How do I write data in my Google App Engine Datastore to com.google.appengine.api.datastore.Text

Question

I have persistent object, with a string property that often is over 500 charachters. Google App Engine says I need to save it as a com.google.appengine.api.datastore.Text.

How do I either convert a String type to a com.google.appengine.api.datastore.Text type so I can use a setMethod() on the property, or otherwise get my long sting data into that persistent value?

Thilo · Accepted Answer · 2010-03-11 05:01:17Z

6

setMethod(new Text(longStringValue));

String value = text.getValue();

If you are trying to update an existing String column to Text, then I am not sure if that is supported. You can try to change the column type from String to Text and see if it still loads (I can imagine that this might work, please let us know if it does). If not, you need to add a new column and have your application merge them appropriately.

answered Mar 11, 2010 at 5:01

Thilo

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5 Comments

Lloyd Over a year ago

When I try that I get the following error: "java.lang.String cannot be cast to com.google.appengine.api.datastore.Text"

Thilo Over a year ago

"try that" = change the column to Text? Too bad. In this case you need to make a new column, and keep the old one, and have your entity migrate its data slowly from the old String column to the new Text column.

Lloyd Over a year ago

You are right. The fact that there were entities with the old datatype in there was causing it grief. Creating a new column and slowly moving there was the right solution. Thanks.

Thilo Over a year ago

What be cool if GAE/J (DataNucleus?) supported conversion between Text and String automatically (as long as the length constraints are met), though. Would make schema migration easier.

Nick Johnson Over a year ago

Changing the column type should work just fine. The only difference between text and string is whether or not they're indexed.

musefan · Accepted Answer · 2012-01-24 10:13:48Z

2

To convert a String type to a com.google.appengine.api.datastore.Text type I used

Text myText = new Text(myString);

edited Jan 24, 2012 at 10:13

musefan

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answered Jan 24, 2012 at 9:04

John Barraco

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