英文:
Why do I get "invalid entity type" with datastore.Put using a datastore.PropertyList in a Go AppEngine aetest?
问题
这个测试在partnermerge_test.go:22行失败，错误信息是datastore: invalid entity type。
package bigdipper
import (
"testing"
"appengine/aetest"
"appengine/datastore"
)
func TestCreateMigrationProposal(t *testing.T) {
c, err := aetest.NewContext(nil)
if err != nil {
t.Fatal(err)
}
defer c.Close()
if _, err := datastore.Put(
c,
datastore.NewKey(c, "ORDER", "order-id-1", 0, nil),
datastore.PropertyList{}); err != nil {
t.Fatal(err)
}
}
这段代码创建了一个名为TestCreateMigrationProposal的测试函数，它使用appengine/aetest和appengine/datastore包进行测试。在测试函数中，它首先创建一个新的上下文c，然后使用datastore.Put函数将一个空的datastore.PropertyList放入名为ORDER、ID为order-id-1的实体中。如果出现错误，测试函数将会失败并打印错误信息。
英文:
This test fails with partnermerge_test.go:22: datastore: invalid entity type
package bigdipper
import (
"testing"
"appengine/aetest"
"appengine/datastore"
)
func TestCreateMigrationProposal(t *testing.T) {
c, err := aetest.NewContext(nil)
if err != nil {
t.Fatal(err)
}
defer c.Close()
if _, err := datastore.Put(
c,
datastore.NewKey(c, "ORDER", "order-id-1", 0, nil),
datastore.PropertyList{}); err != nil {
t.Fatal(err)
}
}
答案1
得分: 1
> Put函数将实体src保存到具有键k的数据存储中。src必须是一个结构体指针或实现PropertyLoadSaver接口；如果是结构体指针，则会跳过该结构体中的任何未导出字段。如果k是不完整的键，则返回的键将是数据存储生成的唯一键。
当尝试将PropertyList作为src使用时，这有点令人困惑。PropertyList并没有实现PropertyLoadSaver接口，但*PropertyList实现了该接口。在PropertyList之前添加一个&符号以获取指向它的指针可以修复这个问题。
package bigdipper
import (
"testing"
"appengine/aetest"
"appengine/datastore"
)
func TestCreateMigrationProposal(t *testing.T) {
c, err := aetest.NewContext(nil)
if err != nil {
t.Fatal(err)
}
defer c.Close()
if _, err := datastore.Put(
c,
datastore.NewKey(c, "ORDER", "order-id-1", 0, nil),
&datastore.PropertyList{}); err != nil {
t.Fatal(err)
}
}
英文:
The docs for the datastore.Put function say:
> Put saves the entity src into the datastore with key k. src must be a
> struct pointer or implement PropertyLoadSaver; if a struct pointer
> then any unexported fields of that struct will be skipped. If k is an
> incomplete key, the returned key will be a unique key generated by the
> datastore.
This was somewhat confusing when trying to use this with a PropertyList as the src. A PropertyList does not implement PropertyLoadSaver, but a *PropertyList does. Adding an & before PropertyList to get a pointer to it fixes this test.
package bigdipper
import (
"testing"
"appengine/aetest"
"appengine/datastore"
)
func TestCreateMigrationProposal(t *testing.T) {
c, err := aetest.NewContext(nil)
if err != nil {
t.Fatal(err)
}
defer c.Close()
if _, err := datastore.Put(
c,
datastore.NewKey(c, "ORDER", "order-id-1", 0, nil),
&datastore.PropertyList{}); err != nil {
t.Fatal(err)
}
}
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