tachybase_todo/docs/en-US/api/resourcer/action.md

Action

Action is the description of the operation process on resource, including database processing and so on. It is like the service layer in other frameworks, and the most simplified implementation can be a Koa middleware function. In the resourcer, common action functions defined for particular resources are wrapped into instances of the type Action, and when the request matches the action of the corresponding resource, the corresponding action is executed.

Constructor

Instead of being instantiated directly, the Action is usually instantiated automatically by the resourcer by calling the static method toInstanceMap() of Action.

constructor(options: ActionOptions)

Parameter

Name	Type	Default	Description
handler	Function	-	Handler
middlewares?	Middleware | Middleware[]	-	Middlewares for the action
values?	Object	-	Default action data
fields?	string[]	-	Default list of targeted fields
appends?	string[]	-	Default list of associated fields to append
except?	string[]	-	Default list of fields to exclude
filter	FilterOptions	-	Default filtering options
sort	string[]	-	Default sorting options
page	number	-	Default page number
pageSize	number	-	Default page size
maxPageSize	number	-	Default max page size

Instance Members

actionName

Name of the action that corresponds to when it is instantiated. It is parsed and fetched from the request at instantiation.

resourceName

Name of the resource that corresponds to when the action is instantiated. It is parsed and fetched from the request at instantiation.

resourceOf

Value of the primary key of the relational resource that corresponds to when the action is instantiated. It is parsed and fetched from the request at instantiation.

readonly middlewares

List of middlewares targeting the action.

params

Action parameters. It contains all relevant parameters for the corresponding action, which are initialized at instantiation according to the defined action parameters. Later when parameters passed from the front-end are parsed in requests, the corresponding parameters are merged according to the merge strategy. Similar merging process is done if there is other middleware processing. When it comes to the hander, the params are the final parameters that have been merged for several times.

The merging process of parameters provides scalability for action processing, and the parameters can be pre-parsed and processed according to business requirements by means of custom middleware. For example, parameter validation for form submission can be implemented in this part.

Refer to [/api/actions] for the pre-defined parameters of different actions.

The parameters also contain a description of the request resource route:

Name	Type	Default	Description
resourceName	string	-	Name of the resource
resourceIndex	string | number	-	Value of the primary key of the resource
associatedName	string	-	Name of the associated resource it belongs to
associatedIndex	string | number	-	Value of the primary key of the associated resource it belongs to
associated	Object	-	Instance of the associated resource it belongs to
actionName	string	-	Name of the action

Example

app.resourcer.define('books', {
  actions: {
    publish(ctx, next) {
      ctx.body = ctx.action.params.values;
      // {
      //   id: 1234567890
      //   publishedAt: '2019-01-01',
      // }
    }
  },
  middlewares: [
    async (ctx, next) => {
      ctx.action.mergeParams({
        values: {
          id: Math.random().toString(36).substr(2, 10),
          publishedAt: new Date(),
        }
      });
      await next();
    }
  ]
});

Instance Methods

mergeParams()

Merge additional parameters to the current set of parameters according to different strategies.

Signature

• mergeParams(params: ActionParams, strategies: MergeStrategies = {})

Parameter

Name	Type	Default	Description
params	ActionParams	-	Additional set of parameters
strategies	MergeStrategies	-	Merge strategies for each parameter

The default merge strategy for built-in actions is as follows:

Name	Type	Default	Merge Strategy	Description
filterByTk	number | string	-	SQL and	Get value of the primary key
filter	FilterOptions	-	SQL and	Get filtering options
fields	string[]	-	Take the union	List of fields
appends	string[]	[]	Take the union	List of associated fields to append
except	string[]	[]	Take the union	List of associated fields to exclude
whitelist	string[]	[]	Take the intersection	Whitelist of fields that can be handled
blacklist	string[]	[]	Take the union	Blacklist of fields that can be handled
sort	string[]	-	SQL order by	Get the sorting options
page	number	-	Override	Page number
pageSize	number	-	Override	Page size
values	Object	-	Deep merge	Operation of the submitted data

Example

ctx.action.mergeParams({
  filter: {
    name: 'foo',
  },
  fields: ['id', 'name'],
  except: ['name'],
  sort: ['id'],
  page: 1,
  pageSize: 10,
  values: {
    name: 'foo',
  },
}, {
  filter: 'and',
  fields: 'union',
  except: 'union',
  sort: 'overwrite',
  page: 'overwrite',
  pageSize: 'overwrite',
  values: 'deepMerge',
});