How to handle JSON in Adept?

[ghost]

I know that there is JSON.adept but I can't find any examples.

[IsaacShelton]

JSON.adept is not very amazing to work with, but I will show an example:

To use JSON.adept, you can do something like this:

pragma default_stdlib '2.8' // In order to pin standard library version to 2.8

import basics
import JSON

func main {
    value1 *JSON = JSONFromFile("data.txt")
    defer value1.destroyAndFree()

    value2 *JSON = JSON("[1, 2, 3, 4, 5]")
    defer value1.destroyAndFree()
    
    /*
    TO CHECK SPECIFIC KINDS:
    func isNull(this *JSON)    bool
    func isBoolean(this *JSON) bool
    func isNumber(this *JSON)  bool
    func isString(this *JSON)  bool
    func isArray(this *JSON)   bool
    func isObject(this *JSON)  bool
    
    AND THEN ACCESS THE CORRECT STRUCT
    struct JSON (kind JSONKind)
    struct JSONField (name String, value *JSON)
    
    struct JSONBoolean (struct JSON, value bool)
    struct JSONString (struct JSON, value String)
    
    struct JSONNumber (struct JSON, value double)
    struct JSONArray (struct JSON, elements <*JSON> List)
    struct JSONObject (struct JSON, fields <JSONField> List)
    
    *JSONObject also has these convenience methods:
    func get(this *JSONObject, field String) *JSON
    func getBooleanOtherwise(this *JSONObject, field String, default_value bool) bool
    func getStringOtherwise(this *JSONObject, field String, default_value POD String) String
    func getNumberOtherwise(this *JSONObject, field String, default_value float) float
    func getNumberOtherwise(this *JSONObject, field String, default_value double) double

    AND ALSO ALL *JSON VALUES ARE toString-able
    func toString(this *JSON) String
    */

    if value1.isObject() {
        object *JSONObject = value1 as *JSONObject
        name String = object.getStringOtherwise("name", "")
        age int = object.getNumberOtherwise("age", 0.0) as int
        print("Person named " + name + " is " + age + " years old")
    }

    if value2.isArray() {
        array *JSONArray = value2 as *JSONArray
        
        each item *JSON in array.elements {
            print("Array item: " + toString(item))
        }
    }
}

[IsaacShelton]

data.json

{
    "firstname": "John",
    "lastname": "Smith",
    "age": 47,
    "married": true
}

main.adept

pragma default_stdlib '2.8' // In order to pin standard library version to 2.8

import basics
import JSON

func main {
    value1 *JSON = JSONFromFile("data.json")
    if value1 == null {
        fprintf(stderr, "Failed to open data.json file\n")
        return
    }
    defer value1.destroyAndFree()

    value2 *JSON = JSON("[1, 2, 3, 4, 5]")
    if value2 == null {
        fprintf(stderr, "Failed to parse value2 data\n")
        return
    }
    defer value2.destroyAndFree()
    
    /*
    TO CHECK SPECIFIC KINDS:
    func isNull(this *JSON)    bool
    func isBoolean(this *JSON) bool
    func isNumber(this *JSON)  bool
    func isString(this *JSON)  bool
    func isArray(this *JSON)   bool
    func isObject(this *JSON)  bool
    
    AND THEN ACCESS THE CORRECT STRUCT
    struct JSON (kind JSONKind)
    struct JSONField (name String, value *JSON)
    
    struct JSONBoolean (struct JSON, value bool)
    struct JSONString (struct JSON, value String)
    
    struct JSONNumber (struct JSON, value double)
    struct JSONArray (struct JSON, elements <*JSON> List)
    struct JSONObject (struct JSON, fields <JSONField> List)
    
    *JSONObject also has these convenience methods:
    func get(this *JSONObject, field String) *JSON
    func getBooleanOtherwise(this *JSONObject, field String, default_value bool) bool
    func getStringOtherwise(this *JSONObject, field String, default_value POD String) String
    func getNumberOtherwise(this *JSONObject, field String, default_value float) float
    func getNumberOtherwise(this *JSONObject, field String, default_value double) double

