Quinn Slack created AVRO-1273:
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Summary: JavaScript dynamic generation of constructor funcs for
Avro records
Key: AVRO-1273
URL: https://issues.apache.org/jira/browse/AVRO-1273
Project: Avro
Issue Type: Improvement
Reporter: Quinn Slack
Priority: Minor
Per https://issues.apache.org/jira/browse/AVRO-485, I have extended Avro's
JavaScript support to dynamically generate constructors for Avro records.
Validation of JS objects against Avro schemas is still supported, but the API
is different: Avro.validate(schema, obj) instead of Validator.validate(schema,
obj). This is a breaking change but may be worth it because there are now
several Avro.* funcs.
Code is at https://github.com/sqs/avro/tree/lang-js/lang/js. I will attach a
diff.
Here is sample usage. We compile a ManyFieldsRecord constructor function using
the Avro schema as input. The constructor function accepts a JS object, which
it validates against the Avro schema and then uses to populate the new object's
fields. Then ManyFieldRecords objects use Object.defineProperty setters to
ensure that the object remains valid Avro.
{code:javascript}
var manyFieldsRecordSchema = {
type: 'record', name: 'ManyFieldsRecord', fields: [
{name: 'nullField', type: 'null'},
{name: 'booleanField', type: 'boolean'},
{name: 'intField', type: 'int'},
{name: 'longField', type: 'long'},
{name: 'floatField', type: 'float'},
{name: 'doubleField', type: 'double'},
{name: 'stringField', type: 'string'},
{name: 'bytesField', type: 'bytes'}
]
};
var compiledTypes = Avro.compile(manyFieldsRecordSchema)
ManyFieldsRecord = compiledTypes.ManyFieldsRecord,
mfr = new ManyFieldsRecord();
test.throws(function() { mfr.nullField = undefined; });
test.throws(function() { mfr.nullField = 1; });
test.throws(function() { mfr.booleanField = 'a'; });
test.throws(function() { mfr.intField = 'a'; }); // TODO: warn if setting
int/long field to a non-integer
test.throws(function() { mfr.longField = 'a'; });
test.throws(function() { mfr.floatField = 'a'; });
test.throws(function() { mfr.doubleField = 'a'; });
test.throws(function() { mfr.stringField = 3; });
mfr.nullField = null;
mfr.booleanField = true;
mfr.intField = 1;
mfr.longField = 2;
mfr.floatField = 3.5;
mfr.doubleField = 4.5;
mfr.stringField = 'a';
test.equal(mfr.nullField, null);
test.equal(mfr.booleanField, true);
test.equal(mfr.intField, 1);
test.equal(mfr.longField, 2);
test.equal(mfr.floatField, 3.5);
test.equal(mfr.doubleField, 4.5);
test.equal(mfr.stringField, 'a');
// Standard JavaScript JSON API interface:
mgr.toJSON(); // --> returns plain JS object (without Avro-validating setters)
JSON.stringify(mfr); // --> returns Avro JSON
{code}
More examples are in the test dir:
https://github.com/sqs/avro/tree/lang-js/lang/js/test.
This is still rough and I am very interested in getting feedback. Thanks!
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