Inappropriate varchar2(4000) type for Edm.String at case of oracle

[SlavaUtesinov]

I created on my own draft of jsreport-oracle-store and when I tried to test it with jsreport I immediately faced a problem at stage of creating sample templates ("sample-template": { "createSamples": true }). The reason is a type selected for Edm.String at case of oracle database is varchar2(4000) (oracle.js). I know, it is restriction of oracle, but on the other hand it is obviously not enough (for example, you use varchar(max) for mssql) even for your own templates. Probably you should use CLOB type for unlimited string content, but at this case you also have to construct another sql scripts for them, because scripts like where clobColumnName = 'value' is not supported for CLOB, moreover possibly some castings to and from CLOB type also have to be done.

module.exports = {
  'Edm.String': 'varchar2(4000)',
  'Edm.DateTimeOffset': 'timestamp',
  'Edm.Boolean': 'number(1)',
  'Edm.Int32': 'number',
  'Edm.Int64': 'number',
  'Edm.Decimal': 'number(18,4)',
  'Edm.Binary': 'clob'
}

[pofider]

Thank you for your analysis, you found a valid need.

• we will add maxLength attribute to the model, so we know what type to use better, it is also in odata standard
• I already pushed the maxLength support usage https://github.com/pofider/node-odata-to-sql
• until we mark all properties, you can just use this hack in oracle store extension

  reporter.documentStore.on('before-init', () => {
    function processType (typeDef) {  
      for (const propName in typeDef) {      
        const propDef = typeDef[propName]
        if (propDef.document && propDef.type === 'Edm.String') {       
          propDef.maxLength = 'max'       
        }    
      }   
    } 

    for (const typeName in reporter.documentStore.model.complexTypes) {
      processType(reporter.documentStore.model.complexTypes[typeName])    
    }
  
    for (const typeName in reporter.documentStore.model.entityTypes) {
      processType(reporter.documentStore.model.entityTypes[typeName])    
    }
  })

This will update the model and set to entity properties maxLength based on the currently used document attribute.

• the conversion string <->clob could be done in the oracle store extension inside executeQuery function, (you now have the entitySet in opts)
• it seems we can skip the problem with the comparison of clob columns. I may be wrong but I think we don't do it in the jsreport.

Please let me know if you are missing something to continue further.
Thank you for your work on oracle-store.

[jorisdebock]

@pofider

I have added the following to the oracle-store pull request: jsreport/jsreport-oracle-store@8f08011

Is this the way to go?

Is this also correct behavior with binary type, since its also a clob? Can you point me to a plugin where binary is used so I can test it?

[jorisdebock]

The following type should also use clob:

• SettingType.value

[jorisdebock]

@pofider instead of using maxLength, is it maybe better to define a new type like "Edm.StringMax"?

Currently in oracle-store-extension there is now this:

if (propDef.type === 'Edm.String' && propDef.document) {
  propDef.maxLength = 'max'
} else if (propDef.type === 'Edm.String' && typeName === 'SettingType' && propName === 'value') {
  propDef.maxLength = 'max'
}

I think its more maintainable and less error prone to use the Edm.StringMax when defining the model