考虑我们有一个带有BinaryField的模型：
from django.db import models
import hashlib
class Target(models.Model):
# ...
image = models.BinaryField(max_length=(1<<24)-1)
# ...
def __str__(self):
return hashlib.md5().update(self.image).hexdigest()
以上代码是否正确计算了图像的MD5摘要？
还是BinaryField内有一些方法或变量来获取传递给update()方法的内存？
更新：当我尝试时：
>>> from pathlib import Path
>>> t = Target(image=Path('../../Experiments/LoginError2.jpg').read_bytes())
>>> t
我遇到以下错误：
AttributeError: 'NoneType' object has no attribute 'hexdigest'
那我在做什么错了？
答案 0 :(得分：1)
关于import React, { Component } from "react";
import PropTypes from "prop-types";
import { connect } from "react-redux";
import classnames from "classnames";
import { Link } from "react-router-dom";
import Moment from "react-moment";
import { addLike, removeLike } from "../../actions/postActions";
class PostedItem extends Component {
onLikeClick(id) {
this.props.addLike(id);
}
onUnlikeClick(id) {
this.props.removeLike(id);
}
findUserLike(likes) {
const { auth } = this.props;
if (likes.filter(like => like.user === auth.user.id).length > 0) {
return true;
} else {
return false;
}
}
render() {
const { post, showActions } = this.props;
return (
<div className="card mb-3">
<div className="row">
<div className="col-md-3 text-center m-auto px-0 py-3">
<img src={post.avatar} alt={post.designation} />
</div>
<div className="col-md-9 m-auto p-0">
<div className="card-body m-2">
<h2 className="card-title">
{post.designation} - {post.location}
</h2>
<div className="mx-2">
<ul className="list-unstyled">
<li>
<b>Date Posted: </b>
<Moment format="DD/MM/YYYY">{post.created}</Moment>
</li>
<li>
<b>Salary: </b>₹{post.salary / 100000} lacs/annum
</li>
<li>
<b>Experience Required: </b>
{post.experience} years
</li>
</ul>
<p className="card-text">{post.description}</p>
</div>
</div>
<div className="card-footer mx-3 p-2">
<div className="row px-3">
{showActions ? (
<span>
<button
onClick={this.onLikeClick.bind(this, post._id)}
type="button"
className="btn btn-light mr-1"
>
<i
className={classnames("fas fa-thumbs-up", {
"text-info": this.findUserLike(post.likes)
})}
/>
<span className="badge badge-light">
{post.likes.length}
</span>
</button>
<button
onClick={this.onUnlikeClick.bind(this, post._id)}
type="button"
className="btn btn-light mr-1"
>
<i className="text-secondary fas fa-thumbs-down" />
</button>
</span>
) : null}
<Link to={`/post/${post._id}`} className="btn btn-info ml-auto">
View Details
</Link>
</div>
</div>
</div>
</div>
</div>
);
}
}
PostedItem.defaultProps = {
showActions: true
};
PostedItem.propTypes = {
addLike: PropTypes.func.isRequired,
removeLike: PropTypes.func.isRequired,
post: PropTypes.object.isRequired,
auth: PropTypes.object.isRequired
};
const mapStateToProps = state => ({
auth: state.auth
});
export default connect(
mapStateToProps,
{ addLike, removeLike }
)(PostedItem);
的更新，您错误地调用了AttributeError方法。
问题是，hexdigest()方法返回update()，而您几乎要尝试在None上调用hexdigest()。这样的链接方法调用仅在前一个方法返回实际对象而不是None的情况下才有效。
您必须分多个步骤进行此呼叫：
None答案 1 :(得分：0)
因此，得出的结论是：BinaryField可以分配字节，也可以读取为字节。
在上面的代码中，哈希处理是错误的，正确的方法是：
hashlib.md5(self.image).hexdigest()