populateFromJSON

Recursively populates a passed associative or dynamic array with the contents of a JSONValue.

This is used where we want to store information on disk but keep it in memory without the overhead of dealing with JSONValues.

Note: This only works with JSONValues that conform to arrays and associative arrays, not such that mix element/value types.

@safe

void

populateFromJSON

(

)

(

ref T target

const JSONValue json

const bool lowercaseKeys = false

const bool lowercaseValues = false

)

if (

isMutable!T

)

Parameters

target T: Reference to target array or associative array to write to.
json JSONValue: Source JSONValue to sync the contents with.
lowercaseKeys bool: Whether or not to save string keys in lowercase.
lowercaseValues bool: Whether or not to save final string values in lowercase.

Throws

Exception if the passed JSONValue had unexpected types.

Examples

1 import std.json : JSONType, JSONValue;
2 
3 {
4     long[string] aa =
5     [
6         "abc" : 123,
7         "def" : 456,
8         "ghi" : 789,
9     ];
10 
11     JSONValue j = JSONValue(aa);
12     typeof(aa) fromJSON;
13 
14     foreach (immutable key, const value; j.objectNoRef)
15     {
16         fromJSON[key] = value.integer;
17     }
18 
19     assert(aa == fromJSON);  // not is
20 
21     auto aaCopy = aa.dup;
22 
23     aa["jlk"] = 12;
24     assert(aa != fromJSON);
25 
26     aa = typeof(aa).init;
27     populateFromJSON(aa, j);
28     assert(aa == aaCopy);
29 }
30 {
31     auto aa =
32     [
33         "abc" : true,
34         "def" : false,
35         "ghi" : true,
36     ];
37 
38     JSONValue j = JSONValue(aa);
39     typeof(aa) fromJSON;
40 
41     foreach (immutable key, const value; j.objectNoRef)
42     {
43         if (value.type == JSONType.true_) fromJSON[key] = true;
44         else if (value.type == JSONType.false_) fromJSON[key] = false;
45         else
46         {
47             assert(0);
48         }
49     }
50 
51     assert(aa == fromJSON);  // not is
52 
53     auto aaCopy = aa.dup;
54 
55     aa["jkl"] = false;
56     assert(aa != fromJSON);
57 
58     aa = typeof(aa).init;
59     populateFromJSON(aa, j);
60     assert(aa == aaCopy);
61 }
62 {
63     auto arr = [ "abc", "def", "ghi", "jkl" ];
64 
65     JSONValue j = JSONValue(arr);
66     typeof(arr) fromJSON;
67 
68     foreach (const value; j.arrayNoRef)
69     {
70         fromJSON ~= value.str;
71     }
72 
73     assert(arr == fromJSON);  // not is
74 
75     auto arrCopy = arr.dup;
76 
77     arr[0] = "no";
78     assert(arr != arrCopy);
79 
80     arr = [];
81     populateFromJSON(arr, j);
82     assert(arr == arrCopy);
83 }
84 {
85     auto aa =
86     [
87         "abc" : [ "def", "ghi", "jkl" ],
88         "def" : [ "MNO", "PQR", "STU" ],
89     ];
90 
91     JSONValue j = JSONValue(aa);
92     typeof(aa)fromJSON;
93 
94     foreach (immutable key, const arrJSON; j.objectNoRef)
95     {
96         foreach (const entry; arrJSON.arrayNoRef)
97         {
98             fromJSON[key] ~= entry.str;
99         }
100     }
101 
102     assert(aa == fromJSON);  // not is
103 
104     auto aaCopy = aa.dup;
105     aaCopy["abc"] = aa["abc"].dup;
106 
107     aa["abc"][0] = "no";
108     aa["ghi"] ~= "VWXYZ";
109     assert(aa != fromJSON);
110 
111     aa = typeof(aa).init;
112     populateFromJSON(aa, j);
113     assert(aa == aaCopy);
114 }
115 {
116     int[3] arr = [ 1, 2, 3 ];
117 
118     JSONValue j = JSONValue(arr);
119 
120     int[3] arr2;
121     arr2.populateFromJSON(j);
122     assert(arr2 == arr);
123 }

populateFromJSON

Parameters

Throws

Examples

Meta

Source