Prevent Salesforce Custom Metadata Text Field Truncation

While working on my Email Invalidation Tool, I ran into Salesforce truncating Custom Metadata text fields at 512 characters. I struggled at first to understand why the static methods – my goto with Custom Metadata – were resulting in broken records. Turns out the solution is simple – use SOQL.

The Problem: Salesforce Truncates Custom Metadata Text Fields

When loading Salesforce Custom Metadata records using the static methods getInstance() or getAll() long strings are truncated at 255 characters (I actually ran into it at 511, but the documentation says 255).

My Use Case, and Reproduction

One of the features I wanted to add to my email invalidation tool was auto-detection of email fields. That’s turned out to be a whole complicated process that I’m still finishing as of this post date. Part of the solution I am using is to create a custom metadata object to store a list of possible fields. For a variety of unimportant reasons I elected to store that information as a JSON string. So I created a long textarea field maxed out at 131,072 characters. Everything went fine at first: the process scans the objects and drops the results into the metadata record. When I looked at the records in the UI or after downloading to a file it looked just as I expected. But when I started to load the records again I got JSON parser errors because the value had been truncated to 511 characters (see note about about 255 vs 511).

Preventing Salesforce Custom Metadata Text Truncation

The answer is to use SOQL. I typically use the static methods when working with Custom Metadata to reduce the number of SOQL queries in my code – but in this case that doesn’t work. To reliably get all the data in long text fields you have to use SOQL.

This approach consistently gives you a truncated values:

Email_Invalidator_Cache__mdt cacheRecord = Email_Invalidator_Cache__mdt.getInstance(
  'Field_Scan'
);

But using a simple SOQL statement to load the same record works just fine:

Email_Invalidator_Cache__mdt cacheRecord = [
  SELECT QualifiedApiName, Cached_Value__c, SystemModstamp
  FROM Email_Invalidator_Cache__mdt
  WHERE DeveloperName = 'Field_Scan'
];

Ask Salesforce to Fix This

There is an idea open requesting a fix to this issue. Please up vote.

Special Thanks

Thank you to Robbie Duncan for helping me out on Ohana Slack with this one.