    AND ALSO ALL *JSON VALUES ARE toString-able
    func toString(this *JSON) String
    */

    if value1.isObject() {
        object *JSONObject = value1 as *JSONObject
        firstname String = object.getStringOtherwise("firstname", "")
        lastname String = object.getStringOtherwise("lastname", "")
        age int = object.getNumberOtherwise("age", 0.0) as int
        married bool = object.getBooleanOtherwise("married", false)
        print("Person named " + firstname + " " + lastname + " is " + age + " years old, and is " + (married ? "" : "not ") + "married")
    }

    if value2.isArray() {
        array *JSONArray = value2 as *JSONArray
        
        each item *JSON in array.elements {
            if item.isNumber() {
                number double = item as *JSONNumber.value
                print("Array item: " + toString(number))
            }
        }
    }
}

[ghost]

The file does exist and is placed in the same directory as the program. JSONFromFile is problematic. It always failed to load the file.

[IsaacShelton]

Are you running it with the correct working directory?

Can you fopen the file?

Are you sure that it's valid json?

I've tested it on multiple platforms and it works when I've tested it

[ghost]

I have switched to use your data.json instead of mine. Same result. It always failed to load the file. Both the Adept source file, the JSON file and the compiled Adept program are in the same directory. Command Prompt is also opened in that very directory.

[IsaacShelton]

I think you might have to run it from command prompt because Windows doesn't have the correct working directory when you double click it if I remember correctly.

You can try using the where() function like this to get around it:

Does the following work?

(This uses the where() function so that the file is relative to the path of the executable)

pragma default_stdlib '2.8' // In order to pin standard library version to 2.8

import basics
import where
import JSON

func main {
    value1 *JSON = JSONFromFile(where() + "data.json")
    if value1 == null {
        fprintf(stderr, "Failed to open data.json file\n")
        return
    }
    defer value1.destroyAndFree()

    value2 *JSON = JSON("[1, 2, 3, 4, 5]")
    if value2 == null {
        fprintf(stderr, "Failed to parse value2 data\n")
        return
    }
    defer value2.destroyAndFree()
    
    /*
    TO CHECK SPECIFIC KINDS:
    func isNull(this *JSON)    bool
    func isBoolean(this *JSON) bool
    func isNumber(this *JSON)  bool
    func isString(this *JSON)  bool
    func isArray(this *JSON)   bool
    func isObject(this *JSON)  bool
    
    AND THEN ACCESS THE CORRECT STRUCT
    struct JSON (kind JSONKind)
    struct JSONField (name String, value *JSON)
    
    struct JSONBoolean (struct JSON, value bool)
    struct JSONString (struct JSON, value String)
    
    struct JSONNumber (struct JSON, value double)
    struct JSONArray (struct JSON, elements <*JSON> List)
    struct JSONObject (struct JSON, fields <JSONField> List)
    
    *JSONObject also has these convenience methods:
    func get(this *JSONObject, field String) *JSON
    func getBooleanOtherwise(this *JSONObject, field String, default_value bool) bool
    func getStringOtherwise(this *JSONObject, field String, default_value POD String) String
    func getNumberOtherwise(this *JSONObject, field String, default_value float) float
    func getNumberOtherwise(this *JSONObject, field String, default_value double) double

    AND ALSO ALL *JSON VALUES ARE toString-able
    func toString(this *JSON) String
    */

    if value1.isObject() {
        object *JSONObject = value1 as *JSONObject
        firstname String = object.getStringOtherwise("firstname", "")
        lastname String = object.getStringOtherwise("lastname", "")
        age int = object.getNumberOtherwise("age", 0.0) as int
        married bool = object.getBooleanOtherwise("married", false)
        print("Person named " + firstname + " " + lastname + " is " + age + " years old, and is " + (married ? "" : "not ") + "married")
    }

    if value2.isArray() {
        array *JSONArray = value2 as *JSONArray
        
        each item *JSON in array.elements {
            if item.isNumber() {
                number double = item as *JSONNumber.value
                print("Array item: " + toString(number))
            }
        }
    }
}

[ghost]

JSONFromFile returns null if the file doesn't exist

I did have a look at 2.7/JSON.adept. JSONFromFile calls JSONFileContents. Even if the file exists, JSONFileContents will return false if it failed to load the file to buffer. I'm new to Adept so I'm not good at reading Adept code, but I can't see anything wrong. Compiler bug is something shouldn't be omitted.

