Match string to object property
I have a set of policies that I want to match a request. If the policy exists, I want to match the request and see if the value matches.
The policies are List<Policies> -> (key: String, value: String) and the request can contain different keys.
Example:
The policies are a set of rules that the request should match.
class Policy {
val key: String,
val value: String
}
The request is a data class that contains different values (all optional), for example surname, firstName, address, ++++
data class Request (
id: Long = 12,
firstName: String = "test",
surname: String = "test",
address: String = "somewhere"
...// more fields
)
The list of policies can look like this (List):
List<Policy> => [
{
key: "surname",
value: "test"
},
{
key: "firstName",
value: "test"
}
]
I don't know how I can match the policies with the request. The Policy.key is a String and the Request can contain all different variations of properties.
How do I match the List of policies with my data class Request?
kotlin
asked Nov 26 '18 at 11:10
Mr.TurtleMr.Turtle
1,17331329
|
show 2 more comments
I have a set of policies that I want to match a request. If the policy exists, I want to match the request and see if the value matches.
The policies are List<Policies> -> (key: String, value: String) and the request can contain different keys.
Example:
The policies are a set of rules that the request should match.
class Policy {
val key: String,
val value: String
}
The request is a data class that contains different values (all optional), for example surname, firstName, address, ++++
data class Request (
id: Long = 12,
firstName: String = "test",
surname: String = "test",
address: String = "somewhere"
...// more fields
)
The list of policies can look like this (List):
List<Policy> => [
{
key: "surname",
value: "test"
},
{
key: "firstName",
value: "test"
}
]
I don't know how I can match the policies with the request. The Policy.key is a String and the Request can contain all different variations of properties.
How do I match the List of policies with my data class Request?
kotlin
asked Nov 26 '18 at 11:10
Mr.TurtleMr.Turtle
1,17331329
1
Why don't you just translate your pseudo-code to code? We have no idea of what your classes look like, so it's hard to produce something other than basically the pseudo-code that you already have.
– JB Nizet
Nov 26 '18 at 11:18
Because I have no clue on how to implement this. I don't know how to match Policy.key (string) to Request.property.
– Mr.Turtle
Nov 26 '18 at 11:27
We don't know either because you didn't post your classes.
– JB Nizet
Nov 26 '18 at 11:29
@JBNizet Added my two classes. Still have no clue on how to match it though.
– Mr.Turtle
Nov 26 '18 at 11:39
OK. As is, you would need reflection to do what you want, which is generally a bad idea. The best thing to do would probably be, if possible, to change the Policy class so that, instead of storing a property name, it would store a function which allows getting a property of a Request, i.e. a(Request) -> Any. Or the Request class should be a Map with keys and values. Where do these requests and policies come from? How are they created?
– JB Nizet
Nov 26 '18 at 11:49
|
show 2 more comments
I have a set of policies that I want to match a request. If the policy exists, I want to match the request and see if the value matches.
The policies are List<Policies> -> (key: String, value: String) and the request can contain different keys.
Example:
The policies are a set of rules that the request should match.
class Policy {
val key: String,
val value: String
}
The request is a data class that contains different values (all optional), for example surname, firstName, address, ++++
data class Request (
id: Long = 12,
firstName: String = "test",
surname: String = "test",
address: String = "somewhere"
...// more fields
)
The list of policies can look like this (List):
List<Policy> => [
{
key: "surname",
value: "test"
},
{
key: "firstName",
value: "test"
}
]
I don't know how I can match the policies with the request. The Policy.key is a String and the Request can contain all different variations of properties.
How do I match the List of policies with my data class Request?
kotlin
asked Nov 26 '18 at 11:10
Mr.TurtleMr.Turtle
1,17331329
I have a set of policies that I want to match a request. If the policy exists, I want to match the request and see if the value matches.
The policies are List<Policies> -> (key: String, value: String) and the request can contain different keys.
