wekan/docs/API/Custom-Fields.md

1. Login as Admin user as Form Data to get Bearer token https://github.com/wekan/wekan/wiki/REST-API#example-call---as-form-data

2. There needs to be Custom Field added to board https://wekan.fi/api/v4.42/#wekan-rest-api-customfields

3. Custom Field at board and card will have same _id https://wekan.fi/api/v4.42/#put_board_list_card

4. When writing Custom Field value to card, like text field, content type needs to be "application/json" and the string needs to be an array:

-d '{ "customFields" : [ { "_id" : "oZHkpcaxDHnbkbqGo", "value" : "foobar" } ] }'

5. For other types of Custom Fields, you can look at Custom Field structure from MongoDB database with nosqlbooster that can also login through ssh to server Wekan snap MongoDB port 27019

In Wekan code (old)

wekan/models/customFields.js , at bottom

//CUSTOM FIELD REST API
if (Meteor.isServer) {
  JsonRoutes.add('GET', '/api/boards/:boardId/custom-fields', function (req, res) {
    Authentication.checkUserId( req.userId);
    const paramBoardId = req.params.boardId;
    JsonRoutes.sendResult(res, {
      code: 200,
      data: CustomFields.find({ boardId: paramBoardId }),
    });
  });

  JsonRoutes.add('GET', '/api/boards/:boardId/custom-fields/:customFieldId', function (req, res) {
    Authentication.checkUserId( req.userId);
    const paramBoardId = req.params.boardId;
    const paramCustomFieldId = req.params.customFieldId;
    JsonRoutes.sendResult(res, {
      code: 200,
      data: CustomFields.findOne({ _id: paramCustomFieldId, boardId: paramBoardId }),
    });
  });

  JsonRoutes.add('POST', '/api/boards/:boardId/custom-fields', function (req, res) {
    Authentication.checkUserId( req.userId);
    const paramBoardId = req.params.boardId;
    const id = CustomFields.direct.insert({
      name: req.body.name,
      type: req.body.type,
      settings: req.body.settings,
      showOnCard: req.body.showOnCard,
      boardId: paramBoardId,
    });

    const customField = CustomFields.findOne({_id: id, boardId: paramBoardId });
    customFieldCreation(req.body.authorId, customField);

    JsonRoutes.sendResult(res, {
      code: 200,
      data: {
        _id: id,
      },
    });
  });

  JsonRoutes.add('DELETE', '/api/boards/:boardId/custom-fields/:customFieldId', function (req, res) {
    Authentication.checkUserId( req.userId);
    const paramBoardId = req.params.boardId;
    const id = req.params.customFieldId;
    CustomFields.remove({ _id: id, boardId: paramBoardId });
    JsonRoutes.sendResult(res, {
      code: 200,
      data: {
        _id: id,
      },
    });
  });
}