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Read preference (#635)
* Completing read preference example in cloud code section * Read preferences for get operation in rest guide * Read preference for queries on rest guide * Read preference for js sdk * Read preference for PHP queries * Improving text including 'argument'
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‎_includes/cloudcode/cloud-code.md‎

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@@ -381,6 +381,7 @@ Parse.Cloud.beforeFind('MyObject', (req) => {
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Parse.Cloud.beforeFind('MyObject2', (req) => {
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req.readPreference = 'SECONDARY_PREFERRED';
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req.subqueryReadPreference = 'SECONDARY';
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req.includeReadPreference = 'PRIMARY';
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});
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```

‎_includes/js/queries.md‎

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@@ -537,3 +537,15 @@ query.distinct("age")
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// There was an error.
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});
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```
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## Read Preference
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When using a MongoDB replica set, you can use the `query.readPreference(readPreference, includeReadPreference, subqueryReadPreference)` function to choose from which replica the objects will be retrieved. The `includeReadPreference` argument chooses from which replica the included pointers will be retrieved and the `subqueryReadPreference` argument chooses in which replica the subqueries will run. The possible values are `PRIMARY` (default), `PRIMARY_PREFERRED`, `SECONDARY`, `SECONDARY_PREFERRED`, or `NEAREST`. If the `includeReadPreference` argument is not passed, the same replica chosen for `readPreference` will be also used for the includes. The same rule applies for the `subqueryReadPreference` argument.
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```javascript
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query.readPreference(
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'SECONDARY',
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'SECONDARY_PREFERRED',
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'NEAREST'
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);
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```

‎_includes/php/queries.md‎

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echo monster->strength(); // Displays 200.
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echo monster->hasSuperHumanStrength(); // Displays true.
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```
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## Read Preference
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When using a MongoDB replica set, you can use the `$query->readPreference(readPreference, includeReadPreference, subqueryReadPreference)` function to choose from which replica the objects will be retrieved. The `includeReadPreference` argument chooses from which replica the included pointers will be retrieved and the `subqueryReadPreference` argument chooses in which replica the subqueries will run. The possible values are `PRIMARY` (default), `PRIMARY_PREFERRED`, `SECONDARY`, `SECONDARY_PREFERRED`, or `NEAREST`. If the `includeReadPreference` argument is not passed, the same replica chosen for `readPreference` will be also used for the includes. The same rule applies for the `subqueryReadPreference` argument.
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```javascript
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$query->readPreference(
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"SECONDARY",
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"SECONDARY_PREFERRED",
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"NEAREST"
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);
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```

‎_includes/rest/objects.md‎

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</code></pre>
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</div>
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When using a MongoDB replica set, you can use the `readPreference` option to choose from which replica the object will be retrieved. You can also use the `includeReadPreference` option to choose from which replica the included pointers will be retrieved. The possible values for both options are `PRIMARY` (default), `PRIMARY_PREFERRED`, `SECONDARY`, `SECONDARY_PREFERRED`, or `NEAREST`. If the `includeReadPreference` option is not set, the same replica chosen for `readPreference` will be also used for the includes.
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<div class="language-toggle">
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<pre><code class="bash">
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curl -X GET \
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-H "X-Parse-Application-Id: <span class="custom-parse-server-appid">${APPLICATION_ID}</span>" \
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-H "X-Parse-REST-API-Key: <span class="custom-parse-server-restapikey">${REST_API_KEY}</span>" \
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-G \
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--data-urlencode 'include=game' \
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--data-urlencode 'readPreference=SECONDARY' \
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--data-urlencode 'includeReadPreference=SECONDARY_PREFERRED' \
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<span class="custom-parse-server-protocol">https</span>://<span class="custom-parse-server-url">YOUR.PARSE-SERVER.HERE</span><span class="custom-parse-server-mount">/parse/</span>classes/GameScore/Ed1nuqPvcm
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</code></pre>
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<pre><code class="python">
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import json,httplib,urllib
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connection = httplib.HTTPSConnection('<span class="custom-parse-server-url">YOUR.PARSE-SERVER.HERE</span>', 443)
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params = urllib.urlencode({"include":"game","readPreference":"SECONDARY","includeReadPreference":"SECONDARY_PREFERRED"})
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connection.connect()
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connection.request('GET', '<span class="custom-parse-server-mount">/parse/</span>classes/GameScore/Ed1nuqPvcm?%s' % params, '', {
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"X-Parse-Application-Id": "<span class="custom-parse-server-appid">${APPLICATION_ID}</span>",
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"X-Parse-REST-API-Key": "<span class="custom-parse-server-restapikey">${REST_API_KEY}</span>"
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})
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result = json.loads(connection.getresponse().read())
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print result
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</code></pre>
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</div>
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## Updating Objects
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To change the data on an object that already exists, send a PUT request to the object URL. Any keys you don't specify will remain unchanged, so you can update just a subset of the object's data. For example, if we wanted to change the score field of our object:

