小编use*_*936的帖子

我正在将文件下载到文件夹,我正在验证该文件确实存在于代码中,但我收到了上述错误.有人可以帮我弄清楚为什么我没有权限阅读这个文件？

    let documentsURL = NSSearchPathForDirectoriesInDomains
           (.DocumentDirectory, .UserDomainMask, true)[0]

    let checkValidation = NSFileManager.defaultManager()

    if (checkValidation.fileExistsAtPath(documentsURL))
    {
        print("FILE AVAILABLE");
    }
    else
    {
        print("FILE NOT AVAILABLE");
    }

    print(documentsURL)

    do{
        let data = try String(contentsOfFile: documentsURL as String,
            encoding: NSASCIIStringEncoding)
        print(data)

    }
    catch let error { print(error) }

错误域= NSCocoaErrorDomain代码= 257"无法打开文件"Documents",因为您无权查看它." UserInfo = {NSFilePath =/var/mobile/Containers/Data/Application/7FA4D6A9-2149-4053-BF08-22E94A00AE34/Documents,NSUnderlyingError = 0x137807200 {Error Domain = NSPOSIXErrorDomain Code = 13"Permission denied"}}

我正在使用“ Django Rest Framework”，并且正在尝试构建RestfulAPI。但是，当我运行我的应用程序时，出现上述错误：AssertionError: The field 'doctor' was declared on serializer AnimalSerialiser, but has not been included in the 'fields' option.我不确定是什么fields，因此无法找到问题所在。

我的models.py：

from __future__ import unicode_literals

from django.db import models

# Create your models here.
class Doctor(models.Model):

    id= models.CharField(max_length=10, primary_key=True, unique=True)
    name = models.CharField(max_length=20)

    def __unicode__(self):
        return self.id

class Animal(models.Model):
    id = models.CharField(max_length=10, primary_key=True, unique=True)
    name = models.CharField(max_length=200)
    gender = models.CharField(max_length=10)
    breed = models.CharField(max_length=200)
    adoption = models.CharField(max_length=10)
    vaccines = models.CharField(max_length=20)
    doctor = models.ForeignKey(Doctor, null=True)

我的serialisers.py：

from …

我正在使用Django Rest Framework我自己的restful API,但我收到上面的错误,我不知道它来自哪里.我已经阅读了有关此错误的其他帖子,但遗憾的是它们没有太多帮助,所以如果有人能指出我哪里出错了,我将不胜感激.当我在模型中创建id时,它开始发生了AutoField,它在Animal模型中标记而不是在标记中Doctor.

我的models.py:

# Create your models here.
class Doctor(models.Model):

    id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=20)

    def __unicode__(self):
        return self.id

class Animal(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=200)
    gender = models.CharField(max_length=10, choices=GENDER)
    breed = models.CharField(max_length=200,)
    adoption = models.BooleanField(default=False)
    vaccines = models.CharField(max_length=20, choices=VACCINES)
    doctor = models.ForeignKey(Doctor, null=True)

    def __unicode__(self):
        return self.id

serialisers.py:

class DoctorSerealiser(serializers.HyperlinkedModelSerializer):
    class Meta:
         model = Doctor
         fields = ('id' , 'name')


class AnimalSerialiser(serializers.HyperlinkedModelSerializer):

    # doctor = DoctorSerealiser(read_only=True)


    class …

我UITableView在故事板中构建了三个单元格,当我运行它时,我在模拟器中有三个单元格,然后是空白区域.我想要做的是根据iOS设备让单元格动态填满屏幕.我怎么做？

我有两张桌子Emp,Dept我试图显示每个部门有多少人和他们的部门名称一起工作,但我无法让它工作.我试过这个,select count(ename) as count from emp group by deptno;但我得到的输出是这样的:

 COUNT
----------
     6
     5
     3

但我也希望显示每个部门的名称.这是我的表格:

抢先:

CREATE TABLE EMP
       (EMPNO NUMBER(4) NOT NULL,
        ENAME VARCHAR2(10),
        JOB VARCHAR2(9),
        MGR NUMBER(4),
        HIREDATE DATE,
        SAL NUMBER(7, 2),
        COMM NUMBER(7, 2),
        DEPTNO NUMBER(2));

INSERT INTO EMP VALUES
        (7369, 'SMITH',  'CLERK',     7902,
        TO_DATE('17-DEC-1980', 'DD-MON-YYYY'),  800, NULL, 20);
INSERT INTO EMP VALUES
        (7499, 'ALLEN',  'SALESMAN',  7698,
        TO_DATE('20-FEB-1981', 'DD-MON-YYYY'), 1600,  300, 30);
INSERT INTO EMP VALUES
        (7521, 'WARD',   'SALESMAN',  7698,
        TO_DATE('22-FEB-1981', …

我正在尝试计算我的文件中有多少行数据,我正在使用这段代码来执行此操作:

data = try String(contentsOfFile: localFilePath as String,
                          encoding: NSASCIIStringEncoding)
let textArr = data.componentsSeparatedByString("\r")
        let myCount = textArr.count
        print(myCount)

然而,无论我的文件中有多少行文本,它似乎总是打印出来1.我在这做错了什么？

我正在使用“Django Rest Framework”并且我正在尝试构建一个 RestfulAPI。但是，当我尝试“makemigrations”（即同步数据库）时出现上述错误。

这是我的模型：

from __future__ import unicode_literals

from django.db import models

# Create your models here.
class Animal(models.Model):
    id = models.CharField(max_length=10, primary_key=True)
    name = models.CharField(max_length=200)
    gender = models.CharField(max_length=10)
    breed = models.CharField(max_length=200)
    adoption = models.CharField(max_length=10)
    vaccines = models.CharField(max_length=20)

class Doctor(models.Model):
    id= models.CharField(max_length=10, primary_key=True)
    name = models.CharField(max_length=20)

以下是我的观点：

from django.contrib.auth.models import User, Group
from rest_framework import viewsets, generics

from cw.myStart.models import Animal
from cw.myStart.serializers import UserSerializer, GroupSerializer, AnimalSerialiser, DoctorSerealiser
from models import Animal, Doctor

class AnimalList(generics.ListCreateAPIVIEW):
   queryset = Animal.objects.all()
   serializer_class …

我有这段代码：

var graphPoints:[Int] = DBController().dosmth()

这调用了一个方法，该方法应该返回一个Int. 但是当传递的值不是时我该如何处理Int？目前它只是抛出这个

fatal error: unexpectedly found nil while unwrapping an Optional value

我想像这样捕捉：

do{
    var graphPoints:[Int] = DBController().dosmth()
}
catch{ }

但这会引发错误。如果有人能指出我做错了什么，将不胜感激。