forked from zbindenren/mqb
/
querybuilder.go
259 lines (237 loc) · 8.17 KB
/
querybuilder.go
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package mqb
import (
"errors"
"fmt"
"math"
"net/http"
"reflect"
"strconv"
"strings"
"github.com/ansel1/merry"
"gopkg.in/mgo.v2"
"gopkg.in/mgo.v2/bson"
)
var (
DefaultPageSize uint = 20 // DefaultPageSize defines how many elements a page contains per default.
)
// Page the paging information.
type Page struct {
Size uint `json:"size"` // Size defines how many elements a page contains.
Items uint `json:"items"` // Items defines the total number of items the corresponding query returns.
Last uint `json:"last"` // Last represents total number of pages a query generates (depends on the page size and the total number of elements returned by the query).
Current uint `json:"current"` // Current is the current page nuber for the query.
}
// Response contains the result of the query, including the Page information.
type Response struct {
Content interface{} `json:"content,omitempty"`
Page Page `json:"page"`
}
// MongoQuery can be used to to create mgo.Query from http request parameters.
type MongoQuery struct {
endPointStruct interface{}
dataBase *mgo.Database
supportedParameters map[string]reflect.Kind
additionalSupportedParamters map[string]reflect.Kind
disabledParameters []string
page Page
}
// NewMongoQuery returns a new MongoQuery.
func NewMongoQuery(endPointStruct interface{}, database *mgo.Database) *MongoQuery {
return &MongoQuery{
dataBase: database,
supportedParameters: createValidParametersMap(endPointStruct),
disabledParameters: []string{},
additionalSupportedParamters: make(map[string]reflect.Kind),
endPointStruct: endPointStruct,
}
}
// CreateQuery creates a mgo.Query from a HTTP Request for a collection represented by endpointStruct.
//
// Examples:
// mq := NewMongoQuery(People{}, db)
// q, _ := mq.CreateQuery(req) // creates a query from the request for the people collection
//
// mq.DisableParameters("name", "sort")
// q, _ := mq.CreateQuery(req) // creates a query from the request for the people collection with the parameters "name" and "sort" disabled.
//
func (mq *MongoQuery) CreateQuery(req *http.Request) (*mgo.Query, error) {
filterMap, err := mq.createQueryFilter(req)
if err != nil {
return nil, err
}
q := mq.dataBase.C(structName(mq.endPointStruct)).Find(filterMap)
selectFields, err := mq.createFieldsMap(req)
q.Select(selectFields)
sortFields, err := mq.createSortFields(req)
if err != nil {
return nil, err
}
q.Sort(sortFields...)
mq.page.Size, err = getUint(req, "limit", DefaultPageSize)
if err != nil {
return nil, merry.Wrap(err).WithHTTPCode(http.StatusBadRequest)
}
mq.page.Current, err = getUint(req, "page", 1)
if err != nil {
return nil, merry.Wrap(err).WithHTTPCode(http.StatusBadRequest)
}
if mq.page.Current == 0 {
return nil, merry.Wrap(errors.New("page cannot be 0")).WithHTTPCode(http.StatusBadRequest)
}
q = q.Limit(int(mq.page.Size))
q = q.Skip(int((mq.page.Current - 1) * mq.page.Size))
return q, nil
}
// Run runs the query on the database and returns a *Response.
func (mq *MongoQuery) Run(req *http.Request) (*Response, error) {
q, err := mq.CreateQuery(req)
if err != nil {
return nil, err
}
// copy query and reset limit and skip values to count total items
// that would be returned for a query
countQuery := &mgo.Query{}
*countQuery = *q
countQuery.Limit(0)
countQuery.Skip(0)
items, err := countQuery.Count()
if err != nil {
return nil, merry.New("could not create count query").Append(err.Error()).WithHTTPCode(http.StatusInternalServerError)
}
response := &Response{
Page: mq.page,
}
response.Page.Items = uint(items)
response.Page.calculateLastPage()
// create a pointer to an empty slice with same type as enpointStruct to store the
// result of the query
slice := reflect.MakeSlice(reflect.SliceOf(reflect.TypeOf(mq.endPointStruct)), 0, 0)
content := reflect.New(slice.Type()).Interface()
err = q.All(content)
if err != nil {
return nil, merry.New("could not execute q.All()").Append(err.Error()).WithHTTPCode(http.StatusInternalServerError)
}
response.Content = content
return response, nil
}
// DisableParameters disables paramters. If a URL query contains any
// of those paramters, an error is returned.
