1.2.1 • Public • Published


    The package adds/removes defaults according to the Thing Description (TD) specification for every property with a default that is not filled with a value. Currently using this version of the TD specification. It is part of the Thingweb-Playground, you can find more information about the Thingweb-Playground here.


    Licensed under the MIT license, see License.


    You can use this package to integrate TD default value adding/removing in your application.

    • Install this package via NPM (npm install @thing-description-playground/defaults) (or clone repo and install the package with npm install)

    • Node.js or Browser import:

      • Node.js: Require the package and use the functions
      const { addDefaults, removeDefaults } = require("@thing-description-playground/defaults")
      • Browser: Import the tdDefaults object as a global by adding a script tag to your html (and optionally declare the variables without namespace).
      <script src="./node_modules/@thing-description-playground/add_defaults/dist/web-bundle.min.js"></script>
      const addDefaults = tdDefaults.addDefaults
      const removeDefaults = tdDefaults.removeDefaults
    • Now you can call the add/remove defaults function to extend/reduce a TD object.


      You can find usage examples in the tests folder, or the web and cli packages.


    • How it works:
      The algorithm shipped with package basically tries to check all possible place (in terms of object hierachy e.g. td.properties.temperature) type combinations (lines 1 - 3). A type refers to one objects default values (e.g. form -> op: application/json). All existing combinations in the given TD, are then passed to a handle function (lines 4, 5). Since there can be nested places of type DataSchema (e.g. if one DataSchema includes another by using oneOf), these need to be handled recursively (lines 6 - 10).
      The handle function (lines 13 - 20) checks the place & type combinations in the given TD, depending on whether it should add or remove default values:

      • add: If the default value(s) corresponding to the place type combination is/are not defined in the current TD, if this is true it adds the default value(s) (lines 14 - 16).
      • remove: If the place type combination value(s) equal the default value(s), if this is true it removes the value(s) (lines 17 - 19).
    • pseudocode:

      #1  | checkAllPossibleDefaultValuePlaces(td) {
      #2  |   for (every type of defaultTypes)
      #3  |     for (every place of possiblePlaces[type])
      #4  |       if (td[place] !== undefined)
      #5  |         handle(td[place], type)
      #6  |       if (type == "DataSchema")
      #7  |         currentPlace = td[place]
      #8  |         while (hasRecursiveElements(currentPlace))
      #9  |           handle(currentPlace, "DataSchema")
      #10 |           currentPlace = currentPlace[recursion]
      #11 | }
      #12 |
      #13 | handle(object, type) {
      #14 |   if (mode == "add")
      #15 |     if (object[type] == undefined)
      #16 |       object[type] = defaultTable[type]
      #17 |   if (mode == "remove")
      #18 |     if (object[type] == defaultTable[type])
      #19 |       delete object[type]
      #20 | }




    npm i @thing-description-playground/defaults

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