Example:
The policies are a set of rules that the request should match.
class Policy {
val key: String,
val value: String
}
The request is a data class that contains different values (all optional), for example surname, firstName, address, ++++
data class Request (
id: Long = 12,
firstName: String = "test",
surname: String = "test",
address: String = "somewhere"
...// more fields
)
The list of policies can look like this (List):
List<Policy> => [
{
key: "surname",
value: "test"
},
{
key: "firstName",
value: "test"
}
]
I don't know how I can match the policies with the request. The Policy.key is a String and the Request can contain all different variations of properties.
How do I match the List of policies with my data class Request?
kotlin
kotlin
asked Nov 26 '18 at 11:10
Mr.TurtleMr.Turtle
1,17331329
asked Nov 26 '18 at 11:10
Mr.TurtleMr.Turtle
1,17331329
edited Nov 26 '18 at 11:36
Mr.Turtle
asked Nov 26 '18 at 11:10
Mr.TurtleMr.Turtle
1,17331329
asked Nov 26 '18 at 11:10
Mr.TurtleMr.Turtle
1,17331329
asked Nov 26 '18 at 11:10
Mr.TurtleMr.Turtle
1,17331329
1,17331329
1
Why don't you just translate your pseudo-code to code? We have no idea of what your classes look like, so it's hard to produce something other than basically the pseudo-code that you already have.
– JB Nizet
Nov 26 '18 at 11:18
Because I have no clue on how to implement this. I don't know how to match Policy.key (string) to Request.property.
– Mr.Turtle
Nov 26 '18 at 11:27
We don't know either because you didn't post your classes.
– JB Nizet
Nov 26 '18 at 11:29
@JBNizet Added my two classes. Still have no clue on how to match it though.
– Mr.Turtle
Nov 26 '18 at 11:39
OK. As is, you would need reflection to do what you want, which is generally a bad idea. The best thing to do would probably be, if possible, to change the Policy class so that, instead of storing a property name, it would store a function which allows getting a property of a Request, i.e. a(Request) -> Any. Or the Request class should be a Map with keys and values. Where do these requests and policies come from? How are they created?
– JB Nizet
Nov 26 '18 at 11:49
|
show 2 more comments
1
Why don't you just translate your pseudo-code to code? We have no idea of what your classes look like, so it's hard to produce something other than basically the pseudo-code that you already have.
– JB Nizet
Nov 26 '18 at 11:18
Because I have no clue on how to implement this. I don't know how to match Policy.key (string) to Request.property.
– Mr.Turtle
Nov 26 '18 at 11:27
We don't know either because you didn't post your classes.
– JB Nizet
Nov 26 '18 at 11:29
@JBNizet Added my two classes. Still have no clue on how to match it though.
– Mr.Turtle
Nov 26 '18 at 11:39
OK. As is, you would need reflection to do what you want, which is generally a bad idea. The best thing to do would probably be, if possible, to change the Policy class so that, instead of storing a property name, it would store a function which allows getting a property of a Request, i.e. a(Request) -> Any. Or the Request class should be a Map with keys and values. Where do these requests and policies come from? How are they created?
– JB Nizet
Nov 26 '18 at 11:49
1
1
Why don't you just translate your pseudo-code to code? We have no idea of what your classes look like, so it's hard to produce something other than basically the pseudo-code that you already have.
– JB Nizet
Nov 26 '18 at 11:18
Why don't you just translate your pseudo-code to code? We have no idea of what your classes look like, so it's hard to produce something other than basically the pseudo-code that you already have.
– JB Nizet
Nov 26 '18 at 11:18
Because I have no clue on how to implement this. I don't know how to match Policy.key (string) to Request.property.
– Mr.Turtle
Nov 26 '18 at 11:27
Because I have no clue on how to implement this. I don't know how to match Policy.key (string) to Request.property.
– Mr.Turtle
Nov 26 '18 at 11:27
We don't know either because you didn't post your classes.
– JB Nizet
Nov 26 '18 at 11:29
We don't know either because you didn't post your classes.
– JB Nizet
Nov 26 '18 at 11:29
@JBNizet Added my two classes. Still have no clue on how to match it though.
