crdb

package module
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 Go to latest Published: Dec 30, 2018 License: MIT Imports: 8 Imported by: 10

README

crdb

Database initialization Utility methods for cockroachDB and Postgres.

usage

go get the package:

go get -u github.com/tomogoma/crdb

Use to initialize your cockroach/postgres database, godoc here:


// 1. Define a DSN to connect to the DB.
// See https://godoc.org/github.com/lib/pq#hdr-Connection_String_Parameters
// for all DSN options.

// Config can be read from a JSON or YAML file.
config := crdb.Config{
    User: "my_username",
    Password: "my_strong_password",
    DBName: "my_db_name",
    SSLMode: "disable",
}
// config#FormatDSN() yields a string like
//    "user='my_username' password='my_strong_password' dbname='my_db_name' sslmode='disable'"
// You can use crdb.Config or format DSN on your own.
DSN := config.FormatDSN()

// 2. Connect to and ping the DBMS.

db, err := crdb.DBConn(DSN)
if err != nil {
    log.Fatalf("Error establishing connection to DB: %v", err)
}

// 3. Instantiate your database and its tables (if not already instantiated)

tableDescs := []string{
    "CREATE TABLE IF NOT EXISTS foos (name VARCHAR(25))",
    "CREATE TABLE IF NOT EXISTS bars (name VARCHAR(25))",
}
err = crdb.InstantiateDB(db, config.DBName, tableDescs...)
if err != nil {
    log.Fatalf("Error instantiating database: %v", err)
}

Documentation

Index

Examples

Constants

View Source 
const (

	// Greater than.
	OpGT = ">"
	// Greater than or equal to.
	OpGTOrET = ">="
	// Equal to.
	OpET = "="
	// Less than or equal to.
	OpLTOrET = "<="
	// Less than.
	OpLT        = "<"
	OpIsNull    = "is_null"
	OpIsNotNull = "is_not_null"
	// This Operator is not a one to one mapping like the rest
	OpContain = "CONTAIN"
	// This Operator is not a one to one mapping like the rest
	OpContainFold = "CONTAIN_FOLD"
)
View Source 
const (
	OrderAsc  = "ASC"
	OrderDesc = "DESC"
)

Variables

This section is empty.

Functions

func AppendUpdate 

func AppendUpdate(upd Update, updCol, updCols string, updArgs []interface{}) (string, []interface{})

AppendUpdate adds the value of upd to updArgs and updCol (column to be updated) to updCols if upd IsUpdating. The result of appending to updCols and updArgs are returned respectively. If upd IsUpdating is false, updCols and updArgs are returned unmodified.

func CloseDBOnError 

func CloseDBOnError(db *sql.DB, err error) (*sql.DB, error)

CloseDBOnError closes connection to the given database if err != nil. It then returns the error.

func ColDesc 

func ColDesc(cols ...string) string

ColDesc returns a string containing cols in the given order separated by ",".

Example 
package main

import (
	"fmt"
	"github.com/tomogoma/crdb"
)

func main() {
	colDesc := crdb.ColDesc("name", "unit_price", "quantity")
	fmt.Print(colDesc)
}

Output:

name, unit_price, quantity

func ColDescTbl 

func ColDescTbl(tbl string, cols ...string) string

ColDescTbl returns a string containing cols for tbl in the given order separated by ",".

Example 
package main

import (
	"fmt"
	"github.com/tomogoma/crdb"
)

func main() {
	tblName := "items"
	colDesc := crdb.ColDescTbl(tblName, "name", "unit_price", "quantity")
	fmt.Print(colDesc)
}

Output:

items.name, items.unit_price, items.quantity

func ConcatWhereClause 

func ConcatWhereClause(c *Comparison, col, where, whereOp string, args []interface{}) (string, []interface{})

ConcatWhereClause calls WhereClause on c, col, args and concatenates it to a previous where clause to have an SQL statement part of the form 

col_one >= 4 AND col_two IS NULL

'col_one >= 4' is picked from where while 'AND' is picked from whereOp and 'col_two IS NULL' is generated using WhereClause. See WhereClause for details.

func DBConn 

func DBConn(dsn string) (*sql.DB, error)

DBConn establishes a connection to the database.

func IgnoreDBNotFoundError 

func IgnoreDBNotFoundError(err error) error

IgnoreDBNotFoundError returns nil if err is nil or is a *pq.Error and has the DB-not-found code (3D000) otherwise it returns err.

func InstantiateDB 

func InstantiateDB(db *sql.DB, dbName string, tableDescs ...string) error

InstantiateDB creates the database and tables based on dbName and tableDescs.

Example 
package main

import (
	"github.com/tomogoma/crdb"
	"log"
)

func main() {
	// 1. Define a DSN to connect to the DB.
	// See https://godoc.org/github.com/lib/pq#hdr-Connection_String_Parameters
	// for all DSN options.

