Need help to send component reference

[maitedev]

Hi, I am trying to use the react-to-print library in my application but without satisfactory results so far. I don't know how I should send the reference to the ReactToPrint component, I appreciate any suggestions. Grateful in advance.
Note: the component I want to print is the FormContent of type class .

    <Paper>
      <Grid container direction="column" spacing={1}>
        <Grid item xs={12}>
          <Grid container direction="row">
            <Grid item xs={6}>
              <FormTopLeft />
            </Grid>
            <Grid item xs={6}>
              <ReactToPrint
                trigger={() => (
                  <Tooltip title="Print">
                    <IconButton>
                      <PrintIcon />
                    </IconButton>
                  </Tooltip>
                )}
                content={() => this.componentRef}
              />
            </Grid>
          </Grid>
          <Divider/>
        </Grid>
        <Grid item xs={12}>
          <FormContent ref={el => (this.componentRef = el)} />
        </Grid>
      </Grid>
    </Paper>

[MatthewHerbst]

Hello. Your usage looks correct. Could you please explain what's not working? Are there any errors?

[maitedev]

Thank you very much for responding so quickly !! In console it shows me the following error when I click the print button:

index.js:1 For "react-to-print" to work only Class based components can be printed.

I don't understand why, because the component where ReactToPrint is mounted is of type class, just like FormContent.
I must be doing something wrong but I don't realize that.

Sometimes he shows me this other:
index.js:1 Warning: Function components cannot be given refs. Attempts to access this ref will fail. Did you mean to use React.forwardRef()?

[MatthewHerbst]

Is FormContent a class or functional component?

[maitedev]

Yes, is a class component, which I am importing into the MainForm component.

[MatthewHerbst]

Do you mind sharing the full code for FormContent and for the component that wraps ReactToPrint?

[maitedev]

MainForm: component that wraps ReactToPrint.

import React, { Component } from "react";
import { Grid, Paper, Divider, Tooltip, IconButton } from "@material-ui/core";
import PrintIcon from "@material-ui/icons/Print";
import FormContent from "./components/FormContent";
import FormTopLeft from "./components/FormTopLeft";
import ReactToPrint from "react-to-print";

class MainForm extends Component {
  render() {
    return (
      <Paper>
        <Grid container direction="column" spacing={1}>
          <Grid item xs={12}>
            <Grid container direction="row">
              <Grid item xs={6}>
                <FormTopLeft />
              </Grid>
              <Grid item xs={6}>
                <ReactToPrint
                  trigger={() => (
                    <Tooltip title="Print">
                      <IconButton>
                        <PrintIcon />
                      </IconButton>
                    </Tooltip>
                  )}
                  content={() => this.componentRef}
                />
              </Grid>
            </Grid>
            <Divider />
          </Grid>
          <Grid item xs={12}>
            <FormContent ref={(el) => (this.componentRef = el)} />
          </Grid>
        </Grid>
      </Paper>
    );
  }
}
export default MainForm;

import React, { Component, Fragment } from "react";
import { withRouter } from 'react-router-dom';
import { connect } from "react-redux";
import { Grid, TextField } from "@material-ui/core";
import * as globalVisibilityActions from "../../../../../../../store/actions/sync";
import * as currentObjectActions from "../../../../../../../store/actions/sync";
import * as apiCallActions from "../../../../../../../store/actions/async/apiCalls/general"

