This is a simple "query builder / executor" for Google's Datastore.
For the moment it is simple, but I would like to build it out with some better features.
The primary purpose right now is to make some go based queries more readable or at least more consistent especially.
All this library does is provide wrappers which can be used to wrap existing datastore queries.
It allows you to preform operations like "and" or "or" between two queries in a more standard way.
It runs key-only queries meaning you will need to query the keys with the resulting query yourself with a GetMulti.
For a runnable demonstration, see the command in cmd/dsquery-example.
Given this data structure:
package example
import (
"cloud.google.com/go/datastore"
)
const (
FruitKind = "Fruit"
)
type Fruit struct {
DSKey *datastore.Key `datastore:"__key__"`
Name string `datastore:",noindex"`
Color string
Producers []string
}And the data
| Key | Name | Color | Producers |
|---|---|---|---|
123 |
Potato |
Brown |
[Ireland, Peru, Scotland] |
234 |
Orange |
Orange |
[USA, Brazil, China] |
345 |
Chilli |
Red |
[Mexico, Turkey, China] |
Say for the query:
- All Fruits that are Orange or Red
fruitQuery := &dsquery.Or{
Name: "root fruit query",
Queries: []*datastore.Query{
datastore.NewQuery(FruitKind).FilterField("Color", "=", "Orange"),
datastore.NewQuery(FruitKind).FilterField("Color", "=", "Red"),
},
SubQueries: nil,
}
keys, err := fruitQuery.Query(dsClient, request.Context())
if err != nil {
logger.Errorf("Query error %v", err)
return
}
logger.Infof("Running GetMulti for %d fruit", len(keys))
fruits := make([]*Fruit, len(keys), len(keys))
if err := dsClient.GetMulti(request.Context(), keys, fruits); err != nil {
logger.Errorf("GetMulti error %v", err)
return err
}Should return: Orange and Chilli
Say for the query:
- All Fruits that are (Orange or Red) AND (Grown in China OR USA)
fruitQuery := &dsquery.And{
Name: "root fruit query",
Queries: []*datastore.Query{},
SubQueries: []dsquery.Query{
&dsquery.Or{
Name: "color query",
Queries: []*datastore.Query{
datastore.NewQuery(FruitKind).FilterField("Color", "=", "Orange"),
datastore.NewQuery(FruitKind).FilterField("Color", "=", "Red"),
},
&dsquery.Or{
Name: "country query",
Queries: []*datastore.Query{
datastore.NewQuery(FruitKind).FilterField("Producers", "=", "USA"),
datastore.NewQuery(FruitKind).FilterField("Producers", "=", "China"),
},
},
}
keys, err := fruitQuery.Query(dsClient, request.Context())
if err != nil {
logger.Errorf("Query error %v", err)
return
}
logger.Infof("Running GetMulti for %d fruit", len(keys))
fruits := make([]*Fruit, len(keys), len(keys))
if err := dsClient.GetMulti(request.Context(), keys, fruits); err != nil {
logger.Errorf("GetMulti error %v", err)
return err
}Should return: Orange and Chilli
Happy to receive PRs.. Especially around documentation and testing.
This project is licensed under the MIT License.