	// Config can be read from a JSON or YAML file.
	config := crdb.Config{
		User:        "root",
		Port:        26257,
		DBName:      "crdb_test",
		SSLMode:     "require",
		SSLCert:     "/etc/cockroachdb/certs/node.crt",
		SSLKey:      "/etc/cockroachdb/certs/node.key",
		SSLRootCert: "/etc/cockroachdb/certs/ca.crt",
	}
	// config#FormatDSN() yields a string like
	//    "user='my_username' password='my_strong_password' dbname='my_db_name' sslmode='disable'"
	// You can use crdb.Config or format DSN on your own.
	DSN := config.FormatDSN()

	// 2. Connect to and ping the DBMS.

	db, err := crdb.DBConn(DSN)
	if err != nil {
		log.Fatalf("Error establishing connection to DB: %v", err)
	}

	// 3. Instantiate your database and its tables (if not already instantiated)

	tableDescs := []string{
		"CREATE TABLE IF NOT EXISTS foos (name VARCHAR(25))",
		"CREATE TABLE IF NOT EXISTS bars (name VARCHAR(25))",
	}
	err = crdb.InstantiateDB(db, config.DBName, tableDescs...)
	if err != nil {
		log.Fatalf("Error instantiating database: %v", err)
	}
}

func OrderBy 

func OrderBy(co *ColOrders, mapFunc func(modelCol interface{}) (string, error)) (string, error)

OrderBy generates an SQL statement part of the form 

ORDER BY col_one ASC, col_two DESC

It determines this using co. mapFunc is used to map the col in each Col to a real column e.g. col_one of tbl_a.col_one. The error returned by mapFunc is returned as is and OrderBy stops generating.

func Pagination 

func Pagination(offset, count int64, args []interface{}) (string, []interface{})

Pagination generates an SQL statement part of the form 

LIMIT $3 OFFSET $4

It appends offset and count to the args and uses the length of the args to determine the index of the offset and count args (3 and 4) before returning the new set of args.

func TryConnect 

func TryConnect(dsn string, db *sql.DB) (*sql.DB, error)

TryConnect attempts to connect to db using dsn if db is nil.

func WhereClause 

func WhereClause(c *Comparison, col string, args []interface{}) (string, []interface{})

WhereClause generates an SQL statement part of the form 

column_one >= $4

...or aborts if c is nil. Note that the 'WHERE' keyword is NOT included in the result. It uses args to determine the index (4) in the statement and returns the same args with c.Val appended. Mapping in the example is done as follows, col => 'column_one', c.Op => '>=' and $4 is generated based on len(args). c.Op uses the provided c.Op value if no standard operator is found.

Types

type BoolUpdate 

type BoolUpdate struct {
	Updating bool
	NewVal   bool
}

func (BoolUpdate) IsUpdating 

func (su BoolUpdate) IsUpdating() bool

func (BoolUpdate) Value 

func (su BoolUpdate) Value() interface{}

type ColOrders 

type ColOrders struct {
	Orders []string
	Cols   []interface{}
}

type Comparison 

type Comparison struct {
	Op  string
	Val interface{}
}

func NewComparisonString 

func NewComparisonString(op string, val string) *Comparison

NewComparisonString returns a pointer to Comparison if val is not empty otherwise nil.

type Config 

type Config struct {
	User           string `json:"user,omitempty" yaml:"user,omitempty"`
	Password       string `json:"password,omitempty" yaml:"password,omitempty"`
	Host           string `json:"host,omitempty" yaml:"host,omitempty"`
	Port           int    `json:"port,omitempty" yaml:"port,omitempty"`
	DBName         string `json:"dbName,omitempty" yaml:"dbName,omitempty"`
	ConnectTimeout int    `json:"connectTimeout,omitempty" yaml:"connectTimeout,omitempty"`
	SSLMode        string `json:"sslMode,omitempty" yaml:"sslMode,omitempty"`
	SSLCert        string `json:"sslCert,omitempty" yaml:"sslCert,omitempty"`
	SSLKey         string `json:"sslKey,omitempty" yaml:"sslKey,omitempty"`
	SSLRootCert    string `json:"sslRootCert,omitempty" yaml:"sslRootCert,omitempty"`

	ConnMaxLifetime *time.Duration `json:"connMaxLifeTime,omitempty" yaml:"connMaxLifeTime,omitempty"`
	MaxIdleConns    *int           `json:"maxIdleConns,omitempty" yaml:"maxIdleConns,omitempty"`
	MaxOpenConns    *int           `json:"maxOpenConns,omitempty" yaml:"maxOpenConns,omitempty"`
}

More detail at https://godoc.org/github.com/lib/pq#hdr-Connection_String_Parameters

func (Config) FormatDSN 

func (d Config) FormatDSN() string

FormatDSN formats Config values into a connection as per https://godoc.org/github.com/lib/pq#hdr-Connection_String_Parameters

type DSNFormatter 

type DSNFormatter interface {
	FormatDSN() string
}

type Float64Update 

type Float64Update struct {
	Updating bool
	NewVal   float64
}

func (Float64Update) IsUpdating 

func (su Float64Update) IsUpdating() bool

func (Float64Update) Value 

func (su Float64Update) Value() interface{}

type Int64Update 

type Int64Update struct {
	Updating bool
	NewVal   int64
}

func (Int64Update) IsUpdating 

func (su Int64Update) IsUpdating() bool

func (Int64Update) Value 

func (su Int64Update) Value() interface{}

type StringUpdate 

type StringUpdate struct {
	Updating bool
	NewVal   string
}

func (StringUpdate) IsUpdating 

func (su StringUpdate) IsUpdating() bool

func (StringUpdate) Value 

func (su StringUpdate) Value() interface{}

type Update 

type Update interface {
	IsUpdating() bool
	Value() interface{}
}

Source Files

View all Source files

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