query

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 Go to latest Published: Mar 4, 2020 License: MIT Imports: 14 Imported by: 0

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var ErrResultClosed = errors.New("result already closed")

ErrResultClosed is returned when trying to close an already closed result.

Functions

This section is empty.

Types

type AndOp 

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

AndOp is the And operator.

func And 

func And(a, b Expr) *AndOp

And creates an expression that evaluates a And b And returns true if both are truthy.

func (*AndOp) Eval 

func (op *AndOp) Eval(ctx EvalStack) (document.Value, error)

Eval implements the Expr interface. It evaluates a and b and returns true if both evalutate to true.

func (AndOp) LeftHand 

func (op AndOp) LeftHand() Expr

func (AndOp) Precedence 

func (op AndOp) Precedence() int

func (AndOp) RightHand 

func (op AndOp) RightHand() Expr

func (AndOp) SetLeftHandExpr 

func (op AndOp) SetLeftHandExpr(a Expr)

func (AndOp) SetRightHandExpr 

func (op AndOp) SetRightHandExpr(b Expr)

type Cast added in v0.5.0 

type Cast struct {
	Expr      Expr
	ConvertTo document.ValueType
}

Cast represents the CAST expression. It returns the primary key of the current document.

func (Cast) Eval added in v0.5.0 

func (c Cast) Eval(ctx EvalStack) (document.Value, error)

Eval returns the primary key of the current document.

type CmpOp 

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

A CmpOp is a comparison operator.

func Eq 

func Eq(a, b Expr) CmpOp

Eq creates an expression that returns true if a equals b.

func Gt 

func Gt(a, b Expr) CmpOp

Gt creates an expression that returns true if a is greater than b.

func Gte 

func Gte(a, b Expr) CmpOp

Gte creates an expression that returns true if a is greater than or equal to b.

func Lt 

func Lt(a, b Expr) CmpOp

Lt creates an expression that returns true if a is lesser than b.

func Lte 

func Lte(a, b Expr) CmpOp

Lte creates an expression that returns true if a is lesser than or equal to b.

func Neq 

func Neq(a, b Expr) CmpOp

Neq creates an expression that returns true if a equals b.

func NewCmpOp added in v0.5.0 

func NewCmpOp(a, b Expr, t scanner.Token) CmpOp

NewCmpOp creates a comparison operator.

func (CmpOp) Eval 

func (op CmpOp) Eval(ctx EvalStack) (document.Value, error)

Eval compares a and b together using the operator specified when constructing the CmpOp and returns the result of the comparison.

func (CmpOp) LeftHand 

func (op CmpOp) LeftHand() Expr

func (CmpOp) Precedence 

func (op CmpOp) Precedence() int

func (CmpOp) RightHand 

func (op CmpOp) RightHand() Expr

func (CmpOp) SetLeftHandExpr 

func (op CmpOp) SetLeftHandExpr(a Expr)

func (CmpOp) SetRightHandExpr 

func (op CmpOp) SetRightHandExpr(b Expr)

type CreateIndexStmt 

type CreateIndexStmt struct {
	IndexName   string
	TableName   string
	Path        document.ValuePath
	IfNotExists bool
	Unique      bool
}

CreateIndexStmt is a DSL that allows creating a full CREATE INDEX statement. It is typically created using the CreateIndex function.

func (CreateIndexStmt) IsReadOnly 

func (stmt CreateIndexStmt) IsReadOnly() bool

IsReadOnly always returns false. It implements the Statement interface.

func (CreateIndexStmt) Run 

func (stmt CreateIndexStmt) Run(tx *database.Transaction, args []driver.NamedValue) (Result, error)

Run runs the Create index statement in the given transaction. It implements the Statement interface.

type CreateTableStmt 

type CreateTableStmt struct {
	TableName   string
	IfNotExists bool
	Config      database.TableConfig
}

CreateTableStmt is a DSL that allows creating a full CREATE TABLE statement.

func (CreateTableStmt) IsReadOnly 

func (stmt CreateTableStmt) IsReadOnly() bool

IsReadOnly always returns false. It implements the Statement interface.

func (CreateTableStmt) Run 

func (stmt CreateTableStmt) Run(tx *database.Transaction, args []driver.NamedValue) (Result, error)