– Mr.Turtle
Nov 26 '18 at 11:39
@JBNizet Added my two classes. Still have no clue on how to match it though.
– Mr.Turtle
Nov 26 '18 at 11:39
OK. As is, you would need reflection to do what you want, which is generally a bad idea. The best thing to do would probably be, if possible, to change the Policy class so that, instead of storing a property name, it would store a function which allows getting a property of a Request, i.e. a
(Request) -> Any. Or the Request class should be a Map with keys and values. Where do these requests and policies come from? How are they created?– JB Nizet
Nov 26 '18 at 11:49
OK. As is, you would need reflection to do what you want, which is generally a bad idea. The best thing to do would probably be, if possible, to change the Policy class so that, instead of storing a property name, it would store a function which allows getting a property of a Request, i.e. a
(Request) -> Any. Or the Request class should be a Map with keys and values. Where do these requests and policies come from? How are they created?– JB Nizet
Nov 26 '18 at 11:49
|
show 2 more comments
1 Answer
1
active
oldest
votes
For your puroposes you need use reflection (you want to find field by name and get value), or change something in your model.
Solution with reflection can be like following:
data class Policy(
val key: String,
val value: String?
)
data class Request(
val id: Int,
val firstName: String? = null,
val surname: String? = null,
val address: String? = null
)
class PolicyException : Exception()
fun checkPolicies(request: Request, policies: List<Policy>) {
policies.forEach { policy ->
val member = request::class.members.find { member -> member.name == policy.key }
val requestMemberValue = member?.call(request)
if (requestMemberValue != policy.value) throw PolicyException()
}
}
fun main(args: Array<String>) {
println("Hello, reflection!")
checkPolicies(Request(id = 0, firstName = "Johnn"), listOf(Policy("firstName", "John")))
}
Also, I changed your policy model to handle nullable values (and still handling properly "null" as string).
But, with this solution you have to be very careful with changing model names. And remeber to do not obfuscate your models.
Also, quite better soltuion is adding Annotation which keeps policy name as annotation property (then problem with changing field name in app will disappear).
answered Nov 26 '18 at 12:10
CililingCililing
776215
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1 Answer
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1 Answer
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active
oldest
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oldest
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active
oldest
votes
For your puroposes you need use reflection (you want to find field by name and get value), or change something in your model.
Solution with reflection can be like following:
data class Policy(
val key: String,
val value: String?
)
data class Request(
val id: Int,
val firstName: String? = null,
val surname: String? = null,
val address: String? = null
)
class PolicyException : Exception()
fun checkPolicies(request: Request, policies: List<Policy>) {
policies.forEach { policy ->
val member = request::class.members.find { member -> member.name == policy.key }
val requestMemberValue = member?.call(request)
if (requestMemberValue != policy.value) throw PolicyException()
}
}
fun main(args: Array<String>) {
println("Hello, reflection!")
checkPolicies(Request(id = 0, firstName = "Johnn"), listOf(Policy("firstName", "John")))
}
Also, I changed your policy model to handle nullable values (and still handling properly "null" as string).
But, with this solution you have to be very careful with changing model names. And remeber to do not obfuscate your models.
Also, quite better soltuion is adding Annotation which keeps policy name as annotation property (then problem with changing field name in app will disappear).
answered Nov 26 '18 at 12:10
CililingCililing
776215
add a comment |
For your puroposes you need use reflection (you want to find field by name and get value), or change something in your model.
Solution with reflection can be like following:
data class Policy(
val key: String,
val value: String?
)
data class Request(
val id: Int,
val firstName: String? = null,
val surname: String? = null,
val address: String? = null
)
class PolicyException : Exception()
fun checkPolicies(request: Request, policies: List<Policy>) {
policies.forEach { policy ->
val member = request::class.members.find { member -> member.name == policy.key }
val requestMemberValue = member?.call(request)
if (requestMemberValue != policy.value) throw PolicyException()
}
}
fun main(args: Array<String>) {
println("Hello, reflection!")
checkPolicies(Request(id = 0, firstName = "Johnn"), listOf(Policy("firstName", "John")))
}
Also, I changed your policy model to handle nullable values (and still handling properly "null" as string).
