Transferring data from a Stream into another

[SE_10190539]

Hi! I'm trying to get all the entries from one Stream Thing and transfer them to another. 

My code looks like this: 

new_entries = Things["TemporalStream"].GetStreamEntriesWithData();
var params = {
values:new_entries
};
Things["MainStream"].AddStreamEntries(params);

I'm getting the error message :: Wrapped java.lang.NullPointerException - See Script Error Log for more details.

Could someone please tell me what I'm doing wrong?

[Arun_C]

HI @SE_10190539 ,

Kindly refer the below articles for how to use 'AddStreamEntries ' service in our custom services in thing.

• How To Use AddStreamEntries snippet service
• Unable to use AddStreamEntries service by creating datashape and then passing values as infotable.

Thanks & Regards,

Arun C

[SE_10190539]

Hi, I'm reading the articles, but I can't find anything that solves my problem. I just want to take the entries from the stream Temporal and copy them into the Main one. 

[Arun_C]

Hi @SE_10190539,

These below given code updates based on the article will helps you to copy data from 1 stream to another another.

//// *** SET UP META DATA FOR INFO TABLE *** ////
let myInfoTable = { dataShape: { fieldDefinitions : {} }, rows: [] };
myInfoTable.dataShape.fieldDefinitions['timestamp']  = { name: 'timestamp', baseType: 'DATETIME' };
myInfoTable.dataShape.fieldDefinitions['location']  = { name: 'location', baseType: 'LOCATION' };
myInfoTable.dataShape.fieldDefinitions['source']    = { name: 'source', baseType: 'STRING' };
myInfoTable.dataShape.fieldDefinitions['sourceType'] = { name: 'sourceType', baseType: 'STRING' };
myInfoTable.dataShape.fieldDefinitions['tags']      = { name: 'tags', baseType: 'TAGS' };
myInfoTable.dataShape.fieldDefinitions['values']    = { name: 'values', baseType: 'INFOTABLE' };


//// *** GET oldData from STREAM *** ////
let oldData = Things["Demo_Stream_ST"].GetStreamEntriesWithData({
	oldestFirst: undefined /* BOOLEAN */ ,
	maxItems: 500 /* NUMBER {"defaultValue":500} */
});

//// *** LOOP the data and add values to myInfoTable *** ////
for (let i = 0; i < oldData.length; i++) {
	// create new values based on Stream DataShape
	let params = {
		infoTableName: "InfoTable",
		dataShapeName: "Demo_Stream_DS"
	};
	let values = Resources["InfoTableFunctions"].CreateInfoTableFromDataShape(params);
    
   // create new values based on Stream DataShape and add values from oldData
    // Demo_Stream_DS entry object
    let newValues = {
        Sno: oldData.rows[i].Sno, // NUMBER
        Name: oldData.rows[i].Name // STRING
    };
	values.AddRow(newValues);
    
    // create new values based on myInfoTable Datashape and add values to their fields
    let newEntry = new Object();
    newEntry.timestamp = oldData.rows[i].timestamp;
    newEntry.location = oldData.rows[i].location;
    newEntry.source = oldData.rows[i].source;
    newEntry.tags = oldData.rows[i].tags;
    newEntry.sourceType = oldData.rows[i].sourceType;
    newEntry.values = values;
    
    // add new Info Table row to Info Table
	myInfoTable.rows[i] = newEntry;
}

    //// *** ADD myInfoTable (HOLDING MULITPLE STREAM ENTRIES) TO STREAM *** ////
Things["Demo_Stream_Duplicate_ST"].AddStreamEntries({
	values: myInfoTable /* INFOTABLE {"dataShape":"StreamEntryWithValues"} */
});
result = "Data Migrated Successfully!";

Kindly take look on it.

Note: You need to carefull when the "AddStreamEntires" services execution in your environment.

Thanks & Regards,

Arun C

[SE_10190539]

Thank you for your reply! I tried this and it is copying the entries into the Main stream. However, I am not getting the data that the entries contain. I guess I could do this by setting the fieldDefinitions with the additional data. Is there a way to copy the column names without having to hard code them?

[Arun_C · Accepted solution]

Hi @SE_10190539 ,

Try to use "Create infotable entry from datashape" snippet by your DataShape Selection it will add code with all field column names are present from your source datashape. 

Thanks & Regards,

Arun C

[SE_10190539]

Thank you!