Что такое decoding error



Handling encoding and decoding errors in Python

By John Lekberg on April 03, 2020.

This week’s blog post is about handling errors when encoding and decoding data. You will learn 6 different ways to handle these errors, ranging from strictly requiring all data to be valid, to skipping over malformed data.

Codecs

Python uses coder-decoders (codecs) to

Encode str objects into bytes objects.

Decode bytes objects into str objects.

(Shift JIS is a codec for the Japanese language.)

What happens when a codec operation fails?

When a codec operation encounters malformed data, that’s an error:

How can I deal with codec operation failures?

Besides raising a UnicodeError exception, there are 5 other ways to deal with codec operation errors:

When encoding and decoding, ignore malformed data:

When encoding and decoding, replace malformed data with a replacement character ( «�» and b»?» ):

When encoding and decoding, replace malformed data with backslashed escape sequences:

When encoding, replace malformed data with XML character references:

When encoding, replace malformed data with \N <. >(named unicode characters):

(There is another error handler, «surrogateescape» , that is out of the scope of this blog post.)

Different error handling strategies are useful in different contexts. Here’s a table of the 6 different errors handlers:

errors=. Do . with malformed data
«strict» Raise UnicodeError
«ignore» Ignore and continue
«replace» Replace with replacement character
«backslashreplace» Replace with backslashed escape sequence
«xmlcharrefreplace» Replace with XML character reference
«namereplace» Replace with \N <. >(named unicode character)

«strict» is the default error handler.

Besides str.encode and bytes.decode, error handling is available .

In conclusion.

In this post you learned 6 different ways to handle codec operation errors. The default strategy ( errors=»strict» ) raises an exception when an error occurs. But, sometimes you want your program to continue processing data, either by omitting bad data ( errors=»ignore» ) or by replacing bad data with replacement characters ( errors=»replace» ). If you are generating a HTML or an XML document, you can replace malformed data with XML character references ( errors=»xmlcharrefreplace» ).

My challenge to you:

This post discussed 6 different ways to handle codec operation errors. There is another way, «surrogateescape» . Learn how to use «surrogateescape» and create an example of decoding-then-encoding a file using it.

If you enjoyed this week’s post, share it with you friends and stay tuned for next week’s post. See you then!

(If you spot any errors or typos on this post, contact me via my contact page.)

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Причины появления decode error Windows Phone и способы устранения

Порой при просмотре видео-роликов в интернете владельцы плиточных смартфонов сталкиваются с проблемами воспроизведения. Такой запрос, как ”decode error Windows Phone что делать” весьма распространен на форумах, посвященных девайсам на платформе от Microsoft. Как правило, подобного рода проблема возникает при попытке просмотра роликов с Ютуб. В особенности часто с ней сталкиваются владельцы смартфонов Lumia.

Данная ошибка имеет несколько причин возникновения. Также существует несколько способов ее устранения.

О причинах decode error на Windows Phone

Сама по себе проблема обозначает ошибку в работе кодека. Довольно часто появляется decode error на Windows Phone Lumia 520. Причины такой неисправности могут быть следующими:

  • — сбой в работе самого кодека;
  • — несовместимость формата ролика с используемым плеером для просмотра;
  • — заполненная кэш-память устройства.

Исправить ситуацию могут несколько способов. Однако, если причина не в плеере устройства, вполне возможно, что для устранения ошибки потребуется возврат к настройкам завода-изготовителя.

Способы устранения ошибки

Итак, попытаемся разобраться как исправить decode error на Windows Phone. Если проблема возникла при попытке просмотра роликов на девайсе, скорее всего, причина кроется в несовместимости формата. И в таком случае устранить неисправность возможно только с помощью загрузки отдельного плеера для просмотра видео различных форматов.

Также возможно устранить проблему с помощью установки специальной программы. Она называется MWFIX. Скачать ее можно в интернете. Она в автоматизированном режиме устраняет неисправность. И поможет решить проблему и предотвратить ее появление в дальнейшем.

Самым быстрым способом для исправления ошибки кодека является перезагрузка девайса. Его нужно отключить от питания, вытащив на пару минут батарею, а затем включить и повторить попытку просмотра. Если же decode error Windows Phone Lumia, или другом девайсе на данной платформе возникла при просмотре ролика на веб-странице, устранить ее сможет перезагрузка сайта.