‎_includes/rest/queries.md‎

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</div>
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You can also constraint by `limit`, `skip`, `sort`.
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## Read Preference
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When using a MongoDB replica set, you can use the `readPreference` option to choose from which replica the objects will be retrieved. You can also use the `includeReadPreference` option to choose from which replica the included pointers will be retrieved and the `subqueryReadPreference` option to choose in which replica the subqueries will run. The possible values these options are `PRIMARY` (default), `PRIMARY_PREFERRED`, `SECONDARY`, `SECONDARY_PREFERRED`, or `NEAREST`. If the `includeReadPreference` option is not set, the same replica chosen for `readPreference` will be also used for the includes. The same rule applies for the `subqueryReadPreference` option.
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<div class="language-toggle">
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<pre><code class="bash">
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curl -X GET \
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-H "X-Parse-Application-Id: <span class="custom-parse-server-appid">${APPLICATION_ID}</span>" \
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-H "X-Parse-REST-API-Key: <span class="custom-parse-server-restapikey">${REST_API_KEY}</span>" \
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-G \
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--data-urlencode 'where={"post":{"$inQuery":{"where":{"image":{"$exists":true}},"className":"Post"}}}' \
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--data-urlencode 'include=post' \
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--data-urlencode 'readPreference=SECONDARY' \
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--data-urlencode 'includeReadPreference=SECONDARY_PREFERRED' \
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--data-urlencode 'subqueryReadPreference=NEAREST' \
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<span class="custom-parse-server-protocol">https</span>://<span class="custom-parse-server-url">YOUR.PARSE-SERVER.HERE</span><span class="custom-parse-server-mount">/parse/</span>classes/Comment
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</code></pre>
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<pre><code class="python">
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import json,httplib,urllib
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connection = httplib.HTTPSConnection('<span class="custom-parse-server-url">YOUR.PARSE-SERVER.HERE</span>', 443)
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params = urllib.urlencode({
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"where":json.dumps({
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"post": {
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"$inQuery": {
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"where": {
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"image": {
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"$exists": True
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}
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},
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"className": "Post"
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}
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}
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}),
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"include":"post",
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"readPreference":"SECONDARY",
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"includeReadPreference":"SECONDARY_PREFERRED",
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"subqueryReadPreference":"NEAREST"
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})
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connection.connect()
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connection.request('GET', '<span class="custom-parse-server-mount">/parse/</span>classes/Comment?%s' % params, '', {
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"X-Parse-Application-Id": "<span class="custom-parse-server-appid">${APPLICATION_ID}</span>",
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"X-Parse-REST-API-Key": "<span class="custom-parse-server-restapikey">${REST_API_KEY}</span>"
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})
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result = json.loads(connection.getresponse().read())
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print result
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</code></pre>
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</div>

‎assets/js/bundle.js‎

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