Create Custom Property for UTM Source in Mixpanel using REGEX_EXTRACT()
in mixpanel ui, create a custom property to extract the value in utm_source=value in an URL with REGEX_EXTRACT()
in mixpanel ui, create a custom property to extract the value in utm_source=value in an URL with REGEX_EXTRACT()
The “syntax error, unexpected ‘)’” message usually means there is a problem with the formula syntax in the Mixpanel custom property builder. Based on the knowledge sources, here are some things to check: 1. Delimiter Must Be a Single ASCII Character:
The split() function in Mixpanel only accepts a single ASCII character as a delimiter, not a string or regex. If you tried to use split with a multi-character delimiter or regex, it will throw a syntax error. For extracting with regex, use REGEX_EXTRACT() instead.2. REGEX_EXTRACT Syntax:
The correct syntax for REGEX_EXTRACT is:
```LBKS For example:
```LBKS regex_extract(properties["page_url"], "[?&]utm_source=([^&#]**)", 1)
```LBKS Make sure:
- You use lowercase `regex_extract` (not uppercase).
- All parentheses are matched and closed.
- The property name is correct and exists in your data.LBKS3. **Check for Extra or Missing Parentheses**:
A common cause of this error is an extra or missing parenthesis. Double-check your formula for this.LBKS4. **Function Name Case Sensitivity**:
Mixpanel’s formula language is case-sensitive. Use `regex_extract`, not `REGEX_EXTRACT`.LBKS**Example (correct usage):**LBKS```LBKSregex_extract(properties["page_url"], "[?&]utm_source=([^&#]**)", 1)LBKS```LBKSLBKSIf you still get the error, ensure that the property you are referencing (e.g., `properties["page_url"]`) actually exists in your events.LBKSFor more details, see the [Custom Properties: Functions reference](https://docs.mixpanel.com/docs/features/custom-properties#functions)<source> [https://docs.mixpanel.com/docs/features/custom-properties#functions</source](https://docs.mixpanel.com/docs/features/custom-properties#functions</source)> .LBKSIf you continue to encounter issues, please provide the exact formula you are using so I can help debug further.
kapa.ai is still learning and improving, please let me know how I did by reacting below.
ℹ️ Tip: Mention @kapa.ai in the thread for follow-ups or DM the app for 1-to-1 help.
Let me check the knowledge base for you again. One moment! 📚
To create a custom property in the Mixpanel UI that extracts the value of utm_source from a URL using REGEX_EXTRACT(), you can use the following formula: LBKSREGEX_EXTRACT(properties["<your_url_property> "], "[?&]utm_source=([^&#]*)", 1)LBKSReplace <your_url_property> with the actual property name that contains your URL (for example, properties["page_url"]).- This regex looks for utm_source= preceded by either ? or &, and captures everything after the = up to the next &, #, or the end of the string.
- The 1 at the end specifies that you want the first capture group, which is the value of utm_source.You can enter this formula in the custom property builder in Mixpanel as described in the documentation. For more on using REGEX_EXTRACT(), see the Custom Properties: Functions reference<source> https://docs.mixpanel.com/docs/features/custom-properties#functions</source> .
kapa.ai is still learning and improving, please let me know how I did by reacting below.
ℹ️ Tip: Mention @kapa.ai in the thread for follow-ups or DM the app for 1-to-1 help.
Hi Elena M., Please stand by as I search the Mixpanel knowledge base for an AI-powered answer. I normally take about 15 seconds or so. In case AI cannot answer your question, feel free to reach out to Mixpanel support at mixpanel.com/get-support. If you have follow-up questions for this thread, please tag me again with your question: @kapa.ai <follow-up question> 👋
Feel free to ask a follow-up question once I've answered by mentioning me with @kapa.ai