[ghost]

Can you fopen the file?

Yes. I can even print the file content with:

import 'sys/cstdio.adept'

func main void {
    f *FILE = fopen('data.json', 'r')
    
    if f == null {
        printf('Failed to open file\n')
    }
    
    c ubyte = fgetc(f); 
    while(c != EOF) { 
        printf('%c', c);
        c = fgetc(f);
    }
    
    defer fclose(f)
}

[ghost]

I've tested it on multiple platforms and it works when I've tested it

Did you test on Windows? The foreign functions look suspicious.

[ghost]

I think you might have to run it from command prompt because Windows doesn't have the correct working directory when you double click it if I remember correctly.

I compile and run the program using the same Windows Command Prompt, so, this is impossible.

[ghost]

Does the following work?

(This uses the where() function so that the file is relative to the path of the executable)

pragma default_stdlib '2.8' // In order to pin standard library version to 2.8

import basics
import where
import JSON

func main {
    value1 *JSON = JSONFromFile(where() + "data.json")
    if value1 == null {
        fprintf(stderr, "Failed to open data.json file\n")
        return
    }
    defer value1.destroyAndFree()

    value2 *JSON = JSON("[1, 2, 3, 4, 5]")
    if value2 == null {
        fprintf(stderr, "Failed to parse value2 data\n")
        return
    }
    defer value2.destroyAndFree()
    
    /*
    TO CHECK SPECIFIC KINDS:
    func isNull(this *JSON)    bool
    func isBoolean(this *JSON) bool
    func isNumber(this *JSON)  bool
    func isString(this *JSON)  bool
    func isArray(this *JSON)   bool
    func isObject(this *JSON)  bool
    
    AND THEN ACCESS THE CORRECT STRUCT
    struct JSON (kind JSONKind)
    struct JSONField (name String, value *JSON)
    
    struct JSONBoolean (struct JSON, value bool)
    struct JSONString (struct JSON, value String)
    
    struct JSONNumber (struct JSON, value double)
    struct JSONArray (struct JSON, elements <*JSON> List)
    struct JSONObject (struct JSON, fields <JSONField> List)
    
    *JSONObject also has these convenience methods:
    func get(this *JSONObject, field String) *JSON
    func getBooleanOtherwise(this *JSONObject, field String, default_value bool) bool
    func getStringOtherwise(this *JSONObject, field String, default_value POD String) String
    func getNumberOtherwise(this *JSONObject, field String, default_value float) float
    func getNumberOtherwise(this *JSONObject, field String, default_value double) double

    AND ALSO ALL *JSON VALUES ARE toString-able
    func toString(this *JSON) String
    */

    if value1.isObject() {
        object *JSONObject = value1 as *JSONObject
        firstname String = object.getStringOtherwise("firstname", "")
        lastname String = object.getStringOtherwise("lastname", "")
        age int = object.getNumberOtherwise("age", 0.0) as int
        married bool = object.getBooleanOtherwise("married", false)
        print("Person named " + firstname + " " + lastname + " is " + age + " years old, and is " + (married ? "" : "not ") + "married")
    }

    if value2.isArray() {
        array *JSONArray = value2 as *JSONArray
        
        each item *JSON in array.elements {
            if item.isNumber() {
                number double = item as *JSONNumber.value
                print("Array item: " + toString(number))
            }
        }
    }
}

No. Doesn't work. For some unknown reasons, it seems value1 is always null.

[IsaacShelton]

Okay that's very weird I'll look into it and see if I can reproduce the issue

[IsaacShelton]

Hopefully we can replace this terrible JSON api with something better, but for now I'll see if I can do a short term fix

[IsaacShelton]

The issue is now fixed in the latest version of AdeptImport.

A new nightly will also be released