Use Typescript decorators to retrieve a property from properties.json and load it on class attribute.
npm install ts-json-properties
!npm
> Use typescript decorator to retrieve a property from properties.json and load it on class attribute.
* @Value(expression) : resolve expression and values the attribute (decorator).
* @Constant(expression) : resolve expression and values the attribute but attribut is frozen (decorator).
* @EnvValue(expression) : resolve expression and values the attribute from process.node.env or from properties if env value doesn't exists (decorator).
* Properties.get() : resolve expression and values the attribute (programmatic).
``bash`
npm install -g typescript
npm install ts-json-properties
In first place, you need to create a properties.json in your project's root and write some data like this :
``json`
{
"product":"MP",
"myOwnData":{
"data1":1
}
}
You can separate your json in multiple json file with the attribute propertiesFile. Just adding this code on your properties.json :
`json`
{
"product":"MP",
"myOwnData":{
"data1":1
},
"propertiesFiles":{
"cwd":"./properties",
"files":{
"documents": "documents.json",
"wsdl": "wsdl.json"
}
}
}
In this case, when Properties load your properties file in memory, it'll provide a JSON like this :
`json
{
"product":"MP",
"myOwnData":{
"data1":1
},
"documents": {
"doc1": "/directory/docs/file.pdf"
},
"wsdl": {
"wsdl1": "..."
}
}
`
Next step, You must initialize Properties in your app.js. Just add this code for that :
`typescript
import {Properties} from 'ts-json-properties';
Properties.initialize(); //Import automatically properties.json
//or load it from another path
Properties.initialize('path/to/properties.json');
`
And finally, you use the decorator to values attributes on your class.
`typescript
import {Value, Properties} from 'ts-json-properties';
export class Foo {
@Value('documents.doc1')
private documents1:string;
constructor(){
console.log('Doc =>', this.documents1); // Doc => /directory/docs/file.pdf
//or with Properties Api
console.log('wsdl', Properties.get('wsdl')); // wsdl => {"wsdl1":"..."}
}
}
`
> Note : All properties returned by or Properties.getValue are immutable.
Define your env variable:
`bash`
export path__to__var = "1000"
Then use @EnvValue:
`typescript
import {Value, Properties} from 'ts-json-properties';
export class Foo {
@EventValue('path.to.var')
private documents1: string;
}
`
> Note: if the env value is undefined, the value will be retrieved from properties.json
`bash ``
$ npm install -g mocha
$ npm test
The MIT License (MIT)
Copyright (c) 2016 Romain Lenzotti
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