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E11000 duplicate key error index in mongodb mongoose
... null value.
In other words, a sparse index is ok with multiple documents all having null values.
sparse indexes
From comments:
Your error says that the key is named mydb.users.$email_1 which makes me suspect that you have an index on both users.email and users.local.email (The former being old an...
Shortcut to create properties in Visual Studio?
I have seen some people creating properties in C# really fast, but how did they do it?
16 Answers
...
Confused about Service vs Factory
...
All angular services are singletons:
Docs (see Services as singletons): https://docs.angularjs.org/guide/services
Lastly, it is important to realize that all Angular services are application singletons. This means that t...
When should I use perror(“…”) and fprintf(stderr, “…”)?
...should use fprintf(stderr, fmt, ...). For example, strtol will return LONG_MAX or LONG_MIN if a string is out of range and set errno to ERANGE. So if strtol fails due to out of range, I would use perror.
– freeboy1015
Aug 24 '12 at 2:22
...
Why do we need C Unions?
...le types together:
enum Type { INTS, FLOATS, DOUBLE };
struct S
{
Type s_type;
union
{
int s_ints[2];
float s_floats[2];
double s_double;
};
};
void do_something(struct S *s)
{
switch(s->s_type)
{
case INTS: // do something with s->s_ints
break;
case F...
How to format an inline code in Confluence?
...ed" option applies to the entire line. The only way to do it (without installing the wikitext editing plugin) is to pick monospaced font.
– HDave
Mar 27 '13 at 17:14
16
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Split list into multiple lists with fixed number of elements
...st[List[X]] =
if (xs.size <= n) xs :: Nil
else (xs.splitAt(n)._1) :: split(n,xs.splitAt(n)._2)
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Django: Display Choice Value
...ing your information via JSON (for instance in a pagination scenario)? Ideally without the overhead of instantiating the Models one by one and calling get_field_display().
– DylanYoung
Mar 23 '17 at 17:34
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How to get year, month, day, hours, minutes, seconds and milliseconds of the current moment in Java?
...t an int to String, make use of String#valueOf().
If your intent is after all to arrange and display them in a human friendly string format, then better use either Java8's java.time.format.DateTimeFormatter (tutorial here),
LocalDateTime now = LocalDateTime.now();
String format1 = now.format(DateTi...
What is PECS (Producer Extends Consumer Super)?
...h element will behave as a Thing when you perform your operation. (You actually cannot add anything to a Collection<? extends Thing>, because you cannot know at runtime which specific subtype of Thing the collection holds.)
Case 2: You want to add things to the collection.
Then the list is a ...