reader

package
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 Go to latest Published: Jul 25, 2024 License: Apache-2.0 Imports: 24 Imported by: 0

README

Reader

Reader service provide ability to read view data.

Introduction

A reader can read a single view or view that has complex structure with to many or to one relations. A view represents a database table, SQL or SQL Template. For multi relation view each view data can be store in different database vendor. Underlying view can provided or autogenerated, datly will map all struct Field using sqlx tag.

You can autogenerated view struct using dql

For example to generate invoice go struct, run the following command:

invoice.sql

SELECT
invoice.*,
item.*
FROM (SELECT * FROM invoice) invoice
JOIN (SELECT * FROM invoice_list_item) item ON item.invoice_id = invoice.id

    datly -C='demo|mysql|demo:demo@tcp(127.0.0.1:3306)/mydb?parseTime=true' -X invoice.sql
    open http://127.0.0.1:8080/v1/api/meta/struct/dev/invoice

Provided struct may optionally define the following method to customize fetched/assembled data.

  • OnFetch(ctx context.Context) error: invoked by reader once record is fetched from database
  • OnRelation(ctx context.Context): invoked by reader once all relations are assembled

Usage

Reading view data

Basic view reader example

package reader_test

import (
	"context"
	"encoding/json"
	"fmt"
	"github.com/viant/datly/reader"
	"github.com/viant/datly/view"
	"log"
	"reflect"
	"time"
)

type Invoice struct {
	Id           int32      `sqlx:"id"`
	CustomerName *string    `sqlx:"customer_name"`
	InvoiceDate  *time.Time `sqlx:"invoice_date"`
	DueDate      *time.Time `sqlx:"due_date"`
	TotalAmount  *string    `sqlx:"total_amount"`
	Items        []*Item
}

type Item struct {
	Id          int32   `sqlx:"id"`
	InvoiceId   *int64  `sqlx:"invoice_id"`
	ProductName *string `sqlx:"product_name"`
	Quantity    *int64  `sqlx:"quantity"`
	Price       *string `sqlx:"price"`
	Total       *string `sqlx:"total"`
}




func ExampleService_ReadDataView() {


	aReader := reader.New()
	conn := aReader.Resource.AddConnector("dbName", "database/sql  driverName", "database/sql dsn")

	invoiceView := view.NewView("invoice", "INVOICE",
		view.WithConnector(conn),
		view.WithCriteria("id"),
		view.WithViewType(reflect.TypeOf(&Invoice{})),
		view.WithOneToMany("Items", "id",
			view.NwReferenceView("", "invoice_id",
				view.NewView("items", "invoice_list_item", view.WithConnector(conn)))),
	)

	aReader.Resource.AddViews(invoiceView)
	if err := aReader.Resource.Init(context.Background()); err != nil {
		log.Fatal(err)
	}

	var  invoices= make([]*Invoice, 0)
	if err := aReader.ReadInto(context.Background(), "invoice", &invoices, reader.WithCriteria( "status = ?",1));err != nil {
		log.Fatal(err)
	}
	invociesJSON, _:=json.Marshal(invoices)
	fmt.Printf("invocies: %s\n", invociesJSON)



}

Reading view data from various databases

A read can read data for one or many database connection while assembling data view.

package reader_test

import (
	"context"
	"encoding/json"
	"fmt"
	"github.com/viant/datly/reader"
	"github.com/viant/datly/view"
	"log"
	"reflect"
	"time"
)

type Trader struct {
    Id          int32      `sqlx:"id"`
    FirstName   *string    `sqlx:"first_name"`
    LastName    *string    `sqlx:"last_name"`
    Email       *string    `sqlx:"email"`
    PhoneNumber *string    `sqlx:"phone_number"`
    JoinDate    *time.Time `sqlx:"join_date"`
    Acl         *Acl
}

