OrientDB 2.2设置属性默认值为JSON字符串遇解析问题求助

Hey there! I’ve run into exactly this problem with OrientDB 2.2 before—super frustrating when the database auto-parses your JSON string default into an embedded object instead of keeping it as a raw string. Let’s break down why this happens and how to fix it.

Why This Happens #

OrientDB has an automatic JSON parsing feature: if it detects that a string value matches valid JSON syntax, it will automatically convert it into an embedded document/object, even if you’ve explicitly set the property type to STRING. That’s why your schema looks correct initially, but inserts end up with parsed objects instead of raw strings.

Step-by-Step Solution #

1. Define the Property with Properly Escaped Default Value #

When creating the property, you need to escape the inner quotes in your JSON string so OrientDB treats the entire value as a raw string, not a JSON object. Use backslashes to escape double quotes inside the default value string.

Here’s the correct SQL command:

CREATE CLASS Person EXTENDS V;
CREATE PROPERTY Person._template STRING DEFAULT '{\\"name\\":\\"default\\",\\"age\\":30}';

2. Update Existing Properties (If Needed) #

If you already created the _template property and need to fix its default value, use the ALTER PROPERTY command with the same escaped string:

ALTER PROPERTY Person._template DEFAULT '{\\"name\\":\\"default\\",\\"age\\":30}';

3. Verify the Fix #

After setting up the property correctly:

• Check the schema with SELECT * FROM metadata:schema WHERE name = 'Person'—you’ll see the default value is stored as the raw escaped string.
• Insert a new record with INSERT INTO Person SET name = 'John' (no need to set _template explicitly).
• Run your query select _template from Person—the result will now be the raw JSON string, not a parsed object.

Alternative: Use Single Quotes Inside JSON #

If escaping backslashes feels cumbersome, you can use single quotes for the JSON key/value pairs instead, then wrap the entire string in double quotes:

CREATE PROPERTY Person._template STRING DEFAULT '{"name":"default","age":30}';

This also prevents OrientDB from auto-parsing the string into an object, and works if your application can handle single-quoted JSON (or you can normalize the quotes later in your code).

内容的提问来源于stack exchange，提问作者Joshua Stillerman