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How to select a single field for all documents in a MongoDB collection?
...uery. In the result set, only the item and qty fields and, by default, the _id field return in the matching documents.
db.inventory.find( { type: 'food' }, { item: 1, qty: 1 } )
In this example from the folks at Mongo, the returned documents will contain only the fields of item, qty, and _id.
Thus...
How to find the JVM version from a program?
...version "12" "1.8.0_201" "1.5.0_22" Java Runtime Environment version, which may be interpreted as a Runtime.Version
java.version.date "2019-03-19" ...
Can “list_display” in a Django ModelAdmin display attributes of ForeignKey fields?
...ion, you can do look ups like:
class UserAdmin(admin.ModelAdmin):
list_display = (..., 'get_author')
def get_author(self, obj):
return obj.book.author
get_author.short_description = 'Author'
get_author.admin_order_field = 'book__author'
...
Flattening a shallow list in Python [duplicate]
...ndexable sequence, consider itertools.chain and company.
>>> list_of_menuitems = [['image00', 'image01'], ['image10'], []]
>>> import itertools
>>> chain = itertools.chain(*list_of_menuitems)
>>> print(list(chain))
['image00', 'image01', 'image10']
It will work...
What does pylint's “Too few public methods” message mean
...they hold.
If your class looks like this:
class MyClass(object):
def __init__(self, foo, bar):
self.foo = foo
self.bar = bar
Consider using a dictionary or a namedtuple instead. Although if a class seems like the best choice, use it. pylint doesn't always know what's best.
D...
What are the calling conventions for UNIX & Linux system calls (and user-space functions) on i386 an
...rameters for Linux system call are passed using registers. %eax for syscall_number. %ebx, %ecx, %edx, %esi, %edi, %ebp are used for passing 6 parameters to system calls.
The return value is in %eax. All other registers (including EFLAGS) are preserved across the int $0x80.
I took following snipp...
Difference between exit() and sys.exit() in Python
...raising SystemExit. sys.exit does so in sysmodule.c:
static PyObject *
sys_exit(PyObject *self, PyObject *args)
{
PyObject *exit_code = 0;
if (!PyArg_UnpackTuple(args, "exit", 0, 1, &exit_code))
return NULL;
/* Raise SystemExit so callers may catch it or clean up. */
PyE...
error C2664: “std::list::list(const std::allocator &)”: 不能将参数 1...
...转换为“const std::allocator &”错误日志：error C2664: std::list<_Ty>::list(const std::allocator<_Ty> &): 不能将参数 1 从std::vector<_Ty>转换为const std::...错误日志：
error C2664: “std::list<_Ty>::list(const std::allocator<_Ty> &)”: 不能将参数 1 从
“std::vect...
How to export revision history from mercurial or git to cvs?
... a git repository. I use the following invocation:
% git cvsimport -d $CVSROOT -C dir_to_create -r cvs -k \
-A /path/to/authors/file cvs_module_to_checkout
The -A option is optional but it helps to make your revision history that's imported from CVS look more git-like (see man git-cvsimport for ...
OfflineSpeech 拓展：离线语音识别 · App Inventor 2 中文网
...界面：从组件面板拖入——
标签 ×2：改名 标签_状态（提示语，字号 14）、标签_字幕（字幕，字号 20）；
按钮 ×2：改名 按钮_开始（文本「🎤 开始说话」）、按钮_停止（文本「⏹ 停止」）；
非可视组件 Offl...