But, with this solution you have to be very careful with changing model names. And remeber to do not obfuscate your models.
Also, quite better soltuion is adding Annotation which keeps policy name as annotation property (then problem with changing field name in app will disappear).
answered Nov 26 '18 at 12:10
CililingCililing
776215
add a comment |
For your puroposes you need use reflection (you want to find field by name and get value), or change something in your model.
Solution with reflection can be like following:
data class Policy(
val key: String,
val value: String?
)
data class Request(
val id: Int,
val firstName: String? = null,
val surname: String? = null,
val address: String? = null
)
class PolicyException : Exception()
fun checkPolicies(request: Request, policies: List<Policy>) {
policies.forEach { policy ->
val member = request::class.members.find { member -> member.name == policy.key }
val requestMemberValue = member?.call(request)
if (requestMemberValue != policy.value) throw PolicyException()
}
}
fun main(args: Array<String>) {
println("Hello, reflection!")
checkPolicies(Request(id = 0, firstName = "Johnn"), listOf(Policy("firstName", "John")))
}
Also, I changed your policy model to handle nullable values (and still handling properly "null" as string).
But, with this solution you have to be very careful with changing model names. And remeber to do not obfuscate your models.
Also, quite better soltuion is adding Annotation which keeps policy name as annotation property (then problem with changing field name in app will disappear).
answered Nov 26 '18 at 12:10
CililingCililing
776215
For your puroposes you need use reflection (you want to find field by name and get value), or change something in your model.
Solution with reflection can be like following:
data class Policy(
val key: String,
val value: String?
)
data class Request(
val id: Int,
val firstName: String? = null,
val surname: String? = null,
val address: String? = null
)
class PolicyException : Exception()
fun checkPolicies(request: Request, policies: List<Policy>) {
policies.forEach { policy ->
val member = request::class.members.find { member -> member.name == policy.key }
val requestMemberValue = member?.call(request)
if (requestMemberValue != policy.value) throw PolicyException()
}
}
fun main(args: Array<String>) {
println("Hello, reflection!")
checkPolicies(Request(id = 0, firstName = "Johnn"), listOf(Policy("firstName", "John")))
}
Also, I changed your policy model to handle nullable values (and still handling properly "null" as string).
But, with this solution you have to be very careful with changing model names. And remeber to do not obfuscate your models.
Also, quite better soltuion is adding Annotation which keeps policy name as annotation property (then problem with changing field name in app will disappear).
answered Nov 26 '18 at 12:10
CililingCililing
776215
edited Nov 26 '18 at 12:33
answered Nov 26 '18 at 12:10
CililingCililing
776215
answered Nov 26 '18 at 12:10
CililingCililing
776215
answered Nov 26 '18 at 12:10
CililingCililing
776215
776215
add a comment |
add a comment |
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1
Why don't you just translate your pseudo-code to code? We have no idea of what your classes look like, so it's hard to produce something other than basically the pseudo-code that you already have.
– JB Nizet
Nov 26 '18 at 11:18
Because I have no clue on how to implement this. I don't know how to match Policy.key (string) to Request.property.
– Mr.Turtle
Nov 26 '18 at 11:27
We don't know either because you didn't post your classes.
– JB Nizet
Nov 26 '18 at 11:29
@JBNizet Added my two classes. Still have no clue on how to match it though.
– Mr.Turtle
Nov 26 '18 at 11:39
OK. As is, you would need reflection to do what you want, which is generally a bad idea. The best thing to do would probably be, if possible, to change the Policy class so that, instead of storing a property name, it would store a function which allows getting a property of a Request, i.e. a
(Request) -> Any. Or the Request class should be a Map with keys and values. Where do these requests and policies come from? How are they created?– JB Nizet
Nov 26 '18 at 11:49