api-console-assets/bower_components/multipart-payload-transformer/multipart-payload-transformer.html

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@license
Copyright 2016 The Advanced REST client authors <arc@mulesoft.com>
Licensed under the Apache License, Version 2.0 (the "License"); you may not
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the License at
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distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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the License.
-->
<link rel="import" href="../polymer/polymer.html">
<link rel="import" href="../fetch-polyfill/fetch-polyfill.html">
<link rel="import" href="../arc-polyfills/arc-polyfills.html">
<!--
An element that contains methods to transform FormData object into Multipart
message and ArrayBuffer

### Example
```
<multipart-payload-transformer form-data="[[formData]]"></multipart-payload-transformer>
```

@group Logic Elements
@element multipart-payload-transformer
-->
<script>
Polymer({
  is: 'multipart-payload-transformer',
  properties: {
    // A form data object to transform.
    formData: Object,
    /**
     * Latest generated boundary value for the multipart forms.
     * Each call to `generateMessage()` or `generatePreview()` will
     * generate new content type and therefore boundary value.
     */
    boundary: {
      type: String,
      notify: true
    },
    /**
     * Latest generated content-type value for the multipart forms.
     * Each call to `generateMessage()` or `generatePreview()` will
     * generate new content type value.
     */
    contentType: {
      type: String,
      notify: true
    }
  },
  /**
   * Generates an ArrayBuffer instance from the FormData object.
   *
   * @return {Promise} A resolved promise when produces ArrayBuffer.
   */
  generateMessage: function() {
    var request = new Request('/', {
      method: 'POST',
      body: this.formData
    });
    var ct = request.headers.get('content-type');
    this._processContentType(ct);
    if (!request.arrayBuffer) {
      return Promise.reject(new Error('Your browser do not support this method.'));
    }
    return request.arrayBuffer();
  },

  _processContentType: function(contentType) {
    this.set('contentType', contentType);
    this.fire('content-type-changed', {
      value: contentType
    });
    var match = contentType.match(/boundary=(.*)/);
    if (!match) {
      return;
    }
    var boundary = match[1];
    this.set('boundary', boundary);
    this.fire('multipart-boundary-changed', {
      value: boundary
    });
  },

  generatePreview: function() {
    if (!this.formData) {
      return Promise.reject(new Error('The FormData property is not set.'));
    }
    return this.generateMessage()
    .then(function(ab) {
      return this._previewFromBuffer(ab);
    }.bind(this));
  },

  _previewFromBuffer: function(buffer) {
    return this.arrayBufferToString(buffer);
  },
  /**
   * Convert ArrayBuffer to readable form
   * @param {ArrayBuffer} buff
   * @returns {String} Converted string
   */
  arrayBufferToString: function(buffer) {
    if (!!buffer.buffer) {
      // Not a ArrayBuffer, need and instance of AB
      // It can't just get buff.buffer because it will use original buffer if the buff is a slice
      // of it.
      var b = buffer.slice(0);
      buffer = b.buffer;
    }
    if ('TextDecoder' in window) {
      var decoder = new TextDecoder('utf-8');
      var view = new DataView(buffer);
      return decoder.decode(view);
    }
    var array = new Uint8Array(buffer);
    var str = '';
    for (var i = 0; i < array.length; ++i) {
      str += String.fromCharCode(array[i]);
    }
    return str;
  }
});
</script>