type Acl struct {
    UserId         int   `sqlx:"USER_ID"`
    IsReadonly     *bool `sqlx:"IS_READONLY"`
    CanUseFeature1 *bool `sqlx:"CAN_USE_FEATURE1"`
}


func ExampleService_MultiDbReadInto() {

	aReader := reader.New()
	mainConn := aReader.Resource.AddConnector("main", "mysql", "database/sql dsn")
	aclConn := aReader.Resource.AddConnector("aci", "dynamodb", "database/sql dsn")

	aView := view.NewView("trader", "TRADER",
		view.WithConnector(mainConn),
		view.WithCriteria("id"),
		view.WithViewType(reflect.TypeOf(&Trader{})),
		view.WithOneToOne("Acl", "id",
			view.NwReferenceView("UserId", "USER_ID",
				view.NewView("trader_acl", "USER_ACL",
					view.WithSQL(`SELECT
                          USER_ID,
                          ARRAY_EXISTS(ROLE, 'READ_ONLY') AS IS_READONLY,
                          ARRAY_EXISTS(PERMISSION, 'FEATURE1') AS CAN_USE_FEATURE1
                    FROM USER_ACL `),
					view.WithConnector(aclConn)))),
	)
	aReader.Resource.AddViews(aView)
	if err := aReader.Resource.Init(context.Background()); err != nil {
		log.Fatal(err)
	}

  var traders = make([]*Invoice, 0)
  if err := aReader.ReadInto(context.Background(), "trader", &traders); err != nil {
    log.Fatal(err)
  }
  traderJSON, _ := json.Marshal(traders)
  fmt.Printf("traders: %s\n", traderJSON)

}

Reading data with SQL template

A view can read from a table, SQL or SQL template

package reader_test


type Product struct {
	Id          int32      `sqlx:"ID"`
	Name        *string    `sqlx:"NAME"`
	VendorId    *int64     `sqlx:"VENDOR_ID"`
	Status      *int64     `sqlx:"STATUS"`
	Created     *time.Time `sqlx:"CREATED"`
	UserCreated *int64     `sqlx:"USER_CREATED"`
	Updated     *time.Time `sqlx:"UPDATED"`
	UserUpdated *int64     `sqlx:"USER_UPDATED"`
	Vendor      *Vendor
	Performance []*Performance
}

type Vendor struct {
	Id          int32      `sqlx:"ID"`
	Name        *string    `sqlx:"NAME"`
	AccountId   *int64     `sqlx:"ACCOUNT_ID"`
	Created     *time.Time `sqlx:"CREATED"`
	UserCreated *int64     `sqlx:"USER_CREATED"`
	Updated     *time.Time `sqlx:"UPDATED"`
	UserUpdated *int64     `sqlx:"USER_UPDATED"`
}

type Performance struct {
	LocationId *int     `sqlx:"location_id"`
	ProductId  *int     `sqlx:"product_id"`
	Quantity   *float64 `sqlx:"quantity"`
	Price      *float64 `sqlx:"price"`
}

var perfTemplate = `SELECT
location_id,
product_id,
SUM(quantity) AS quantity,
AVG(payment) * 1.25 AS price
FROM bqdev.product_performance t
WHERE 1 = 1
#if($Unsafe.period == "today")
    AND TIMESTAMP_TRUNC(t.timestamp, DAY) = TIMESTAMP_TRUNC(CURRENT_TIMESTAMP(), DAY)
#elseif ($Unsafe.period == "yesterday")
    AND TIMESTAMP_TRUNC(t.timestamp, DAY) = TIMESTAMP_TRUNC(TIMESTAMP_ADD(CURRENT_TIMESTAMP(), INTERVAL -1 DAY),  DAY)
#end
GROUP BY 1, 2`



func ExampleService_ReadWithTemplate() {


	aReader := reader.New()
	mainConn := aReader.Resource.AddConnector("main", "mysql", "database/sql dsn")
	aclConn := aReader.Resource.AddConnector("perf", "bigquery", "database/sql dsn")


