How to solve the problem of incorrectly displaying default pictures in uniapp development

When developing using uniapp, we sometimes encounter the problem that the picture cannot be displayed or the default picture is incorrectly displayed. This kind of problem may bring bad experience to users, so it is also very important to solve this problem. This article will introduce several common solutions to help you solve the problem of incorrectly displaying default images in uniapp development.

1. Check whether the image path is correct
When developing using uniapp, the most common error is the wrong image path. First, we need to check whether the image path is correct. In uniapp, there are two types of paths: absolute paths and relative paths. When using relative paths, you need to pay attention to the relative position of the file level and the level where the image is located. We can use the browser's developer tools to check whether the image is loaded successfully in the Network. If loading fails, you should check whether the image path is correct.

2. Check whether the image file format is correct
If the image path is correct, but the image still displays the default image, then the format of the image may be incorrect. uniapp supports pictures in multiple formats, such as jpg, png, gif, etc. If the image format is incorrect, it may cause the image to not display properly. Therefore, we need to check whether the image is in the correct format.

3. Check whether the network is normal
If the above two methods cannot solve the problem, it may be caused by network problems. We need to check whether the network is normal. If there is a network failure, the image may not be loaded. We can check if there are any network errors in the console.

4. Use v-if to determine whether the picture exists
If the network is normal, then the picture itself may not exist. In uniapp, we can use the v-if instruction to determine whether the image exists. If the picture does not exist, the default picture is displayed. The following is a sample code:

<template>
  <img v-if="picExist" :src="picUrl">
  <img v-else src="defaultPicUrl">
</template>
<script>
export default {
  data() {
    return {
      picUrl: '/static/img/pic.jpg',
      defaultPicUrl: '/static/img/default-pic.jpg',
      picExist: true
    }
  },
  methods: {
    checkPicExist() {
      let _this = this
      let img = new Image()
      img.onload = function() {
        _this.picExist = true
      }
      img.onerror = function() {
        _this.picExist = false
      }
      img.src = _this.picUrl
    }
  },
  mounted() {
    this.checkPicExist()
  }
}
</script>

In the above code, we use a checkPicExist function to check whether the picture exists. If present, the correct image is displayed; if not present, the default image is displayed.

The above are several common solutions. Different problems require different methods to solve. I hope this article can help you solve the problem of incorrectly displaying default pictures in uniapp development.

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