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Bsontypes
Paco Zamora Martinez edited this page Dec 23, 2015
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LuaMongo automatically marshals data between Lua types and BSON types. Here is the mapping:
| Lua Type | BSON Type | Notes |
|---|---|---|
| nil | Null | value |
| boolean | Boolean | |
| number | Floating point | |
| string | String | |
| table | new BSON Document by iterating pairs | |
| mongo.Date | UTC Datetime | milliseconds since epoch, 64-bit, precision lost |
| mongo.Timestamp | Timestamp | special mongodb type, 64-bit, precision lost |
| mongo.RegEx | Regular Expression | |
| mongo.NumberInt | 32-bit integer | |
| mongo.NumberLong | 64-bit integer | precision lost |
| mongo.Symbol | Symbol | |
| mongo.ObjectId | ObjectID | MongoDB document ID |
| thread | UNSUPPORTED | |
| function | UNSUPPORTED | |
| userdata | UNSUPPORTED |
###How To Use BSON Types You use the non-native types as follows:
store 'foo' as an integer, and 'bar' as a float
db:insert('test.values', { foo = mongo.NumberInt(5), bar = 5 }
###64-bit Integer Precision Warning
Many BSON types are natively 64-bit integers. However, Lua numbers only support 52-bits of integer precision. Thus, if you convert these BSON types into Lua, you may lose precision.
###Implementation Notes
The various BSON type objects (e.g. mongo.Date) work by creating a table with the following structure:
t[1] = value
getmetatable(t).__bsontype = numeric_code_of_bson_type
When the marshalling code sees a table with this metatable field, it will change how it marshals the object. You can find this in utils.cpp [90].