	aView := view.NewView("product", "PRODUCT",
		view.WithConnector(mainConn),
		view.WithCriteria("ID"),
		view.WithViewType(reflect.TypeOf(&Product{})),
		view.WithOneToOne("Vendor", "VENDOR_ID",
			view.NwReferenceView("ID", "ID",
				view.NewView("product_vendor", "VENDOR",
					view.WithConnector(mainConn)))),
		view.WithOneToMany("Performance", "ID",
			view.NwReferenceView("ProductId", "product_id",
				view.NewView("performance", "product_performance",
					view.WithTemplate(view.NewTemplate("performance",
						view.WithTemplateParameter(view.NewParameter("period",
							view.NewQueryLocation("period"),
							view.WithParameterType(reflect.TypeOf("")),
						)))),
					view.WithConnector(aclConn)))),
	)

	aReader.Resource.AddViews(aView)
	if err := aReader.Resource.Init(context.Background()); err != nil {
		log.Fatal(err)
	}

	var products = make([]*Product, 0)

	if err := aReader.ReadInto(context.Background(), "trader", &products, 
		reader.WithParameter("performance:period", "today")
	); err != nil {
		log.Fatal(err)
	}
	productsJSON, _ := json.Marshal(products)
	fmt.Printf("products: %s\n", productsJSON)

}

Reading data with lifecycle hooks

Data view underlying struct has ability to customize final data by implementing the following methods:

  • OnFetch(ctx context.Context) error: invoked by reader once record is fetched from database
  • OnRelation(ctx context.Context): invoked by reader once all relations are assembled
package reader_test

import (
  "context"
  "encoding/json"
  "fmt"
  "github.com/viant/datly/reader"
  "github.com/viant/datly/view"
  "github.com/viant/parsly"
  "github.com/viant/sqlparser"
  "github.com/viant/sqlparser/expr"
  "github.com/viant/sqlparser/node"
  "log"
  "reflect"
 )

type Audience struct {
  Id              int32   `sqlx:"ID"`
  Name            *string `sqlx:"NAME"`
  MatchExpression *string `sqlx:"MATCH_EXPRESSION"`
  dealIds         []int   `sqlx:"-"`
  Deals           []*Deal
}

type Deal struct {
  Id   int32   `sqlx:"ID"`
  Name *string `sqlx:"NAME"`
  Fee  *string `sqlx:"FEE"`
}

func (a *Audience) OnFetch(ctx context.Context) error {
  if a.MatchExpression != nil && *a.MatchExpression != "" {
    qualify := expr.Qualify{}
    cursor := parsly.NewCursor("", []byte(*a.MatchExpression), 0)
    if err := sqlparser.ParseQualify(cursor, &qualify); err != nil {
      return err
    }

    sqlparser.Traverse(qualify.X, func(n node.Node) bool {
      switch actual := n.(type) {
      case *expr.Binary:
        x := sqlparser.Stringify(actual.X)
        if strings.ToLower(actual.Op) == "in" && strings.ToLower(x) == "deals" {
          par := actual.Y.(*expr.Parenthesis)
          values := par.Raw[1 : len(par.Raw)-1]
          for _, value := range strings.Split(values, ",") {
            value = strings.TrimSpace(value)
            if intVal, err := strconv.Atoi(value); err == nil {
              a.dealIds = append(a.dealIds, intVal)
            }
          }
          return true
        }
      }
      return true
    })
  }
  return nil
}

func ExampleService_LifeCycleReadInto() {

  aReader := reader.New()
  mainConn := aReader.Resource.AddConnector("main", "mysql", "database/sql dsn")

  aView := view.NewView("audience", "AUDIENCE",
    view.WithConnector(mainConn),
    view.WithCriteria("ID"),
    view.WithViewType(reflect.TypeOf(&Audience{})),
    view.WithOneToMany("Deals", "deal_ids",
      view.NwReferenceView("ID", "id",
        view.NewView("deal", "DEAL", view.WithConnector(mainConn)))),
  )

  aReader.Resource.AddViews(aView)
  if err := aReader.Resource.Init(context.Background()); err != nil {
    log.Fatal(err)
  }

  var traders = make([]*Audience, 0)
  if err := aReader.ReadInto(context.Background(), "trader", &traders); err != nil {
    log.Fatal(err)
  }
  traderJSON, _ := json.Marshal(traders)
  fmt.Printf("traders: %s\n", traderJSON)
}

Documentation

Index

Constants

This section is empty.