Если ни один из представленных способов не устраняет ошибку, то стоит обратить внимание на заполненность кэш-памяти. Очищать ее придется в ручную. Необходимо проверить на наличие информационного мусора в папках «Фотографии” и «Музыка”. Также стоит проверить наличие ненужных файлов в электронной почте. У активных пользователей девайсов ненужная информация может накапливаться быстро.

Наиболее эффективный способ удаления ненужных изображений требует выхода в SkyDrive. В этом облачном хранилище автоматически сохраняются фото самого пользователя, а также те, которые были получены из социальных сетей и сторонних ресурсов. Как только вы удалите данные из него, со смартфона они сотрутся автоматически.

В том случае, когда ни один из перечисленных способов не срабатывает. Восстановить работоспособность кодека может восстановить возврат к настройкам завода-изготовителя. Сделать сброс можно с помощью аппаратных кнопок, а также из раздела настроек девайса. Однако, перед этим необходимо сохранить пользовательские данные с помощью резервной копии. В противном случае все программы, настройки, фото и музыка будут утеряны безвозвратно.

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Error Decoding and Retrying with Feign Clients

Introduction

Feign is a declarative web service client. It makes the client implementation process fast. You can simply define a Java interface with a readable method names and annotations, and make it a functioning web client. You can refer to the readme[1] to have the basic knowledge on Feign. Also there are ample of blogs that you can refer. Through this post, I am going to explain on how you can achieve Error Decoding, and Retrying functionality in a Feign client.

Setting up dependencies

This post uses spring-cloud-starter Hoxton.RELEASE version of spring cloud. In the pom file, you need to add the spring-cloud-starter-parent as the parent-pom file and spring-cloud-dependencies as the dependency management. Spring-cloud-dependencies provide the spring-cloud dependency versions according to the parent pom version. Thereafter you need to add the following dependencies for the rest of implementation:

  • spring-boot-starter
  • spring-boot-starter-web
  • spring-cloud-starter-openfeign

It’s worth mentioning that feign was created and maintained by Netflix OSS and currently maintained separately from Nextflix. Once you wire-up all dependencies, the final pom file would look like below:

Enable feign clients and define a feign client

To enable feign clients, you need to use @EnableFeignClients annotation in the main class definition. Then you can simply create an interface to the external web-services. In this post I’m not going to talk about the annotations because you can find a good documentation here [1][2]. Following is a sample interface I created for this post:

Enabling logging for feign client

First I decided to talk about logging as this helps to demonstrate the behaviors in next steps.
To enable extended logging for feign clients, you need to follow two steps.

  1. Enabling DEBUG log-level for feign client
  2. Change feign client log-level (valid values are NONE, BASIC, HEADERS, FULL)

After this configuration, you can view Request-Response logs in the microservice log. You can further increase logging by changing the logger-level to HEADER or FULL.
Throughout this post, I am discussing about configuring the feign client through application.yml file. But there are multiple ways of doing the same.

Error Decoder for Feign client

You can use error-decoder to act based on the erroneous HTTP responses. I have observed that error-decoder does not get triggered on success scenarios. To implement an error-decoder, you need to implement a class using ErrorDecoder interface and add that in the configuration.

Retryer for Feign client

Retryer could be a useful entity to retry your request in case of failure (network failures by default). You can configure default retryer with parameters by extending Retryer.Default class.

Furthermore, if you need to retry based on HTTP status, you can throw RetryableException at error-decoder. Same goes, if you want to retry based on HTTP-headers.

Following is a sample log, which demonstrate re-trying 5 times before giving-up.

In the above log, you can see that same request attempted 5 times back-to-back before it was declared as a failure. You can change the default values through the Retryer implementation to desired. Furthermore, you can alter the error-decoder to refer specific HTTP headers (eg: Retry-After header).

Conclusion

Through this post, I discussed on Feign clients with two different use-cases. First you have seen, how to react based on HTTP error statuses and later about retrying requests. I hope this will be beneficial for your spring boot application development.

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[Fixed] JSONDecodeError: Expecting Value: Line 1 column 1 (char 0)

JSONDecodeError: Expecting value: line 1 column 1 (char 0) occurs while working with JSON (JavaScript Object Notation) format. You might be storing some data or trying to fetch JSON data from an API(Application Programming Interface). In this guide, we will discuss where it can creep in and how to resolve it.

How can JSONDecodeError: Expecting value: line 1 column 1 (char 0) occur?

JSONDecodeError means there is an incorrect JSON format being followed. For instance, the JSON data may be missing a curly bracket, have a key that does not have a value, and data not enclosed within double-quotes or some other syntactic error.