func (mq *MongoQuery) DisableParameters(paramters ...string) {
for _, p := range paramters {
if !contains(mq.disabledParameters, p) {
mq.disabledParameters = append(mq.disabledParameters, p)
}
}
mq.supportedParameters = createValidParametersMap(mq.endPointStruct, mq.disabledParameters...)
for k, v := range mq.additionalSupportedParamters {
mq.supportedParameters[k] = v
}
}
// AddOrOverwriteValidParameter adds or overwrites a valid parmeter with name and reflect.Kind.
func (mq *MongoQuery) AddOrOverwriteValidParameter(name string, value reflect.Kind) {
mq.additionalSupportedParamters[name] = value
for k, v := range mq.additionalSupportedParamters {
mq.supportedParameters[k] = v
}
}
func (mq *MongoQuery) createQueryFilter(req *http.Request) (map[string]interface{}, error) {
filter := make(map[string]interface{})
for parameterName, parameterValues := range req.URL.Query() {
s := []interface{}{}
if kind, ok := mq.supportedParameters[parameterName]; ok {
// meta parameters are not filters
if _, ok := validMetaParameters[parameterName]; ok {
continue
}
switch kind {
case reflect.Bool:
for _, v := range parameterValues {
b, err := strconv.ParseBool(v)
if err != nil {
return nil, merry.Wrap(err).WithHTTPCode(http.StatusBadRequest)
}
s = append(s, b)
}
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
for _, v := range parameterValues {
i, err := strconv.Atoi(v)
if err != nil {
return nil, merry.Wrap(err).WithHTTPCode(http.StatusBadRequest)
}
s = append(s, i)
}
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
for _, v := range parameterValues {
i, err := strconv.ParseUint(v, 10, 0)
if err != nil {
return nil, merry.Wrap(err).WithHTTPCode(http.StatusBadRequest)
}
s = append(s, uint(i))
}
case reflect.Float32, reflect.Float64:
for _, v := range parameterValues {
f, err := strconv.ParseFloat(v, 64)
if err != nil {
return nil, merry.Wrap(err).WithHTTPCode(http.StatusBadRequest)
}
s = append(s, f)
}
case reflect.String:
if len(parameterValues) == 1 {
if bson.IsObjectIdHex(parameterValues[0]) {
s = []interface{}{bson.ObjectIdHex(parameterValues[0])}
} else {
s = []interface{}{bson.RegEx{Pattern: parameterValues[0], Options: ""}}
}
} else {
for _, v := range parameterValues {
if bson.IsObjectIdHex(v) {
s = append(s, bson.ObjectIdHex(v))
} else {
s = append(s, v)
}
}
}
default:
return nil, merry.Wrap(fmt.Errorf("reflection kind '%s' is not supported", kind)).WithHTTPCode(http.StatusBadRequest)
}
} else {
return nil, merry.Wrap(fmt.Errorf("parameter '%s' is not supported", parameterName)).WithHTTPCode(http.StatusBadRequest)
}
if len(s) == 1 {
filter[parameterName] = s[0]
} else {
filter[parameterName] = map[string]interface{}{
"$in": s,
}
}
}
return filter, nil
}
func (mq *MongoQuery) createFieldsMap(req *http.Request) (map[string]interface{}, error) {
fields := make(map[string]interface{})
if _field, ok := req.URL.Query()["field"]; ok {
for _, v := range _field {
if _, ok := mq.supportedParameters[v]; !ok {
return nil, fmt.Errorf("unsupported field value: %s", v)
}
fields[v] = 1
}
}
return fields, nil
}
func (mq *MongoQuery) createSortFields(req *http.Request) ([]string, error) {
sortFields := []string{}
if _sortField, ok := req.URL.Query()["sort"]; ok {
for _, v := range _sortField {
if _, ok := mq.supportedParameters[strings.Trim(v, "-")]; !ok {
return nil, merry.Wrap(fmt.Errorf("unsupported field value: %s", v)).WithHTTPCode(http.StatusBadRequest)
}
sortFields = append(sortFields, v)
}
}
return sortFields, nil
}
func (p *Page) calculateLastPage() {
p.Last = uint(math.Ceil(float64(p.Items) / float64(p.Size)))
}