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Class transformer

If you want to transform the raw json values you get from SapphireDb to a typed class you can do this using the described method.
The advantages are type conversions for example from string to integer or date and you are also able to do field mappings if necessary.


You have to create a custom class transformer that maps the raw json to a typed class.
This example uses class-transformer by typestack

\f:(typescript:Angular) providers: [\n \t{ provide: SapphireClassTransformer, useClass: CustomClassTransformer }\n ] \f:(typescript:transformer.ts) export class CustomClassTransformer extends SapphireClassTransformer {\n \tclassToPlain<T>(value: T[] | T): any {\n \t\treturn classToPlain(value);\n \t}\n\n \tplainToClass<T>(value: any, classType: ClassType<T>): T[] | T {\n \t\treturn plainToClass(classType, value);\n \t}\n }


This example maps the content of the before used entries to an integer

\f:(typescript:Angular) export class ClassTransformerComponent implements OnInit {\n \tcollection: DefaultCollection<ExampleEntry>;\n \tvalues$: Observable<ExampleEntry[]>;\n\n \tconstructor(private db: SapphireDbService) { }\n\n \tngOnInit() {\n \t\t// Pass the class as second parameter\n \t\tthis.collection = this.db.collection('demo.entries', ExampleEntry);\n \t\tthis.values$ = this.collection.values();\n \t}\n } \f:(typescript:example-entry.ts) class ExampleEntry {\n \tid?: string;\n\n \t@Transform((v: string) => parseInt(v, null), { toClassOnly: true })\n \t@Transform((v: number) => `123${v}`, { toPlainOnly: true })\n \tcontent: number;\n\n \tconstructor() {\n \t\tthis.content = 126;\n \t}\n }

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