Questions tagged [null]
5104 questions
1
votes
1
answer
10
Views
Nullcheck Children Chain in Typescript
Using strict null checking is great, but it's also resulting in this sort of silliness:
if (x)
if (x.y)
if (x.y.z)
if (x.y.z.stringProperty)
console.log(x.y.z.stringProperty)
Is there a way to do this null checking without repetition?
Thanks!
1
votes
2
answer
1.6k
Views
Remove null values from array using Array.indexOf?
I'm trying to find if there's a null value in my array without using for loops, mainly something similar to Array.indexOf. Undefined is NOT a string, it's a null value that comes up as undefined when I use console.log(ARRPREFIX)
var arr = ["**", undefined, null];
if (arr.indexOf(null) > -1) {
cons...
1
votes
2
answer
280
Views
How to return only one specific null field with GSON?
If I have a simple object as follows:
String name;
String email;
int age;
boolean isDeveloper;
Then let's say JSON object received have values:
{"name":null,"email":null,"age":26,"isDeveloper":true}
When deserializing this JSON using GSON as default I have:
{"age":26,"isDeveloper":true}
But email f...
1
votes
1
answer
5.3k
Views
java: Using Buffered Reader and checking if String is null
why doesn´t if (txtLine == null) { break; };work? or maybe the correct answer is why does it still set the string txtLine to null (literally). The way I understand it, it should break the moment the string is null? I don´t want it to set the string to "null". but stop when there are no mo...
-1
votes
1
answer
47
Views
NULL substitute for a double in C language 99 standard
I am working on a Circularly-Doubly-Linked List with a sentinel in the C language with the 99 standard. The headers I am allowed to use for class are stdio.h, stdlib.h, and assert.h only.
The sentinel is a struct and the structs have a value data member which is a double value. I was wondering if...
1
votes
2
answer
35
Views
Where condition in oracle request
I have a a date field who can be null in an Oracle Database.
I want to select the row with the highest date.
But if there is only one row with a null date and I use the max clause it will be ignored.
SELECT val1, val2
from T_DER
WHERE DATE_AP = ( SELECT MAX (DATE_AP) FROM T_DER WHERE AE= 'XXX')
A...
0
votes
0
answer
8
Views
My photo field still showing null in my table structure after inserting images using mysql statement
use work;
update applicants
set photo = (load_file("C:\Users\CEO\Pictures\MY PHOTOS\OT.jpg"))
where ID = 2001;
When I execute the query in MySQL workbench, it runs successfully, displaying 0 row(s) affected Rows matched: 1 Changed: 0 Warning
But when I decide to view my table records, the value...
1
votes
2
answer
784
Views
npgsql : Selecting a null data throws exception with error “Column is Null”
I am running npgsql v3.7 with .NetCore on Ubuntu.
When I execute a select query and a cell in any row in the results is null, an exception is thrown with the error message "Column is null".
I am having to work around this by putting every column in the select clause inside a case statement which tes...
1
votes
2
answer
4.8k
Views
Slim 3 getParsedBody() always null and empty
I'm am using the Slim Framework Version 3 and have some problems.
$app-> post('/', function($request, $response){
$parsedBody = $request->getParsedBody()['email'];
var_dump($parsedBody);
});
result is always:
null
Can you help me ?
1
votes
1
answer
2.3k
Views
NULL statement in VHDL
What is the actual purpose of null statement in VHDL? Consider the following codes
1-
CASE s IS
BEGIN
WHEN 0 => y NULL;
END CASE;
2-
CASE s IS
BEGIN
WHEN 0 => y
1
votes
2
answer
497
Views
Ignore null values in descending order using Django Rest Framework
I am using Django for my website, and hence decided to use Django Rest Framework for building my REST APIs. For a particular model, i want to filter on a text field (using SearchFilter for that), filter on a few categorical fields (FilterBackend with a FilterSet defined) and be able to order data ba...
1
votes
1
answer
1.5k
Views
How to have a null value for MySQL in Python
This is my version of SQL command line.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 122
Server version: 5.0.95 Source distribution
I have a table, and from Python, I want to write the last column as a null. Eventually, the last column of a particular row wi...
1
votes
2
answer
44
Views
ObjectMapper - How to send null value in JSON
According to third party API spec, I need to send null value in JSON using ObjectMapper if no value exists,
Expected results : "optional": null
If optional value exists, then send "optional": "value"
I didn't find such option in Jackson – Working with Maps and nulls
Code:
requestVO = new RequestV...
1
votes
2
answer
35
Views
Spark SQL Ranking for nullable unicode strings
We are working on Spark SQL. We are doing ranking using some nullable string fields.