Variables

View Source 
var Dif = func(t1, t2 time.Time) time.Duration {
	return t1.Sub(t2)
}
View Source 
var Now = time.Now

Functions

This section is empty.

Types

type Builder 

type Builder struct{}

Builder represent SQL Builder

func NewBuilder 

func NewBuilder() *Builder

NewBuilder creates Builder instance

func (*Builder) Build 

func (b *Builder) Build(ctx context.Context, opts ...BuilderOption) (*cache.ParmetrizedQuery, error)

Build builds SQL Select statement

func (*Builder) CacheMetaSQL 

func (b *Builder) CacheMetaSQL(ctx context.Context, aView *view.View, selector *view.Statelet, batchData *view.BatchData, relation *view.Relation, parent *expand.ViewContext) (*cache.ParmetrizedQuery, error)

func (*Builder) CacheSQL 

func (b *Builder) CacheSQL(ctx context.Context, aView *view.View, selector *view.Statelet) (*cache.ParmetrizedQuery, error)

func (*Builder) CacheSQLWithOptions 

func (b *Builder) CacheSQLWithOptions(ctx context.Context, aView *view.View, statelet *view.Statelet, batchData *view.BatchData, relation *view.Relation, parent *expand.ViewContext) (*cache.ParmetrizedQuery, error)

func (*Builder) ExactMetaSQL 

func (b *Builder) ExactMetaSQL(ctx context.Context, aView *view.View, selector *view.Statelet, batchData *view.BatchData, relation *view.Relation, parent *expand.ViewContext) (*cache.ParmetrizedQuery, error)

type BuilderOption 

type BuilderOption func(*builderOptions)

func WithBuilderBatchData 

func WithBuilderBatchData(batchData *view.BatchData) BuilderOption

WithBuilderBatchData with batch data

func WithBuilderExclude 

func WithBuilderExclude(columnsIn, pagination bool) BuilderOption

WithExcludeAll excludes all

func WithBuilderExpander 

func WithBuilderExpander(expander expand.Expander) BuilderOption

WithBuilderExpander sets expander

func WithBuilderParent 

func WithBuilderParent(parent *expand.ViewContext) BuilderOption

WithBuilderParent sets parent

func WithBuilderPartitions 

func WithBuilderPartitions(partitions *view.Partitions) BuilderOption

func WithBuilderRelation 

func WithBuilderRelation(relation *view.Relation) BuilderOption

WithBuilderRelation sets relation

func WithBuilderStatelet 

func WithBuilderStatelet(statelet *view.Statelet) BuilderOption

WithBuilderStatelet set statelet

func WithBuilderView 

func WithBuilderView(view *view.View) BuilderOption

WithBuilderView sets view

type Event 

type Event string
const (
	Pending Event = "Pending"
	Error   Event = "Error"
	Success Event = "Success"
)

type Exclude 

type Exclude struct {
	ColumnsIn  bool
	Pagination bool
}

type OnFetcher 

type OnFetcher interface {
	OnFetch(ctx context.Context) error
}

OnFetcher lifecycle interface that if entity implements, OnFetch(ctx context.NormalizeObject) is call after record is fetched from db

type OnRelationer 

type OnRelationer interface {
	OnRelation(ctx context.Context)
}

OnRelationer lifecycle interface that if entity implements, OnRelation(ctx context.NormalizeObject) is call after relation is assembled

