# 流式传输 JSON Lines { #stream-json-lines }

当你想以“流”的方式发送一系列数据时，可以使用 JSON Lines。

/// info | 信息

新增于 FastAPI 0.134.0。

///

## 什么是流 { #what-is-a-stream }

“流式传输”数据意味着你的应用会在整段数据全部准备好之前，就开始把每个数据项发送给客户端。

也就是说，它会先发送第一个数据项，客户端会接收并开始处理它，而此时你的应用可能还在生成下一个数据项。

```mermaid
sequenceDiagram
    participant App
    participant Client

    App->>App: Produce Item 1
    App->>Client: Send Item 1
    App->>App: Produce Item 2

	}

	CheckUser(t, user2, user)
}

func TestJoinsForSlice(t *testing.T) {
	users := []User{
		*GetUser("slice-joins-1", Config{Company: true, Manager: true, Account: true}),
		*GetUser("slice-joins-2", Config{Company: true, Manager: true, Account: true}),
		*GetUser("slice-joins-3", Config{Company: true, Manager: true, Account: true}),
	}

	DB.Create(&users)

	var userIDs []uint

	// ErrEmptySlice empty slice found
	ErrEmptySlice = errors.New("empty slice found")
	// ErrDryRunModeUnsupported dry run mode unsupported
	ErrDryRunModeUnsupported = errors.New("dry run mode unsupported")
	// ErrInvalidDB invalid db
	ErrInvalidDB = errors.New("invalid db")
	// ErrInvalidValue invalid value
	ErrInvalidValue = errors.New("invalid value, should be pointer to struct or slice")

	sort.Slice(result.Pets, func(i, j int) bool {
		return result.Pets[i].ID < result.Pets[j].ID
	})
	sort.Slice(result.Team, func(i, j int) bool {
		return result.Team[i].ID < result.Team[j].ID
	})
	sort.Slice(result.Friends, func(i, j int) bool {
		return result.Friends[i].ID < result.Friends[j].ID
	})
	sort.Slice(result2.Pets, func(i, j int) bool {

			t.Errorf("%v: expect: %+v, got %+v", utils.FileWithLineNum(), expect, got)
			return
		}

		if reflect.ValueOf(got).Kind() == reflect.Slice {
			if reflect.ValueOf(expect).Kind() == reflect.Slice {
				if reflect.ValueOf(got).Len() == reflect.ValueOf(expect).Len() {
					for i := 0; i < reflect.ValueOf(got).Len(); i++ {
						name := fmt.Sprintf(reflect.ValueOf(got).Type().Name()+" #%v", i)

		}

		switch reflectValue.Kind() {
		case reflect.Slice, reflect.Array:
			var (
				elem        reflect.Value
				isArrayKind = reflectValue.Kind() == reflect.Array
			)

			if !update || reflectValue.Len() == 0 {
				update = false
				if isArrayKind {
					db.Statement.ReflectValue.Set(reflect.Zero(reflectValue.Type()))
				} else {

		if now.After(ent.ExpiresAt) {
			continue
		}
		maps[ent.Key] = ent.Value
		// keys = append(keys, ent.Key)
	}
	return maps
}

// Keys returns a slice of the keys in the cache, from oldest to newest.
// Expired entries are filtered out.
func (c *LRU[K, V]) Keys() []K {
	c.mu.RLock()
	defer c.mu.RUnlock()
	keys := make([]K, 0, len(c.items))
	now := time.Now()

// When sent as a parameter, the caller gives up ownership of the byte slice.
// When returned as response, the handler also gives up ownership of the byte slice.
func NewBytesWith(b []byte) *Bytes {
	bb := Bytes(b)
	return &bb
}

// NewBytesWithCopyOf returns a new byte slice with a copy of the provided content.
func NewBytesWithCopyOf(b []byte) *Bytes {
	if b == nil {
		bb := Bytes(nil)

o=Object.keys(this.tokens.links);if(o.length>0)for(;(r=this.tokenizer.rules.inline.reflinkSearch.exec(n))!=null;)o.includes(r[0].slice(r[0].lastIndexOf("[")+1,-1))&&(n=n.slice(0,r.index)+"["+"a".repeat(r[0].length-2)+"]"+n.slice(this.tokenizer.rules.inline.reflinkSearch.lastIndex))}for(;(r=this.tokenizer.rules.inline.anyPunctuation.exec(n))!=null;)n=n.slice(0,r.index)+"++"+n.slice(this.tokenizer.rules.inline.anyPunctuation.lastIndex);let i;for(;(r=this.tokenizer.rules.inline.blockSkip.exec(n))!=null;)...

	a := arena.NewArena()
	defer a.Free()

	tt := arena.New[T1](a)
	tt.n = 1

	ts := arena.MakeSlice[T1](a, 99, 100)
	if len(ts) != 99 {
		t.Errorf("Slice() len = %d, want 99", len(ts))
	}
	if cap(ts) != 100 {
		t.Errorf("Slice() cap = %d, want 100", cap(ts))
	}
	ts[1].n = 42
}

func TestSmokeLarge(t *testing.T) {
	a := arena.NewArena()
	defer a.Free()
	for i := 0; i < 10*64; i++ {