class FormContent extends Component {
  state = {
    max_capacity: 0,   
  }
  componentDidMount() {
    this.props.updateGlobalVisibilityViewType();
    this.setState({
      ...this.state,
      max_capacity: this.props.boxData.max_capacity,
    })
  };
  handleChange = event => {
    const targetField = event.target.name
    const targetValue = event.target.value
    this.props.updateCurrentObjectFieldsOnChange(targetField, targetValue);
  };
  render() {
    const { box_number } = this.props.boxData;
    const readOnly = this.props.isEditMode;
    const zone = this.props.boxData.zone ? this.props.boxData.zone : {}  
    return (
      <Fragment>
        <form>
          <Grid
            container
            direction="row"
            spacing={6}
            style={{ textAlign: "left" }}      
          >
            <Grid item xs={6}>
              <TextField
                inputProps={{
                  readOnly: Boolean(readOnly),
                  disabled: Boolean(readOnly),
                }}
                fullWidth
                name="box_number"
                type="number"
                label="Box number"
                value={box_number || ""}
                onChange={this.handleChange}
              />
            </Grid>
            <Grid item xs={6}>
              <TextField
                inputProps={{
                  readOnly: Boolean(true),
                  disabled: Boolean(true),
                }}
                fullWidth
                name="max_capacity"
                type="number"
                label="Max capacity"
                value={this.state.max_capacity || 0}
              />
            </Grid>
          </Grid>
        </form>
      </Fragment>
    );
  }
}

const mapStateToProps = state => {
  return {
    boxData: state.currentObject.currentObject,
    isEditMode: state.globalVisibility.isEditModeDisabled,  
  };
};

const mapDispatchToProps = dispatch => {
  const viewType = 'formType';
  return {
    updateGlobalVisibilityViewType: () => dispatch(globalVisibilityActions.updateGlobalVisibilityViewType(viewType)),
    updateCurrentObjectFieldsOnChange: (targetField, targetValue) => 
    dispatch(currentObjectActions.updateCurrentObjectFieldsOnChange(targetField, targetValue)),
};

export default withRouter(connect(mapStateToProps, mapDispatchToProps)(FormContent));

[MatthewHerbst]

Hmm. There are a few possible culprits. It's possible that withRouter returns a functional component instead of a class one. It's also possible that for some reason the Fragment is causing a problem. Could you try exporting the component without the router and/or changing the Fragment to a div?

[maitedev]

I made both changes, I used a div and not Fragment and I did without the withRouter library.
When the component mount, it shows me the following error in the console:
index.js:1 Warning: Function components cannot be given refs. Attempts to access this ref will fail. Did you mean to use
React.forwardRef()?

When clicking on the print button, the same error continues:
index.js: 1 For "react-to-print" to work only Class based components can be printed.

[MatthewHerbst]

Very strange. Do you mind creating a codesandbox or similar with a full example so I can play with the code?

[maitedev]

Today I prepare it.
I'm very sorry to be stealing your time.

[MatthewHerbst]

No problem at all, looking forward to solving the problem

[maitedev]

Hi Matthew, here is the link of the test I did in codesandbox: https://codesandbox.io/s/zen-nash-xgkvn?file=/src/App.js

The only difference it has with the FormContent component, which I have in my project, is the use of Redux.
I tried to comment "react-redux" in my project, and the print worked correctly.

[maitedev]

Hello, I wanted to know if the react-to-print library has any problem to work, if Redux is being used in the component that you want to print?

[MatthewHerbst]

Hi @maitedev not sure I follow? react-to-print uses no dependencies except for prop-types. It makes sense that connect from react-redux would be the problem. I think an easy solution would be to create a class component in the middle so that you can pass the class to ReactToPrint, and then the class will render the FormContent

[maitedev]

Thank you very much Matthew, with that intermediate class that you suggested to me, I solved the problem. Thank you!!!

https://codesandbox.io/s/interesting-cookies-k1bg9?file=/src/deliverySheet/ComponentToPrint.js

[MatthewHerbst]

Glad you got it working! In the future we'll be able to support functional components, but doing so will require a breaking change so I'm trying to delay it as long as is reasonable.

[zedtux]

Thank you for this, I was in the same boat as @maitedev !

Would be great to add something on the README.md in order to inform about the issue with Redux 🙏

[MatthewHerbst]

@zedtux done! #316

[zedtux]

Awesome, thank you @MatthewHerbst !