Metadata API readMetadata truncates base64 values?

Question

I'm trying to use readMetadata in the metadata API to download various things about an org. This works great for most everything but base64 values are always truncated..

Here's my test aura component:

<aura:component implements="flexipage:availableForRecordHome,force:hasRecordId" access="global" >
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing 
        elit, sed do eiusmod tempor incididunt ut labore 
        et dolore magna aliqua. Ut enim ad minim veniam, quis 
        nostrud exercitation ullamco laboris nisi ut aliquip 
        ex ea commodo consequat. Duis aute irure dolor in 
        reprehenderit in voluptate velit esse cillum dolore eu 
        fugiat nulla pariatur. Excepteur sint occaecat 
        cupidatat non proident, sunt in culpa qui officia 
        deserunt mollit anim id est laborum.</p>
</aura:component>

Here's a request I send to soapui to test:

<soapenv:Envelope ...>
   <soapenv:Header>
      <met:SessionHeader>
         <met:sessionId>yadda.yadda</met:sessionId>
      </met:SessionHeader>
   </soapenv:Header>
    <soapenv:Body>
        <met:readMetadata>
            <met:type>AuraDefinitionBundle</met:type>
            <met:fullNames>MetadataApiTest</met:fullNames>
        </met:readMetadata>
    </soapenv:Body>
</soapenv:Envelope>

The response:

<soapenv:Envelope ...>
   <soapenv:Body>
      <readMetadataResponse>
         <result>
            <records xsi:type="AuraDefinitionBundle">
               <fullName>MetadataApiTest</fullName>
               <apiVersion>52.0</apiVersion>
               <auraDefinitions>
                  <auraDefinition>
                     <defType>1(db=1,api=CONTROLLER)</defType>
                     <source>KHsKCW15QWN0aW9uIDogZnVuY3Rpb24oY29tcG9uZW50LCBldmVudCwgaGVscGVyKSAKICAgIHsKICAgICAgICB2YXIgeCA9IDE7CiAgICAgICAgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyAKICAgICAgICB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IAogICAgICAgIHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgCiAg</source>
                  </auraDefinition>
                  <auraDefinition>
                     <defType>2(db=2,api=COMPONENT)</defType>
                     <source>PGF1cmE6Y29tcG9uZW50IGltcGxlbWVudHM9ImZsZXhpcGFnZTphdmFpbGFibGVGb3JSZWNvcmRIb21lLGZvcmNlOmhhc1JlY29yZElkIiBhY2Nlc3M9Imdsb2JhbCIgPgoJPHA+TG9yZW0gaXBzdW0gZG9sb3Igc2l0IGFtZXQsIGNvbnNlY3RldHVyIGFkaXBpc2NpbmcgCiAgICAgICAgZWxpdCwgc2VkIGRvIGVpdXNtb2QgdGVtcG9yIGluY2lkaWR1bnQgdXQgbGFib3JlIAogICAgICAgIGV0IGRvbG9yZSBtYWduYSBhbGlxdWEuIFV0IGVuaW0gYWQg</source>
                  </auraDefinition>
               </auraDefinitions>
               <controllerContent>KHsKCW15QWN0aW9uIDogZnVuY3Rpb24oY29tcG9uZW50LCBldmVudCwgaGVscGVyKSAKICAgIHsKICAgICAgICB2YXIgeCA9IDE7CiAgICAgICAgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyAKICAgICAgICB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IAogICAgICAgIHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgeCsrOyB4Kys7IHgrKzsgCiAg</controllerContent>
               <description>here is a description.</description>
               <markup>PGF1cmE6Y29tcG9uZW50IGltcGxlbWVudHM9ImZsZXhpcGFnZTphdmFpbGFibGVGb3JSZWNvcmRIb21lLGZvcmNlOmhhc1JlY29yZElkIiBhY2Nlc3M9Imdsb2JhbCIgPgoJPHA+TG9yZW0gaXBzdW0gZG9sb3Igc2l0IGFtZXQsIGNvbnNlY3RldHVyIGFkaXBpc2NpbmcgCiAgICAgICAgZWxpdCwgc2VkIGRvIGVpdXNtb2QgdGVtcG9yIGluY2lkaWR1bnQgdXQgbGFib3JlIAogICAgICAgIGV0IGRvbG9yZSBtYWduYSBhbGlxdWEuIFV0IGVuaW0gYWQg</markup>
               <type>Component</type>
            </records>
         </result>
      </readMetadataResponse>
   </soapenv:Body>
</soapenv:Envelope>

When I decode the response, I get only this much:

<aura:component implements="flexipage:availableForRecordHome,force:hasRecordId" access="global" >
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing 
        elit, sed do eiusmod tempor incididunt ut labore 
        et dolore magna aliqua. Ut enim ad 

All base64 values that I see get truncated at about this same size (or maybe this exact size - I have not checked).

I see types like profiles having no problem returning 500kb responses, so I don't think it's a size issue.

I'm not using a wsdl - this is building the requests and parsing the responses 'by hand', because I'm a glutton for punishment or something. Everything else works and the base64 responses are short but look fine otherwise.

Any help?

Answer 1

I stumbled across this looking for an answer and did some investigation. It looks like that for both AuraDefinitionBundle and LightningComponentBundle the behaviour is the same, readMetadata does indeed appear to truncate the source property at 255 (base64) characters, which I am assuming is undocumented, but default behaviour as a way of limiting response payload sizes. I worked around this by doing a further query to the tooling objects AuraDefinition and LightningComponentResource, to retrieve the full source in text format e.g.

SELECT DefType, Source FROM AuraDefinition WHERE AuraDefinitionBundleId WHERE Id = '0Abam000000tvUpCAI'

or for LightningComponentBundle:

SELECT FilePath, Source FROM LightningComponentResource WHERE LightningComponentBundleId = '0Rbam000001SKWICA4'

Hope it helps someone.