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Type:
Task
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Resolution: Fixed
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: Export to Language
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Labels:
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Not Needed
Request
Explore adding a variable declarations template to the BSON Transpiler templates.
ObjectIdSymbolDeclarationsTemplate: &ObjectIdSymbolDeclarationsTemplate null
Motivation
Go handles some functionality by returning both a value as well as any error encountered while parsing the value. For example, when trying to parse an objectID from hex, you would handle errors inline
objectID, err := primitive.ObjectIDFromHex("5ab901c29ee65f5c8550c5b9") if err != nil { log.Fatal(err) } // use objectID for something
While this follows the "go way" of error-handling, the `ObjectIdSymbolArgsTemplate`, for example, expects only functionality that will return an object id alone. This requires the go templates to use closures to handle errors that might occur at runtime
// This would be embedded in some CRUD Operation // and is what would be transpiled from // { _id: ObjectID("5ab901c29ee65f5c8550c5b9") } bson.D{{"_id", func(hex string) primitive.ObjectID { objectID, err := primitive.ObjectIDFromHex(hex) if err != nil { log.Fatal(err) } return objectID }("5ab901c29ee65f5c8550c5b9")}}
This does not look very natural and could be a source of confusion for go developers trying to export code.
Proposal
The closure method may possibly be avoided by adding the new template `ObjectIdSymbolDeclarationsTemplate` where variables are declared to be used within the args template
ObjectIdSymbolDeclarationsTemplate: &ObjectIdSymbolDeclarationsTemplate !!js/function >
(arg, count) => {
return `objectID${count}, err := primitive.ObjectIDFromHex(${arg})
if err != nil {
log.Fatal(err)
}`
}
ObjectIdSymbolArgsTemplate: &ObjectIdSymbolArgsTemplate !!js/function >
(_, count) => {
return `objectID${count}`
}
This would be transpiled into the following
objectID1, err := primitive.ObjectIDFromHex("5ab901c29ee65f5c8550c5b9") if err != nil { log.Fatal(err) } // this would be embedded in some CRUD Operation bson.D{{"_id", objectID1}}