Generally, the error expecting value: line 1 column 1 (char 0) error can occur due to the following reasons.

  • Non-JSON conforming quoting
  • Empty JSON file
  • XML output (that is, a string starting with 1. Non-JSON conforming quoting

JSON or JavaScript Object Notation has a similar format to that of the python dictionary datatype. A dictionary requires a key or value to be enclosed in quotes if it is a string. Similarly, the JSON standard defines that keys need not be a string. However, keys should always be enclosed within double quotes. Not following this standard can also raise an error.

2. Empty JSON file

For this example, we have taken an empty JSON file named test.py and another file named test.py, which contains the code given below. Using context manager, we open the JSON file in reading mode and load it using the load method. However, an error is thrown because the JSON file is empty.

3. XML output (that is, a string starting with

The Extensible Markup Language, or simply XML, is a simple text-based format for representing structured information: documents, data, configuration, books, transactions, invoices, and much more. Similar to JSON, it is an older way of storing data. Earlier APIs used to return data in XML format ; however, JSON is nowadays the preferred choice. Let’s see how we can face the expecting value: line 1 column 1 (char 0) type error in this case.

Let’s break down what is happening here.

  • For ease of example, suppose API returns an XML format data, as shown above.
  • Now, when we try to load that response from API, we will get a type error.

Resolving JSONDecodeError: Expecting value: line 1 column 1 (char 0)

1. Solution for Non-JSON conforming quoting

To resolve the type error in this case, you need to ensure that the keys and values are enclosed within the double quotes. This is necessary because it is a part of JSON syntax. It is important to realize that JSON only uses double quotes, not single quotes.

2. Solution for empty JSON file

The solution for this is self-evident in the name. To resolve the type error, in this case, make sure that the JSON file or the response from an API is not empty. If the file is empty, add content to it, and for a response from an API, use try-except to handle the error, which can be empty JSON or a 404 error, for instance.

The above code takes in a word and returns all the information related to it in a JSON format. Now in order to show how we can handle the Expecting value: line 1 column 1 (char 0) type error, we have altered the URL. entries have been changed to enties. Therefore we will get an invalid response which will not be of the JSON format. However, this is merely done to imitate the error when you might get an invalid response from an API.

  • Now, if you try to run the code above, you will be prompted to enter a word. The response is saved into the data variable and later converted to a string.
  • However, in the try block json.loads method, which parses JSON string to python dictionary raises an error.
  • This is because the response sent by API is not of JSON format, hence can’t be parsed, resulting in JSONDecodeError.
  • JSONDecodeError gets handled by the try-except block, and a “Response content is not valid JSON” gets printed as an outcome.

3. Solution for XML output(that is, a string starting with

To avoid type errors resulting from an XML format, we will convert it to a JSON format. However, firstly install this library.

Let’s elaborate on the code above:

  • We have imported two libraries, namely JSON and xmltodict.
  • Using the context manager with, XML file test.xml is opened in read mode. Thereafter using the xmltodict parse method, it is converted to a dictionary type, and the file is closed.
  • json.dumps() takes in a JSON object and returns a string of that object.
  • Again using context manager with, a JSON file is created, XML data that was converted to a JSON string is written on it, and the file is closed.

JSONDecodeError: Expecting value: line 1 column 1 (char 0) Django

This issue is caused by the failure of Pipenv 2018.10.9. To resolve this issue, use Pipenv 2018.5.18. For more, read here.

Are you facing this error in Flask?

Many times, when you receive the data from HTTP requests, they are fetched as bytes. So, if you face JSONDecodeError, you might be dealing with a JSON in bytes. First, you need to decode the JSON by using response.decode(‘utf-8’) . This will create a string, and then you can parse it.

json.loads() method can be used to parse JSON in python. For instance:
import json
json_string = ‘<"a":"1", "b":"2", "c":"3">‘
json_to_dict = json.loads(json_string)
print(json_to_dict)
print(type(json_to_dict))

import os
file_path = «/home/nikhilomkar/Desktop/test.json»
print(«File is empty!» if os.stat(file_path).st_size == 0 else «File isn’t empty!» )
The following code checks if the file is empty and prints the File is empty! If true, else, the File isn’t empty!.

Conclusion JSONDecodeError: Expecting value: line 1 column 1 (char 0)

The following article discussed the JSONDecodeError: Expecting value: line 1 column 1 (char 0). This error is due to various decoding and formatting errors. We looked at likely situations where it can occur and how to resolve it.

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