I'm attempting to read JSON from a configuration file using file.readAll(). I can open and perform the read, but can't figure out how to convert the ArrayBuffer to a string or ultimately I want to make use of the JSON in the file. Considering the file "foo.json" in my data folder: { "name" : "value" , "things" : [ ] } I'm reading it using the following code: function readConfig ( ) { var file = AppFramework . file ( AppFramework . userHomePath + "/ArcGIS/Runtime/Data/foo.json" ) ; if ( file . exists ) { if ( file . open ( File . OpenModeReadOnly ) ) { var data = file . readAll ( ) ; // get the json? file . close ( ) ; } } } but I can't seem to get the text or JSON from the binary data that readAll() returns. It looks like I could use a loop and readLine() which returns a string, then check for file.atEnd, but it seems like there must be a better way. Obviously I'm new on the QML/JS journey and would sure appreciate a push in the right direction. Thanks in advance!

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AppFramework.file.readAll()

Mike_Quetel

I'm attempting to read JSON from a configuration file using file.readAll(). I can open and perform the read, but can't figure out how to convert the ArrayBuffer to a string or ultimately I want to make use of the JSON in the file.

Considering the file "foo.json" in my data folder:

<SPAN class="punctuation token">{</SPAN>
	<SPAN class="string token">"name"</SPAN><SPAN class="punctuation token">:</SPAN> <SPAN class="string token">"value"</SPAN><SPAN class="punctuation token">,</SPAN>
	<SPAN class="string token">"things"</SPAN><SPAN class="punctuation token">:</SPAN> <SPAN class="punctuation token">[</SPAN><SPAN class="punctuation token">]</SPAN>
<SPAN class="punctuation token">}</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

I'm reading it using the following code:

    <SPAN class="keyword token">function</SPAN> <SPAN class="token function">readConfig</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
        <SPAN class="keyword token">var</SPAN> file <SPAN class="operator token">=</SPAN> AppFramework<SPAN class="punctuation token">.</SPAN><SPAN class="token function">file</SPAN><SPAN class="punctuation token">(</SPAN>AppFramework<SPAN class="punctuation token">.</SPAN>userHomePath <SPAN class="operator token">+</SPAN> <SPAN class="string token">"/ArcGIS/Runtime/Data/foo.json"</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
        <SPAN class="keyword token">if</SPAN> <SPAN class="punctuation token">(</SPAN>file<SPAN class="punctuation token">.</SPAN>exists<SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
            <SPAN class="keyword token">if</SPAN> <SPAN class="punctuation token">(</SPAN>file<SPAN class="punctuation token">.</SPAN><SPAN class="token function">open</SPAN><SPAN class="punctuation token">(</SPAN>File<SPAN class="punctuation token">.</SPAN>OpenModeReadOnly<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
                <SPAN class="keyword token">var</SPAN> data <SPAN class="operator token">=</SPAN> file<SPAN class="punctuation token">.</SPAN><SPAN class="token function">readAll</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
                <SPAN class="comment token">// get the json?</SPAN>
                file<SPAN class="punctuation token">.</SPAN><SPAN class="token function">close</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
            <SPAN class="punctuation token">}</SPAN>
        <SPAN class="punctuation token">}</SPAN>
    <SPAN class="punctuation token">}</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

but I can't seem to get the text or JSON from the binary data that readAll() returns. It looks like I could use a loop and readLine() which returns a string, then check for file.atEnd, but it seems like there must be a better way.

Obviously I'm new on the QML/JS journey and would sure appreciate a push in the right direction. Thanks in advance!

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Accepted answers

Anonymous User

Hi Mike

In the AppFramework of AppStudio there is a component called FileFolder which has methods to read/write json (and text) files which you could probably use here.

FileFolder QML Type | ArcGIS

e.g. something like:

const folder = AppFramework<SPAN class="" style="color: #999999; border: 0px; font-weight: inherit;">.</SPAN><SPAN class="" style="color: #d74444; border: 0px; font-weight: inherit;">fileFolder</SPAN><SPAN class="" style="color: #999999; border: 0px; font-weight: inherit;">(</SPAN>AppFramework<SPAN class="" style="color: #999999; border: 0px; font-weight: inherit;">.</SPAN>userHomePath <SPAN class="" style="color: #a67f59; background: rgba(255, 255, 255, 0.5); border: 0px; font-weight: inherit;">+</SPAN> <SPAN class="" style="color: #669900; border: 0px; font-weight: inherit;">"/ArcGIS/Runtime/Data"</SPAN><SPAN class="" style="color: #999999; border: 0px; font-weight: inherit;">)</SPAN><SPAN class="" style="color: #999999; border: 0px; font-weight: inherit;">;
const jsonData = folder.readJsonFile("foo.json")
console.log(JSON.stringify(jsonData))</SPAN>

All comments

Mike_Quetel

Thank you! Much simpler than my approach.