The problem is: In Spark SQL, null values come first in the ranking. But, We want null value to come in the end. So, we have applied a CASE WHEN logic. As we are having Unicode data, "ZZZZZZZZ" will not be coming...
1
votes
2
answer
3.7k
Views
How to return null char reference
How do i return a null value? I created a local char set to null...but is there a different way to return a null lvalue?
char& String::operator[](int index) {
char s = NULL;
if (index > length) {
cout
1
votes
3
answer
1.6k
Views
All Null, Any Null is possible guava Predicate
I'm currently facing a code readability issue. The problem is the following:
Have three objects
// initialization skipped, all of three could be null as result of their initalization
Object obj1;
Object obj2;
Object obj3;
I want to create two booleans from them as follows:
// all are null
boolean bo...
1
votes
3
answer
6.2k
Views
MySQL insert NULL instead of 0000-00-00 date
I have birthday column as a date defined in my table. When i insert a person and left blank birthday field, i get 0000-00-00 and i want to get NULL values. when i insert date as birthday i get date, which is fine.
i tried :
Create table (
birthday DATE NULL,
birthday DATE DEFAULT NULL,
birthday DATE...
59
votes
5
answer
4.6k
Views
Will printf still have a cost even if I redirect output to /dev/null?
We have a daemon that contains a lot of print messages. Since we are working on an embedded device with a weak CPU and other constraint hardware, we want to minimize any kinds of costs (IO, CPU, etc..) of printf messages in our final version. (Users don't have a console)
My teammate and I have a dis...
0
votes
0
answer
4
Views
recognizing the null token in Antlr4
I want to parse this list.
identifier ( item1, item2, item3 ...)
It has 2 important rules.
Items are separated by ',' or blank.
if there is comma, then it recognize null token as ' '.
For example, these a same sentences
func ( ' ' item2 ' ')
func ( ' ',item2,' ')
func ( , item2 , ) skip;
1
votes
2
answer
686
Views
Select the last value of each column, per user, the simplest way
This is an extended version of a related previous question. I have posted it a new question for Erwin Brandstetter suggested me to do so. (I realized that I actually wanted this, after people replied to my first question)
Having the following data (blank means NULL):
ID User ColA ColB ColC...
1
votes
2
answer
1k
Views
Select the last value of each column, with a single query
Having the following data (blank means NULL):
ID ColA ColB ColC
1 15 20
2 11 4
3 3
How can I get the last not-NULL values of each column in a single query? So the resulting for the given data would be:
ColA ColB ColC
11 3 20
I ha...
1
votes
2
answer
1.6k
Views
Check if Class is Nothing, or Structure is default value, using a single condition
I've written my own method for programmatically selecting an item in a ComboBox:
Function SelectItem(ByVal item As Object, ByVal comboBox As ComboBox) As Boolean
If Not comboBox.Items.Contains(item) Then
comboBox.Items.Add(item)
End If
comboBox.SelectedItem = item
Return True
End Function
The "item"...
1
votes
4
answer
1.2k
Views
Getting a Null Pointer Exception in my program. What am I doing wrong? [closed]
Having null pointer exception in my program at the bolded part, what am I doing wrong? Any insight would be nice. Thank you. Some background on me, I am a biochemist, very new to programming. If there is a null created somewhere, how can I take care of it and not allow it to terminate and create a r...
1
votes
2
answer
2.3k
Views
sql server null value in where clause
There is one table which is having only one row with 4 date columns ,initially all date value are null so
if Exists(select 1 from rep_master where pacdt_1=null OR
pacdt_2=null OR
pacdt_3=null OR
pacdt_4=null)
select 0
else
select 1
this one is returning 1
if Exists(select 1 from rep_master where IS...
1
votes
2
answer
1k
Views
How to do jquery validation on something that is equal to zero, but not when its null/empty
So I want to validate a textbox that I have, the user can leave this box blank which is fine. However if they enter the number 0 in it, I want an error message to appear. However if it say is it null, it validates as an error when it is empty as well.
I have done is it equal to "0" in quotes, how...
1
votes
4
answer
5.5k
Views
Grails - Cannot invoke method getAt() on null object
I am getting an error when trying to append a book to a list of classes list of books. Any ideas as to why or what I could do to fix it?
//For each book in a class...
for (int k = 0; k < rows.size(); k++) {
Book book = new Book()
//Assign the values to a new book object
book.id = rows[k]....
1
votes
1
answer
4k
Views
Oracle: Is it possible to accurately join null fields from two different tables?
I have four fields -- itemnum, storeloc, binnum, and quantity.
I am trying to select data, where the first three fields match, but binnum is sometimes null. When I perform my sum on quantity, the calculation is not correct because of the NULL binnum. The database has an index where there can only be...
