Question: I'm using react and I am faced with a problem.

I have a component that needs to accept another component as prop, and pass into the same component other props.
Example:

```
export default class Item extends React.Component {
    render() {
        return (<div onClick={this.props.onClick}>Some content.</div>)
    }
}

Item.propTypes = {
    onClick: PropTypes.func.isRequired
}

export default class Container extends React.Component {
    onClick() {
        // Do something.
    }
    render() {
        // render here the item and passing it my onClick method.
    }
}

Container.propTypes = {
    item: PropTypes.element.isRequired
}

```

Edit:
So I probably can use the es5 syntax and do something like this:

```
React.createElement(item, {
    onClick: this.onClick
});

```

But how can I achieve that in es6?

Answer: 
The property name in the datastore is `"Email"` with capital E, not `"email"`.

It's case-sensitive, must be queried with capital E:

```
query = datastore.NewQuery("UserAccount").Filter("Email =", "test@example.com")

```

If you would want it to be saved / retrieved with small `e`, you could use [tags](https://stackoverflow.com/questions/10858787/what-are-the-uses-for-tags-in-go/30889373#30889373) to do the mapping, e.g.:

```
type UserAccount struct {
    Email string `datastore:"email"`
    // other fields...
}

```
To be able to find an entity in the result of a query/filter by a property that property **must** have had indexing enabled (in the model definition) at the time when the entity was created and the datastore's background indexing task(s) must be completed for it.

If you enable indexing for that property **after** the entity was created you need to re-write the property so that the indexing tasks are triggered for it, see: <https://stackoverflow.com/a/34583510/4495081>.

The "Saving search indexes" message is a generic one printed before the operation takes place, it doesn't mean the result of the operation will be non-empty.

You don't need to worry that your `index.yaml` file is empty. Not all indexes need to be present in the `index.yaml` file, only the more complex/composite ones need to. Your filter can be matched using the built-in indexes (after the above-mentioned indexing requirements are met). From [Indexes](https://cloud.google.com/datastore/docs/concepts/indexes):

> 
> There are two types of indexes:
> 
> 
> * *Built-in indexes*
> 
> 
> By default, Cloud Datastore automatically predefines an index for each property of each entity kind. These single property indexes are
>  suitable for simple types of queries.
> * *Composite indexes*
> 
> 
> Composite indexes index multiple property values per indexed entity. Composite indexes support complex queries and are defined in
>  an index configuration file (index.yaml).
> 
> 
>