Anonymous User

Hi Mike

In the AppFramework of AppStudio there is a component called FileFolder which has methods to read/write json (and text) files which you could probably use here.

FileFolder QML Type | ArcGIS

e.g. something like:

const folder = AppFramework<SPAN class="" style="color: #999999; border: 0px; font-weight: inherit;">.</SPAN><SPAN class="" style="color: #d74444; border: 0px; font-weight: inherit;">fileFolder</SPAN><SPAN class="" style="color: #999999; border: 0px; font-weight: inherit;">(</SPAN>AppFramework<SPAN class="" style="color: #999999; border: 0px; font-weight: inherit;">.</SPAN>userHomePath <SPAN class="" style="color: #a67f59; background: rgba(255, 255, 255, 0.5); border: 0px; font-weight: inherit;">+</SPAN> <SPAN class="" style="color: #669900; border: 0px; font-weight: inherit;">"/ArcGIS/Runtime/Data"</SPAN><SPAN class="" style="color: #999999; border: 0px; font-weight: inherit;">)</SPAN><SPAN class="" style="color: #999999; border: 0px; font-weight: inherit;">;
const jsonData = folder.readJsonFile("foo.json")
console.log(JSON.stringify(jsonData))</SPAN>

Mike_Quetel

This code snippet works fine, but its seems silly/inefficient to have to loop through a file like this:

<SPAN class="keyword token">let</SPAN> data <SPAN class="operator token">=</SPAN> <SPAN class="string token">""</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">let</SPAN> file <SPAN class="operator token">=</SPAN> AppFramework<SPAN class="punctuation token">.</SPAN><SPAN class="token function">file</SPAN><SPAN class="punctuation token">(</SPAN>filePath<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">if</SPAN> <SPAN class="punctuation token">(</SPAN>file<SPAN class="punctuation token">.</SPAN>exists<SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
	<SPAN class="keyword token">if</SPAN> <SPAN class="punctuation token">(</SPAN>file<SPAN class="punctuation token">.</SPAN><SPAN class="token function">open</SPAN><SPAN class="punctuation token">(</SPAN>File<SPAN class="punctuation token">.</SPAN>OpenModeReadOnly<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
    	<SPAN class="keyword token">do</SPAN> <SPAN class="punctuation token">{</SPAN>
        	data <SPAN class="operator token">+</SPAN><SPAN class="operator token">=</SPAN> file<SPAN class="punctuation token">.</SPAN><SPAN class="token function">readLine</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
    	<SPAN class="punctuation token">}</SPAN> <SPAN class="keyword token">while</SPAN> <SPAN class="punctuation token">(</SPAN><SPAN class="operator token">!</SPAN>file<SPAN class="punctuation token">.</SPAN>atEnd<SPAN class="punctuation token">)</SPAN>
        file<SPAN class="punctuation token">.</SPAN><SPAN class="token function">close</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
        <SPAN class="keyword token">try</SPAN> <SPAN class="punctuation token">{</SPAN>
            <SPAN class="keyword token">let</SPAN> json <SPAN class="operator token">=</SPAN> JSON<SPAN class="punctuation token">.</SPAN><SPAN class="token function">parse</SPAN><SPAN class="punctuation token">(</SPAN>data<SPAN class="punctuation token">)</SPAN>
            <SPAN class="keyword token">return</SPAN> json<SPAN class="punctuation token">;</SPAN>
        <SPAN class="punctuation token">}</SPAN> <SPAN class="keyword token">catch</SPAN><SPAN class="punctuation token">(</SPAN>err<SPAN class="punctuation token">)</SPAN> <SPAN class="punctuation token">{</SPAN>
        	console<SPAN class="punctuation token">.</SPAN><SPAN class="token function">log</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="string token">"Failed to parse JSON, error returned '"</SPAN> <SPAN class="operator token">+</SPAN> err<SPAN class="punctuation token">.</SPAN>messsage <SPAN class="operator token">+</SPAN> <SPAN class="string token">"'"</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
        <SPAN class="punctuation token">}</SPAN>
    <SPAN class="punctuation token">}</SPAN> 
<SPAN class="punctuation token">}</SPAN>‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍
<SPAN class="keyword token">return</SPAN> <SPAN class="keyword token">null</SPAN><SPAN class="punctuation token">;</SPAN>‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

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