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Using Django bulk_create objects in foreign keys?

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I was reading up on Django bulk_create and a few of its "flaws": " This has a number of caveats though: 1. The model's save() method will not be called, and the pre_save and post_save signals will not be sent. 2. It does not work with child models in a multi-table inheritance scenario. 3. If the model's primary key is an AutoField it does not retrieve and set the primary key attribute, as save() does. " I didn't fully understand it. So if I have a list of objects, pass it into bulk_create: objList = [a, b, c,] #none are saved model.objects.bulk_create(objList) Could I still use these objects

rendering and saving images through Blender python

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问题 I am trying to render and save multiple images through python script in blender. I know how to render and save the image through the Blender GUI but I want to do it all through my script since I am using a set of nested loops and need to save multiple images. I am able to render the image and I guess save the image with the output being successful. But I am not sure where it saves to and when I try to edit the filepath it gives me the error of the context being incorrect. 回答1: Here's what I

Saving and Reloading ListView using Shared Preferences [Saving onDestroy()]

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I am creating a To Do List. Right now my app adds and removes data to and from a ListView. However, when I close my application the data gets erased. I want to use SharedPreferences to save the data onDestroy(), then when my app opens I wanted the data to reload. However, I don't know how to go about accomplishing this task. Can anybody help me with saving a ListView using Shared Preferences (aka I am looking for code)? There are tutorials for just one shared preference I am looking to dynamically add multiple strings when my application closes. Then when I reopen it, the data will appear. I

How to store CLLocation using Core Data (iPhone)?

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问题 I'm trying to save a location and retrieve the location on a map afterward using Core Location, MapKit and Core Data frameworks. What I've done is I just made entity named POI and added properties such as latitude (double type), longitude (double type) with few others. Simply put, my app saves POI with two NSNumbers. (lat and long) but I feel like there must be a smarter way to store CLLocation than that. cheers. 回答1: What you're doing is fine. You should save the latitude and longitude as

How to use a contract class in android?

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问题 I'm a little bit confused because I don't know how I should interpret the tutorial here: http://developer.android.com/training/basics/data-storage/databases.html#DbHelper My code until now looks like this: public final class DatabaseContract { // To prevent someone from accidentally instantiating the contract class, // give it an empty constructor. public DatabaseContract() {} public static abstract class Table1 implements BaseColumns { public static final String TABLE_NAME = "nameOfTable";

TypeError: Mismatch between array dtype ('object') and format specifier ('%.18e')

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I have the following array: X = np.array([image_array_to_vector1,image_array_to_vector2,image_array_to_vector3,image_array_to_vector4]) A print out of X looks as follows: [array([167, 167, 169, ..., 1, 1, 1], dtype=uint8) array([42, 43, 43, ..., 41, 36, 34], dtype=uint8) array([0, 0, 0, ..., 0, 0, 0], dtype=uint8) array([0, 0, 0, ..., 0, 0, 0], dtype=uint8)] When I try to save the data as txt: X_to_text_file = np.savetxt('x.txt',X) I get the following: File "/Library/Python/2.7/site-packages/numpy/lib/npyio.py", line 1258, in savetxt % (str(X.dtype), format)) TypeError: Mismatch between array

How to ensure make sure I´m not accessing data until it´s loaded in?

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问题 I´m new at programming and I my code gets the error: fatal error: unexpectedly found nil while unwrapping an Optional value 2017-10-27 16:06:16.755817+0200 Inspireme1.0[836:85307] fatal error: unexpectedly found nil while unwrapping an Optional value (lldb) New error: fatal error: Index out of range 2017-10-27 19:08:05.488502+0200 Inspireme1.0[1262:771572] fatal error: Index out of range (lldb) I already looked it up here but I don´t know how to apply this in my case: How to ensure I'm not

UICollectionView not showing pictures [duplicate]

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问题 This question already has an answer here : Don't have the pictures from directory on CollectionView (1 answer) Closed 6 years ago . I am showing the Pictures in all of the Directories however It does not display the pictures. I am putting NSLog in the code so that I can find out which code is working and I only get "j" in the log. I do not see the "a" in the log. What do you think is wrong? - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view.

Saving EditText and retrieve it automatically

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问题 hi I'm trying to save the EditText widget values in the internal memory of the phone/tablet so that they can be retrieved automatically by the app when it closes or the activity stops. All off this will work using a save button.(The values of the widget are inputed by the user). 回答1: You should use the shared preference ,shared preference is used to store the data in locally app whenever need you can access it . use this link https://www.journaldev.com/9412/android-shared-preferences-example

Save loop data in vector

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问题 when I run my script, all the values are displayed, but I want all the values in vector, so what can I do? x=[1 2 3 4 5]; y=[1 2 3 4 5]; xx=[1.2 1.6 1.8 2.4 2.8 3.4 4.9 2.6]; yy=[1.2 1.6 1.8 2.5 2.8 3.3 4.9 2.5]; plot(x,y,'.g',xx,yy,'*b') for j=1:length(xx) if xx(j)<x(1) value=0 elseif xx(j) >x(1) & xx(j)<x(2) value=1 elseif xx(j) >x(2) & xx(j)<x(3) value=2 elseif xx(j) >x(3) & xx(j)<x(4) value=3 elseif xx(j) >x(4) & xx(j)<x(5) value=4 elseif xx(j) >x(5) & xx(j)<x(6) value=5 else value= NaN