[Feature Request] Custom operators

This feature allow developers to define new operators.

For example:

1. define a new operator json_contains template

(alias, values)=> `JSON_CONTAINS(${alias}, ${values})`

1. use like filter=roles||json_contains||ROLE_A,ROLE_B
2. generate

andWhere('JSON_CONTAINS(roles, :roles)',{roles: JSON.stringify(roles)})

[prevostc]

If that helps, I was able to implement a custom operator by overriding mapOperatorsToQuery on the service

  protected mapOperatorsToQuery(cond: QueryFilter, param: any): { str: string; params: ObjectLiteral } {
    if (cond.field === "tags") {
      let str: string
      let params: ObjectLiteral = { [param]: cond.value }

      const field = this.getFieldWithAlias(cond.field)
      switch (cond.operator) {
        case "$cont":
          str = `${field} @> :${param}::jsonb`
          params = { [param]: `${JSON.stringify(cond.value)}` }
          break
        default:
          str = `${field} = :${param}::jsonb`
          break
      }
      return { str, params }
    } else {
      return super.mapOperatorsToQuery(cond, param)
    }
  }

This is a bit of a manual work, but it could be generalised. And it makes sense to override the service protected methods to add new functionality.

Maybe all that is needed is a “Custom operator” section on the wiki.

[rgolea]

@Diluka the PR I pushed would have fixed the problem (hopefully)