type Option 

type Option func(session *Session) error

Option represents a session option

func WithCacheDisabled 

func WithCacheDisabled(flag bool) Option

WithCacheDisabled return

func WithCacheRefresh 

func WithCacheRefresh() Option

func WithCriteria 

func WithCriteria(whereClause string, parameters ...interface{}) Option

WithCriteria returns criteria option

func WithDryRun 

func WithDryRun() Option

WithDryRun returns with dry run option

func WithIncludeSQL 

func WithIncludeSQL(flag bool) Option

WithIncludeSQL with include SQL

func WithMetrics 

func WithMetrics(metrics *response.Metrics) Option

WithMetrics returns with dry run option

func WithParameter 

func WithParameter(name string, value interface{}) Option

WithParameter returns set parameter option

func WithParent 

func WithParent(parent *view.View) Option

WithParent returns parent option

func WithResourceState 

func WithResourceState(states *view.State) Option

WithResourceState returns states option

func WithRevealMetric 

func WithRevealMetric(flag bool) Option

type Output 

type Output struct {
	Data        interface{}
	DataType    reflect.Type
	DataPtr     interface{} //slice pointer
	DataSummary interface{}
	Metrics     response.Metrics
	Filters     predicate.Filters //filter used by request
}

Session groups view required to Read view

type ParentData 

type ParentData struct {
	View     *view.View
	Selector *view.Statelet
}

Session groups view required to Read view

func (*ParentData) AsParam 

func (d *ParentData) AsParam() *expand.ViewContext

type Service 

type Service struct {
	// contains filtered or unexported fields
}

Service represents reader service

func New 

func New() *Service

New creates Service instance

func (*Service) BuildCriteria 

func (s *Service) BuildCriteria(ctx context.Context, value interface{}, options *codec.CriteriaBuilderOptions) (*codec.Criteria, error)

func (*Service) HandleSQLError 

func (s *Service) HandleSQLError(err error, session *Session, aView *view.View, matcher *cache.ParmetrizedQuery, stats *response.SQLExecution) (*response.SQLExecution, error)

func (*Service) NewExecutionInfo 

func (s *Service) NewExecutionInfo(session *Session, index *cache.ParmetrizedQuery, cacheStats *cache.Stats, cacheError error) *response.SQLExecution

func (*Service) Read 

func (s *Service) Read(ctx context.Context, session *Session) error

Read select view from database based on View and assign it to dest. ParentDest has to be pointer.

func (*Service) ReadInto 

func (s *Service) ReadInto(ctx context.Context, dest interface{}, aView *view.View, opts ...Option) error

ReadInto reads Data into provided destination, * dDest` is required. It has to be a pointer to `interface{}` or pointer to slice of `T` or `*T`

type Session 

type Session struct {
	IncludeSQL    bool
	CacheDisabled bool
	RevealMetric  bool
	CacheRefresh  cache.Refresh
	DryRun        bool
	View          *view.View
	State         *view.State
	Parent        *view.View
	Output
	MetricPtr *response.Metrics
	// contains filtered or unexported fields
}

Session groups view required to Read view

func NewSession 

func NewSession(dest interface{}, aView *view.View, opts ...Option) (*Session, error)

NewSession creates a session

func (*Session) AddCriteria 

func (s *Session) AddCriteria(aView *view.View, criteria string, placeholders ...interface{})

AddCriteria adds the supplied view criteria

func (*Session) AddMetric 

func (s *Session) AddMetric(m *response.Metric)

func (*Session) HandleViewMeta 

func (s *Session) HandleViewMeta(meta interface{}) error

func (*Session) Init 

func (s *Session) Init() error

Init initializes session

func (*Session) IsCacheEnabled 

func (s *Session) IsCacheEnabled(aView *view.View) bool

func (*Session) Lookup 

func (s *Session) Lookup(v *view.View) *structology.State

func (*Session) ParentData 

func (s *Session) ParentData() (*ParentData, bool)

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