Please, see Pass-through framework for more information on data conversions.
How to see mapped type
This is pretty easy, insert a record into a table using standard DBMS tools, and then query it like this:
Convenience conversion methods
Convenience conversion methods are used after data was loaded into models due to read operations
ActiveJDBC provides a number of getter methods for conversion. Most conversions use the underlying Convert class. Here are some examples:
Most all types can be converted to String, including a CLOB. Consider this example, where column CONTENT is defined as CLOB:
Here is a list conversion getters available in models:
BigDecimal getBigDecimal(String attributeName) Boolean getBoolean(String attributeName) byte getBytes(String attributeName) Date getDate(String attributeName) Double getDouble(String attributeName) Float getFloat(String attributeName) Integer getInteger(String attributeName) Long getLong(String attributeName) Short getShort(String attributeName) String getString(String attributeName) Time getTime(String attributeName) Timestamp getTimestamp(String attributeName)
Converters are triggered during model save operations
A Converter can convert values from one type to another. Currently there are a few converters available: blank to null, zero to null, date (date to string and string to date), and timestamp (timestamp to string and string to timestamp).
Converters will always convert from the original type of the value (for example, java.lang.String for a value like
1926-06-01) to the type of the convenience conversion method called, and they are registered to model attributes. So for the
setDate("dob", "1926-06-01") call, if there is a converter from String (original value type) to java.sql.Date (setting a date with setDate) registered for the attribute
dob, it will be used and the value set will be of type java.sql.Date. The same applies to getters, the other way around.
Date converters can do conversions between formatted string and java.sql.Date. Here is an example that registers date converters to
and here how to use them:
Person p = new Person(); // will convert String to java.sql.Date p.setDate("dob", "06/23/1912"); // will convert Date to String, if dob value in model is of type Date String str = p.getString("dob"); // will convert Date to String p.setString("dob", new Date()); // will convert String to java.sql.Date, if dob value in model is of type String Date date = p.getDate("dob");
Timestamp converters are identical to date converters, but do conversion to and from java.sql.Timestamp. Here is an example of declaration:
The blank to null converter transforms any
java.lang.String values that are empty or contain only whitespaces to null. It works with any getter or setter. Here is an example that registers it to two attributes:
The zero to null converter works as the blank to null converter, but transforms
java.lang.Number values that are equal zero to null. Here is example of declaration:
Custom setters and getters
If you like more control over types, you can provide typed getters and setters:
and then use it like this:
For more information on setters and getters, see Setters and getters
What happens if I stick a wrong type?
If you do this:
you are going to get an exception from the DBMS itself, if it cannot convert the type:
org.javalite.activejdbc.DBException: com.mysql.jdbc.MysqlDataTruncation: Data truncation: Incorrect date value: '1' for column 'dob' at row 1, Query: INSERT INTO students (first_name, dob, last_name) VALUES (?, ?, ?), params: John,1,Doe at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2868) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1573) at com.mysql.jdbc.ServerPreparedStatement.serverExecute(ServerPreparedStatement.java:1169) at com.mysql.jdbc.ServerPreparedStatement.executeInternal(ServerPreparedStatement.java:693)
ActiveJDBC is a pass-through framework - it will pass data to lower level to handle.
Different data types for the same attribute
Is this possible? Yes, for instance, take this example:
This will work for MySQL, and the driver will convert the String
2011-12-3 during insert or update. However, if you retain a reference to this model, the internal value type is going to remain String.
Should I care about types?
Not so much. Just use the models with types you think are appropriate, and ActiveJDBC together with the driver will handle most of what you need. In case you get a conversion exception from the driver, do a due diligence then.
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