141 lines
2.9 KiB
Go
141 lines
2.9 KiB
Go
/*
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Copyright 2021 The Dapr Authors
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package query
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import (
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"encoding/json"
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"fmt"
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)
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const (
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FILTER = "filter"
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SORT = "sort"
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PAGE = "page"
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ASC = "ASC"
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DESC = "DESC"
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)
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type Sorting struct {
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Key string `json:"key"`
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Order string `json:"order,omitempty"`
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}
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type Pagination struct {
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Limit int `json:"limit"`
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Token string `json:"token,omitempty"`
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}
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type Query struct {
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Filters map[string]interface{} `json:"filter"`
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Sort []Sorting `json:"sort"`
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Page Pagination `json:"page"`
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// derived from Filters
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Filter Filter
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}
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type Visitor interface {
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// returns "equal" expression
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VisitEQ(*EQ) (string, error)
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// returns "in" expression
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VisitIN(*IN) (string, error)
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// returns "and" expression
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VisitAND(*AND) (string, error)
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// returns "or" expression
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VisitOR(*OR) (string, error)
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// receives concatenated filters and finalizes the native query
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Finalize(string, *Query) error
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}
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type Builder struct {
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visitor Visitor
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}
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func NewQueryBuilder(visitor Visitor) *Builder {
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return &Builder{
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visitor: visitor,
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}
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}
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func (h *Builder) BuildQuery(q *Query) error {
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filters, err := h.buildFilter(q.Filter)
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if err != nil {
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return err
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}
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return h.visitor.Finalize(filters, q)
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}
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func (h *Builder) buildFilter(filter Filter) (string, error) {
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if filter == nil {
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return "", nil
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}
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switch f := filter.(type) {
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case *EQ:
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return h.visitor.VisitEQ(f)
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case *IN:
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return h.visitor.VisitIN(f)
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case *OR:
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return h.visitor.VisitOR(f)
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case *AND:
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return h.visitor.VisitAND(f)
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default:
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return "", fmt.Errorf("unsupported filter type %#v", filter)
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}
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}
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func (q *Query) UnmarshalJSON(data []byte) error {
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var m map[string]interface{}
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err := json.Unmarshal(data, &m)
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if err != nil {
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return err
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}
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if elem, ok := m[FILTER]; ok {
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q.Filter, err = parseFilter(elem)
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if err != nil {
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return err
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}
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}
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// setting sorting
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if elem, ok := m[SORT]; ok {
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arr, ok := elem.([]interface{})
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if !ok {
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return fmt.Errorf("%q must be an array", SORT)
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}
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jdata, err := json.Marshal(arr)
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if err != nil {
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return err
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}
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if err = json.Unmarshal(jdata, &q.Sort); err != nil {
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return err
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}
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}
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// setting pagination
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if elem, ok := m[PAGE]; ok {
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page, ok := elem.(map[string]interface{})
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if !ok {
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return fmt.Errorf("%q must be a map", PAGE)
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}
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jdata, err := json.Marshal(page)
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if err != nil {
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return err
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}
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if err = json.Unmarshal(jdata, &q.Page); err != nil {
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return err
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}
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}
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return nil
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}
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