Run runs the Create table statement in the given transaction. It implements the Statement interface.

type DeleteStmt 

type DeleteStmt struct {
	TableName string
	WhereExpr Expr
}

DeleteStmt is a DSL that allows creating a full Delete query.

func (DeleteStmt) IsReadOnly 

func (stmt DeleteStmt) IsReadOnly() bool

IsReadOnly always returns false. It implements the Statement interface.

func (DeleteStmt) Run 

func (stmt DeleteStmt) Run(tx *database.Transaction, args []driver.NamedValue) (Result, error)

Run deletes matching documents by batches of deleteBufferSize documents. Some engines can't iterate while deleting keys (https://github.com/etcd-io/bbolt/issues/146) and some can't create more than one iterator per read-write transaction (https://github.com/dgraph-io/badger/issues/1093). To deal with these limitations, Run will iterate on a limited number of documents, copy the keys to a buffer and delete them after the iteration is complete, and it will do that until there is no document left to delete. Increasing deleteBufferSize will occasionate less key searches (O(log n) for most engines) but will take more memory.

type DropIndexStmt 

type DropIndexStmt struct {
	IndexName string
	IfExists  bool
}

DropIndexStmt is a DSL that allows creating a DROP INDEX query.

func (DropIndexStmt) IsReadOnly 

func (stmt DropIndexStmt) IsReadOnly() bool

IsReadOnly always returns false. It implements the Statement interface.

func (DropIndexStmt) Run 

func (stmt DropIndexStmt) Run(tx *database.Transaction, args []driver.NamedValue) (Result, error)

Run runs the DropIndex statement in the given transaction. It implements the Statement interface.

type DropTableStmt 

type DropTableStmt struct {
	TableName string
	IfExists  bool
}

DropTableStmt is a DSL that allows creating a DROP TABLE query.

func (DropTableStmt) IsReadOnly 

func (stmt DropTableStmt) IsReadOnly() bool

IsReadOnly always returns false. It implements the Statement interface.

func (DropTableStmt) Run 

func (stmt DropTableStmt) Run(tx *database.Transaction, args []driver.NamedValue) (Result, error)

Run runs the DropTable statement in the given transaction. It implements the Statement interface.

type EvalStack 

type EvalStack struct {
	Tx       *database.Transaction
	Document document.Document
	Params   []driver.NamedValue
	Cfg      *database.TableConfig
}

EvalStack contains information about the context in which the expression is evaluated. Any of the members can be nil except the transaction.

type Expr 

type Expr interface {
	Eval(EvalStack) (document.Value, error)
}

An Expr evaluates to a value.

func Add added in v0.5.0 

func Add(a, b Expr) Expr

Add creates an expression thats evaluates to the result of a + b.

func BitwiseAnd added in v0.5.0 

func BitwiseAnd(a, b Expr) Expr

BitwiseAnd creates an expression thats evaluates to the result of a & b.

func BitwiseOr added in v0.5.0 

func BitwiseOr(a, b Expr) Expr

BitwiseOr creates an expression thats evaluates to the result of a & b.

func BitwiseXor added in v0.5.0 

func BitwiseXor(a, b Expr) Expr

BitwiseXor creates an expression thats evaluates to the result of a & b.

func Div added in v0.5.0 

func Div(a, b Expr) Expr

Div creates an expression thats evaluates to the result of a / b.

func GetFunc added in v0.5.0 

func GetFunc(name string, args ...Expr) (Expr, error)

GetFunc return a function expression by name.

func Mod added in v0.5.0 

func Mod(a, b Expr) Expr

Mod creates an expression thats evaluates to the result of a % b.

func Mul added in v0.5.0 

func Mul(a, b Expr) Expr

Mul creates an expression thats evaluates to the result of a * b.

func Or 

func Or(a, b Expr) Expr

Or creates an expression that first evaluates a, returns true if truthy, then evaluates b, returns true if truthy Or false if falsy.

func Sub added in v0.5.0 

func Sub(a, b Expr) Expr

Sub creates an expression thats evaluates to the result of a - b.

type FieldSelector 

type FieldSelector []string

A FieldSelector is a ResultField that extracts a field from a document at a given path.

