Answers.Body: <p>Personally I'd write a tiny php script but you could use the api explorer under <code>civicrm/api</code>: </p>
  
  <ol>
  <li>Chose entity contact and action get</li>
  <li>Add your search criteria</li>
  <li>Add option "limit" to something high enough (Defaults to 25) or combine with option "offset"</li>
  <li>Hit "chain api call"</li>
  <li>Chose entity contact and action create</li>
  <li>Enter json like "{source: 'your source'}"</li>
  <li>Run</li>
  </ol>
  
  <p>You could test it with one contact by adding it's id in the get criteria.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-10-11T08:14:01.570Z
Answers.Text: Christia, did you figure it out?
Answers.UserDisplayName: nielo
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-10-05T08:37:19.353Z
Answers.LastActivityDate: 2016-10-05T08:43:28.323Z
Answers.LastEditDate: 2016-10-05T08:43:28.323Z
Answers.UserDisplayName: nielo
Body: <p>I have over 50,000 contacts that I would like to batch-edit with the same contact "source" information. What is the best way to do this?</p>
  
Tags: <import><database><fields>
Title: Batch edit one contact field (source) with same information
ThreadText: # Batch edit one contact field (source) with same information
  
  (Asked by: username_0 on 2016-10-03)
  
  I have over 50,000 contacts that I would like to batch-edit with the same contact "source" information. What is the best way to do this?
  
  **Tags:** import, database, fields
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2016-10-05. Score: 2 | Accepted answer
  
  Personally I'd write a tiny php script but you could use the api explorer under `civicrm/api`:
  
  1. Chose entity contact and action get
  2. Add your search criteria
  3. Add option "limit" to something high enough (Defaults to 25) or combine with option "offset"
  4. Hit "chain api call"
  5. Chose entity contact and action create
  6. Enter json like "{source: 'your source'}"
  7. Run
  
  You could test it with one contact by adding it's id in the get criteria.
  
  > **Comments:**
  > **username_1**: username_0, did you figure it out?  
  
  ---
  
  