPart directly from the row?
public static string GetCellTextValue(this Row row, WorkbookPart workbookPart, string column)
{
var cells = row.Elements<Cell>();
var cell = cells.Where(p => p.CellReference == column + row.RowIndex.ToString()).FirstOrDefault();
if (cell.DataType != null)
{
if (cell.DataType == CellValues.SharedString)
{
int id = -1;
if (Int32.TryParse(cell.InnerText, out id))
{
SharedStringItem item = workbookPart.SharedStringTablePart.SharedStringTable.Elements<SharedStringItem>().ElementAt(id);
if (item.Text != null)
{
return item.Text.Text;
}
else if (item.InnerText != null)
{
return item.InnerText;
}
else if (item.InnerXml != null)
{
return item.InnerXml;
}
}
}
}
return string.Empty;
}
Unfortunately, none of the strongly-typed classes of the Open XML SDK (e.g., Workbook, Worksheet, Row) have properties pointing back to the OpenXmlPart (e.g., WorkbookPart, WorksheetPart) in which they are contained or any other part related to their immediate container. Unless you amend your API in other ways, you will have to pass that WorkbookPart.
I want to
1.map item from observable to another one if it has already saved in database.
2.otherwise, use it as it is.
and keep their order in result.
Saved item has some property like tag, and item from observable is 'raw', it doesn't have any property.
I wrote code like this and run testMethod.
class Item {
final String key;
String tag;
Item(this.key);
#override
String toString() {
return ('key:$key,tag:$tag');
}
}
class Sample {
///this will generate observable with 'raw' items.
static Observable<Item> getItems() {
return Observable.range(1, 5).map((index) => Item(index.toString()));
}
///this will find saved item from repository if it exists.
static Future<Item> findItemByKey(String key) async {
//simulate database search
await Future.delayed(Duration(seconds: 1));
if (key == '1' || key == '4') {
final item = Item(key)..tag = 'saved';
return item;
} else
return null;
}
static void testMethod() {
getItems().map((item) async {
final savedItem = await findItemByKey(item.key);
if (savedItem == null) {
print('not saved:$item');
return item;
} else {
print('saved:$savedItem');
return savedItem;
}
}).listen((item) {});
}
The result is not expected one.
expected:
saved:key:1,tag:saved
not saved:key:2,tag:null
not saved:key:3,tag:null
saved:key:4,tag:saved
not saved:key:5,tag:null
actual:
not saved:key:2,tag:null
not saved:key:3,tag:null
not saved:key:5,tag:null
saved:key:1,tag:saved
saved:key:4,tag:saved
How to keep their order in result?
I answer myself to close this question.
According to pskink's comment, use asyncMap or concatMap solve my problem. Thanks!!
below is new implementation of testMethod.
asyncMap version:
getItems().asyncMap((item) {
final savedItem = findItemByKey(item.key);
if (savedItem != null)
return savedItem;
else
return Future.value(item);
}).listen(print);
concatMap version:
getItems().concatMap((item) {
final savedItem = findItemByKey(item.key);
if (savedItem != null)
return Observable.fromFuture(savedItem);
else
return Observable.just(item);
}).listen(print);
I have 3 methods these are same methods only some parameters will be change I want to write one method how can i write
public string method1(int id)
{
var getAllStudents = rep.Students.Where(e => e.StudentId == id).ToList();
foreach (var item in getAllStudents)
{
if (item.isActive != true)
return "Error";
}
return "OK";
}
public string method2(int id)
{
var getAllTeachers = rep.Teachers.Where(e => e.TeacherId == id).ToList();
foreach (var item in getAllTeachers)
{
if (item.isActive != true)
return "Error";
}
return "OK";
}
public string method3(int id)
{
var getAllClasses = rep.Classes.Where(e => e.ClassId == id).ToList();
foreach (var item in getAllClasses)
{
if (item.isActive != true)
return "Error";
}
return "OK";
}
I think there is very easy way to write 1 method. the think is where parameter has different id..
Thanks.
Avoid conditional logic based on arguments. This leads to fragile code because every parameter combination has to be tested to be considered reliable. This leads to complex code that is easily prone to bugs. Having simpler single-purpose methods are typically much more reliable and easier to understand and maintain.
For instance given your example and assuming that "rep" was your instance's DbContext...
public bool IsActiveStudent(int id)
{
bool result = rep.Students.Any(x => x.StudentId == id && x.IsActive);
return result;
}
public bool IsActiveTeacher(int id)
{
bool result = rep.Teachers.Any(x => x.TeacherId == id && x.IsActive);
return result;
}
public bool IsActiveClass(int id)
{
bool result = rep.Classes.Any(x => x.ClassId == id && x.IsActive);
return result;
}
These can be essentially one-liners by simply returning the .Any() result. I tend to favour selecting the result into a variable first and returning it on a separate line since it makes it easier to breakpoint and inspect.
If you need to return a string for "Ok" vs. "Error" then:
return result ? "OK" : "Error";
Methods should strive to do one thing, and do it well. Easy to understand and troubleshoot if need be. Adding parameters and conditional code inside the method merely makes the code more volatile and leaves openings for bugs. In the end it doesn't make the code much shorter when the initial method could be simplified.
You can not overload methods if they signatures are the same.
You have two methods with the same signature:
public string checkexist(int id)
What you can do is to rename your methods, like this:
public interface WriteSomethingHere {
public boolean isStudentExist(int id);
public boolean isTeacherExist(int id);
public boolean isClassExist(int id);
}
I just found answer using generic repo
public T GetEntity<T>(int Id)
where T : class
{
using (MyEntities rpContext = new MyEntities())
{
return rpContext.Set<T>().Find(e => e.Id == Id);
}
}
after calling
var entityStudent = GetEntity<Student>(1);
var entityTeacher = GetEntity<Teacher>(1);
var entityClasses = GetEntity<Classes>(1);
You have Create Enumeration
Public Enum ParameterStaus:short
{
Student=1,
Teacher=2,
Classess=3
}
public string method2(int id.ParameterStatus status)
{
if(status==ParameterStatus.Teacher)
{
var getAllTeachers = rep.Teachers.Where(e => e.TeacherId == id).ToList();
foreach (var item in getAllTeachers )
{
if (item.isActive != true)
return "Error";
}
return "OK";
}
}
Else if(status==ParameterStatus.Student)
{
var getAllStudents = rep.Students.Where(e => e.StudentId == id).ToList();
foreach (var item in getAllStudents)
{
if (item.isActive != true)
return "Error";
}
return "OK";
}
Else
{
var getAllClasses = rep.Classes.Where(e => e.ClassId == id).ToList();
foreach (var item in getAllClasses)
{
if (item.isActive != true)
return "Error";
}
return "OK";
}
}