Json 到 Spring 表达式映射异常

Question

当我尝试发出具有如下请求正文的 POST 请求（来自邮递员）时，我面临映射异常：

类型定义错误：[简单类型，类org.springframework.expression.spel.support.ReflectiveMethodResolver]；嵌套异常是 com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class org.springframework.expression.spel.support.ReflectiveMethodResolver 并且没有发现创建 BeanSerializer 的属性（为避免异常，禁用 SerializationFeature.FAIL_ON_EMPTY_BEANS）（通过参考链：com.freddiemac.security.policy.Policy["accessPolicies"]->java.util.ArrayList[0]->com.freddiemac.security.policy.AccessPolicy["condition"]->org.springframework.expression .spel.standard.SpelExpression["evaluationContext"]->org.springframework.expression.spel.support.StandardEvaluationContext["methodResolvers"]->java.util.ArrayList[0])

POST 调用 - 请求正文：

{
"accessPolicies": [{
    "policyId": 1,
    "resource": [
        "/my-resource"
    ],
    "action": [
        "POST"
    ],
    "condition": "#claims['userRoles'].contains('developer')", // this is mapped as Spring expression in java
    "effect": "Allow"
}]

}

POJO 类：

private String policyId;
private List<String> resource;
private List<String> action; 
private List<String> role;
private Expression  condition; // import from :  org.springframework.expression.Expression;

你能帮我解决这个问题吗？提前致谢。

Answer 1

Expression 接口没有序列化器，所以接收String，它确实有有效的序列化器。

然后你可以使用SpelExpressionParser 到parse String into a valid Expression。

class PostRequestDto {

    private String serviceId;
    private String version;
    private List<AccessPolicy> accessPolicies;
    // Getters and setters omitted for brevity
}

class AccessPolicy {
    private String policyId;
    private List<String> resource;
    private List<String> action;
    private List<String> role;
    private String condition; // utilize String serializer when accepting SpEL Expression
    private String effect;

    // Getters and setters omitted for brevity

    // parse received String to derive SpEL Expression 
    public Expression getConditionExpression() {
        // proper error handling omitted for brevity
        ExpressionParser expressionParser = new SpelExpressionParser();
        return expressionParser.parseExpression( this.condition );
    }
}