func (FieldSelector) Eval 

func (f FieldSelector) Eval(stack EvalStack) (document.Value, error)

Eval extracts the document from the context and selects the right field. It implements the Expr interface.

func (FieldSelector) Name 

func (f FieldSelector) Name() string

Name joins the chunks of the fields selector with the . separator.

type InsertStmt 

type InsertStmt struct {
	TableName  string
	FieldNames []string
	Values     LiteralExprList
}

InsertStmt is a DSL that allows creating a full Insert query.

func (InsertStmt) IsReadOnly 

func (stmt InsertStmt) IsReadOnly() bool

IsReadOnly always returns false. It implements the Statement interface.

func (InsertStmt) Run 

func (stmt InsertStmt) Run(tx *database.Transaction, args []driver.NamedValue) (Result, error)

Run the Insert statement in the given transaction. It implements the Statement interface.

type KVPair 

type KVPair struct {
	K string
	V Expr
}

KVPair associates an identifier with an expression.

type KVPairs 

type KVPairs []KVPair

KVPairs is a list of KVPair.

func (KVPairs) Eval 

func (kvp KVPairs) Eval(ctx EvalStack) (document.Value, error)

Eval turns a list of KVPairs into a document.

type LiteralExprList 

type LiteralExprList []Expr

LiteralExprList is a list of expressions.

func (LiteralExprList) Eval 

func (l LiteralExprList) Eval(stack EvalStack) (document.Value, error)

Eval evaluates all the expressions and returns a litteralValueList. It implements the Expr interface.

type LiteralValue 

type LiteralValue document.Value

A LiteralValue represents a litteral value of any type defined by the value package.

func BlobValue added in v0.5.0 

func BlobValue(v []byte) LiteralValue

BlobValue creates a litteral value of type Blob.

func BoolValue 

func BoolValue(v bool) LiteralValue

BoolValue creates a litteral value of type Bool.

func DocumentValue 

func DocumentValue(d document.Document) LiteralValue

DocumentValue creates a litteral value of type Document.

func DurationValue added in v0.5.0 

func DurationValue(v time.Duration) LiteralValue

DurationValue creates a litteral value of type Duration.

func Float64Value 

func Float64Value(v float64) LiteralValue

Float64Value creates a litteral value of type Float64.

func IntValue 

func IntValue(v int) LiteralValue

IntValue creates a litteral value of type Int.

func NullValue 

func NullValue() LiteralValue

NullValue creates a litteral value of type Null.

func TextValue added in v0.5.0 

func TextValue(v string) LiteralValue

TextValue creates a litteral value of type Text.

func (LiteralValue) Eval 

func (l LiteralValue) Eval(EvalStack) (document.Value, error)

Eval returns l. It implements the Expr interface.

type NamedParam 

type NamedParam string

NamedParam is an expression which represents the name of a parameter.

func (NamedParam) Eval 

func (p NamedParam) Eval(stack EvalStack) (document.Value, error)

Eval looks up for the parameters in the stack for the one that has the same name as p and returns the value.

type OrOp 

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

OrOp is the And operator.

func (*OrOp) Eval 

func (op *OrOp) Eval(ctx EvalStack) (document.Value, error)

Eval implements the Expr interface. It evaluates a and b and returns true if a or b evalutate to true.

func (OrOp) LeftHand 

func (op OrOp) LeftHand() Expr

func (OrOp) Precedence 

func (op OrOp) Precedence() int

func (OrOp) RightHand 

func (op OrOp) RightHand() Expr

func (OrOp) SetLeftHandExpr 

func (op OrOp) SetLeftHandExpr(a Expr)

func (OrOp) SetRightHandExpr 

func (op OrOp) SetRightHandExpr(b Expr)

type PKFunc added in v0.5.0 

type PKFunc struct{}

PKFunc represents the pk() function. It returns the primary key of the current document.

func (PKFunc) Eval added in v0.5.0 

func (k PKFunc) Eval(ctx EvalStack) (document.Value, error)

Eval returns the primary key of the current document.

type PositionalParam 

type PositionalParam int

PositionalParam is an expression which represents the position of a parameter.

