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Tolerim
a month ago

How can I fix the error message stating 'unimplemented or unreasonable conversion requested'?

Whenever I attempt to perform an action on a large number of records, the action results in an error. I have implemented the stringify function as below:

stringify(rec, "ISTRANSACTION=${IsTransaction}^COMPANYID=${CompanyId}^PRTRANSACTIONSEQ=${PrTransactionSeq}^SPRICE=${SPrice}^SQUANTITY=${SQuantity}^", JSON) into SelectionVar;
The error message reads "unimplemented or unreasonable conversion requested". The code expects the selection string to be passed to a PL/SQL function, which processes the selection string as a 'VARCHAR2' data type. When I tried to change the selection string data type to CLOB in the function, it worked for more manageable record quantities, but failed when dealing with a substantially larger number of records. Is there an alternative workaround to fix this error?

The function which receives the selection string is provided below:

FUNCTION Get_Records(
   selectionstring  IN VARCHAR2 )  RETURN VARCHAR2
IS 
   records               jsonarray := 
   jsonarray.parse(selectionstring_);
   currentselection     VARCHAR2(32000);
BEGIN
   //Code
END;
Answers(2)
avatar
Vogi
a month ago
Verified Answer
The error message "unimplemented or unreasonable conversion requested" is usually caused by an unsupported format conversion. It is possible that the selection string data type is too large for the function to handle. You could try using a different data type such as BLOB instead of CLOB. You could also try using the JSON.stringify() function with a replacer parameter instead of the current implementation. The replacer parameter can be used to transform values and properties encountered during the stringification process. Here's an example of how you can use the replacer parameter: 
function replacer(key, value) {
  if (typeof value === 'string') {
    return undefined;
  }
  return value;
}

JSON.stringify({ name: 'John', age: 30 }, replacer);
This will remove all string values from the resulting JSON string. I hope this helps!

Sources

ORA-01460: unimplemented or unreasonable conversion requested tipsJavascript JSON.stringify function is not workingJSON.stringify() - JavaScript | MDN - Mozilla Developer
avatar
Tolerim
a month ago
The 'unimplemented or unreasonable conversion requested' error is related to the size of the VARCHAR2 datatype used for the selection string. Since the maximum size of a VARCHAR2 is 32767, it cannot handle larger data sizes. Changing the datatype to CLOB solves this problem for some more number of records but does not work for a lot number of records as expected. One solution to this problem is to split the input parameter into smaller parts (i.e., smaller than 32767) and call the function multiple times with different parts of the input parameter. Then, concatenate the results to get the final output. Another solution is to use a BLOB datatype instead of a CLOB, which allows storing larger data sizes. To use BLOB, you need to convert the input parameter to binary data using utl_raw.cast_to_raw function and decode it inside the function using utl_raw.cast_to_varchar2 function. Here is an example of how to use BLOB in your code: 
selection_string_  IN BLOB )  RETURN VARCHAR2
IS 
   records_               json_array := 
   json_array(parse(utl_raw.cast_to_varchar2(selection_string_)));
   current_selection_     VARCHAR2(32000);
BEGIN
   -- Code
END;
In this example, we have changed the datatype of the input parameter to BLOB and used utl_raw.cast_to_raw function to convert the input parameter to binary data. In the function, we have used utl_raw.cast_to_varchar2 function to decode the binary data back to VARCHAR2. This should solve the problem with large data sizes.
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