Koa Params Extractor

Extract Koa's request parameters

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Helps to get parameters (headers, params, query, body) that can be distributed or in different locations in a consistent way

1. find in alias location. (ctx.xxx)
2. find in req location. (ctx.req.xxx)
3. find in request location. (ctx.request.xxx)

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Install

$ npm i koa-params-extractor

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Usage

const paramsExtractor = require('koa-params-extractor');

router.post('/user', async (ctx) => {
  const { id, username, password } = paramsExtractor.extract(ctx);
    
  const response = await signUpUser({ id, username, password });
  ctx.body = response;
});

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Extract

paramsExtractor.extract(ctx, parameters = [parameter.headers, parameter.params, parameter.query, parameter.body]);

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Parameters

function Parameter(
  where = new Where(null, true, true, true),
  options = { name: null, combineLevel: 0, as: null, index: undefined }
) {
  this.where = where;
  this.name = options.name;
  this.combineLevel = options.combineLevel;
  this.as = options.as;
  this.index = options.index;
}

function Where(name, koaRequest, nodeRequest, context) {
  this.name = name;
  this.koaRequest = koaRequest;
  this.nodeRequest = nodeRequest;
  this.context = context;
}

• Parameters defines the information of the parameters to pass.

  • where defines where to find the parameter.
    • If where is not an instance of Where, the parameter is where .
    • If where is an instance of Where, the parameter is found in ctx with information from where.
  • name is the name of the parameter.
    • If name exists, the same name is taken from the parameter's location.
  • combineLevel is the level at which the imported arguments are to be combined.
    • 0 means the imported parameter is the parameter to pass.
    • 1 means the imported parameter is a child of the parameter to pass.
  • as specifies a name when passing a parameter.
  • index is index of the parameter to pass.

• Where defines where to find the parameter.

  • name is the name of the location from which to retrieve the parameter.
  • koaRequest means to find the location of a parameter in ctx.request.
  • nodeRequest means to find the location of a parameter in ctx.req.
  • context means to find the location of a parameter in ctx.

• The default value is params, query, header, body, cookies defined.

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