func (PositionalParam) Eval 

func (p PositionalParam) Eval(stack EvalStack) (document.Value, error)

Eval looks up for the parameters in the stack for the one that is has the same position as p and returns the value.

type Query 

type Query struct {
	Statements []Statement
}

A Query can execute statements against the database. It can read or write data from any table, or even alter the structure of the database. Results are returned as streams.

func New 

func New(statements ...Statement) Query

New creates a new query with the given statements.

func (Query) Exec 

func (q Query) Exec(tx *database.Transaction, args []driver.NamedValue, forceReadOnly bool) (*Result, error)

Exec the query within the given transaction. If the one of the statements requires a read-write transaction and tx is not, tx will get promoted.

func (Query) Run 

func (q Query) Run(db *database.Database, args []driver.NamedValue) (*Result, error)

Run executes all the statements in their own transaction and returns the last result.

type Result 

type Result struct {
	document.Stream
	// contains filtered or unexported fields
}

Result of a query.

func (*Result) Close 

func (r *Result) Close() (err error)

Close the result stream. After closing the result, Stream is not supposed to be used. If the result stream was already closed, it returns ErrResultClosed.

func (Result) LastInsertId 

func (r Result) LastInsertId() (int64, error)

LastInsertId is not supported and returns an error. Use LastInsertKey instead.

func (Result) LastInsertKey 

func (r Result) LastInsertKey() ([]byte, error)

LastInsertKey returns the database's auto-generated key after, for example, an INSERT into a table with primary key.

func (Result) RowsAffected 

func (r Result) RowsAffected() (int64, error)

RowsAffected returns the number of rows affected by the query.

type ResultField 

type ResultField interface {
	Iterate(stack EvalStack, fn func(field string, value document.Value) error) error
	Name() string
}

A ResultField is a field that will be part of the result document that will be returned at the end of a Select statement.

type ResultFieldExpr added in v0.5.0 

type ResultFieldExpr struct {
	Expr

	ExprName string
}

ResultFieldExpr turns any expression into a ResultField.

func (ResultFieldExpr) Iterate added in v0.5.0 

func (r ResultFieldExpr) Iterate(stack EvalStack, fn func(field string, value document.Value) error) error

Iterate evaluates Expr and calls fn once with the result.

func (ResultFieldExpr) Name added in v0.5.0 

func (r ResultFieldExpr) Name() string

Name returns the raw expression.

type SelectStmt 

type SelectStmt struct {
	TableName        string
	WhereExpr        Expr
	OrderBy          FieldSelector
	OrderByDirection scanner.Token
	OffsetExpr       Expr
	LimitExpr        Expr
	Selectors        []ResultField
}

SelectStmt is a DSL that allows creating a full Select query.

func (SelectStmt) IsReadOnly 

func (stmt SelectStmt) IsReadOnly() bool

IsReadOnly always returns true. It implements the Statement interface.

func (SelectStmt) Run 

func (stmt SelectStmt) Run(tx *database.Transaction, args []driver.NamedValue) (Result, error)

Run the Select statement in the given transaction. It implements the Statement interface.

type Statement 

type Statement interface {
	Run(*database.Transaction, []driver.NamedValue) (Result, error)
	IsReadOnly() bool
}

A Statement represents a unique action that can be executed against the database.

type UpdateStmt 

type UpdateStmt struct {
	TableName string
	Pairs     map[string]Expr
	WhereExpr Expr
}

UpdateStmt is a DSL that allows creating a full Update query.

func (UpdateStmt) IsReadOnly 

func (stmt UpdateStmt) IsReadOnly() bool

IsReadOnly always returns false. It implements the Statement interface.

func (UpdateStmt) Run 

func (stmt UpdateStmt) Run(tx *database.Transaction, args []driver.NamedValue) (Result, error)

Run runs the Update table statement in the given transaction. It implements the Statement interface.

type Wildcard 

type Wildcard struct{}

A Wildcard is a ResultField that iterates over all the fields of a document.

func (Wildcard) Iterate 

func (w Wildcard) Iterate(stack EvalStack, fn func(fd string, v document.Value) error) error

Iterate call the document iterate method.

func (Wildcard) Name 

func (w Wildcard) Name() string

Name returns the "*" character.

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