1
votes
1
answer
1k
Views
Invalid string or buffer length when inserting null in byte type field
I get the following exception when inserting :
ERROR [HY090] [Informix .NET provider]Invalid string or buffer length.
When
obj.Request_file = null;//of byte[] type
using (IfxConnection con = new IfxConnection(ConfigurationSettings.AppSettings["con1"].ToString()))
{
con.Open();
StringBuilder cmdTxt...
1
votes
3
answer
3.2k
Views
Entity framework + Lambda expression null comparison not working
i have a simple select:
this works:
User = ent.e_user.FirstOrDefault(x => x.usr_name == UserName && x.password == null);
Even if var Password is equal to null
this doesn't work:
String Password = null;
if(Password == null)
{
//it enters here
}
User = ent.e_user.FirstOrDefault(x => x.usr_name == U...
1
votes
1
answer
794
Views
Sparse columns not showing any savings
Ive ran a test comparing a table with a few sparse columns to a table with no sparse columns, and i am seeing zero space saving.
I have two tables, both storing Address info mainly in varchar columns.
both tables allow nulls, one has columns sparse property set.
I insert 1000 rows of default values...
1
votes
2
answer
974
Views
Android pick image from Gallery NullPointerException?
I am currently trying to create an App, which allows the user to pic an image from gallery and upload it to a server. But i'm still stuck in picking an image.
I followed a tutorial exactly, but when launching the activity i get a NullPointer.
Do you guys see any errors?
Thanks in advance!
Heres the...
1
votes
1
answer
1.5k
Views
Passing a NULL value to a GUID
I am a total beginner at VB.NET so you may need to bear with me but I need to edit this code behind so that a null value is passed to my database for the 'imageurl' field. The front end is a web form where a user can enter details of a book, with the option of uploading a book cover.
I want to chang...
1
votes
1
answer
793
Views
Reading NULL values with MFCs RFX (Record Field Exchange)
I'm using RFX (Record Field Exchange) to move data from a ODBC data source to my Recordset object. Numbers are moved with RFX_Int (within DoFieldExchange) and apparently the database NULL (not a value) is mapped to a pseudo null value AFX_RFX_INT_PSEUDO_NULL. Unfortunately this sentinel value is def...
1
votes
1
answer
94
Views
How do I index values in a multiple data type array in Lua?
This is a strange question but it baffles me. I want to be able to store x and y co-ords on an id based system such as: id.1.x = 10, id.1.y = 15: id.2.x = 50, id.2.y = 42 and I am trying to make a function to do it for me, I am having issues. here's my code
a = { p = {x,y}}
function box(xpos,ypos,id...
1
votes
3
answer
1.4k
Views
Javascript Email validation that allows a null value
I have this on submit function that checks for the email field to have a properly formatted address. Works fine. However, I want the field to allow a null value as this particular input is optional and not required. I know this should be simple, Im missing the obvious. Someone point me in the right...
1
votes
2
answer
853
Views
Simple SQL, Setting default value for multiple columns in a table
So I'm doing homework for a class and I have been stuck on this problem for days, apparently I'm not as good at google as I need to be.
Here it is:
"Change the StoreReps table so that NULL values can’t be entered in the first and last
name columns."
My Code (does not work):
Alter Table StoreRep M...
1
votes
4
answer
2.4k
Views
Remove Duplicates … With NULLs
In MS SQL Server I am trying to remove duplicates from a table with nulls. Que the groans. Lots and lots of NULLs. The bottom line is I need to retain one copy of any duplicate record with or without NULLs. I basically wantNULL to act like a normal record with a value of "NULL" for the duration of t...
1
votes
3
answer
8.1k
Views
Printing string array also prints null
When I am printing contents of a string array the output is printing 'null' as well. I am not sure what's wrong with this. Here is the output, what I expect is the output without 'null'
null(wa?>=0)nullnull*(wo?>=0)nullnull*(4*wa?+7*wo?>=50)nullnull*(d1=10)nullnull*((d2=1)+(k=2))nullnull
Thanks and...
1
votes
1
answer
1.4k
Views
How to update to NULL a field in solr using XML?
In solr 4 is possible to make partial document updates. For example:
1
newvalue
updates myfield to "newvalue" in record 1 without affecting other fields.
But how can I update myfield to NULL?
I tried with
but obviously it sets an empty string (not NULL) and for date fields raises an error.
Is there...
1
votes
1
answer
1.7k
Views
Foreach System.NullReferenceException: Object reference not set to an instance of an object
I get System.NullReferenceException: Object reference not set to an instance of an object in this:
var offeredItems = new List(Trade.steamMyOfferedItems);
foreach (var item in offeredItems) {
Trade.RemoveItem(item);
}
What is different than in all such questions is that the exception is in line 3 fr...