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Showing content from https://github.com/peterlevel1/dva-reducer below:

peterlevel1/dva-reducer: dva reducer helper, redux reducer helper, extend the target prop inside the tree

1. this is mainly used to be a helper for the dva's reducer
2. also can be treated as a fast copy tool without deep walking into the json tree
3. of course, redux reducer can also be applied with dvaReducer
4. support default value as the placeholder
5. call dvaReducer with no arg can be a useful method to cancel the ctrl+c|ctrl+v work

npm install dva-reducer --save

git clone https://github.com/peterlevel1/dva-reducer.git someDir/dva-reducer
cd someDir/dva-reducer
npm install
npm run test

// file: some dir/app.js
var dvaReducer = require("dva-reducer")
var dva = require("dva")

dva.model({
  namespace: "caculator",
  state: {
    num: {
      num1: {
        num2: {
          num3: {
            num4: 0
          }
        }
      }
    }
  },
  reducers: {
    // the traditional reducer to update a value:
    // if the nested relation is a little deep,
    // we see the result of code is horrible,
    // and many bugs may show here, to avoid that you must be careful about the pyramid codes,
    // or you would meet some unknown bug
    "add": function(state, action) {
      return {
        ...state,
        num: {
          ...state.num,
          num1: {
            ...state.num.num1,
            num2: {
              ...state.num.num1.num2,
              num3: {
                ...state.num.num1.num2.num3,
                num4: state.num.num1.num2.num3.num4 - action.payload
              }
            }
          }
        }
      }
    },
    // we see the graceful codes with dvaReducer here
    "minus": dvaReducer({
      props: "num.num1.num2.num3.num4",
      update: function (state, payload, value) {
        return value - payload
      }
    })
  }
})

dva.route(...)
dva.start(...)

module.exports = dva

// file: some component or some route
dispatch({
  type: "caculator/add",
  payload: 10
})

dispatch({
  type: "caculator/minus",
  payload: 3
})

require("some dir/test.js")

// some dir/test.js
var dva = require("some dir/app.js")
var assert = require("assert")

var num = dva._getState().caculator.num
assert.equal(num, 7, "caculator.num: " + num)
// true

• dvaReducer: a factory to make the dva reducer

  • @param {Object|Null} opts if no arg, the reducer would be an save reducer, the reducer would receive(state, action), action.payload must be provided to override the state's some props directly, say: dispatch({type: "some namespace/save", payload: { num: 1 }}), and the state is: { num: 0 }, so the state would be { num: 1 }

    • @param {Function} update to update the payload, the update take 3 arg: (state, payload, value), state: the state received by the reducer, payload: the action.payload, received by the reducer, so payload prop should exist on the action, value: the src value for the target prop

    • @param {Array|String} props the last one of the props is the target prop to be updated, "dva.is.awesome", "dva is awesome", ["dva", "is", "awesome"] would all be acceptable, so the target prop is awesome ready to be updated when reducer called by the dispatch method of the redux store

    • @param {*|Function} defaultValue when payload not provided, defaultValue would be the placeholder if defaultValue is function, it should return the value for the target prop, defaultValue is useful when you want a value to be a constant, say: hide: active: false(defaultValue), show: active: true(defaultValue)

  • @return {Function} reducer after the configurations, the reducer is just what we really want

• reducer(state, action)

  • @param {Object|Array} state object is advised for the type of the state

  • @param {Object} action the action type must be resolved by the upper layer logic

    • @param {Boolean} partial default value is true, set partial false if ensure to override the prop value, when payload and the action are both object

    • @param {*} payload the new value for the target prop(the last prop)

  • @return {Object} an object with required route line props updated

this would close the logs if sth wrong when dvaReducer valid your arg or prop value, so my advice is to see the test of dvaReducer first, and read the param doc up there, what's more, make some tests to keep everything in your control

var obj = {x: 1}
var state = {
  a: obj,
  b: {
    c: {
      d: 100
    }
  }
}

var action = {
  payload: 5
}

var reducer = dvaReducer({
  props: "b.c.d"
})

var nextState = reducer(state, action)

// nextState.a is equal to state.a, as the "a" prop is not within b.c.d
// but nextState.b or nextState.b.c or nextState.b.c.d is not equal to the state's according value

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