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Sometime response.data is string instead of object

Freshabout 21 hours ago
Mar 14, 20260 views
Confidence Score74%
74%

Problem

I don't know why but with the same api, sometime axios's response.data is string instead of object. See the below figure. Context - axios version: 0.18.0 - Environment: React native Expo SDK 29, window 10

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1 Fix

Canonical Fix
Unverified Fix
New Fix – Awaiting Verification

Ensure Consistent Response Data Type in Axios

Medium Risk

The issue arises because the API sometimes returns a JSON string instead of a JSON object. This can happen if the server is not consistently formatting its responses, or if there are specific conditions under which the API returns a string (such as error messages or specific endpoints). Axios does not automatically parse strings into objects, leading to inconsistent data types in response.data.

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  1. 1

    Check API Response Type

    Before processing the response, check if response.data is a string. If it is, attempt to parse it into an object.

    javascript
    if (typeof response.data === 'string') {
  response.data = JSON.parse(response.data);
}
  2. 2

    Implement Axios Interceptor

    Set up an Axios response interceptor to handle the parsing of response data globally. This will ensure that any response received is checked and parsed if necessary.

    javascript
    axios.interceptors.response.use(
  response => {
    if (typeof response.data === 'string') {
      response.data = JSON.parse(response.data);
    }
    return response;
  },
  error => {
    return Promise.reject(error);
  }
);
  3. 3

    Update API Documentation

    If applicable, update the API documentation to clarify the expected response format. Ensure that the API team is aware of the inconsistency and can address it on the server side.

  4. 4

    Add Error Handling for JSON Parsing

    Implement error handling for the JSON parsing step to catch any potential errors that may arise from invalid JSON strings.

    javascript
    try {
  response.data = JSON.parse(response.data);
} catch (e) {
  console.error('Failed to parse response data:', e);
  // Handle the error appropriately
}

Validation

Test the API calls in various scenarios to ensure that response.data is consistently an object. Use console logs or debugging tools to verify the type of response.data after implementing the changes.

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Environment

Submitted by

AC

Alex Chen

2450 rep

Tags

axioshttpapi